| author | Christian Urban <christian.urban@kcl.ac.uk> |
| Tue, 17 Nov 2020 00:36:16 +0000 | |
| changeset 806 | 0d3bc1d0d987 |
| parent 778 | 3e5f5d19f514 |
| child 826 | b0352633bf48 |
| permissions | -rw-r--r-- |
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% !TEX program = xelatex |
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\documentclass[dvipsnames,14pt,t,xelatex,aspectratio=169,xcolor={table}]{beamer}
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\usepackage{../slides}
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\usepackage{../graphics}
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\usepackage{../langs}
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\usepackage{../data}
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\usepackage{tcolorbox}
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\newtcolorbox{mybox}{colback=red!5!white,colframe=red!75!black}
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\newtcolorbox{mybox2}[1]{colback=red!5!white,colframe=red!75!black,fonttitle=\bfseries,title=#1}
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\hfuzz=220pt |
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\lstset{language=Scala,
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style=mystyle, |
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numbersep=0pt, |
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numbers=none, |
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xleftmargin=0mm} |
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\newcommand{\bl}[1]{\textcolor{blue}{#1}}
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% beamer stuff |
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\renewcommand{\slidecaption}{CFL 01, King's College London}
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%% https://cs.rit.edu/~hh/teaching/_media/cc18/lectures/lect1/main.pdf |
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%% https://cs.rit.edu/~hh/teaching/_media/cc18/lectures/lect2/main.pdf |
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%% https://cs.rit.edu/~hh/teaching/_media/cc18/lectures/lect3/main.pdf |
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\begin{document}
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%\begin{frame}[t]
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%\begin{mybox}
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%A physical explanation the \emph{dynamic matrix}\\
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%lots of text |
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%\end{mybox}
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%\begin{mybox2}{Test}
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%A physical explanation the \emph{dynamic matrix}\\
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%lots of text |
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%\end{mybox2}
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%\begin{mybox3}{Test}
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%A physical explanation the \emph{dynamic matrix}\\
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%lots of text |
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%\end{mybox3}
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%\end{frame}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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\begin{frame}[t]
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\frametitle{%
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\begin{tabular}{@ {}c@ {}}
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\\[-3mm] |
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\LARGE Compilers and \\[-1mm] |
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\LARGE Formal Languages\\[-3mm] |
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\end{tabular}}
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\begin{center}
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%\includegraphics[scale=0.3]{pics/ante1.jpg}\hspace{5mm}
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%\includegraphics[scale=0.31]{pics/ante2.jpg}\\
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%\footnotesize\textcolor{gray}{Antikythera automaton, 100 BC (Archimedes?)}
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\end{center}
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\normalsize |
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\begin{center}
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\begin{tabular}{ll}
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Email: & christian.urban at kcl.ac.uk\\ |
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%Office Hours: & Thursdays 12 -- 14\\ |
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%Location: & N7.07 (North Wing, Bush House)\\ |
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Slides \& Progs: & KEATS\\ |
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\end{tabular}
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\end{center}
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\begin{center}
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\begin{tikzpicture}
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\node[drop shadow,fill=white,inner sep=0pt] |
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{\footnotesize\rowcolors{1}{capri!10}{white}
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\begin{tabular}{|p{4.8cm}|p{4.8cm}|}\hline
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\cellcolor{blue!50}
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1 Introduction, Languages & 6 While-Language \\ |
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2 Regular Expressions, Derivatives & 7 Compilation, JVM \\ |
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3 Automata, Regular Languages & 8 Compiling Functional Languages \\ |
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4 Lexing, Tokenising & 9 Optimisations \\ |
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5 Grammars, Parsing & 10 LLVM \\ \hline |
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\end{tabular}%
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}; |
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\end{tikzpicture}
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\end{center}
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\end{frame}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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\begin{frame}<1-12>[c]
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\frametitle{The Goal of this Module\ldots}
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\begin{center}
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\begin{tikzpicture}[scale=1,
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node/.style={
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rectangle,rounded corners=3mm, |
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very thick,draw=black!50,minimum height=18mm, minimum width=20mm, |
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top color=white,bottom color=black!20,drop shadow}] |
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\node at (3.05, 1.8) {\Large\bf \ldots{} you write a compiler};
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\node (0) at (-2.3,0) {};
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\node [above=5mm of 0] |
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{\makebox[0mm]{\footnotesize
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\begin{tabular}{@{}l@{}}input\\[-1mm]program\end{tabular}}};
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\node (A) at (0,0) [node] {};
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\node [below right] at (A.north west) {lexer};
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\node (B) at (3,0) [node] {};
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\node [below right=1mm] at (B.north west) {\mbox{}\hspace{-1mm}parser};
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\node (C) at (6,0) [node] {};
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\node [below right] at (C.north west) {\mbox{}\hspace{-1mm}code gen};
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\node (1) at (8.4,0) {};
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\node [above=5mm of 1] |
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{\makebox[0mm]{\footnotesize
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\begin{tabular}{@{}r@{}}binary\\[-1mm]code\end{tabular}}};
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\draw [->,line width=4mm] (0) -- (A); |
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\draw [->,line width=4mm] (A) -- (B); |
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\draw [->,line width=4mm] (B) -- (C); |
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\draw [->,line width=4mm] (C) -- (1); |
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\end{tikzpicture}
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\end{center}
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\only<2,3,4>{
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\begin{textblock}{1}(1,2.1)
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\begin{bubble}[9.8cm]
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\normalsize |
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lexer input: a string\smallskip\\ |
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\hspace{5mm}\code{"read(n);"}\medskip\\
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lexer output: a sequence of tokens\smallskip\\ |
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\hspace{5mm}\code{key(read) lpar id(n) rpar semi}
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\end{bubble}
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\end{textblock}}
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\only<3,4>{
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\begin{textblock}{1}(6,7.8)
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\begin{tabular}{c}
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\includegraphics[scale=0.2]{../pics/rosetta.jpg}\\[-2mm]
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\footnotesize lexing $\Rightarrow$ recognising words (Stone of Rosetta) |
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\end{tabular}
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\end{textblock}}
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\only<4>{
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\begin{textblock}{1}(0.5,12)\small
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\begin{tabular}{l@{}c@{}l}
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\pcode{if} & $\;\Rightarrow\;$ & keyword\\
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\pcode{iffoo} & $\;\Rightarrow\;$ & identifier\\
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\end{tabular}
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\end{textblock}}
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\only<6>{
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\begin{textblock}{1}(1,1.5)
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\begin{bubble}[8.5cm]
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\normalsize |
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parser input: a sequence of tokens\smallskip\\ |
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{\small\hspace{5mm}\code{key(read) lpar id(n) rpar semi}}\smallskip\\
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parser output: an abstract syntax tree\smallskip\\ |
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\footnotesize |
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\hspace{2cm}\begin{tikzpicture}
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\node {\code{read}}
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child {node {\code{lpar}}}
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child {node {\code{n}}}
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child {node {\code{rpar}}};
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\end{tikzpicture}
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\end{bubble}
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\end{textblock}}
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\only<8,9>{
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\begin{textblock}{1}(1,1.5)
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\begin{bubble}[4cm]
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\normalsize |
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code generation:\smallskip\\ |
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\hspace{5mm}\code{istore 2}\\
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\hspace{5mm}\code{iload 2}\\
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\hspace{5mm}\code{ldc 10}\\
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\hspace{5mm}\code{isub}\\
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\hspace{5mm}\code{ifeq Label2}\\
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\hspace{5mm}\code{iload 2}\\
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\hspace{5mm}\code{...}\\
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\end{bubble}
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\end{textblock}}
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\only<9>{
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\begin{textblock}{6}(8.4,7)
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\begin{bubble}[5cm]
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\mbox{\begin{tikzpicture}[scale=0.58,rounded corners=0mm]
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\begin{axis}[axis x line=bottom, axis y line=left, ylabel=secs,
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xlabel=n, |
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enlargelimits=0.05, |
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ybar interval=0.7, legend style=small] |
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\addplot file {interpreted2.data};
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\addplot file {compiled2.data};
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%\legend{interpreted, compiled}
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\end{axis}
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\end{tikzpicture}}
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\end{bubble}
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\end{textblock}}
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\only<10>{
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\begin{textblock}{6}(1,3)
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\begin{bubble}[11cm]
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Compiler explorers, e.g.: \url{https://gcc.godbolt.org} \;\video{https://youtu.be/ysaBmhMEyUg}
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\begin{tikzpicture}[]
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\node (0) at (-2.3,0) {\includegraphics[scale=0.3]{pics/csource.png}};
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\node (1) [right=35mm] at (0) {\includegraphics[scale=0.3]{pics/cassmbl.png}};
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\draw [->,line width=4mm, red] (0) -- (1); |
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\node (2) [below=20mm] at (0) {\LARGE\bf source};
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\node (3) [right=40mm] at (2) {\LARGE\bf binary};
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\draw [->,line width=1mm] (2) -- (3); |
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\end{tikzpicture}
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\end{bubble}
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\end{textblock}}
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\only<11>{
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\begin{textblock}{6}(1,3)
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\begin{bubble}[11cm]
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Compiler explorer for Java: \url{https://javap.yawk.at}
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\begin{tikzpicture}[]
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\node (0) at (-2.3,0) {\includegraphics[scale=0.4]{pics/jsource.png}};
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\node (1) [right=35mm] at (0) {\includegraphics[scale=0.4]{pics/jassmbl.png}};
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\draw [->,line width=4mm, red] (0) -- (1); |
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\node (2) [below=20mm] at (0) {\LARGE\bf source};
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\node (3) [right=40mm] at (2) {\LARGE\bf byte code};
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\draw [->,line width=1mm] (2) -- (3); |
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\end{tikzpicture}
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\end{bubble}
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\end{textblock}}
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\end{frame}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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\begin{frame}[t]
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\frametitle{Why Study Compilers?}
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John Regehr {\small(Univ.~Utah, LLVM compiler hacker)}
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\here{https://blog.regehr.org/archives/1419}
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\smallskip\\ |
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\begin{bubble}[10.5cm]
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\bf ``\ldots{}It’s effectively a perpetual
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employment act for solid compiler hackers.'' |
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\end{bubble}
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\onslide<1->{
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\only<2>{
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\begin{itemize}
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\item {\bf Hardware is getting weirder
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rather than getting clocked faster.} |
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\begin{itemize}
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\item[] ``Almost all processors are multicores nowadays and it looks |
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like there is increasing asymmetry in resources across cores. |
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Processors come with vector units, crypto accelerators etc. We have |
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DSPs, GPUs, ARM big.little, and Xeon Phi. This is only scratching the |
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surface.'' |
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\end{itemize}
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\end{itemize}}
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\only<3>{
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\begin{itemize}
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\item {\bf We’re getting tired of low-level languages and
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their associated security disasters.} |
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\begin{itemize}
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\item [] ``We want to write new code, to whatever extent possible, in |
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safer, higher-level languages. Compilers are caught right in the |
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middle of these opposing trends: one of their main jobs is to help |
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bridge the large and growing gap between increasingly high-level |
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languages and increasingly wacky platforms.'' |
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\end{itemize}
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\end{itemize}}}
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\end{frame}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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\begin{frame}[c]
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\frametitle{Why Bother with Compilers?}
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\textbf{Boeing 777's}: First flight in 1994. They want to achieve
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triple redundancy for potential hardware faults. |
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\here{http://www.citemaster.net/get/db3a81c6-548e-11e5-9d2e-00163e009cc7/R8.pdf}\bigskip
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They compile 1 Ada program to\medskip |
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\begin{itemize}
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\item Intel 80486 |
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\item Motorola 68040 (old Macintosh's) |
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\item AMD 29050 (RISC chips used often in laser printers) |
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\end{itemize}\medskip\medskip
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using 3 independent compilers.\bigskip\pause |
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\small Airbus uses C and static analysers. Recently started using CompCert. |
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\only<1->{%
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\begin{textblock}{6}(8,4.5)
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\includegraphics[scale=0.28]{../pics/777.png}
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\end{textblock}}
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\end{frame}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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\begin{frame}[c]
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\frametitle{What Do Compilers Do?}
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Remember BF*** from PEP? |
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\begin{center}
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\begin{tabular}{rcl}
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\bl{\texttt{>}} & $\Rightarrow$ & move one cell right\\
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\bl{\texttt{<}} & $\Rightarrow$ & move one cell left\\
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\bl{\texttt{+}} & $\Rightarrow$ & increase cell by one\\
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\bl{\texttt{-}} & $\Rightarrow$ & decrease cell by one\\
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\bl{\texttt{.}} & $\Rightarrow$ & print current cell\\
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\bl{\texttt{,}} & $\Rightarrow$ & input current cell\\
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\bl{\texttt{[}} & $\Rightarrow$ & loop begin\\
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\bl{\texttt{]}} & $\Rightarrow$ & loop end\medskip\\
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& $\Rightarrow$ & everything else is a comment\\ |
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\end{tabular}
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|
342 |
\end{center}
|
|
343 |
||
344 |
\end{frame}
|
|
345 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
346 |
||
347 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
348 |
\begin{frame}[c]
|
|
349 |
\frametitle{A ``Compiler'' for BF*** to C}
|
|
350 |
||
351 |
\begin{center}
|
|
352 |
\begin{tabular}{rcl}
|
|
353 |
\bl{\texttt{>}} & $\Rightarrow$ & \texttt{ptr++}\\
|
|
354 |
\bl{\texttt{<}} & $\Rightarrow$ & \texttt{ptr--}\\
|
|
355 |
\bl{\texttt{+}} & $\Rightarrow$ & \texttt{(*ptr)++}\\
|
|
356 |
\bl{\texttt{-}} & $\Rightarrow$ & \texttt{(*ptr)--}\\
|
|
357 |
\bl{\texttt{.}} & $\Rightarrow$ & \texttt{putchar(*ptr)}\\
|
|
358 |
\bl{\texttt{,}} & $\Rightarrow$ & \texttt{*ptr = getchar()}\\
|
|
359 |
\bl{\texttt{[}} & $\Rightarrow$ & \texttt{while(*ptr)\{}\\
|
|
360 |
\bl{\texttt{]}} & $\Rightarrow$ & \texttt{\}}\medskip\\
|
|
361 |
& $\Rightarrow$ & ignore everything else\\ |
|
362 |
\end{tabular}
|
|
363 |
\end{center}\bigskip
|
|
364 |
||
365 |
\texttt{char field[30000]\\ char *ptr = \&field[15000]}
|
|
366 |
||
367 |
\end{frame}
|
|
368 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
369 |
||
370 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
371 |
\begin{frame}[c]
|
|
| 757 | 372 |
\frametitle{Another~``Compiler''~for~BF~to~C}
|
| 756 | 373 |
|
374 |
\begin{center}
|
|
375 |
\begin{tabular}{rcl}
|
|
376 |
\bl{\texttt{>\ldots>}} & $\Rightarrow$ & \texttt{ptr += n}\\
|
|
377 |
\bl{\texttt{<\ldots<}} & $\Rightarrow$ & \texttt{ptr -= n}\\
|
|
378 |
\bl{\texttt{+\ldots+}} & $\Rightarrow$ & \texttt{(*ptr) += n}\\
|
|
379 |
\bl{\texttt{-\ldots-}} & $\Rightarrow$ & \texttt{(*ptr) -= n}\\
|
|
380 |
\bl{\texttt{.}} & $\Rightarrow$ & \texttt{putchar(*ptr)}\\
|
|
381 |
\bl{\texttt{,}} & $\Rightarrow$ & \texttt{*ptr = getchar()}\\
|
|
382 |
\bl{\texttt{[}} & $\Rightarrow$ & \texttt{while(*ptr)\{}\\
|
|
383 |
\bl{\texttt{]}} & $\Rightarrow$ & \texttt{\}}\medskip\\
|
|
384 |
& $\Rightarrow$ & ignore everything else\\ |
|
385 |
\end{tabular}
|
|
386 |
\end{center}\bigskip
|
|
387 |
||
388 |
\texttt{char field[30000]\\ char *ptr = \&field[15000]}
|
|
389 |
||
390 |
\end{frame}
|
|
391 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 757 | 392 |
|
| 756 | 393 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
394 |
\begin{frame}[t]
|
|
395 |
\frametitle{A Brief Compiler History}
|
|
396 |
||
397 |
\bigskip |
|
398 |
\begin{itemize}
|
|
399 |
\item Turing Machines, 1936 (a tape as memory) |
|
400 |
\item Regular Expressions, 1956\\ |
|
401 |
\item The first compiler for COBOL, 1957\\ (Grace Hopper)\medskip |
|
402 |
\item But surprisingly research papers are still published nowadays\\ |
|
403 |
\item ``Parsing: The Solved Problem That Isn't'' |
|
404 |
\here{https://tratt.net/laurie/blog/entries/parsing_the_solved_problem_that_isnt.html}
|
|
405 |
\end{itemize}
|
|
406 |
||
407 |
||
408 |
\begin{textblock}{8.5}(5,7.6)
|
|
409 |
\begin{flushright}
|
|
410 |
\includegraphics[scale=0.3]{pics/hopper.jpg}\\
|
|
411 |
\footnotesize\textcolor{gray}{Grace Hopper}\smallskip\\
|
|
412 |
||
413 |
{\small\textcolor{gray}{(she made it to David Letterman's Tonight Show
|
|
414 |
\here{https://youtu.be/3N_ywhx6_K0?t=31})}}
|
|
415 |
\end{flushright}
|
|
416 |
\end{textblock}
|
|
417 |
||
418 |
\end{frame}
|
|
419 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
420 |
||
421 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
422 |
\begin{frame}[c]
|
|
| 757 | 423 |
\frametitle{Some Housekeeping}
|
424 |
||
425 |
\textbf{Exams will be online:}\bigskip
|
|
426 |
||
427 |
\begin{itemize}
|
|
428 |
\item final exam in January (30\%) |
|
429 |
\item mid-term shortly after Reading Week (10\%)\bigskip |
|
430 |
||
431 |
\item weekly engagement (10\%) |
|
432 |
\end{itemize}\bigskip\bigskip\pause
|
|
433 |
||
434 |
||
435 |
\textbf{Weekly Homework (optional):}
|
|
436 |
\begin{itemize}
|
|
437 |
\item uploaded on KEATS, send answers via email, responded individually |
|
438 |
\item \alert{\bf all} questions in the exam and mid-term will be from the HW!!
|
|
439 |
\end{itemize}
|
|
440 |
||
441 |
\end{frame}
|
|
442 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
443 |
||
444 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
445 |
\begin{frame}[c]
|
|
446 |
\frametitle{Some Housekeeping}
|
|
447 |
||
448 |
\textbf{Coursework (5 accounting for 45\%):}\bigskip
|
|
449 |
||
450 |
\begin{itemize}
|
|
451 |
\item matcher (5\%) |
|
452 |
\item lexer (8\%) |
|
453 |
\item parser / interpreter (10\%) |
|
454 |
\item JVM compiler (10\%) |
|
455 |
\item LLVM compiler (12\%) |
|
456 |
\end{itemize}\bigskip\pause
|
|
457 |
||
458 |
you can use any programming language you like (Haskell, Rust)\\\pause |
|
459 |
you can use any code I showed you and uploaded to KEATS\ldots\textbf{BUT NOTHING ELSE!}\pause
|
|
460 |
||
461 |
\end{frame}
|
|
462 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
463 |
||
464 |
||
465 |
||
466 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
467 |
\begin{frame}[c]
|
|
468 |
\frametitle{Lectures 1 - 5}
|
|
469 |
||
470 |
transforming strings into structured data\\[10mm] |
|
471 |
||
472 |
{\LARGE\bf Lexing} {\hfill{}based on regular expressions}\medskip\\
|
|
473 |
\hspace{5mm}(recognising ``words'')\\[6mm]
|
|
474 |
||
475 |
{\LARGE\bf Parsing}\medskip\\
|
|
476 |
\hspace{5mm}(recognising ``sentences'')
|
|
477 |
||
478 |
\begin{textblock}{1}(10,9.1)
|
|
479 |
\begin{tabular}{c}
|
|
480 |
\includegraphics[scale=0.1]{../pics/rosetta.jpg}\\[-2mm]
|
|
481 |
\footnotesize Stone of Rosetta |
|
482 |
\end{tabular}
|
|
483 |
\end{textblock}
|
|
484 |
||
485 |
\end{frame}
|
|
486 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
487 |
||
488 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
489 |
\begin{frame}[c]
|
|
| 756 | 490 |
\frametitle{Lectures 1 - 5}
|
491 |
||
492 |
transforming strings into structured data\\[10mm] |
|
493 |
||
494 |
{\LARGE\bf Lexing} {\hfill{}based on regular expressions}\medskip\\
|
|
495 |
\hspace{5mm}(recognising ``words'')\\[6mm]
|
|
496 |
||
497 |
{\LARGE\bf Parsing}\medskip\\
|
|
498 |
\hspace{5mm}(recognising ``sentences'')
|
|
499 |
||
500 |
\begin{textblock}{1}(10,9.1)
|
|
501 |
\begin{tabular}{c}
|
|
502 |
\includegraphics[scale=0.1]{../pics/rosetta.jpg}\\[-2mm]
|
|
503 |
\footnotesize Stone of Rosetta |
|
504 |
\end{tabular}
|
|
505 |
\end{textblock}
|
|
506 |
||
507 |
\end{frame}
|
|
508 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
509 |
||
510 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
511 |
\begin{frame}[c]
|
|
512 |
\frametitle{Lectures 5 - 10}
|
|
513 |
||
514 |
code generation for a small imperative and a small functional language\\[10mm] |
|
515 |
||
516 |
{\LARGE\bf Interpreters}\medskip\\
|
|
517 |
\hspace{5mm}(directly runs a program)\\[6mm]
|
|
518 |
||
519 |
{\LARGE\bf Compilers}\medskip\\
|
|
520 |
\hspace{5mm}(generate JVM code and LLVM-IR code)
|
|
521 |
||
522 |
\begin{textblock}{1}(8.8,8.1)
|
|
523 |
\begin{tabular}{c@{}c}
|
|
524 |
\includegraphics[scale=0.4]{../pics/javaduke.png} &
|
|
525 |
\includegraphics[scale=0.23]{../pics/llvmlogo.png}
|
|
526 |
\end{tabular}
|
|
527 |
\end{textblock}
|
|
528 |
||
529 |
\end{frame}
|
|
| 757 | 530 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 756 | 531 |
|
532 |
||
533 |
||
534 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
535 |
\begin{frame}[t]
|
|
| 757 | 536 |
\frametitle{Familiar Regular Expresssions}
|
| 756 | 537 |
\small |
538 |
\begin{center}
|
|
539 |
\texttt{[a-z0-9\_$\backslash{}$.-]+ @ [a-z0-9$\backslash{}$.-]+ . [a-z$\backslash{}$.]\{2,6\}}
|
|
540 |
\end{center}\smallskip
|
|
541 |
||
542 |
\begin{center}
|
|
543 |
\begin{tabular}{@{}lp{8.5cm}@{}}
|
|
544 |
\pcode{re*} & matches 0 or more times\\
|
|
545 |
\pcode{re+} & matches 1 or more times\\
|
|
546 |
\pcode{re?} & matches 0 or 1 times\\
|
|
547 |
\pcode{re\{n\}} & matches exactly \pcode{n} number of times\\
|
|
548 |
\pcode{re\{n,m\}} & matches at least \pcode{n} and at most {\tt m} times\\
|
|
549 |
\pcode{[...]} & matches any single character inside the brackets\\
|
|
550 |
\pcode{[^...]} & matches any single character not inside the
|
|
551 |
brackets\\ |
|
552 |
\pcode{a-z A-Z} & character ranges\\
|
|
553 |
\pcode{\\d} & matches digits; equivalent to \pcode{[0-9]}\\
|
|
554 |
\pcode{.} & matches every character except newline\\
|
|
555 |
\pcode{(re)} & groups regular expressions and remembers
|
|
556 |
the matched text |
|
557 |
\end{tabular}
|
|
558 |
\end{center}
|
|
559 |
||
| 757 | 560 |
\end{frame}
|
561 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
562 |
||
563 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
564 |
\begin{frame}[c]
|
|
565 |
\frametitle{Some ``innocent'' examples}
|
|
566 |
||
567 |
Let's try two examples |
|
568 |
||
569 |
\begin{center}
|
|
570 |
\bl{\texttt{(a*)*b}}
|
|
571 |
\hspace{2cm}
|
|
572 |
\bl{\texttt{[a?]\{n\}[a]\{n\}}}
|
|
573 |
\end{center}\bigskip\pause
|
|
574 |
||
575 |
and match them with strings of the form |
|
576 |
||
577 |
\begin{center}
|
|
578 |
\bl{\texttt{a}},
|
|
579 |
\bl{\texttt{aa}},
|
|
580 |
\bl{\texttt{aaa}},
|
|
581 |
\bl{\texttt{aaaa}},
|
|
582 |
\bl{\texttt{aaaaa}},
|
|
583 |
\bl{$\underbrace{\texttt{a}...\texttt{a}}_n$}
|
|
584 |
\end{center}
|
|
| 756 | 585 |
|
586 |
\end{frame}
|
|
587 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
588 |
||
| 631 | 589 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
590 |
\begin{frame}[c]
|
| 745 | 591 |
\frametitle{Why Bother with Regexes?}
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
592 |
|
| 745 | 593 |
\begin{columns}[t,onlytextwidth]
|
594 |
\begin{column}{1.8cm}
|
|
595 |
\mbox{}
|
|
596 |
\end{column}
|
|
597 |
\begin{column}{.5\textwidth}
|
|
598 |
\small{}Ruby, Python, Java 8\medskip\\
|
|
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
599 |
\begin{tikzpicture}\footnotesize
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
600 |
\begin{axis}[
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
601 |
xlabel={$n$},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
602 |
x label style={at={(1.05,0.0)}},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
603 |
ylabel={time in secs},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
604 |
enlargelimits=false, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
605 |
xtick={0,5,...,30},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
606 |
xmax=33, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
607 |
ymax=35, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
608 |
ytick={0,5,...,30},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
609 |
scaled ticks=false, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
610 |
axis lines=left, |
| 745 | 611 |
width=\textwidth, |
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
612 |
height=4cm, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
613 |
legend entries={Python,Ruby},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
614 |
legend pos=north west, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
615 |
legend cell align=left] |
| 559 | 616 |
\addplot[blue,mark=*, mark options={fill=white}] table {re-python.data};
|
617 |
\addplot[brown,mark=triangle*, mark options={fill=white}] table {re-ruby.data};
|
|
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
618 |
\end{axis}
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
619 |
\end{tikzpicture}
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
620 |
\begin{tikzpicture}\footnotesize
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
621 |
\begin{axis}[
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
622 |
xlabel={$n$},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
623 |
x label style={at={(1.05,0.0)}},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
624 |
ylabel={time in secs},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
625 |
enlargelimits=false, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
626 |
xtick={0,5,...,30},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
627 |
xmax=33, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
628 |
ymax=35, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
629 |
ytick={0,5,...,30},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
630 |
scaled ticks=false, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
631 |
axis lines=left, |
| 745 | 632 |
width=\textwidth, |
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
633 |
height=4cm, |
| 767 | 634 |
legend entries={Python, Java 8, JavaScript, Swift},
|
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
635 |
legend pos=north west, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
636 |
legend cell align=left] |
| 559 | 637 |
\addplot[blue,mark=*, mark options={fill=white}] table {re-python2.data};
|
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
638 |
\addplot[cyan,mark=*, mark options={fill=white}] table {re-java.data};
|
| 631 | 639 |
\addplot[red,mark=*, mark options={fill=white}] table {re-js.data};
|
| 767 | 640 |
\addplot[magenta,mark=*, mark options={fill=white}] table {re-swift.data};
|
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
641 |
\end{axis}
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
642 |
\end{tikzpicture}
|
| 745 | 643 |
% |
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
644 |
\end{column}
|
| 745 | 645 |
\begin{column}{.5\textwidth}
|
646 |
\small{}Us (after next lecture)\medskip\\
|
|
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
647 |
\begin{tikzpicture}\footnotesize
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
648 |
\begin{axis}[
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
649 |
xlabel={$n$},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
650 |
x label style={at={(1.07,0.0)}},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
651 |
ylabel={time in secs},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
652 |
enlargelimits=false, |
|
442
84d6714840c9
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
437
diff
changeset
|
653 |
xtick={0,5000,...,10000},
|
|
84d6714840c9
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
437
diff
changeset
|
654 |
xmax=11000, |
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
655 |
ymax=35, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
656 |
ytick={0,5,...,30},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
657 |
scaled ticks=false, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
658 |
axis lines=left, |
| 745 | 659 |
width=\textwidth, |
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
660 |
height=4cm] |
|
437
fe387fcbf2ee
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
428
diff
changeset
|
661 |
\addplot[green,mark=square*,mark options={fill=white}] table {re2.data};
|
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
662 |
\addplot[black,mark=square*,mark options={fill=white}] table {re3.data};
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
663 |
\end{axis}
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
664 |
\end{tikzpicture}
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
665 |
\begin{tikzpicture}\footnotesize
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
666 |
\begin{axis}[
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
667 |
xlabel={$n$},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
668 |
x label style={at={(1.07,0.0)}},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
669 |
ylabel={time in secs},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
670 |
enlargelimits=false, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
671 |
ymax=35, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
672 |
ytick={0,5,...,30},
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
673 |
scaled ticks=false, |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
674 |
axis lines=left, |
| 745 | 675 |
width=\textwidth, |
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
676 |
height=4cm] |
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
677 |
\addplot[black,mark=square*,mark options={fill=white}] table {re3a.data};
|
|
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
678 |
\end{axis}
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
679 |
\end{tikzpicture}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
680 |
\end{column}
|
| 745 | 681 |
\end{columns}
|
682 |
\medskip |
|
683 |
||
684 |
\begin{textblock}{3}(-0.1,3.3)
|
|
685 |
\small\hfill\bl{\texttt{[a?]\{n\}[a]\{n\}}}:
|
|
686 |
\end{textblock}
|
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
687 |
|
| 745 | 688 |
\begin{textblock}{3}(-0.1,8.7)
|
689 |
\small\hfill\bl{\texttt{(a*)*b}}:
|
|
690 |
\end{textblock}
|
|
691 |
||
692 |
\begin{textblock}{3}(0.3,13)
|
|
693 |
\small{}matching with strings
|
|
694 |
\bl{$\underbrace{\texttt{a}...\texttt{a}}_n$}
|
|
695 |
\end{textblock}
|
|
696 |
||
| 510 | 697 |
\end{frame}
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
698 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 631 | 699 |
|
700 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
701 |
\begin{frame}[c,fragile]
|
|
702 |
\frametitle{Incidents}
|
|
703 |
||
704 |
\begin{itemize}
|
|
705 |
\item a global outage on 2 July 2019 at \textbf{Cloudflare}
|
|
706 |
(first one for six years)\medskip |
|
707 |
||
708 |
\begin{center}\small\color{blue}
|
|
709 |
\begin{verbatim}
|
|
710 |
(?:(?:\"|'|\]|\}|\\|\d|(?:nan|infinity|true|false| |
|
711 |
null|undefined|symbol|math)|\`|\-|\+)+[)]*;?((?:\s |
|
712 |
|-|~|!|{}|\|\||\+)*.*(?:.*=.*)))
|
|
713 |
\end{verbatim}
|
|
714 |
\end{center}\bigskip\bigskip\bigskip\bigskip\bigskip\bigskip\bigskip
|
|
715 |
||
716 |
\item on 20 July 2016 the \textbf{Stack Exchange} webpage went down
|
|
| 745 | 717 |
because of an evil regular expression |
718 |
\here{https://stackstatus.net/post/147710624694/outage-postmortem-july-20-2016}
|
|
| 631 | 719 |
\end{itemize}
|
720 |
||
| 745 | 721 |
\begin{textblock}{6}(6,7.6)
|
| 728 | 722 |
\includegraphics[scale=0.14]{../pics/cloudflare.png}\\
|
| 631 | 723 |
\footnotesize |
| 745 | 724 |
It serves more web traffic than Twitter, Amazon, Apple, |
725 |
Instagram, Bing \& Wikipedia combined. |
|
726 |
\here{https://blog.cloudflare.com/details-of-the-cloudflare-outage-on-july-2-2019/}
|
|
| 631 | 727 |
\end{textblock}
|
728 |
||
729 |
\end{frame}
|
|
730 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
731 |
||
| 560 | 732 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
733 |
\begin{frame}[c]
|
|
734 |
\frametitle{Evil Regular Expressions}
|
|
735 |
||
736 |
\begin{itemize}
|
|
737 |
\item \alert{R}egular \alert{e}xpression \alert{D}enial \alert{o}f \alert{S}ervice (ReDoS)\medskip
|
|
| 745 | 738 |
\item Some evil regular expressions:\medskip |
| 560 | 739 |
\begin{itemize}
|
| 745 | 740 |
\item \bl{\texttt{[a?]\{n\}\;[a]\{n\}}}
|
741 |
\item \bl{\texttt{(a*)*\;b}}
|
|
742 |
\item \bl{\texttt{([a-z]+)*}}
|
|
743 |
\item \bl{\texttt{(a + aa)*}}
|
|
744 |
\item \bl{\texttt{(a + a?)*}}
|
|
| 560 | 745 |
\end{itemize}
|
746 |
||
747 |
\item sometimes also called \alert{catastrophic backtracking}
|
|
748 |
\item this is a problem for \alert{N}etwork \alert{I}ntrusion
|
|
| 631 | 749 |
\alert{D}etection systems, Cloudflare, StackExchange, Atom editor
|
| 560 | 750 |
\item \url{https://vimeo.com/112065252}
|
751 |
\end{itemize}
|
|
752 |
||
753 |
\end{frame}
|
|
754 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
755 |
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
756 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
757 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 631 | 758 |
%\begin{frame}[c]
|
759 |
%\frametitle{Today}
|
|
760 |
% |
|
761 |
%\begin{itemize}
|
|
762 |
%\item While the ultimate goal is to implement a small compiler for the JVM |
|
763 |
% \ldots\bigskip |
|
764 |
%\end{itemize}
|
|
765 |
% |
|
766 |
%Let's start with: |
|
767 |
% |
|
768 |
%\begin{itemize}
|
|
769 |
%\item a web-crawler |
|
770 |
%\item an email harvester |
|
| 559 | 771 |
%\item \textcolor{gray}{(a web-scraper)}
|
| 631 | 772 |
%\end{itemize}
|
773 |
% |
|
774 |
%\end{frame}
|
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
775 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 0 | 776 |
|
| 2 | 777 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 631 | 778 |
%\begin{frame}[t]
|
779 |
%\frametitle{A Web-Crawler}
|
|
780 |
% |
|
781 |
%\mbox{}\\[10mm]
|
|
782 |
% |
|
783 |
%\begin{enumerate}
|
|
784 |
%\item given an URL, read the corresponding webpage |
|
785 |
%\item extract all links from it |
|
786 |
%\item call the web-crawler again for all these links |
|
787 |
%\end{enumerate}
|
|
788 |
% |
|
789 |
%\end{frame}
|
|
| 2 | 790 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
791 |
||
792 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 631 | 793 |
%\begin{frame}[t]
|
794 |
%\frametitle{A Web-Crawler}
|
|
795 |
% |
|
796 |
%\mbox{}\\[10mm]
|
|
797 |
% |
|
798 |
% |
|
799 |
%\begin{enumerate}
|
|
800 |
%\item given an URL, read the corresponding webpage |
|
801 |
%\item if not possible print, out a problem |
|
802 |
%\item if possible, extract all links from it |
|
803 |
%\item call the web-crawler again for all these links |
|
804 |
%\end{enumerate}\bigskip\pause
|
|
805 |
% |
|
806 |
%\small (we need a bound for the number of recursive calls) |
|
807 |
% |
|
808 |
%\small (the purpose is to check all links on my own webpage) |
|
809 |
%\end{frame}
|
|
| 2 | 810 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
811 |
||
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
812 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
813 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 631 | 814 |
%\begin{frame}[c]
|
815 |
% |
|
816 |
%\begin{textblock}{1}(2,5)
|
|
817 |
%\begin{tabular}{c}
|
|
818 |
%\includegraphics[scale=0.15]{pics/servers.png}\\[-2mm]
|
|
819 |
%\small Server |
|
820 |
%\end{tabular}
|
|
821 |
%\end{textblock}
|
|
822 |
% |
|
823 |
%\begin{textblock}{1}(5.6,4)
|
|
824 |
% \begin{tikzpicture}[scale=1.1]
|
|
825 |
% \draw[white] (0,1) node (X) {};
|
|
826 |
% \draw[white] (2,1) node (Y) {};
|
|
827 |
% \draw[white] (0,0) node (X1) {};
|
|
828 |
% \draw[white] (2,0) node (Y1) {};
|
|
829 |
% \draw[white] (0,-1) node (X2) {};
|
|
830 |
% \draw[white] (2,-1) node (Y2) {};
|
|
831 |
% \draw[red, <-, line width = 2mm] (X) -- (Y); |
|
832 |
% \node [inner sep=5pt,label=above:\textcolor{black}{GET request}] at ($ (X)!.5!(Y) $) {};
|
|
833 |
% \draw[red, ->, line width = 2mm] (X1) -- (Y1); |
|
834 |
% \node [inner sep=5pt,label=above:\textcolor{black}{webpage}] at ($ (X1)!.5!(Y1) $) {};
|
|
835 |
% \draw[red, <-, line width = 2mm] (X2) -- (Y2); |
|
836 |
% \node [inner sep=7pt,label=above:\textcolor{black}{POST data}] at ($ (X2)!.5!(Y2) $) {};
|
|
837 |
% \end{tikzpicture}
|
|
838 |
%\end{textblock}
|
|
839 |
% |
|
840 |
% |
|
841 |
%\begin{textblock}{1}(9,5.5)
|
|
842 |
%\begin{tabular}{c}
|
|
843 |
%\includegraphics[scale=0.15]{pics/laptop.png}\\[-2mm]
|
|
844 |
%\small Browser |
|
845 |
%\end{tabular}
|
|
846 |
%\end{textblock}
|
|
847 |
%\end{frame}
|
|
848 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
849 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
850 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
851 |
|
| 0 | 852 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 631 | 853 |
%\begin{frame}[c]
|
854 |
%\frametitle{Scala}
|
|
855 |
% |
|
856 |
%\small A simple Scala function for reading webpages: |
|
857 |
%\bigskip |
|
858 |
% |
|
859 |
%\footnotesize |
|
860 |
%\lstinputlisting{../progs/app0.scala}
|
|
861 |
%\medskip\pause |
|
862 |
% |
|
863 |
%\lstinline{get_page("""https://nms.kcl.ac.uk/christian.urban/""")}
|
|
864 |
%\bigskip\medskip\pause |
|
865 |
% |
|
866 |
% |
|
867 |
%\small A slightly more complicated version for handling errors: |
|
868 |
%\smallskip |
|
869 |
% |
|
870 |
%\footnotesize |
|
871 |
%\lstinputlisting[xleftmargin=-4mm]{../progs/app1.scala}
|
|
872 |
% |
|
873 |
% |
|
874 |
%\end{frame}
|
|
| 0 | 875 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
876 |
||
|
98
1f3d89fe9820
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
97
diff
changeset
|
877 |
|
|
1f3d89fe9820
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
97
diff
changeset
|
878 |
|
|
1f3d89fe9820
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
97
diff
changeset
|
879 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 757 | 880 |
%\begin{frame}[t]
|
881 |
%\frametitle{A Regular Expression}
|
|
882 |
% |
|
883 |
%\begin{itemize}
|
|
884 |
%\item \ldots{} is a pattern or template for specifying strings
|
|
885 |
%\end{itemize}\bigskip
|
|
886 |
% |
|
887 |
%\begin{center}
|
|
888 |
%\only<1>{\scode{"https?://[^"]*"}}%
|
|
889 |
%\only<2>{\scode{""""https?://[^"]*"""".r}}
|
|
890 |
%\end{center}\bigskip\bigskip
|
|
891 |
% |
|
892 |
%matches for example\smallskip\\ |
|
893 |
%\hspace{2mm}\code{"http://www.foobar.com"}\\
|
|
894 |
%\hspace{2mm}\code{"https://www.tls.org"}\smallskip\\
|
|
895 |
% |
|
896 |
%but not\smallskip\\ |
|
897 |
%\hspace{2mm}\code{"http://www."foo"bar.com"}\\
|
|
898 |
% |
|
899 |
%\end{frame}
|
|
| 3 | 900 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
901 |
||
902 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 632 | 903 |
%\begin{frame}[c]
|
904 |
%\frametitle{Finding Operations in Scala}
|
|
905 |
% |
|
906 |
%{\bf\code{rexp.findAllIn(string)}}\medskip
|
|
907 |
% |
|
908 |
%returns a list of all (sub)strings that match the |
|
909 |
%regular expression |
|
910 |
%\bigskip\bigskip |
|
911 |
% |
|
912 |
% |
|
913 |
%{\bf\code{rexp.findFirstIn(string)}}\medskip
|
|
914 |
% |
|
915 |
%returns either |
|
916 |
% |
|
917 |
%\begin{itemize}
|
|
918 |
%\item \code{None} if no (sub)string matches or
|
|
919 |
%\item \code{Some(s)} with the first (sub)string
|
|
920 |
%\end{itemize}
|
|
921 |
% |
|
922 |
%\end{frame}
|
|
| 0 | 923 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
924 |
||
925 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 631 | 926 |
%\begin{frame}[c]
|
927 |
% |
|
928 |
%\footnotesize |
|
929 |
%\lstinputlisting{../progs/app2.scala}
|
|
930 |
% |
|
931 |
%\end{frame}
|
|
|
254
dcd4688690ce
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
253
diff
changeset
|
932 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 0 | 933 |
|
|
254
dcd4688690ce
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
253
diff
changeset
|
934 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 631 | 935 |
%\begin{frame}[c]
|
936 |
% |
|
937 |
%\small |
|
938 |
%A version that only crawls links in ``my'' domain:\bigskip |
|
939 |
% |
|
940 |
%\footnotesize |
|
941 |
%\lstinputlisting{../progs/app3.scala}
|
|
942 |
% |
|
943 |
%\end{frame}
|
|
| 0 | 944 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
945 |
||
946 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 631 | 947 |
%\begin{frame}[c]
|
948 |
%\lstset{xleftmargin=-4mm}
|
|
949 |
%\small |
|
950 |
%A little email harvester: |
|
951 |
% |
|
952 |
%\footnotesize |
|
953 |
%\lstinputlisting{../progs/app4.scala}\bigskip
|
|
954 |
% |
|
955 |
%\tiny |
|
956 |
%\url{http://net.tutsplus.com/tutorials/other/8-regular-expressions-you-should-know/}
|
|
957 |
% |
|
958 |
%\end{frame}
|
|
| 3 | 959 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
960 |
||
961 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 14 | 962 |
\begin{frame}[t]
|
| 757 | 963 |
\frametitle{(Basic) Regular Expressions}
|
| 0 | 964 |
|
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
965 |
Their inductive definition: |
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
966 |
|
| 14 | 967 |
|
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
968 |
\begin{textblock}{6}(2,7.5)
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
969 |
\begin{tabular}{@ {}rrl@ {\hspace{13mm}}l}
|
| 512 | 970 |
\bl{$r$} & \bl{$::=$} & \bl{$\ZERO$} & nothing\\
|
|
428
a47c4227a0c6
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
334
diff
changeset
|
971 |
& \bl{$\mid$} & \bl{$\ONE$} & empty string / \pcode{""} / $[]$\\
|
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
972 |
& \bl{$\mid$} & \bl{$c$} & character\\
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
973 |
& \bl{$\mid$} & \bl{$r_1 + r_2$} & alternative / choice\\
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
974 |
& \bl{$\mid$} & \bl{$r_1 \cdot r_2$} & sequence\\
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
975 |
& \bl{$\mid$} & \bl{$r^*$} & star (zero or more)\\
|
| 3 | 976 |
\end{tabular}
|
977 |
\end{textblock}
|
|
978 |
||
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
979 |
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
980 |
\only<2->{\footnotesize
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
981 |
\begin{textblock}{9}(2,0.5)
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
982 |
\begin{bubble}[9.8cm]
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
983 |
\lstinputlisting{../progs/app01.scala}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
984 |
\end{bubble}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
985 |
\end{textblock}}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
986 |
|
|
254
dcd4688690ce
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
253
diff
changeset
|
987 |
\end{frame}
|
| 3 | 988 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
989 |
||
990 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 506 | 991 |
%\begin{frame}[t]
|
992 |
%\frametitle{Regular Expressions}
|
|
993 |
% |
|
994 |
%\small |
|
995 |
%In Scala:\bigskip |
|
996 |
% |
|
997 |
%\footnotesize |
|
998 |
%\lstinputlisting{../progs/app51.scala}
|
|
999 |
% |
|
1000 |
% |
|
1001 |
%\end{frame}
|
|
| 0 | 1002 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
1003 |
||
1004 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1005 |
\begin{frame}[t]
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1006 |
\frametitle{Strings}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1007 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1008 |
\ldots are lists of characters. For example \code{"hello"}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1009 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1010 |
\begin{center}
|
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1011 |
\bl{$[h, e, l, l, o]$} or just \bl{$hello$}
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1012 |
\end{center}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1013 |
|
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1014 |
the empty string: \bl{$[]$} or \bl{\pcode{""}}\bigskip\\
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1015 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1016 |
the concatenation of two strings: |
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1017 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1018 |
\begin{center}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1019 |
\bl{$s_1 \,@\, s_2$}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1020 |
\end{center}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1021 |
|
| 631 | 1022 |
\bl{\textit{foo $@$ bar = foobar}}\\
|
1023 |
\bl{\textit{baz $@\, []$ = baz}}
|
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1024 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1025 |
\end{frame}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1026 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1027 |
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1028 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1029 |
\begin{frame}[c]
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1030 |
\frametitle{Languages, Strings}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1031 |
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1032 |
\begin{itemize}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1033 |
\item \alert{\bf Strings} are lists of characters, for example
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1034 |
\begin{center}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1035 |
\bl{$[]$},\;\bl{$abc$} \hspace{2cm}(Pattern match: \bl{$c\!::\!s$})
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1036 |
\end{center}\bigskip
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1037 |
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1038 |
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1039 |
\item A \alert{\bf language} is a set of strings, for example\medskip
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1040 |
\begin{center}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1041 |
\bl{$\{[], hello, \textit{foobar}, a, abc\}$}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1042 |
\end{center}\bigskip
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1043 |
|
|
332
4755ad4b457b
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
331
diff
changeset
|
1044 |
\item \alert{\bf Concatenation} of strings and languages
|
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1045 |
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1046 |
\begin{center}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1047 |
\begin{tabular}{rcl}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1048 |
\bl{$\textit{foo}\;@\;bar$} & \bl{$=$} & \bl{$\textit{foobar}$}\medskip\\
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1049 |
\bl{$A\;@\;B$} & \bl{$\dn$} & \bl{$\{ s_1\,@\,s_2 \;\mid\; s_1 \in A \wedge s_2 \in B\}$}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1050 |
\end{tabular}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1051 |
\end{center}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1052 |
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1053 |
%\item The \alert{\bf meaning} of a regular expression is a set of
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1054 |
% strings, or language. |
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1055 |
\end{itemize}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1056 |
|
| 762 | 1057 |
\only<2>{
|
1058 |
\begin{textblock}{4}(10.5,8)
|
|
1059 |
\small |
|
1060 |
Let |
|
1061 |
||
1062 |
\bl{$A = \{foo, bar\}$} \bl{$B = \{a, b\}$}
|
|
1063 |
\[ |
|
1064 |
\bl{A \,@\, B = \{fooa, foob, bara, barb\}}
|
|
1065 |
\] |
|
1066 |
\end{textblock}}
|
|
1067 |
||
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1068 |
\end{frame}
|
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1069 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1070 |
|
| 761 | 1071 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
1072 |
\begin{frame}[c]
|
|
| 762 | 1073 |
\frametitle{Two Corner Cases}
|
1074 |
||
1075 |
\Large |
|
1076 |
\begin{center}
|
|
1077 |
\bl{$A \,@\, \{[]\} = \;?$}\bigskip\bigskip\pause\\
|
|
1078 |
\bl{$A \,@\, \{\} = \;?$}
|
|
1079 |
\end{center}
|
|
1080 |
||
1081 |
\end{frame}
|
|
1082 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1083 |
||
1084 |
||
1085 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1086 |
\begin{frame}[c]
|
|
| 761 | 1087 |
\frametitle{The Meaning of a Regex}
|
1088 |
||
1089 |
...all the strings a regular expression can match. |
|
1090 |
||
1091 |
\begin{center}
|
|
1092 |
\begin{tabular}{rcl}
|
|
1093 |
\bl{$L(\ZERO)$} & \bl{$\dn$} & \bl{$\{\}$}\\
|
|
1094 |
\bl{$L(\ONE)$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
1095 |
\bl{$L(c)$} & \bl{$\dn$} & \bl{$\{[c]\}$}\\
|
|
1096 |
\bl{$L(r_1 + r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \cup L(r_2)$}\\
|
|
1097 |
\bl{$L(r_1 \cdot r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \,@\, L(r_2)$}\\
|
|
1098 |
\bl{$L(r^*)$} & \bl{$\dn$} & \\
|
|
1099 |
\end{tabular}
|
|
1100 |
\end{center}
|
|
1101 |
||
1102 |
\begin{textblock}{14}(1.5,13.5)\small
|
|
1103 |
\bl{$L$} is a function from regular expressions to
|
|
1104 |
sets of strings (languages):\smallskip\\ |
|
1105 |
\bl{\quad$L$ : Rexp $\Rightarrow$ Set$[$String$]$}
|
|
1106 |
\end{textblock}
|
|
1107 |
||
1108 |
\end{frame}
|
|
1109 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1110 |
||
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1111 |
|
| 0 | 1112 |
|
| 5 | 1113 |
|
| 631 | 1114 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
1115 |
\begin{frame}[c]
|
|
1116 |
\frametitle{The Power Operation}
|
|
1117 |
||
1118 |
\begin{itemize}
|
|
1119 |
\item The \alert{\textbf{\boldmath$n$th Power}} of a language:
|
|
1120 |
||
1121 |
\begin{center}
|
|
1122 |
\begin{tabular}{lcl}
|
|
1123 |
\bl{$A^0$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
1124 |
\bl{$A^{n+1}$} & \bl{$\dn$} & \bl{$A \,@\, A^n$}
|
|
1125 |
\end{tabular}
|
|
1126 |
\end{center}\bigskip
|
|
1127 |
||
1128 |
\item[] For example |
|
1129 |
||
1130 |
\begin{center}
|
|
1131 |
\begin{tabular}{lcl@{\hspace{10mm}}l}
|
|
1132 |
\bl{$A^4$} & \bl{$=$} & \bl{$A \,@\, A \,@\, A \,@\, A$} & \bl{$(@\,\{[]\})$}\\
|
|
1133 |
\bl{$A^1$} & \bl{$=$} & \bl{$A$} & \bl{$(@\,\{[]\})$}\\
|
|
1134 |
\bl{$A^0$} & \bl{$=$} & \bl{$\{[]\}$}\\
|
|
1135 |
\end{tabular}
|
|
1136 |
\end{center}
|
|
1137 |
||
1138 |
\end{itemize}
|
|
1139 |
||
1140 |
\end{frame}
|
|
| 762 | 1141 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 631 | 1142 |
|
| 743 | 1143 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
1144 |
\begin{frame}[c]
|
|
| 745 | 1145 |
\frametitle{The Meaning of a Regex}
|
| 743 | 1146 |
|
| 762 | 1147 |
\begin{textblock}{15}(1,4)
|
| 743 | 1148 |
\begin{tabular}{rcl}
|
1149 |
\bl{$L(\ZERO)$} & \bl{$\dn$} & \bl{$\{\}$}\\
|
|
1150 |
\bl{$L(\ONE)$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
1151 |
\bl{$L(c)$} & \bl{$\dn$} & \bl{$\{[c]\}$}\\
|
|
1152 |
\bl{$L(r_1 + r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \cup L(r_2)$}\\
|
|
| 762 | 1153 |
\bl{$L(r_1 \cdot r_2)$} & \bl{$\dn$} & \bl{$\{ s_1 \,@\, s_2 \;|\; s_1 \in L(r_1) \wedge s_2 \in L(r_2) \}$}\\
|
1154 |
\bl{$L(r^*)$} & \bl{$\dn$} & \onslide<2->{\bl{$\bigcup_{0 \le n} L(r)^n$}}\\
|
|
1155 |
\end{tabular}\bigskip
|
|
1156 |
||
1157 |
%\onslide<2->{
|
|
1158 |
%\hspace{5mm}\bl{$L(r)^0 \;\dn\; \{[]\}$}\\
|
|
1159 |
%\bl{$L(r)^{n+1} \;\dn\; L(r) \,@\, L(r)^n$}\hspace{9mm}\onslide<3->{\small\textcolor{gray}{(append on sets)}\\
|
|
1160 |
%\small\hspace{5cm}\textcolor{gray}{$\{ s_1 @ s_2 \;|\; s_1\in L(r) \wedge s_2 \in L(r)^n \}$}}
|
|
1161 |
%} |
|
| 743 | 1162 |
\end{textblock}
|
1163 |
||
1164 |
\end{frame}
|
|
| 762 | 1165 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 743 | 1166 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
1167 |
\begin{frame}[c]
|
|
| 631 | 1168 |
\frametitle{The Star Operation}
|
1169 |
||
1170 |
\begin{itemize}
|
|
1171 |
\item The \alert{\bf Kleene Star} of a \underline{language}:
|
|
1172 |
\bigskip |
|
1173 |
||
1174 |
\begin{center}
|
|
1175 |
\begin{tabular}{c}
|
|
1176 |
\bl{$A\star \dn \bigcup_{0\le n} A^n$}
|
|
1177 |
\end{tabular}
|
|
1178 |
\end{center}\bigskip
|
|
1179 |
||
1180 |
\item[] This expands to |
|
1181 |
||
1182 |
\[ |
|
1183 |
\bl{A^0 \cup A^1 \cup A^2 \cup A^3 \cup A^4 \cup \ldots}
|
|
1184 |
\] |
|
1185 |
||
1186 |
or |
|
1187 |
||
1188 |
\small |
|
1189 |
\[ |
|
1190 |
\bl{\{[]\} \;\cup\; A \;\cup\; A\,@\,A \;\cup\;
|
|
1191 |
A\,@\,A\,@\,A \;\cup\; A\,@\,A\,@\,A\,@\,A \cup \ldots} |
|
1192 |
\] |
|
1193 |
||
1194 |
\end{itemize}
|
|
1195 |
||
1196 |
\end{frame}
|
|
1197 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 762 | 1198 |
|
1199 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1200 |
\begin{frame}[c]
|
|
1201 |
\frametitle{The Meaning of a Regex}
|
|
1202 |
||
1203 |
\begin{textblock}{15}(1,4)
|
|
1204 |
\begin{tabular}{rcl}
|
|
1205 |
\bl{$L(\ZERO)$} & \bl{$\dn$} & \bl{$\{\}$}\\
|
|
1206 |
\bl{$L(\ONE)$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
1207 |
\bl{$L(c)$} & \bl{$\dn$} & \bl{$\{[c]\}$}\\
|
|
1208 |
\bl{$L(r_1 + r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \cup L(r_2)$}\\
|
|
1209 |
\bl{$L(r_1 \cdot r_2)$} & \bl{$\dn$} & \bl{$\{ s_1 \,@\, s_2 \;|\; s_1 \in L(r_1) \wedge s_2 \in L(r_2) \}$}\\
|
|
1210 |
\bl{$L(r^*)$} & \bl{$\dn$} & \bl{$(L(r))\star$}\\
|
|
1211 |
\end{tabular}
|
|
| 631 | 1212 |
|
| 762 | 1213 |
\end{textblock}
|
1214 |
||
1215 |
\end{frame}
|
|
1216 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1217 |
||
1218 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1219 |
\begin{frame}[c]
|
|
1220 |
\frametitle{The Meaning of Matching}
|
|
1221 |
||
1222 |
\begin{bubble}[10cm]
|
|
1223 |
\large\bf |
|
1224 |
A regular expression \bl{$r$} matches a string~\bl{$s$}
|
|
1225 |
provided |
|
1226 |
||
1227 |
\begin{center}
|
|
1228 |
\bl{$s \in L(r)$}\\
|
|
1229 |
\end{center}
|
|
1230 |
\end{bubble}\bigskip\bigskip
|
|
1231 |
||
1232 |
\ldots and the point of the next lecture is |
|
1233 |
to decide this problem as fast as possible (unlike Python, |
|
1234 |
Ruby, Java) |
|
1235 |
||
1236 |
\end{frame}
|
|
1237 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1238 |
||
1239 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1240 |
\begin{frame}[c]
|
|
1241 |
\frametitle{Questions}
|
|
1242 |
||
1243 |
\begin{itemize}
|
|
1244 |
\item Say \bl{$A = \{[a],[b],[c],[d]\}$}.\bigskip
|
|
1245 |
||
1246 |
\item[] |
|
1247 |
How many strings are in \bl{$A^4$}\,?
|
|
1248 |
\bigskip\medskip\pause |
|
1249 |
||
1250 |
||
1251 |
\item[] |
|
1252 |
What if \bl{$A = \{[a],[b],[c],[]\}$};\\
|
|
1253 |
how many strings are then in \bl{$A^4$}\,?
|
|
1254 |
\end{itemize}
|
|
1255 |
||
1256 |
\end{frame}
|
|
1257 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1258 |
||
1259 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1260 |
% \begin{frame}[c]
|
|
1261 |
% \frametitle{Languages (Sets of Strings)}
|
|
1262 |
||
1263 |
% \begin{itemize}
|
|
1264 |
||
1265 |
% \item A \alert{\bf Language} is a set of strings, for example\medskip
|
|
1266 |
% \begin{center}
|
|
1267 |
% \bl{$\{[], hello, foobar, a, abc\}$}
|
|
1268 |
% \end{center}\bigskip
|
|
1269 |
||
1270 |
% \item \alert{\bf Concatenation} for strings and languages
|
|
1271 |
||
1272 |
% \begin{center}
|
|
1273 |
% \begin{tabular}{rcl}
|
|
1274 |
% \bl{$foo\;@\;bar$} & \bl{$=$} & \bl{$foobar$}\medskip\\
|
|
1275 |
% \bl{$A\;@\;B$} & \bl{$\dn$} & \bl{$\{ s_1\,@\,s_2 \;\mid\; s_1 \in A \wedge s_2 \in B\}$}
|
|
1276 |
% \end{tabular}
|
|
1277 |
% \end{center}
|
|
1278 |
% \bigskip |
|
1279 |
||
1280 |
% \small |
|
1281 |
% \item [] For example \bl{$A = \{foo, bar\}$}, \bl{$B = \{a, b\}$}
|
|
1282 |
||
1283 |
% \[ |
|
1284 |
% \bl{A \,@\, B = \{fooa, foob, bara, barb\}}
|
|
1285 |
% \] |
|
1286 |
||
1287 |
||
1288 |
||
1289 |
||
1290 |
% \end{itemize}
|
|
1291 |
% \end{frame}
|
|
1292 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1293 |
||
1294 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1295 |
% \begin{frame}[c]
|
|
1296 |
% \frametitle{Two Corner Cases}
|
|
1297 |
||
1298 |
% \Large |
|
1299 |
% \begin{center}
|
|
1300 |
% \bl{$A \,@\, \{[]\} = \;?$}\bigskip\bigskip\pause\\
|
|
1301 |
% \bl{$A \,@\, \{\} = \;?$}
|
|
1302 |
% \end{center}
|
|
1303 |
||
1304 |
% \end{frame}
|
|
1305 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1306 |
||
1307 |
||
1308 |
||
1309 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1310 |
% \begin{frame}[c]
|
|
1311 |
% \frametitle{The Meaning of a Regex}
|
|
1312 |
||
1313 |
% ...all the strings a regular expression can match. |
|
1314 |
||
1315 |
% \begin{center}
|
|
1316 |
% \begin{tabular}{rcl}
|
|
1317 |
% \bl{$L(\ZERO)$} & \bl{$\dn$} & \bl{$\{\}$}\\
|
|
1318 |
% \bl{$L(\ONE)$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
1319 |
% \bl{$L(c)$} & \bl{$\dn$} & \bl{$\{[c]\}$}\\
|
|
1320 |
% \bl{$L(r_1 + r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \cup L(r_2)$}\\
|
|
1321 |
% \bl{$L(r_1 \cdot r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \,@\, L(r_2)$}\\
|
|
1322 |
% \bl{$L(r^*)$} & \bl{$\dn$} & \\
|
|
1323 |
% \end{tabular}
|
|
1324 |
% \end{center}
|
|
1325 |
||
1326 |
% \begin{textblock}{14}(1.5,13.5)\small
|
|
1327 |
% \bl{$L$} is a function from regular expressions to
|
|
1328 |
% sets of strings (languages):\smallskip\\ |
|
1329 |
% \bl{\quad$L$ : Rexp $\Rightarrow$ Set$[$String$]$}
|
|
1330 |
% \end{textblock}
|
|
1331 |
||
1332 |
% \end{frame}
|
|
1333 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1334 |
||
1335 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1336 |
% \begin{frame}[c]
|
|
1337 |
% \frametitle{The Power Operation}
|
|
1338 |
||
1339 |
% \begin{itemize}
|
|
1340 |
% \item The \alert{\textbf{\boldmath$n$th Power}} of a language:
|
|
1341 |
||
1342 |
% \begin{center}
|
|
1343 |
% \begin{tabular}{lcl}
|
|
1344 |
% \bl{$A^0$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
1345 |
% \bl{$A^{n+1}$} & \bl{$\dn$} & \bl{$A \,@\, A^n$}
|
|
1346 |
% \end{tabular}
|
|
1347 |
% \end{center}\bigskip
|
|
1348 |
||
1349 |
% \item[] For example |
|
1350 |
||
1351 |
% \begin{center}
|
|
1352 |
% \begin{tabular}{lcl@{\hspace{10mm}}l}
|
|
1353 |
% \bl{$A^4$} & \bl{$=$} & \bl{$A \,@\, A \,@\, A \,@\, A$} & \bl{$(@\,\{[]\})$}\\
|
|
1354 |
% \bl{$A^1$} & \bl{$=$} & \bl{$A$} & \bl{$(@\,\{[]\})$}\\
|
|
1355 |
% \bl{$A^0$} & \bl{$=$} & \bl{$\{[]\}$}\\
|
|
1356 |
% \end{tabular}
|
|
1357 |
% \end{center}
|
|
1358 |
||
1359 |
% \end{itemize}
|
|
1360 |
||
1361 |
% \end{frame}
|
|
1362 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1363 |
||
1364 |
||
| 631 | 1365 |
|
| 0 | 1366 |
|
1367 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 762 | 1368 |
% \begin{frame}[c]
|
1369 |
% \frametitle{Written Exam}
|
|
|
253
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1370 |
|
| 762 | 1371 |
% \begin{itemize}
|
1372 |
% \item Accounts for 80\%.\bigskip |
|
|
253
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1373 |
|
| 762 | 1374 |
% \item The question ``\textit{Is this relevant for
|
1375 |
% the exam?}'' is very demotivating for the lecturer!\bigskip\\ |
|
|
253
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1376 |
|
| 762 | 1377 |
% \item Deal: Whatever is in the homework (and is not marked |
1378 |
% ``\textit{optional}'') is relevant for the exam.\bigskip
|
|
|
330
0806e45d873c
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
328
diff
changeset
|
1379 |
|
| 762 | 1380 |
% \item Each lecture has also a handout. There are also handouts about |
1381 |
% notation and Scala. |
|
1382 |
% \end{itemize}
|
|
|
253
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1383 |
|
| 762 | 1384 |
% \end{frame}
|
|
253
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1385 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1386 |
|
|
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1387 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 762 | 1388 |
% \begin{frame}[t]
|
1389 |
% \frametitle{Coursework}
|
|
| 0 | 1390 |
|
| 762 | 1391 |
% \begin{itemize}
|
1392 |
% \item Accounts for 20\%. Two strands. Choose \alert{\bf one}!\bigskip
|
|
1393 |
% \end{itemize}
|
|
| 0 | 1394 |
|
| 762 | 1395 |
% \begin{columns}[t]
|
1396 |
% \begin{column}{.5\textwidth}
|
|
1397 |
% \underline{\bf Strand 1}\medskip
|
|
1398 |
% \begin{itemize}
|
|
1399 |
% \item 4 programming tasks: |
|
1400 |
% \begin{itemize}
|
|
1401 |
% \item matcher (4\%, 11.10.) |
|
1402 |
% \item lexer (5\%, 04.11.) |
|
1403 |
% \item parser (5\%, 22.11.) |
|
1404 |
% \item compiler (6\%, 13.12.) |
|
1405 |
% \end{itemize}
|
|
1406 |
% \item in any lang.~you like,\\ but I want to see the\\ code |
|
1407 |
% \end{itemize}
|
|
1408 |
% \end{column}
|
|
|
253
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1409 |
|
| 762 | 1410 |
% \hspace{-45pt}\vrule{}\hspace{10pt}
|
1411 |
% \begin{column}{.5\textwidth}
|
|
1412 |
% \underline{\bf Strand 2}\smallskip\begin{itemize}
|
|
1413 |
% \item one task: prove the correctness of a regular expression matcher in |
|
1414 |
% the \underline{Isabelle} theorem prover
|
|
1415 |
% \item 20\%, submission on~13.12.\hspace{-5mm}\mbox{}
|
|
1416 |
% \end{itemize}
|
|
1417 |
% \end{column}
|
|
1418 |
% \end{columns}\medskip
|
|
|
253
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1419 |
|
| 762 | 1420 |
% \small |
1421 |
% \begin{itemize}
|
|
1422 |
% \item Solving more than one strand will {\bf not} give you more
|
|
1423 |
% marks. |
|
| 506 | 1424 |
|
| 762 | 1425 |
% \end{itemize}
|
|
253
75c469893514
added coursework
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
252
diff
changeset
|
1426 |
|
| 762 | 1427 |
% \end{frame}
|
| 0 | 1428 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
1429 |
||
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1430 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 745 | 1431 |
%\begin{frame}[c]
|
1432 |
%\frametitle{Lecture Capture}
|
|
1433 |
% |
|
1434 |
%\begin{itemize}
|
|
1435 |
%\item Hope it works\ldots\pause actually no, it does not!\medskip\pause |
|
1436 |
%\item It is important to use lecture capture wisely\\ (it is only the ``baseline''): |
|
1437 |
%\begin{itemize}
|
|
1438 |
%\item Lecture recordings are a study and revision aid. |
|
1439 |
%\item Statistically, there is a clear and direct link between attendance and |
|
1440 |
% attainment: students who do not attend lectures, do less well in exams. |
|
1441 |
%\end{itemize}
|
|
1442 |
% |
|
1443 |
%\item Attending a lecture is more than watching it online -- if you do not |
|
1444 |
%attend, you miss out! |
|
1445 |
% |
|
1446 |
%\end{itemize}
|
|
1447 |
% |
|
1448 |
%\end{frame}
|
|
| 506 | 1449 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
1450 |
||
1451 |
||
1452 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1453 |
\begin{frame}[c]
|
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1454 |
\frametitle{\begin{tabular}{c}\\[3cm]\alert{Questions?}\end{tabular}}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1455 |
|
| 769 | 1456 |
|
1457 |
\begin{tabular}{lll}
|
|
1458 |
TAs: & Anton Luca-Dorin & (took the module last year)\\ |
|
1459 |
& Chengsong Tan & (PhD student working on derivatives) |
|
1460 |
\end{tabular}
|
|
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1461 |
\mbox{}
|
|
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1462 |
\end{frame}
|
| 769 | 1463 |
|
1464 |
\begin{frame}[c]
|
|
1465 |
\begin{mybox3}{Coursework}
|
|
1466 |
Do we need to provide instructions on running the coursework files |
|
1467 |
if we're using languages other than Scala? Thanks |
|
1468 |
\end{mybox3}\pause
|
|
1469 |
||
1470 |
\begin{mybox2}{Zip-File for Coursework}
|
|
1471 |
Please, please submit a zipfile that generates a subdirectory |
|
1472 |
\begin{center}
|
|
1473 |
\texttt{NameFamilyName}
|
|
1474 |
\end{center}
|
|
1475 |
\end{mybox2}
|
|
1476 |
\end{frame}
|
|
1477 |
||
1478 |
||
1479 |
\begin{frame}[c]
|
|
1480 |
\begin{mybox3}{Coursework}
|
|
1481 |
What is the purpose of the workshop session on the timetable? |
|
1482 |
||
1483 |
Slightly confused about how to undertake cw1 and what exactly we |
|
1484 |
should be implementing. This is more for clarification of the cw1 |
|
1485 |
structure, including the implementation and questions present in |
|
1486 |
cw1. |
|
1487 |
\end{mybox3}
|
|
1488 |
\end{frame}
|
|
1489 |
||
1490 |
\begin{frame}[c]
|
|
1491 |
\begin{mybox3}{What is the trick?}\small
|
|
1492 |
What was the trick to improve the evil regular expressions matcher |
|
1493 |
to have such good results compared to other programming languages? |
|
1494 |
Is it working better on casual regular expressions (the ones that |
|
1495 |
Python and Java handle pretty well), too? Or was it just optimised |
|
1496 |
for these evil ones? |
|
1497 |
\end{mybox3}
|
|
1498 |
||
1499 |
\begin{mybox3}{}\small
|
|
1500 |
It was shown in the lectures that the pattern matching algorithms |
|
1501 |
currently implemented in popular programming languages (Python, JS, |
|
1502 |
Java, etc) are far slower than the algorithm we are going to be |
|
1503 |
implementing in this module. My question is why do these programming |
|
1504 |
languages not implement the algorithm that we are going to implement |
|
1505 |
in this module? |
|
1506 |
\end{mybox3}
|
|
1507 |
\end{frame}
|
|
1508 |
||
1509 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1510 |
\begin{frame}[c]
|
|
1511 |
\frametitle{Thanks to Martin Mikusovic}
|
|
1512 |
||
1513 |
\bigskip |
|
1514 |
\begin{center}
|
|
1515 |
\begin{tikzpicture}
|
|
1516 |
\begin{axis}[
|
|
1517 |
xlabel={$n$},
|
|
1518 |
x label style={at={(1.05,0.0)}},
|
|
1519 |
ylabel={time in secs},
|
|
1520 |
enlargelimits=false, |
|
1521 |
xtick={0,5,...,30},
|
|
1522 |
xmax=33, |
|
1523 |
ymax=35, |
|
1524 |
ytick={0,10,...,30},
|
|
1525 |
scaled ticks=false, |
|
1526 |
axis lines=left, |
|
1527 |
width=9cm, |
|
1528 |
height=5.5cm, |
|
1529 |
legend entries={Java 8, Python, JavaScript, Swift},
|
|
1530 |
legend pos=north west, |
|
1531 |
legend cell align=left] |
|
1532 |
\addplot[blue,mark=*, mark options={fill=white}] table {re-python2.data};
|
|
1533 |
\addplot[cyan,mark=*, mark options={fill=white}] table {re-java.data};
|
|
1534 |
\addplot[red,mark=*, mark options={fill=white}] table {re-js.data};
|
|
1535 |
\addplot[magenta,mark=*, mark options={fill=white}] table {re-swift.data};
|
|
1536 |
\end{axis}
|
|
1537 |
\end{tikzpicture}
|
|
1538 |
\end{center}
|
|
1539 |
||
1540 |
Regex: \bl{$(a^*)^* \cdot b$}
|
|
1541 |
||
1542 |
Strings of the form \bl{$\underbrace{\,a\ldots a\,}_{n}$}
|
|
1543 |
||
1544 |
\end{frame}
|
|
1545 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1546 |
||
1547 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1548 |
\begin{frame}[c]
|
|
1549 |
\frametitle{Same Example in Java 9+}
|
|
1550 |
||
1551 |
\begin{center}
|
|
1552 |
\begin{tikzpicture}
|
|
1553 |
\begin{axis}[
|
|
1554 |
xlabel={$n$},
|
|
1555 |
x label style={at={(1.09,-0.15)}},
|
|
1556 |
ylabel={time in secs},
|
|
1557 |
scaled x ticks=false, |
|
1558 |
enlargelimits=false, |
|
1559 |
xtick distance=10000, |
|
1560 |
xmax=44000, |
|
1561 |
ytick={0,10,...,30},
|
|
1562 |
ymax=35, |
|
1563 |
axis lines=left, |
|
1564 |
width=9cm, |
|
1565 |
height=5cm, |
|
1566 |
legend entries={Java \liningnums{9}+},
|
|
1567 |
legend pos=north west, |
|
1568 |
legend cell align=left] |
|
1569 |
\addplot[blue,mark=square*,mark options={fill=white}] table {re-java9.data};
|
|
1570 |
\end{axis}
|
|
1571 |
\end{tikzpicture}
|
|
1572 |
\end{center}
|
|
1573 |
||
1574 |
Regex: \bl{$(a^*)^* \cdot b$}
|
|
1575 |
||
1576 |
Strings of the form \bl{$\underbrace{\,a\ldots a\,}_{n}$}
|
|
1577 |
||
1578 |
\end{frame}
|
|
1579 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
| 778 | 1580 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
1581 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
1582 |
% Questions |
|
| 769 | 1583 |
|
1584 |
\begin{frame}[c]
|
|
1585 |
\begin{mybox3}{}
|
|
1586 |
Are there any (common) languages that have a built-in regex |
|
1587 |
implementation matching the set of functions of a formal 'simple' |
|
1588 |
regular expression, as opposed to an 'extended' regular expression |
|
1589 |
implemented in most regex-supporting languages? |
|
1590 |
\end{mybox3}
|
|
1591 |
\end{frame}
|
|
1592 |
||
1593 |
\begin{frame}[c]
|
|
1594 |
\begin{mybox3}{Passing Mark}
|
|
1595 |
I believe the assessment is 70\% coursework (broken into 10\% weekly |
|
1596 |
stuff, 15\% mid term exam and 45\% CW in any programming language) |
|
1597 |
and 30\% January exam. However, I would like to know if we just need |
|
1598 |
40\% overall to pass the module or pass the each component |
|
1599 |
individually? |
|
1600 |
\end{mybox3}
|
|
1601 |
||
1602 |
\hfill$\Rightarrow$ 40\% overall |
|
1603 |
\end{frame}
|
|
1604 |
||
1605 |
\begin{frame}[c]
|
|
1606 |
\begin{mybox3}{Regexes}
|
|
1607 |
Can we determine all the possible regular expressions matching a |
|
1608 |
certain string? If we take into account all the possible ways to |
|
1609 |
combine the operations: \bl{$\ZERO$}, \bl{$\ONE$},
|
|
1610 |
\bl{$r_1 + r_2$}, \bl{$r_1 \cdot r_2$}, \bl{$r^*$}?
|
|
1611 |
\end{mybox3}
|
|
1612 |
\end{frame}
|
|
1613 |
||
1614 |
\begin{frame}[c]
|
|
1615 |
\begin{mybox3}{\bl{$L$} + Equivalence}
|
|
1616 |
When we explain why two regular expressions are not equivalent, what |
|
1617 |
method is better for us, using mathematics formulas or making an |
|
1618 |
example? |
|
1619 |
\end{mybox3}
|
|
1620 |
\begin{mybox3}{}
|
|
1621 |
Meaning of Regex and Operations |
|
1622 |
\end{mybox3}
|
|
1623 |
\end{frame}
|
|
1624 |
||
1625 |
\begin{frame}[c]
|
|
1626 |
\begin{mybox3}{\bl{$L$}}
|
|
1627 |
Can the function L be applied to anything other than regular |
|
1628 |
expressions? For example would L(L(c)) return anything? |
|
1629 |
\end{mybox3}
|
|
1630 |
||
1631 |
\hfill $\Rightarrow$ No |
|
1632 |
\end{frame}
|
|
1633 |
||
1634 |
\begin{frame}[c]
|
|
1635 |
\begin{mybox3}{\bl{$(a?)\{n\} \cdot a\{n\}$}}
|
|
1636 |
In the evil regexes section, is there any reason why in the regex |
|
1637 |
\texttt{[a?]\{n\}[a]\{n\}} the square brackets are used? It is defined as a
|
|
1638 |
single character from the square brackets, however there is just one |
|
1639 |
character, so it seems like it is not necessary. Maybe it is just |
|
1640 |
necessary for the first part, because ? is a token instead of a |
|
1641 |
character and we need to refer to a? as a ``unit''? Could regular |
|
1642 |
brackets be used instead? Is there any difference apart from the |
|
1643 |
fact that it would create a group? Also, are the regexes |
|
1644 |
\texttt{[a?]\{n\}} and
|
|
1645 |
\texttt{a\{0,3\}} equivalent?
|
|
1646 |
\end{mybox3}
|
|
1647 |
\end{frame}
|
|
1648 |
||
1649 |
\begin{frame}[c]
|
|
1650 |
\begin{mybox3}{Python + Parser Combinators (CW3)}\small
|
|
1651 |
Hi Christian, |
|
1652 |
||
1653 |
I don’t see a problem: you certainly have higher order functions and |
|
1654 |
it is easy to implement algebraic data types using classes. As far |
|
1655 |
as I can see that’s all you need. You don’t get the static types but |
|
1656 |
that should be obvious. Basically if you can do it in LISP you can |
|
1657 |
do it in Python. The only problem could be stack overflows due to a |
|
1658 |
lack of tail recursion optimisation. On the other hand you can |
|
1659 |
simulate laziness using generators. |
|
1660 |
||
1661 |
Cheers, |
|
1662 |
Thorsten |
|
1663 |
\end{mybox3}
|
|
1664 |
||
1665 |
Trees \url{https://youtu.be/7tCNu4CnjVc}
|
|
1666 |
||
1667 |
Laziness \url{https://youtu.be/5jwV3zxXc8E}
|
|
1668 |
||
1669 |
\end{frame}
|
|
1670 |
||
1671 |
\begin{frame}[c]
|
|
1672 |
\begin{mybox3}{}
|
|
1673 |
What suggestions do you have for us to get the most out of this |
|
1674 |
module, especially in the online format? I.e. form discussion |
|
1675 |
groups, will you have office hours? |
|
1676 |
\end{mybox3}
|
|
1677 |
||
1678 |
\small |
|
1679 |
\hfill $\Rightarrow$\mbox{} Discussion Forum on KEATS
|
|
1680 |
||
1681 |
\hfill online tutorial sessions |
|
1682 |
||
1683 |
\hfill ??? |
|
1684 |
||
1685 |
\hfill PL-groups for ``exotic'' langs |
|
1686 |
\end{frame}
|
|
1687 |
||
1688 |
\begin{frame}[c]
|
|
1689 |
\small |
|
1690 |
\begin{mybox3}{}
|
|
1691 |
Where do most students struggle with this module? What will the format |
|
1692 |
of the exam be? What is the most efficient way of studying for the |
|
1693 |
exam? There are plenty of resources available on KEATS, but is there |
|
1694 |
anything else you'd recommend us to study? Although (just by skimming |
|
1695 |
the headings) the module seems to be a combination of practical and |
|
1696 |
theoretical matters, exactly in what field would the syllabus be |
|
1697 |
applied? Besides these questions and the ones other students asked, is |
|
1698 |
there anything else we should know? Thank you! |
|
1699 |
\end{mybox3}
|
|
1700 |
\end{frame}
|
|
1701 |
||
1702 |
||
1703 |
\begin{frame}[c]
|
|
1704 |
\end{frame}
|
|
1705 |
||
1706 |
\begin{frame}[c]
|
|
1707 |
\end{frame}
|
|
1708 |
||
1709 |
\begin{frame}[c]
|
|
1710 |
\end{frame}
|
|
1711 |
||
1712 |
\begin{frame}[c]
|
|
1713 |
\end{frame}
|
|
1714 |
||
1715 |
\begin{frame}[c]
|
|
1716 |
\end{frame}
|
|
1717 |
||
|
255
96a99237fa42
updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
254
diff
changeset
|
1718 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 0 | 1719 |
\end{document}
|
1720 |
||
1721 |
%%% Local Variables: |
|
1722 |
%%% mode: latex |
|
1723 |
%%% TeX-master: t |
|
1724 |
%%% End: |
|
1725 |