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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{../graphicss}
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\usepackage{../langs}
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\usepackage{../data}
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\usetikzlibrary{cd}
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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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\newtcolorbox{mybox3}[1]{colback=Cyan!5!white,colframe=Cyan!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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%
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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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|
|
341 |
\bl{\texttt{[}} & $\Rightarrow$ & loop begin\\
|
|
|
342 |
\bl{\texttt{]}} & $\Rightarrow$ & loop end\medskip\\
|
|
|
343 |
& $\Rightarrow$ & everything else is a comment\\
|
|
|
344 |
\end{tabular}
|
|
|
345 |
\end{center}
|
|
|
346 |
|
|
|
347 |
\end{frame}
|
|
|
348 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
349 |
|
|
|
350 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
351 |
\begin{frame}[c]
|
|
|
352 |
\frametitle{A ``Compiler'' for BF*** to C}
|
|
|
353 |
|
|
|
354 |
\begin{center}
|
|
|
355 |
\begin{tabular}{rcl}
|
|
|
356 |
\bl{\texttt{>}} & $\Rightarrow$ & \texttt{ptr++}\\
|
|
|
357 |
\bl{\texttt{<}} & $\Rightarrow$ & \texttt{ptr--}\\
|
|
|
358 |
\bl{\texttt{+}} & $\Rightarrow$ & \texttt{(*ptr)++}\\
|
|
|
359 |
\bl{\texttt{-}} & $\Rightarrow$ & \texttt{(*ptr)--}\\
|
|
|
360 |
\bl{\texttt{.}} & $\Rightarrow$ & \texttt{putchar(*ptr)}\\
|
|
|
361 |
\bl{\texttt{,}} & $\Rightarrow$ & \texttt{*ptr = getchar()}\\
|
|
|
362 |
\bl{\texttt{[}} & $\Rightarrow$ & \texttt{while(*ptr)\{}\\
|
|
|
363 |
\bl{\texttt{]}} & $\Rightarrow$ & \texttt{\}}\medskip\\
|
|
|
364 |
& $\Rightarrow$ & ignore everything else\\
|
|
|
365 |
\end{tabular}
|
|
|
366 |
\end{center}\bigskip
|
|
|
367 |
|
|
|
368 |
\texttt{char field[30000]\\ char *ptr = \&field[15000]}
|
|
|
369 |
|
|
|
370 |
\end{frame}
|
|
|
371 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
372 |
|
|
|
373 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
374 |
\begin{frame}[c]
|
|
|
375 |
\frametitle{Another~``Compiler''~for~BF~to~C}
|
|
|
376 |
|
|
|
377 |
\begin{center}
|
|
|
378 |
\begin{tabular}{rcl}
|
|
|
379 |
\bl{\texttt{>\ldots>}} & $\Rightarrow$ & \texttt{ptr += n}\\
|
|
|
380 |
\bl{\texttt{<\ldots<}} & $\Rightarrow$ & \texttt{ptr -= n}\\
|
|
|
381 |
\bl{\texttt{+\ldots+}} & $\Rightarrow$ & \texttt{(*ptr) += n}\\
|
|
|
382 |
\bl{\texttt{-\ldots-}} & $\Rightarrow$ & \texttt{(*ptr) -= n}\\
|
|
|
383 |
\bl{\texttt{.}} & $\Rightarrow$ & \texttt{putchar(*ptr)}\\
|
|
|
384 |
\bl{\texttt{,}} & $\Rightarrow$ & \texttt{*ptr = getchar()}\\
|
|
|
385 |
\bl{\texttt{[}} & $\Rightarrow$ & \texttt{while(*ptr)\{}\\
|
|
|
386 |
\bl{\texttt{]}} & $\Rightarrow$ & \texttt{\}}\medskip\\
|
|
|
387 |
& $\Rightarrow$ & ignore everything else\\
|
|
|
388 |
\end{tabular}
|
|
|
389 |
\end{center}\bigskip
|
|
|
390 |
|
|
|
391 |
\texttt{char field[30000]\\ char *ptr = \&field[15000]}
|
|
|
392 |
|
|
|
393 |
\end{frame}
|
|
|
394 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
395 |
|
|
|
396 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
397 |
\begin{frame}[t]
|
|
|
398 |
\frametitle{A Brief Compiler History}
|
|
|
399 |
|
|
|
400 |
\bigskip
|
|
|
401 |
\begin{itemize}
|
|
|
402 |
\item Turing Machines, 1936 (a tape as memory)
|
|
|
403 |
\item Regular Expressions, 1956\\
|
|
|
404 |
\item The first compiler for COBOL, 1957\\ (Grace Hopper)\medskip
|
|
|
405 |
\item But surprisingly research papers are still published nowadays\\
|
|
|
406 |
\item ``Parsing: The Solved Problem That Isn't''
|
|
|
407 |
\here{https://tratt.net/laurie/blog/entries/parsing_the_solved_problem_that_isnt.html}
|
|
|
408 |
\end{itemize}
|
|
|
409 |
|
|
|
410 |
|
|
|
411 |
\begin{textblock}{8.5}(5,7.6)
|
|
|
412 |
\begin{flushright}
|
|
|
413 |
\includegraphics[scale=0.3]{pics/hopper.jpg}\\
|
|
|
414 |
\footnotesize\textcolor{gray}{Grace Hopper}\smallskip\\
|
|
|
415 |
|
|
|
416 |
{\small\textcolor{gray}{(she made it to David Letterman's Tonight Show
|
|
|
417 |
\here{https://youtu.be/3N_ywhx6_K0?t=31})}}
|
|
|
418 |
\end{flushright}
|
|
|
419 |
\end{textblock}
|
|
|
420 |
|
|
|
421 |
\end{frame}
|
|
|
422 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
423 |
|
|
|
424 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
425 |
\begin{frame}[c]
|
|
|
426 |
\frametitle{Some Housekeeping}
|
|
|
427 |
|
|
|
428 |
\textbf{Exam will be online:}\bigskip
|
|
|
429 |
|
|
|
430 |
\begin{itemize}
|
|
|
431 |
\item final exam in January (35\%)
|
|
|
432 |
\item five CWs (65\%)
|
|
|
433 |
\end{itemize}\bigskip\bigskip\pause
|
|
|
434 |
|
|
|
435 |
|
|
|
436 |
\textbf{Weekly Homework (optional):}
|
|
|
437 |
\begin{itemize}
|
|
|
438 |
\item uploaded on KEATS, send answers via email, (try to!) respond individually
|
|
|
439 |
\item \alert{\bf all} questions in the exam will be from the HWs!!
|
|
|
440 |
\end{itemize}
|
|
|
441 |
|
|
|
442 |
\end{frame}
|
|
|
443 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
444 |
|
|
|
445 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
446 |
\begin{frame}[c]
|
|
|
447 |
\frametitle{Some Housekeeping}
|
|
|
448 |
|
|
|
449 |
\textbf{Coursework (5 accounting for 65\%):}\bigskip
|
|
|
450 |
|
|
|
451 |
\begin{itemize}
|
|
|
452 |
\item matcher (5\%)
|
|
|
453 |
\item lexer (10\%)
|
|
|
454 |
\item parser / interpreter (10\%)
|
|
|
455 |
\item JVM compiler (15\%)
|
|
|
456 |
\item LLVM compiler (25\%)
|
|
|
457 |
\end{itemize}\bigskip\pause
|
|
|
458 |
|
|
|
459 |
you can use \alert{any} programming language you like (Haskell, Rust)\\\pause
|
|
|
460 |
you can use any code I show you and is uploaded to KEATS\ldots\textbf{BUT NOTHING ELSE!}
|
|
|
461 |
|
|
|
462 |
\end{frame}
|
|
|
463 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
464 |
|
|
|
465 |
|
|
|
466 |
|
|
|
467 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
468 |
\begin{frame}[c]
|
|
|
469 |
\frametitle{Lectures 1 - 5}
|
|
|
470 |
|
|
|
471 |
transforming strings into structured data\\[10mm]
|
|
|
472 |
|
|
|
473 |
{\LARGE\bf Lexing} {\hfill{}based on regular expressions}\medskip\\
|
|
|
474 |
\hspace{5mm}(recognising ``words'')\\[6mm]
|
|
|
475 |
|
|
|
476 |
{\LARGE\bf Parsing}\medskip\\
|
|
|
477 |
\hspace{5mm}(recognising ``sentences'')
|
|
|
478 |
|
|
|
479 |
\begin{textblock}{1}(10,9.1)
|
|
|
480 |
\begin{tabular}{c}
|
|
|
481 |
\includegraphics[scale=0.1]{../pics/rosetta.jpg}\\[-2mm]
|
|
|
482 |
\footnotesize Stone of Rosetta
|
|
|
483 |
\end{tabular}
|
|
|
484 |
\end{textblock}
|
|
|
485 |
|
|
|
486 |
\end{frame}
|
|
|
487 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
488 |
|
|
|
489 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
490 |
\begin{frame}[c]
|
|
|
491 |
\frametitle{Lectures 1 - 5}
|
|
|
492 |
|
|
|
493 |
transforming strings into structured data\\[10mm]
|
|
|
494 |
|
|
|
495 |
{\LARGE\bf Lexing} {\hfill{}based on regular expressions}\medskip\\
|
|
|
496 |
\hspace{5mm}(recognising ``words'')\\[6mm]
|
|
|
497 |
|
|
|
498 |
{\LARGE\bf Parsing}\medskip\\
|
|
|
499 |
\hspace{5mm}(recognising ``sentences'')
|
|
|
500 |
|
|
|
501 |
\begin{textblock}{1}(10,9.1)
|
|
|
502 |
\begin{tabular}{c}
|
|
|
503 |
\includegraphics[scale=0.1]{../pics/rosetta.jpg}\\[-2mm]
|
|
|
504 |
\footnotesize Stone of Rosetta
|
|
|
505 |
\end{tabular}
|
|
|
506 |
\end{textblock}
|
|
|
507 |
|
|
|
508 |
\end{frame}
|
|
|
509 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
510 |
|
|
|
511 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
512 |
\begin{frame}[c]
|
|
|
513 |
\frametitle{Lectures 5 - 10}
|
|
|
514 |
|
|
|
515 |
code generation for a small imperative and a small functional language\\[10mm]
|
|
|
516 |
|
|
|
517 |
{\LARGE\bf Interpreters}\medskip\\
|
|
|
518 |
\hspace{5mm}(directly runs a program)\\[6mm]
|
|
|
519 |
|
|
|
520 |
{\LARGE\bf Compilers}\medskip\\
|
|
|
521 |
\hspace{5mm}(generate JVM code and LLVM-IR code)
|
|
|
522 |
|
|
|
523 |
\begin{textblock}{1}(8.8,8.1)
|
|
|
524 |
\begin{tabular}{c@{}c}
|
|
|
525 |
\includegraphics[scale=0.4]{../pics/javaduke.png} &
|
|
|
526 |
\includegraphics[scale=0.23]{../pics/llvmlogo.png}
|
|
|
527 |
\end{tabular}
|
|
|
528 |
\end{textblock}
|
|
|
529 |
|
|
|
530 |
\end{frame}
|
|
|
531 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
532 |
|
|
|
533 |
|
|
|
534 |
|
|
|
535 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
536 |
\begin{frame}[t]
|
|
|
537 |
\frametitle{Familiar Regular Expresssions}
|
|
|
538 |
\small
|
|
|
539 |
\begin{center}
|
|
|
540 |
\texttt{[a-z0-9\_$\backslash{}$.-]+ @ [a-z0-9$\backslash{}$.-]+ . [a-z$\backslash{}$.]\{2,6\}}
|
|
|
541 |
\end{center}\smallskip
|
|
|
542 |
|
|
|
543 |
\begin{center}
|
|
|
544 |
\begin{tabular}{@{}lp{8.5cm}@{}}
|
|
|
545 |
\pcode{re*} & matches 0 or more times\\
|
|
|
546 |
\pcode{re+} & matches 1 or more times\\
|
|
|
547 |
\pcode{re?} & matches 0 or 1 times\\
|
|
|
548 |
\pcode{re\{n\}} & matches exactly \pcode{n} number of times\\
|
|
|
549 |
\pcode{re\{n,m\}} & matches at least \pcode{n} and at most {\tt m} times\\
|
|
|
550 |
\pcode{[...]} & matches any single character inside the brackets\\
|
|
|
551 |
\pcode{[^...]} & matches any single character not inside the
|
|
|
552 |
brackets\\
|
|
|
553 |
\pcode{a-z A-Z} & character ranges\\
|
|
|
554 |
\pcode{\\d} & matches digits; equivalent to \pcode{[0-9]}\\
|
|
|
555 |
\pcode{.} & matches every character except newline\\
|
|
|
556 |
\pcode{(re)} & groups regular expressions and remembers
|
|
|
557 |
the matched text
|
|
|
558 |
\end{tabular}
|
|
|
559 |
\end{center}
|
|
|
560 |
|
|
|
561 |
\end{frame}
|
|
|
562 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
563 |
|
|
|
564 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
565 |
\begin{frame}[c]
|
|
|
566 |
\frametitle{Some ``innocent'' examples}
|
|
|
567 |
|
|
|
568 |
Let's try two examples
|
|
|
569 |
|
|
|
570 |
\begin{center}
|
|
|
571 |
\bl{\texttt{(a*)*b}}
|
|
|
572 |
\hspace{2cm}
|
|
|
573 |
\bl{\texttt{[a?]\{n\}[a]\{n\}}}
|
|
|
574 |
\end{center}\bigskip\pause
|
|
|
575 |
|
|
|
576 |
and match them with strings of the form
|
|
|
577 |
|
|
|
578 |
\begin{center}
|
|
|
579 |
\bl{\texttt{a}},
|
|
|
580 |
\bl{\texttt{aa}},
|
|
|
581 |
\bl{\texttt{aaa}},
|
|
|
582 |
\bl{\texttt{aaaa}},
|
|
|
583 |
\bl{\texttt{aaaaa}},
|
|
|
584 |
\bl{$\underbrace{\texttt{a}...\texttt{a}}_n$}
|
|
|
585 |
\end{center}
|
|
|
586 |
|
|
|
587 |
\end{frame}
|
|
|
588 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
589 |
|
|
|
590 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
591 |
\begin{frame}[c]
|
|
|
592 |
\frametitle{Why Bother with Regexes?}
|
|
|
593 |
|
|
|
594 |
\begin{columns}[t,onlytextwidth]
|
|
|
595 |
\begin{column}{1.8cm}
|
|
|
596 |
\mbox{}
|
|
|
597 |
\end{column}
|
|
|
598 |
\begin{column}{.5\textwidth}
|
|
|
599 |
\small{}Ruby, Python, Java 8\medskip\\
|
|
|
600 |
\begin{tikzpicture}\footnotesize
|
|
|
601 |
\begin{axis}[
|
|
|
602 |
xlabel={$n$},
|
|
|
603 |
x label style={at={(1.05,0.0)}},
|
|
|
604 |
ylabel={time in secs},
|
|
|
605 |
enlargelimits=false,
|
|
|
606 |
xtick={0,5,...,30},
|
|
|
607 |
xmax=33,
|
|
|
608 |
ymax=35,
|
|
|
609 |
ytick={0,5,...,30},
|
|
|
610 |
scaled ticks=false,
|
|
|
611 |
axis lines=left,
|
|
|
612 |
width=\textwidth,
|
|
|
613 |
height=4cm,
|
|
|
614 |
legend entries={Python,Ruby},
|
|
|
615 |
legend pos=north west,
|
|
|
616 |
legend cell align=left]
|
|
|
617 |
\addplot[blue,mark=*, mark options={fill=white}] table {re-python.data};
|
|
|
618 |
\addplot[brown,mark=triangle*, mark options={fill=white}] table {re-ruby.data};
|
|
|
619 |
\end{axis}
|
|
|
620 |
\end{tikzpicture}
|
|
|
621 |
\begin{tikzpicture}\footnotesize
|
|
|
622 |
\begin{axis}[
|
|
|
623 |
xlabel={$n$},
|
|
|
624 |
x label style={at={(1.05,0.0)}},
|
|
|
625 |
ylabel={time in secs},
|
|
|
626 |
enlargelimits=false,
|
|
|
627 |
xtick={0,5,...,30},
|
|
|
628 |
xmax=33,
|
|
|
629 |
ymax=35,
|
|
|
630 |
ytick={0,5,...,30},
|
|
|
631 |
scaled ticks=false,
|
|
|
632 |
axis lines=left,
|
|
|
633 |
width=\textwidth,
|
|
|
634 |
height=4cm,
|
|
|
635 |
legend entries={Python, Java 8, JavaScript, Swift},
|
|
|
636 |
legend pos=north west,
|
|
|
637 |
legend cell align=left]
|
|
|
638 |
\addplot[blue,mark=*, mark options={fill=white}] table {re-python2.data};
|
|
|
639 |
\addplot[cyan,mark=*, mark options={fill=white}] table {re-java.data};
|
|
|
640 |
\addplot[red,mark=*, mark options={fill=white}] table {re-js.data};
|
|
|
641 |
\addplot[magenta,mark=*, mark options={fill=white}] table {re-swift.data};
|
|
|
642 |
\end{axis}
|
|
|
643 |
\end{tikzpicture}
|
|
|
644 |
%
|
|
|
645 |
\end{column}
|
|
|
646 |
\begin{column}{.5\textwidth}
|
|
|
647 |
\small{}Us (after next lecture)\medskip\\
|
|
|
648 |
\begin{tikzpicture}\footnotesize
|
|
|
649 |
\begin{axis}[
|
|
|
650 |
xlabel={$n$},
|
|
|
651 |
x label style={at={(1.07,0.0)}},
|
|
|
652 |
ylabel={time in secs},
|
|
|
653 |
enlargelimits=false,
|
|
|
654 |
xtick={0,5000,...,10000},
|
|
|
655 |
xmax=11000,
|
|
|
656 |
ymax=35,
|
|
|
657 |
ytick={0,5,...,30},
|
|
|
658 |
scaled ticks=false,
|
|
|
659 |
axis lines=left,
|
|
|
660 |
width=\textwidth,
|
|
|
661 |
height=4cm]
|
|
|
662 |
\addplot[green,mark=square*,mark options={fill=white}] table {re2.data};
|
|
|
663 |
\addplot[black,mark=square*,mark options={fill=white}] table {re3.data};
|
|
|
664 |
\end{axis}
|
|
|
665 |
\end{tikzpicture}
|
|
|
666 |
\begin{tikzpicture}\footnotesize
|
|
|
667 |
\begin{axis}[
|
|
|
668 |
xlabel={$n$},
|
|
|
669 |
x label style={at={(1.07,0.0)}},
|
|
|
670 |
ylabel={time in secs},
|
|
|
671 |
enlargelimits=false,
|
|
|
672 |
ymax=35,
|
|
|
673 |
ytick={0,5,...,30},
|
|
|
674 |
scaled ticks=false,
|
|
|
675 |
axis lines=left,
|
|
|
676 |
width=\textwidth,
|
|
|
677 |
height=4cm]
|
|
|
678 |
\addplot[black,mark=square*,mark options={fill=white}] table {re3a.data};
|
|
|
679 |
\end{axis}
|
|
|
680 |
\end{tikzpicture}
|
|
|
681 |
\end{column}
|
|
|
682 |
\end{columns}
|
|
|
683 |
\medskip
|
|
|
684 |
|
|
|
685 |
\begin{textblock}{3}(-0.1,3.3)
|
|
|
686 |
\small\hfill\bl{\texttt{[a?]\{n\}[a]\{n\}}}:
|
|
|
687 |
\end{textblock}
|
|
|
688 |
|
|
|
689 |
\begin{textblock}{3}(-0.1,8.7)
|
|
|
690 |
\small\hfill\bl{\texttt{(a*)*b}}:
|
|
|
691 |
\end{textblock}
|
|
|
692 |
|
|
|
693 |
\begin{textblock}{3}(0.3,13)
|
|
|
694 |
\small{}matching with strings
|
|
|
695 |
\bl{$\underbrace{\texttt{a}...\texttt{a}}_n$}
|
|
|
696 |
\end{textblock}
|
|
|
697 |
|
|
|
698 |
\end{frame}
|
|
|
699 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
700 |
|
|
|
701 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
702 |
\begin{frame}[c,fragile]
|
|
|
703 |
\frametitle{Incidents}
|
|
|
704 |
|
|
|
705 |
\begin{itemize}
|
|
|
706 |
\item a global outage on 2 July 2019 at \textbf{Cloudflare}
|
|
|
707 |
(first one for six years)\medskip
|
|
|
708 |
|
|
|
709 |
\begin{center}\small\color{blue}
|
|
|
710 |
\begin{verbatim}
|
|
|
711 |
(?:(?:\"|'|\]|\}|\\|\d|(?:nan|infinity|true|false|
|
|
|
712 |
null|undefined|symbol|math)|\`|\-|\+)+[)]*;?((?:\s
|
|
|
713 |
|-|~|!|{}|\|\||\+)*.*(?:.*=.*)))
|
|
|
714 |
\end{verbatim}
|
|
|
715 |
\end{center}\bigskip\bigskip\bigskip\bigskip\bigskip\bigskip\bigskip
|
|
|
716 |
|
|
|
717 |
\item on 20 July 2016 the \textbf{Stack Exchange} webpage went down
|
|
|
718 |
because of an evil regular expression
|
|
|
719 |
\here{https://stackstatus.net/post/147710624694/outage-postmortem-july-20-2016}
|
|
|
720 |
\end{itemize}
|
|
|
721 |
|
|
|
722 |
\begin{textblock}{6}(6,7.6)
|
|
|
723 |
\includegraphics[scale=0.14]{../pics/cloudflare.png}\\
|
|
|
724 |
\footnotesize
|
|
|
725 |
It serves more web traffic than Twitter, Amazon, Apple,
|
|
|
726 |
Instagram, Bing \& Wikipedia combined.
|
|
|
727 |
\here{https://blog.cloudflare.com/details-of-the-cloudflare-outage-on-july-2-2019/}
|
|
|
728 |
\end{textblock}
|
|
|
729 |
|
|
|
730 |
\end{frame}
|
|
|
731 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
732 |
|
|
|
733 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
734 |
\begin{frame}[c]
|
|
|
735 |
\frametitle{Evil Regular Expressions}
|
|
|
736 |
|
|
|
737 |
\begin{itemize}
|
|
|
738 |
\item \alert{R}egular \alert{e}xpression \alert{D}enial \alert{o}f \alert{S}ervice (ReDoS)\medskip
|
|
|
739 |
\item Some evil regular expressions:\medskip
|
|
|
740 |
\begin{itemize}
|
|
|
741 |
\item \bl{\texttt{[a?]\{n\}\;[a]\{n\}}}
|
|
|
742 |
\item \bl{\texttt{(a*)*\;b}}
|
|
|
743 |
\item \bl{\texttt{([a-z]+)*}}
|
|
|
744 |
\item \bl{\texttt{(a + aa)*}}
|
|
|
745 |
\item \bl{\texttt{(a + a?)*}}
|
|
|
746 |
\end{itemize}
|
|
|
747 |
|
|
|
748 |
\item sometimes also called \alert{catastrophic backtracking}
|
|
|
749 |
\item this is a problem for \alert{N}etwork \alert{I}ntrusion
|
|
|
750 |
\alert{D}etection systems, Cloudflare, StackExchange, Atom editor
|
|
|
751 |
\item \url{https://vimeo.com/112065252}
|
|
|
752 |
\end{itemize}
|
|
|
753 |
|
|
|
754 |
\end{frame}
|
|
|
755 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
756 |
|
|
|
757 |
|
|
|
758 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
759 |
%\begin{frame}[c]
|
|
|
760 |
%\frametitle{Today}
|
|
|
761 |
%
|
|
|
762 |
%\begin{itemize}
|
|
|
763 |
%\item While the ultimate goal is to implement a small compiler for the JVM
|
|
|
764 |
% \ldots\bigskip
|
|
|
765 |
%\end{itemize}
|
|
|
766 |
%
|
|
|
767 |
%Let's start with:
|
|
|
768 |
%
|
|
|
769 |
%\begin{itemize}
|
|
|
770 |
%\item a web-crawler
|
|
|
771 |
%\item an email harvester
|
|
|
772 |
%\item \textcolor{gray}{(a web-scraper)}
|
|
|
773 |
%\end{itemize}
|
|
|
774 |
%
|
|
|
775 |
%\end{frame}
|
|
|
776 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
777 |
|
|
|
778 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
779 |
%\begin{frame}[t]
|
|
|
780 |
%\frametitle{A Web-Crawler}
|
|
|
781 |
%
|
|
|
782 |
%\mbox{}\\[10mm]
|
|
|
783 |
%
|
|
|
784 |
%\begin{enumerate}
|
|
|
785 |
%\item given an URL, read the corresponding webpage
|
|
|
786 |
%\item extract all links from it
|
|
|
787 |
%\item call the web-crawler again for all these links
|
|
|
788 |
%\end{enumerate}
|
|
|
789 |
%
|
|
|
790 |
%\end{frame}
|
|
|
791 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
792 |
|
|
|
793 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
794 |
%\begin{frame}[t]
|
|
|
795 |
%\frametitle{A Web-Crawler}
|
|
|
796 |
%
|
|
|
797 |
%\mbox{}\\[10mm]
|
|
|
798 |
%
|
|
|
799 |
%
|
|
|
800 |
%\begin{enumerate}
|
|
|
801 |
%\item given an URL, read the corresponding webpage
|
|
|
802 |
%\item if not possible print, out a problem
|
|
|
803 |
%\item if possible, extract all links from it
|
|
|
804 |
%\item call the web-crawler again for all these links
|
|
|
805 |
%\end{enumerate}\bigskip\pause
|
|
|
806 |
%
|
|
|
807 |
%\small (we need a bound for the number of recursive calls)
|
|
|
808 |
%
|
|
|
809 |
%\small (the purpose is to check all links on my own webpage)
|
|
|
810 |
%\end{frame}
|
|
|
811 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
812 |
|
|
|
813 |
|
|
|
814 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
815 |
%\begin{frame}[c]
|
|
|
816 |
%
|
|
|
817 |
%\begin{textblock}{1}(2,5)
|
|
|
818 |
%\begin{tabular}{c}
|
|
|
819 |
%\includegraphics[scale=0.15]{pics/servers.png}\\[-2mm]
|
|
|
820 |
%\small Server
|
|
|
821 |
%\end{tabular}
|
|
|
822 |
%\end{textblock}
|
|
|
823 |
%
|
|
|
824 |
%\begin{textblock}{1}(5.6,4)
|
|
|
825 |
% \begin{tikzpicture}[scale=1.1]
|
|
|
826 |
% \draw[white] (0,1) node (X) {};
|
|
|
827 |
% \draw[white] (2,1) node (Y) {};
|
|
|
828 |
% \draw[white] (0,0) node (X1) {};
|
|
|
829 |
% \draw[white] (2,0) node (Y1) {};
|
|
|
830 |
% \draw[white] (0,-1) node (X2) {};
|
|
|
831 |
% \draw[white] (2,-1) node (Y2) {};
|
|
|
832 |
% \draw[red, <-, line width = 2mm] (X) -- (Y);
|
|
|
833 |
% \node [inner sep=5pt,label=above:\textcolor{black}{GET request}] at ($ (X)!.5!(Y) $) {};
|
|
|
834 |
% \draw[red, ->, line width = 2mm] (X1) -- (Y1);
|
|
|
835 |
% \node [inner sep=5pt,label=above:\textcolor{black}{webpage}] at ($ (X1)!.5!(Y1) $) {};
|
|
|
836 |
% \draw[red, <-, line width = 2mm] (X2) -- (Y2);
|
|
|
837 |
% \node [inner sep=7pt,label=above:\textcolor{black}{POST data}] at ($ (X2)!.5!(Y2) $) {};
|
|
|
838 |
% \end{tikzpicture}
|
|
|
839 |
%\end{textblock}
|
|
|
840 |
%
|
|
|
841 |
%
|
|
|
842 |
%\begin{textblock}{1}(9,5.5)
|
|
|
843 |
%\begin{tabular}{c}
|
|
|
844 |
%\includegraphics[scale=0.15]{pics/laptop.png}\\[-2mm]
|
|
|
845 |
%\small Browser
|
|
|
846 |
%\end{tabular}
|
|
|
847 |
%\end{textblock}
|
|
|
848 |
%\end{frame}
|
|
|
849 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
850 |
|
|
|
851 |
|
|
|
852 |
|
|
|
853 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
854 |
%\begin{frame}[c]
|
|
|
855 |
%\frametitle{Scala}
|
|
|
856 |
%
|
|
|
857 |
%\small A simple Scala function for reading webpages:
|
|
|
858 |
%\bigskip
|
|
|
859 |
%
|
|
|
860 |
%\footnotesize
|
|
|
861 |
%\lstinputlisting{../progs/app0.scala}
|
|
|
862 |
%\medskip\pause
|
|
|
863 |
%
|
|
|
864 |
%\lstinline{get_page("""https://nms.kcl.ac.uk/christian.urban/""")}
|
|
|
865 |
%\bigskip\medskip\pause
|
|
|
866 |
%
|
|
|
867 |
%
|
|
|
868 |
%\small A slightly more complicated version for handling errors:
|
|
|
869 |
%\smallskip
|
|
|
870 |
%
|
|
|
871 |
%\footnotesize
|
|
|
872 |
%\lstinputlisting[xleftmargin=-4mm]{../progs/app1.scala}
|
|
|
873 |
%
|
|
|
874 |
%
|
|
|
875 |
%\end{frame}
|
|
|
876 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
877 |
|
|
|
878 |
|
|
|
879 |
|
|
|
880 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
881 |
%\begin{frame}[t]
|
|
|
882 |
%\frametitle{A Regular Expression}
|
|
|
883 |
%
|
|
|
884 |
%\begin{itemize}
|
|
|
885 |
%\item \ldots{} is a pattern or template for specifying strings
|
|
|
886 |
%\end{itemize}\bigskip
|
|
|
887 |
%
|
|
|
888 |
%\begin{center}
|
|
|
889 |
%\only<1>{\scode{"https?://[^"]*"}}%
|
|
|
890 |
%\only<2>{\scode{""""https?://[^"]*"""".r}}
|
|
|
891 |
%\end{center}\bigskip\bigskip
|
|
|
892 |
%
|
|
|
893 |
%matches for example\smallskip\\
|
|
|
894 |
%\hspace{2mm}\code{"http://www.foobar.com"}\\
|
|
|
895 |
%\hspace{2mm}\code{"https://www.tls.org"}\smallskip\\
|
|
|
896 |
%
|
|
|
897 |
%but not\smallskip\\
|
|
|
898 |
%\hspace{2mm}\code{"http://www."foo"bar.com"}\\
|
|
|
899 |
%
|
|
|
900 |
%\end{frame}
|
|
|
901 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
902 |
|
|
|
903 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
904 |
%\begin{frame}[c]
|
|
|
905 |
%\frametitle{Finding Operations in Scala}
|
|
|
906 |
%
|
|
|
907 |
%{\bf\code{rexp.findAllIn(string)}}\medskip
|
|
|
908 |
%
|
|
|
909 |
%returns a list of all (sub)strings that match the
|
|
|
910 |
%regular expression
|
|
|
911 |
%\bigskip\bigskip
|
|
|
912 |
%
|
|
|
913 |
%
|
|
|
914 |
%{\bf\code{rexp.findFirstIn(string)}}\medskip
|
|
|
915 |
%
|
|
|
916 |
%returns either
|
|
|
917 |
%
|
|
|
918 |
%\begin{itemize}
|
|
|
919 |
%\item \code{None} if no (sub)string matches or
|
|
|
920 |
%\item \code{Some(s)} with the first (sub)string
|
|
|
921 |
%\end{itemize}
|
|
|
922 |
%
|
|
|
923 |
%\end{frame}
|
|
|
924 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
925 |
|
|
|
926 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
927 |
%\begin{frame}[c]
|
|
|
928 |
%
|
|
|
929 |
%\footnotesize
|
|
|
930 |
%\lstinputlisting{../progs/app2.scala}
|
|
|
931 |
%
|
|
|
932 |
%\end{frame}
|
|
|
933 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
934 |
|
|
|
935 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
936 |
%\begin{frame}[c]
|
|
|
937 |
%
|
|
|
938 |
%\small
|
|
|
939 |
%A version that only crawls links in ``my'' domain:\bigskip
|
|
|
940 |
%
|
|
|
941 |
%\footnotesize
|
|
|
942 |
%\lstinputlisting{../progs/app3.scala}
|
|
|
943 |
%
|
|
|
944 |
%\end{frame}
|
|
|
945 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
946 |
|
|
|
947 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
948 |
%\begin{frame}[c]
|
|
|
949 |
%\lstset{xleftmargin=-4mm}
|
|
|
950 |
%\small
|
|
|
951 |
%A little email harvester:
|
|
|
952 |
%
|
|
|
953 |
%\footnotesize
|
|
|
954 |
%\lstinputlisting{../progs/app4.scala}\bigskip
|
|
|
955 |
%
|
|
|
956 |
%\tiny
|
|
|
957 |
%\url{http://net.tutsplus.com/tutorials/other/8-regular-expressions-you-should-know/}
|
|
|
958 |
%
|
|
|
959 |
%\end{frame}
|
|
|
960 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
961 |
|
|
|
962 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
963 |
\begin{frame}[t]
|
|
|
964 |
\frametitle{(Basic) Regular Expressions}
|
|
|
965 |
|
|
|
966 |
Their inductive definition:
|
|
|
967 |
|
|
|
968 |
|
|
|
969 |
\begin{textblock}{6}(2,7.5)
|
|
|
970 |
\begin{tabular}{@ {}rrl@ {\hspace{13mm}}l}
|
|
|
971 |
\bl{$r$} & \bl{$::=$} & \bl{$\ZERO$} & nothing\\
|
|
|
972 |
& \bl{$\mid$} & \bl{$\ONE$} & empty string / \pcode{""} / $[]$\\
|
|
|
973 |
& \bl{$\mid$} & \bl{$c$} & character\\
|
|
|
974 |
& \bl{$\mid$} & \bl{$r_1 + r_2$} & alternative / choice\\
|
|
|
975 |
& \bl{$\mid$} & \bl{$r_1 \cdot r_2$} & sequence\\
|
|
|
976 |
& \bl{$\mid$} & \bl{$r^*$} & star (zero or more)\\
|
|
|
977 |
\end{tabular}
|
|
|
978 |
\end{textblock}
|
|
|
979 |
|
|
|
980 |
|
|
|
981 |
\only<2->{\footnotesize
|
|
|
982 |
\begin{textblock}{9}(2,0.5)
|
|
|
983 |
\begin{bubble}[9.8cm]
|
|
|
984 |
\lstinputlisting{../progs/app01.scala}
|
|
|
985 |
\end{bubble}
|
|
|
986 |
\end{textblock}}
|
|
|
987 |
|
|
|
988 |
\end{frame}
|
|
|
989 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
990 |
|
|
|
991 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
992 |
%\begin{frame}[t]
|
|
|
993 |
%\frametitle{Regular Expressions}
|
|
|
994 |
%
|
|
|
995 |
%\small
|
|
|
996 |
%In Scala:\bigskip
|
|
|
997 |
%
|
|
|
998 |
%\footnotesize
|
|
|
999 |
%\lstinputlisting{../progs/app51.scala}
|
|
|
1000 |
%
|
|
|
1001 |
%
|
|
|
1002 |
%\end{frame}
|
|
|
1003 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1004 |
|
|
|
1005 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1006 |
\begin{frame}[t]
|
|
|
1007 |
\frametitle{Strings}
|
|
|
1008 |
|
|
|
1009 |
\ldots are lists of characters. For example \code{"hello"}
|
|
|
1010 |
|
|
|
1011 |
\begin{center}
|
|
|
1012 |
\bl{$[h, e, l, l, o]$} or just \bl{$hello$}
|
|
|
1013 |
\end{center}
|
|
|
1014 |
|
|
|
1015 |
the empty string: \bl{$[]$} or \bl{\pcode{""}}\bigskip\\
|
|
|
1016 |
|
|
|
1017 |
the concatenation of two strings:
|
|
|
1018 |
|
|
|
1019 |
\begin{center}
|
|
|
1020 |
\bl{$s_1 \,@\, s_2$}
|
|
|
1021 |
\end{center}
|
|
|
1022 |
|
|
|
1023 |
\bl{\textit{foo $@$ bar = foobar}}\\
|
|
|
1024 |
\bl{\textit{baz $@\, []$ = baz}}
|
|
|
1025 |
|
|
|
1026 |
\end{frame}
|
|
|
1027 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1028 |
|
|
|
1029 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1030 |
\begin{frame}[c]
|
|
|
1031 |
\frametitle{Languages, Strings}
|
|
|
1032 |
|
|
|
1033 |
\begin{itemize}
|
|
|
1034 |
\item \alert{\bf Strings} are lists of characters, for example
|
|
|
1035 |
\begin{center}
|
|
|
1036 |
\bl{$[]$},\;\bl{$abc$} \hspace{2cm}(Pattern match: \bl{$c\!::\!s$})
|
|
|
1037 |
\end{center}\bigskip
|
|
|
1038 |
|
|
|
1039 |
|
|
|
1040 |
\item A \alert{\bf language} is a set of strings, for example\medskip
|
|
|
1041 |
\begin{center}
|
|
|
1042 |
\bl{$\{[], hello, \textit{foobar}, a, abc\}$}
|
|
|
1043 |
\end{center}\bigskip
|
|
|
1044 |
|
|
|
1045 |
\item \alert{\bf Concatenation} of strings and languages
|
|
|
1046 |
|
|
|
1047 |
\begin{center}
|
|
|
1048 |
\begin{tabular}{rcl}
|
|
|
1049 |
\bl{$\textit{foo}\;@\;bar$} & \bl{$=$} & \bl{$\textit{foobar}$}\medskip\\
|
|
|
1050 |
\bl{$A\;@\;B$} & \bl{$\dn$} & \bl{$\{ s_1\,@\,s_2 \;\mid\; s_1 \in A \wedge s_2 \in B\}$}
|
|
|
1051 |
\end{tabular}
|
|
|
1052 |
\end{center}
|
|
|
1053 |
|
|
|
1054 |
%\item The \alert{\bf meaning} of a regular expression is a set of
|
|
|
1055 |
% strings, or language.
|
|
|
1056 |
\end{itemize}
|
|
|
1057 |
|
|
|
1058 |
\only<2>{
|
|
|
1059 |
\begin{textblock}{4}(10.5,8)
|
|
|
1060 |
\small
|
|
|
1061 |
Let
|
|
|
1062 |
|
|
|
1063 |
\bl{$A = \{foo, bar\}$} \bl{$B = \{a, b\}$}
|
|
|
1064 |
\[
|
|
|
1065 |
\bl{A \,@\, B = \{fooa, foob, bara, barb\}}
|
|
|
1066 |
\]
|
|
|
1067 |
\end{textblock}}
|
|
|
1068 |
|
|
|
1069 |
\end{frame}
|
|
|
1070 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1071 |
|
|
|
1072 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1073 |
\begin{frame}[c]
|
|
|
1074 |
\frametitle{Two Corner Cases}
|
|
|
1075 |
|
|
|
1076 |
\Large
|
|
|
1077 |
\begin{center}
|
|
|
1078 |
\bl{$A \,@\, \{[]\} = \;?$}\bigskip\bigskip\pause\\
|
|
|
1079 |
\bl{$A \,@\, \{\} = \;?$}
|
|
|
1080 |
\end{center}
|
|
|
1081 |
|
|
|
1082 |
\end{frame}
|
|
|
1083 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1084 |
|
|
|
1085 |
|
|
|
1086 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1087 |
\begin{frame}[c]
|
|
|
1088 |
\frametitle{The Meaning of a Regex}
|
|
|
1089 |
|
|
|
1090 |
...all the strings a regular expression can match.
|
|
|
1091 |
|
|
|
1092 |
\begin{center}
|
|
|
1093 |
\begin{tabular}{rcl}
|
|
|
1094 |
\bl{$L(\ZERO)$} & \bl{$\dn$} & \bl{$\{\}$}\\
|
|
|
1095 |
\bl{$L(\ONE)$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
|
1096 |
\bl{$L(c)$} & \bl{$\dn$} & \bl{$\{[c]\}$}\\
|
|
|
1097 |
\bl{$L(r_1 + r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \cup L(r_2)$}\\
|
|
|
1098 |
\bl{$L(r_1 \cdot r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \,@\, L(r_2)$}\\
|
|
|
1099 |
\bl{$L(r^*)$} & \bl{$\dn$} & \\
|
|
|
1100 |
\end{tabular}
|
|
|
1101 |
\end{center}
|
|
|
1102 |
|
|
|
1103 |
\begin{textblock}{14}(1.5,13.5)\small
|
|
|
1104 |
\bl{$L$} is a function from regular expressions to
|
|
|
1105 |
sets of strings (languages):\smallskip\\
|
|
|
1106 |
\bl{\quad$L$ : Rexp $\Rightarrow$ Set$[$String$]$}
|
|
|
1107 |
\end{textblock}
|
|
|
1108 |
|
|
|
1109 |
\end{frame}
|
|
|
1110 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1111 |
|
|
|
1112 |
|
|
|
1113 |
|
|
|
1114 |
|
|
|
1115 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1116 |
\begin{frame}[c]
|
|
|
1117 |
\frametitle{The Power Operation}
|
|
|
1118 |
|
|
|
1119 |
\begin{itemize}
|
|
|
1120 |
\item The \alert{\textbf{\boldmath$n$th Power}} of a language:
|
|
|
1121 |
|
|
|
1122 |
\begin{center}
|
|
|
1123 |
\begin{tabular}{lcl}
|
|
|
1124 |
\bl{$A^0$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
|
1125 |
\bl{$A^{n+1}$} & \bl{$\dn$} & \bl{$A \,@\, A^n$}
|
|
|
1126 |
\end{tabular}
|
|
|
1127 |
\end{center}\bigskip
|
|
|
1128 |
|
|
|
1129 |
\item[] For example
|
|
|
1130 |
|
|
|
1131 |
\begin{center}
|
|
|
1132 |
\begin{tabular}{lcl@{\hspace{10mm}}l}
|
|
|
1133 |
\bl{$A^4$} & \bl{$=$} & \bl{$A \,@\, A \,@\, A \,@\, A$} & \bl{$(@\,\{[]\})$}\\
|
|
|
1134 |
\bl{$A^1$} & \bl{$=$} & \bl{$A$} & \bl{$(@\,\{[]\})$}\\
|
|
|
1135 |
\bl{$A^0$} & \bl{$=$} & \bl{$\{[]\}$}\\
|
|
|
1136 |
\end{tabular}
|
|
|
1137 |
\end{center}
|
|
|
1138 |
|
|
|
1139 |
\end{itemize}
|
|
|
1140 |
|
|
|
1141 |
\end{frame}
|
|
|
1142 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1143 |
|
|
|
1144 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1145 |
\begin{frame}[c]
|
|
|
1146 |
\frametitle{The Meaning of a Regex}
|
|
|
1147 |
|
|
|
1148 |
\begin{textblock}{15}(1,4)
|
|
|
1149 |
\begin{tabular}{rcl}
|
|
|
1150 |
\bl{$L(\ZERO)$} & \bl{$\dn$} & \bl{$\{\}$}\\
|
|
|
1151 |
\bl{$L(\ONE)$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
|
1152 |
\bl{$L(c)$} & \bl{$\dn$} & \bl{$\{[c]\}$}\\
|
|
|
1153 |
\bl{$L(r_1 + r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \cup L(r_2)$}\\
|
|
|
1154 |
\bl{$L(r_1 \cdot r_2)$} & \bl{$\dn$} & \bl{$\{ s_1 \,@\, s_2 \;|\; s_1 \in L(r_1) \wedge s_2 \in L(r_2) \}$}\\
|
|
|
1155 |
\bl{$L(r^*)$} & \bl{$\dn$} & \onslide<2->{\bl{$\bigcup_{0 \le n} L(r)^n$}}\\
|
|
|
1156 |
\end{tabular}\bigskip
|
|
|
1157 |
|
|
|
1158 |
%\onslide<2->{
|
|
|
1159 |
%\hspace{5mm}\bl{$L(r)^0 \;\dn\; \{[]\}$}\\
|
|
|
1160 |
%\bl{$L(r)^{n+1} \;\dn\; L(r) \,@\, L(r)^n$}\hspace{9mm}\onslide<3->{\small\textcolor{gray}{(append on sets)}\\
|
|
|
1161 |
%\small\hspace{5cm}\textcolor{gray}{$\{ s_1 @ s_2 \;|\; s_1\in L(r) \wedge s_2 \in L(r)^n \}$}}
|
|
|
1162 |
%}
|
|
|
1163 |
\end{textblock}
|
|
|
1164 |
|
|
|
1165 |
\end{frame}
|
|
|
1166 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1167 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1168 |
\begin{frame}[c]
|
|
|
1169 |
\frametitle{The Star Operation}
|
|
|
1170 |
|
|
|
1171 |
\begin{itemize}
|
|
|
1172 |
\item The \alert{\bf Kleene Star} of a \underline{language}:
|
|
|
1173 |
\bigskip
|
|
|
1174 |
|
|
|
1175 |
\begin{center}
|
|
|
1176 |
\begin{tabular}{c}
|
|
|
1177 |
\bl{$A\star \dn \bigcup_{0\le n} A^n$}
|
|
|
1178 |
\end{tabular}
|
|
|
1179 |
\end{center}\bigskip
|
|
|
1180 |
|
|
|
1181 |
\item[] This expands to
|
|
|
1182 |
|
|
|
1183 |
\[
|
|
|
1184 |
\bl{A^0 \cup A^1 \cup A^2 \cup A^3 \cup A^4 \cup \ldots}
|
|
|
1185 |
\]
|
|
|
1186 |
|
|
|
1187 |
or
|
|
|
1188 |
|
|
|
1189 |
\small
|
|
|
1190 |
\[
|
|
|
1191 |
\bl{\{[]\} \;\cup\; A \;\cup\; A\,@\,A \;\cup\;
|
|
|
1192 |
A\,@\,A\,@\,A \;\cup\; A\,@\,A\,@\,A\,@\,A \cup \ldots}
|
|
|
1193 |
\]
|
|
|
1194 |
|
|
|
1195 |
\end{itemize}
|
|
|
1196 |
|
|
|
1197 |
\end{frame}
|
|
|
1198 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1199 |
|
|
|
1200 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1201 |
\begin{frame}[c]
|
|
|
1202 |
\frametitle{The Meaning of a Regex}
|
|
|
1203 |
|
|
|
1204 |
\begin{textblock}{15}(1,4)
|
|
|
1205 |
\begin{tabular}{rcl}
|
|
|
1206 |
\bl{$L(\ZERO)$} & \bl{$\dn$} & \bl{$\{\}$}\\
|
|
|
1207 |
\bl{$L(\ONE)$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
|
1208 |
\bl{$L(c)$} & \bl{$\dn$} & \bl{$\{[c]\}$}\\
|
|
|
1209 |
\bl{$L(r_1 + r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \cup L(r_2)$}\\
|
|
|
1210 |
\bl{$L(r_1 \cdot r_2)$} & \bl{$\dn$} & \bl{$\{ s_1 \,@\, s_2 \;|\; s_1 \in L(r_1) \wedge s_2 \in L(r_2) \}$}\\
|
|
|
1211 |
\bl{$L(r^*)$} & \bl{$\dn$} & \bl{$(L(r))\star$}\\
|
|
|
1212 |
\end{tabular}
|
|
|
1213 |
|
|
|
1214 |
\end{textblock}
|
|
|
1215 |
|
|
|
1216 |
\end{frame}
|
|
|
1217 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1218 |
|
|
|
1219 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1220 |
\begin{frame}[c]
|
|
|
1221 |
\frametitle{The Meaning of Matching}
|
|
|
1222 |
|
|
|
1223 |
\begin{bubble}[10cm]
|
|
|
1224 |
\large\bf
|
|
|
1225 |
A regular expression \bl{$r$} matches a string~\bl{$s$}
|
|
|
1226 |
provided
|
|
|
1227 |
|
|
|
1228 |
\begin{center}
|
|
|
1229 |
\bl{$s \in L(r)$}\\
|
|
|
1230 |
\end{center}
|
|
|
1231 |
\end{bubble}\bigskip\bigskip
|
|
|
1232 |
|
|
|
1233 |
\ldots and the point of the next lecture is
|
|
|
1234 |
to decide this problem as fast as possible (unlike Python,
|
|
|
1235 |
Ruby, Java)
|
|
|
1236 |
|
|
|
1237 |
\end{frame}
|
|
|
1238 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1239 |
|
|
|
1240 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1241 |
\begin{frame}[c]
|
|
|
1242 |
\frametitle{Questions}
|
|
|
1243 |
|
|
|
1244 |
\begin{itemize}
|
|
|
1245 |
\item Say \bl{$A = \{[a],[b],[c],[d]\}$}.\bigskip
|
|
|
1246 |
|
|
|
1247 |
\item[]
|
|
|
1248 |
How many strings are in \bl{$A^4$}\,?
|
|
|
1249 |
\bigskip\medskip\pause
|
|
|
1250 |
|
|
|
1251 |
|
|
|
1252 |
\item[]
|
|
|
1253 |
What if \bl{$A = \{[a],[b],[c],[]\}$};\\
|
|
|
1254 |
how many strings are then in \bl{$A^4$}\,?
|
|
|
1255 |
\end{itemize}
|
|
|
1256 |
|
|
|
1257 |
\end{frame}
|
|
|
1258 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1259 |
|
|
|
1260 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1261 |
% \begin{frame}[c]
|
|
|
1262 |
% \frametitle{Languages (Sets of Strings)}
|
|
|
1263 |
|
|
|
1264 |
% \begin{itemize}
|
|
|
1265 |
|
|
|
1266 |
% \item A \alert{\bf Language} is a set of strings, for example\medskip
|
|
|
1267 |
% \begin{center}
|
|
|
1268 |
% \bl{$\{[], hello, foobar, a, abc\}$}
|
|
|
1269 |
% \end{center}\bigskip
|
|
|
1270 |
|
|
|
1271 |
% \item \alert{\bf Concatenation} for strings and languages
|
|
|
1272 |
|
|
|
1273 |
% \begin{center}
|
|
|
1274 |
% \begin{tabular}{rcl}
|
|
|
1275 |
% \bl{$foo\;@\;bar$} & \bl{$=$} & \bl{$foobar$}\medskip\\
|
|
|
1276 |
% \bl{$A\;@\;B$} & \bl{$\dn$} & \bl{$\{ s_1\,@\,s_2 \;\mid\; s_1 \in A \wedge s_2 \in B\}$}
|
|
|
1277 |
% \end{tabular}
|
|
|
1278 |
% \end{center}
|
|
|
1279 |
% \bigskip
|
|
|
1280 |
|
|
|
1281 |
% \small
|
|
|
1282 |
% \item [] For example \bl{$A = \{foo, bar\}$}, \bl{$B = \{a, b\}$}
|
|
|
1283 |
|
|
|
1284 |
% \[
|
|
|
1285 |
% \bl{A \,@\, B = \{fooa, foob, bara, barb\}}
|
|
|
1286 |
% \]
|
|
|
1287 |
|
|
|
1288 |
|
|
|
1289 |
|
|
|
1290 |
|
|
|
1291 |
% \end{itemize}
|
|
|
1292 |
% \end{frame}
|
|
|
1293 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1294 |
|
|
|
1295 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1296 |
% \begin{frame}[c]
|
|
|
1297 |
% \frametitle{Two Corner Cases}
|
|
|
1298 |
|
|
|
1299 |
% \Large
|
|
|
1300 |
% \begin{center}
|
|
|
1301 |
% \bl{$A \,@\, \{[]\} = \;?$}\bigskip\bigskip\pause\\
|
|
|
1302 |
% \bl{$A \,@\, \{\} = \;?$}
|
|
|
1303 |
% \end{center}
|
|
|
1304 |
|
|
|
1305 |
% \end{frame}
|
|
|
1306 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1307 |
|
|
|
1308 |
|
|
|
1309 |
|
|
|
1310 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1311 |
% \begin{frame}[c]
|
|
|
1312 |
% \frametitle{The Meaning of a Regex}
|
|
|
1313 |
|
|
|
1314 |
% ...all the strings a regular expression can match.
|
|
|
1315 |
|
|
|
1316 |
% \begin{center}
|
|
|
1317 |
% \begin{tabular}{rcl}
|
|
|
1318 |
% \bl{$L(\ZERO)$} & \bl{$\dn$} & \bl{$\{\}$}\\
|
|
|
1319 |
% \bl{$L(\ONE)$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
|
1320 |
% \bl{$L(c)$} & \bl{$\dn$} & \bl{$\{[c]\}$}\\
|
|
|
1321 |
% \bl{$L(r_1 + r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \cup L(r_2)$}\\
|
|
|
1322 |
% \bl{$L(r_1 \cdot r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \,@\, L(r_2)$}\\
|
|
|
1323 |
% \bl{$L(r^*)$} & \bl{$\dn$} & \\
|
|
|
1324 |
% \end{tabular}
|
|
|
1325 |
% \end{center}
|
|
|
1326 |
|
|
|
1327 |
% \begin{textblock}{14}(1.5,13.5)\small
|
|
|
1328 |
% \bl{$L$} is a function from regular expressions to
|
|
|
1329 |
% sets of strings (languages):\smallskip\\
|
|
|
1330 |
% \bl{\quad$L$ : Rexp $\Rightarrow$ Set$[$String$]$}
|
|
|
1331 |
% \end{textblock}
|
|
|
1332 |
|
|
|
1333 |
% \end{frame}
|
|
|
1334 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1335 |
|
|
|
1336 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1337 |
% \begin{frame}[c]
|
|
|
1338 |
% \frametitle{The Power Operation}
|
|
|
1339 |
|
|
|
1340 |
% \begin{itemize}
|
|
|
1341 |
% \item The \alert{\textbf{\boldmath$n$th Power}} of a language:
|
|
|
1342 |
|
|
|
1343 |
% \begin{center}
|
|
|
1344 |
% \begin{tabular}{lcl}
|
|
|
1345 |
% \bl{$A^0$} & \bl{$\dn$} & \bl{$\{[]\}$}\\
|
|
|
1346 |
% \bl{$A^{n+1}$} & \bl{$\dn$} & \bl{$A \,@\, A^n$}
|
|
|
1347 |
% \end{tabular}
|
|
|
1348 |
% \end{center}\bigskip
|
|
|
1349 |
|
|
|
1350 |
% \item[] For example
|
|
|
1351 |
|
|
|
1352 |
% \begin{center}
|
|
|
1353 |
% \begin{tabular}{lcl@{\hspace{10mm}}l}
|
|
|
1354 |
% \bl{$A^4$} & \bl{$=$} & \bl{$A \,@\, A \,@\, A \,@\, A$} & \bl{$(@\,\{[]\})$}\\
|
|
|
1355 |
% \bl{$A^1$} & \bl{$=$} & \bl{$A$} & \bl{$(@\,\{[]\})$}\\
|
|
|
1356 |
% \bl{$A^0$} & \bl{$=$} & \bl{$\{[]\}$}\\
|
|
|
1357 |
% \end{tabular}
|
|
|
1358 |
% \end{center}
|
|
|
1359 |
|
|
|
1360 |
% \end{itemize}
|
|
|
1361 |
|
|
|
1362 |
% \end{frame}
|
|
|
1363 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1364 |
|
|
|
1365 |
|
|
|
1366 |
|
|
|
1367 |
|
|
|
1368 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1369 |
% \begin{frame}[c]
|
|
|
1370 |
% \frametitle{Written Exam}
|
|
|
1371 |
|
|
|
1372 |
% \begin{itemize}
|
|
|
1373 |
% \item Accounts for 80\%.\bigskip
|
|
|
1374 |
|
|
|
1375 |
% \item The question ``\textit{Is this relevant for
|
|
|
1376 |
% the exam?}'' is very demotivating for the lecturer!\bigskip\\
|
|
|
1377 |
|
|
|
1378 |
% \item Deal: Whatever is in the homework (and is not marked
|
|
|
1379 |
% ``\textit{optional}'') is relevant for the exam.\bigskip
|
|
|
1380 |
|
|
|
1381 |
% \item Each lecture has also a handout. There are also handouts about
|
|
|
1382 |
% notation and Scala.
|
|
|
1383 |
% \end{itemize}
|
|
|
1384 |
|
|
|
1385 |
% \end{frame}
|
|
|
1386 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1387 |
|
|
|
1388 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1389 |
% \begin{frame}[t]
|
|
|
1390 |
% \frametitle{Coursework}
|
|
|
1391 |
|
|
|
1392 |
% \begin{itemize}
|
|
|
1393 |
% \item Accounts for 20\%. Two strands. Choose \alert{\bf one}!\bigskip
|
|
|
1394 |
% \end{itemize}
|
|
|
1395 |
|
|
|
1396 |
% \begin{columns}[t]
|
|
|
1397 |
% \begin{column}{.5\textwidth}
|
|
|
1398 |
% \underline{\bf Strand 1}\medskip
|
|
|
1399 |
% \begin{itemize}
|
|
|
1400 |
% \item 4 programming tasks:
|
|
|
1401 |
% \begin{itemize}
|
|
|
1402 |
% \item matcher (4\%, 11.10.)
|
|
|
1403 |
% \item lexer (5\%, 04.11.)
|
|
|
1404 |
% \item parser (5\%, 22.11.)
|
|
|
1405 |
% \item compiler (6\%, 13.12.)
|
|
|
1406 |
% \end{itemize}
|
|
|
1407 |
% \item in any lang.~you like,\\ but I want to see the\\ code
|
|
|
1408 |
% \end{itemize}
|
|
|
1409 |
% \end{column}
|
|
|
1410 |
|
|
|
1411 |
% \hspace{-45pt}\vrule{}\hspace{10pt}
|
|
|
1412 |
% \begin{column}{.5\textwidth}
|
|
|
1413 |
% \underline{\bf Strand 2}\smallskip\begin{itemize}
|
|
|
1414 |
% \item one task: prove the correctness of a regular expression matcher in
|
|
|
1415 |
% the \underline{Isabelle} theorem prover
|
|
|
1416 |
% \item 20\%, submission on~13.12.\hspace{-5mm}\mbox{}
|
|
|
1417 |
% \end{itemize}
|
|
|
1418 |
% \end{column}
|
|
|
1419 |
% \end{columns}\medskip
|
|
|
1420 |
|
|
|
1421 |
% \small
|
|
|
1422 |
% \begin{itemize}
|
|
|
1423 |
% \item Solving more than one strand will {\bf not} give you more
|
|
|
1424 |
% marks.
|
|
|
1425 |
|
|
|
1426 |
% \end{itemize}
|
|
|
1427 |
|
|
|
1428 |
% \end{frame}
|
|
|
1429 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1430 |
|
|
|
1431 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1432 |
%\begin{frame}[c]
|
|
|
1433 |
%\frametitle{Lecture Capture}
|
|
|
1434 |
%
|
|
|
1435 |
%\begin{itemize}
|
|
|
1436 |
%\item Hope it works\ldots\pause actually no, it does not!\medskip\pause
|
|
|
1437 |
%\item It is important to use lecture capture wisely\\ (it is only the ``baseline''):
|
|
|
1438 |
%\begin{itemize}
|
|
|
1439 |
%\item Lecture recordings are a study and revision aid.
|
|
|
1440 |
%\item Statistically, there is a clear and direct link between attendance and
|
|
|
1441 |
% attainment: students who do not attend lectures, do less well in exams.
|
|
|
1442 |
%\end{itemize}
|
|
|
1443 |
%
|
|
|
1444 |
%\item Attending a lecture is more than watching it online -- if you do not
|
|
|
1445 |
%attend, you miss out!
|
|
|
1446 |
%
|
|
|
1447 |
%\end{itemize}
|
|
|
1448 |
%
|
|
|
1449 |
%\end{frame}
|
|
|
1450 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1451 |
|
|
|
1452 |
|
|
|
1453 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1454 |
\begin{frame}[c]
|
|
|
1455 |
\frametitle{\begin{tabular}{c}\\[3cm]\alert{Questions?}\end{tabular}}
|
|
|
1456 |
|
|
|
1457 |
|
|
|
1458 |
\begin{tabular}{lll}
|
|
|
1459 |
TAs: & Finley Warman & (took the module last year)\\
|
|
|
1460 |
& Chengsong Tan & (PhD student working on derivatives)
|
|
|
1461 |
\end{tabular}
|
|
|
1462 |
\mbox{}
|
|
|
1463 |
\end{frame}
|
|
|
1464 |
|
|
|
1465 |
\begin{frame}[c]
|
|
|
1466 |
\end{frame}
|
|
|
1467 |
|
|
|
1468 |
\begin{frame}[c]
|
|
|
1469 |
\end{frame}
|
|
|
1470 |
|
|
|
1471 |
\begin{frame}[c]
|
|
|
1472 |
\end{frame}
|
|
|
1473 |
|
|
|
1474 |
\begin{frame}[c]
|
|
|
1475 |
\end{frame}
|
|
|
1476 |
|
|
|
1477 |
\begin{frame}[c]
|
|
|
1478 |
\end{frame}
|
|
|
1479 |
|
|
|
1480 |
\begin{frame}[c]
|
|
|
1481 |
\end{frame}
|
|
|
1482 |
|
|
|
1483 |
\begin{frame}[c]
|
|
|
1484 |
\end{frame}
|
|
|
1485 |
|
|
|
1486 |
\begin{frame}[c]
|
|
|
1487 |
\end{frame}
|
|
|
1488 |
|
|
|
1489 |
\begin{frame}[c]
|
|
|
1490 |
\end{frame}
|
|
|
1491 |
|
|
|
1492 |
\begin{frame}[c]
|
|
|
1493 |
\end{frame}
|
|
|
1494 |
|
|
|
1495 |
\begin{frame}[c]
|
|
|
1496 |
\end{frame}
|
|
|
1497 |
|
|
|
1498 |
\begin{frame}[c]
|
|
|
1499 |
\end{frame}
|
|
|
1500 |
|
|
|
1501 |
\begin{frame}[c]
|
|
|
1502 |
\end{frame}
|
|
|
1503 |
|
|
|
1504 |
\begin{frame}[c]
|
|
|
1505 |
\end{frame}
|
|
|
1506 |
|
|
|
1507 |
|
|
|
1508 |
\begin{frame}[c]
|
|
|
1509 |
\begin{mybox3}{Coursework}
|
|
|
1510 |
Do we need to provide instructions on running the coursework files
|
|
|
1511 |
if we're using languages other than Scala? Thanks
|
|
|
1512 |
\end{mybox3}\pause
|
|
|
1513 |
|
|
|
1514 |
\begin{mybox2}{Zip-File for Coursework}
|
|
|
1515 |
Please, please submit a zipfile that generates a subdirectory
|
|
|
1516 |
\begin{center}
|
|
|
1517 |
\texttt{NameFamilyName}
|
|
|
1518 |
\end{center}
|
|
|
1519 |
\end{mybox2}
|
|
|
1520 |
\end{frame}
|
|
|
1521 |
|
|
|
1522 |
|
|
|
1523 |
\begin{frame}[c]
|
|
|
1524 |
\begin{mybox3}{Coursework}
|
|
|
1525 |
What is the purpose of the workshop session on the timetable?
|
|
|
1526 |
|
|
|
1527 |
Slightly confused about how to undertake cw1 and what exactly we
|
|
|
1528 |
should be implementing. This is more for clarification of the cw1
|
|
|
1529 |
structure, including the implementation and questions present in
|
|
|
1530 |
cw1.
|
|
|
1531 |
\end{mybox3}
|
|
|
1532 |
\end{frame}
|
|
|
1533 |
|
|
|
1534 |
\begin{frame}[c]
|
|
|
1535 |
\begin{mybox3}{What is the trick?}\small
|
|
|
1536 |
What was the trick to improve the evil regular expressions matcher
|
|
|
1537 |
to have such good results compared to other programming languages?
|
|
|
1538 |
Is it working better on casual regular expressions (the ones that
|
|
|
1539 |
Python and Java handle pretty well), too? Or was it just optimised
|
|
|
1540 |
for these evil ones?
|
|
|
1541 |
\end{mybox3}
|
|
|
1542 |
|
|
|
1543 |
\begin{mybox3}{}\small
|
|
|
1544 |
It was shown in the lectures that the pattern matching algorithms
|
|
|
1545 |
currently implemented in popular programming languages (Python, JS,
|
|
|
1546 |
Java, etc) are far slower than the algorithm we are going to be
|
|
|
1547 |
implementing in this module. My question is why do these programming
|
|
|
1548 |
languages not implement the algorithm that we are going to implement
|
|
|
1549 |
in this module?
|
|
|
1550 |
\end{mybox3}
|
|
|
1551 |
\end{frame}
|
|
|
1552 |
|
|
|
1553 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1554 |
\begin{frame}[c]
|
|
|
1555 |
\frametitle{Thanks to Martin Mikusovic}
|
|
|
1556 |
|
|
|
1557 |
\bigskip
|
|
|
1558 |
\begin{center}
|
|
|
1559 |
\begin{tikzpicture}
|
|
|
1560 |
\begin{axis}[
|
|
|
1561 |
xlabel={$n$},
|
|
|
1562 |
x label style={at={(1.05,0.0)}},
|
|
|
1563 |
ylabel={time in secs},
|
|
|
1564 |
enlargelimits=false,
|
|
|
1565 |
xtick={0,5,...,30},
|
|
|
1566 |
xmax=33,
|
|
|
1567 |
ymax=35,
|
|
|
1568 |
ytick={0,10,...,30},
|
|
|
1569 |
scaled ticks=false,
|
|
|
1570 |
axis lines=left,
|
|
|
1571 |
width=9cm,
|
|
|
1572 |
height=5.5cm,
|
|
|
1573 |
legend entries={Java 8, Python, JavaScript, Swift},
|
|
|
1574 |
legend pos=north west,
|
|
|
1575 |
legend cell align=left]
|
|
|
1576 |
\addplot[blue,mark=*, mark options={fill=white}] table {re-python2.data};
|
|
|
1577 |
\addplot[cyan,mark=*, mark options={fill=white}] table {re-java.data};
|
|
|
1578 |
\addplot[red,mark=*, mark options={fill=white}] table {re-js.data};
|
|
|
1579 |
\addplot[magenta,mark=*, mark options={fill=white}] table {re-swift.data};
|
|
|
1580 |
\end{axis}
|
|
|
1581 |
\end{tikzpicture}
|
|
|
1582 |
\end{center}
|
|
|
1583 |
|
|
|
1584 |
Regex: \bl{$(a^*)^* \cdot b$}
|
|
|
1585 |
|
|
|
1586 |
Strings of the form \bl{$\underbrace{\,a\ldots a\,}_{n}$}
|
|
|
1587 |
|
|
|
1588 |
\end{frame}
|
|
|
1589 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1590 |
|
|
|
1591 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1592 |
\begin{frame}[c]
|
|
|
1593 |
\frametitle{Same Example in Java 9+}
|
|
|
1594 |
|
|
|
1595 |
\begin{center}
|
|
|
1596 |
\begin{tikzpicture}
|
|
|
1597 |
\begin{axis}[
|
|
|
1598 |
xlabel={$n$},
|
|
|
1599 |
x label style={at={(1.09,-0.15)}},
|
|
|
1600 |
ylabel={time in secs},
|
|
|
1601 |
scaled x ticks=false,
|
|
|
1602 |
enlargelimits=false,
|
|
|
1603 |
xtick distance=10000,
|
|
|
1604 |
xmax=44000,
|
|
|
1605 |
ytick={0,10,...,30},
|
|
|
1606 |
ymax=35,
|
|
|
1607 |
axis lines=left,
|
|
|
1608 |
width=9cm,
|
|
|
1609 |
height=5cm,
|
|
|
1610 |
legend entries={Java \liningnums{9}+},
|
|
|
1611 |
legend pos=north west,
|
|
|
1612 |
legend cell align=left]
|
|
|
1613 |
\addplot[blue,mark=square*,mark options={fill=white}] table {re-java9.data};
|
|
|
1614 |
\end{axis}
|
|
|
1615 |
\end{tikzpicture}
|
|
|
1616 |
\end{center}
|
|
|
1617 |
|
|
|
1618 |
Regex: \bl{$(a^*)^* \cdot b$}
|
|
|
1619 |
|
|
|
1620 |
Strings of the form \bl{$\underbrace{\,a\ldots a\,}_{n}$}
|
|
|
1621 |
|
|
|
1622 |
\end{frame}
|
|
|
1623 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1624 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1625 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1626 |
% Questions
|
|
|
1627 |
|
|
|
1628 |
\begin{frame}[c]
|
|
|
1629 |
\begin{mybox3}{}
|
|
|
1630 |
Are there any (common) languages that have a built-in regex
|
|
|
1631 |
implementation matching the set of functions of a formal 'simple'
|
|
|
1632 |
regular expression, as opposed to an 'extended' regular expression
|
|
|
1633 |
implemented in most regex-supporting languages?
|
|
|
1634 |
\end{mybox3}
|
|
|
1635 |
\end{frame}
|
|
|
1636 |
|
|
|
1637 |
\begin{frame}[c]
|
|
|
1638 |
\begin{mybox3}{Regexes}
|
|
|
1639 |
Can we determine all the possible regular expressions matching a
|
|
|
1640 |
certain string? If we take into account all the possible ways to
|
|
|
1641 |
combine the operations: \bl{$\ZERO$}, \bl{$\ONE$},
|
|
|
1642 |
\bl{$r_1 + r_2$}, \bl{$r_1 \cdot r_2$}, \bl{$r^*$}?
|
|
|
1643 |
\end{mybox3}
|
|
|
1644 |
\end{frame}
|
|
|
1645 |
|
|
|
1646 |
\begin{frame}[c]
|
|
|
1647 |
\begin{mybox3}{\bl{$L$} + Equivalence}
|
|
|
1648 |
When we explain why two regular expressions are not equivalent, what
|
|
|
1649 |
method is better for us, using mathematics formulas or making an
|
|
|
1650 |
example?
|
|
|
1651 |
\end{mybox3}
|
|
|
1652 |
\begin{mybox3}{}
|
|
|
1653 |
Meaning of Regex and Operations
|
|
|
1654 |
\end{mybox3}
|
|
|
1655 |
\end{frame}
|
|
|
1656 |
|
|
|
1657 |
\begin{frame}[c]
|
|
|
1658 |
\begin{mybox3}{\bl{$L$}}
|
|
|
1659 |
Can the function L be applied to anything other than regular
|
|
|
1660 |
expressions? For example would L(L(c)) return anything?
|
|
|
1661 |
\end{mybox3}
|
|
|
1662 |
|
|
|
1663 |
\hfill $\Rightarrow$ No
|
|
|
1664 |
\end{frame}
|
|
|
1665 |
|
|
|
1666 |
\begin{frame}[c]
|
|
|
1667 |
\begin{mybox3}{\bl{$(a?)\{n\} \cdot a\{n\}$}}
|
|
|
1668 |
In the evil regexes section, is there any reason why in the regex
|
|
|
1669 |
\texttt{[a?]\{n\}[a]\{n\}} the square brackets are used? It is defined as a
|
|
|
1670 |
single character from the square brackets, however there is just one
|
|
|
1671 |
character, so it seems like it is not necessary. Maybe it is just
|
|
|
1672 |
necessary for the first part, because ? is a token instead of a
|
|
|
1673 |
character and we need to refer to a? as a ``unit''? Could regular
|
|
|
1674 |
brackets be used instead? Is there any difference apart from the
|
|
|
1675 |
fact that it would create a group? Also, are the regexes
|
|
|
1676 |
\texttt{[a?]\{n\}} and
|
|
|
1677 |
\texttt{a\{0,3\}} equivalent?
|
|
|
1678 |
\end{mybox3}
|
|
|
1679 |
\end{frame}
|
|
|
1680 |
|
|
|
1681 |
\begin{frame}[c]
|
|
|
1682 |
\begin{mybox3}{Python + Parser Combinators (CW3)}\small
|
|
|
1683 |
Hi Christian,
|
|
|
1684 |
|
|
|
1685 |
I don’t see a problem: you certainly have higher order functions and
|
|
|
1686 |
it is easy to implement algebraic data types using classes. As far
|
|
|
1687 |
as I can see that’s all you need. You don’t get the static types but
|
|
|
1688 |
that should be obvious. Basically if you can do it in LISP you can
|
|
|
1689 |
do it in Python. The only problem could be stack overflows due to a
|
|
|
1690 |
lack of tail recursion optimisation. On the other hand you can
|
|
|
1691 |
simulate laziness using generators.
|
|
|
1692 |
|
|
|
1693 |
Cheers,
|
|
|
1694 |
Thorsten
|
|
|
1695 |
\end{mybox3}
|
|
|
1696 |
|
|
|
1697 |
Trees \url{https://youtu.be/7tCNu4CnjVc}
|
|
|
1698 |
|
|
|
1699 |
Laziness \url{https://youtu.be/5jwV3zxXc8E}
|
|
|
1700 |
|
|
|
1701 |
\end{frame}
|
|
|
1702 |
|
|
|
1703 |
\begin{frame}[c]
|
|
|
1704 |
\begin{mybox3}{}
|
|
|
1705 |
What suggestions do you have for us to get the most out of this
|
|
|
1706 |
module, especially in the online format? I.e. form discussion
|
|
|
1707 |
groups, will you have office hours?
|
|
|
1708 |
\end{mybox3}
|
|
|
1709 |
|
|
|
1710 |
\small
|
|
|
1711 |
\hfill $\Rightarrow$\mbox{} Discussion Forum on KEATS
|
|
|
1712 |
|
|
|
1713 |
\hfill online tutorial sessions
|
|
|
1714 |
|
|
|
1715 |
\end{frame}
|
|
|
1716 |
|
|
|
1717 |
\begin{frame}[c]
|
|
|
1718 |
\small
|
|
|
1719 |
\begin{mybox3}{}
|
|
|
1720 |
Where do most students struggle with this module? What will the format
|
|
|
1721 |
of the exam be? What is the most efficient way of studying for the
|
|
|
1722 |
exam? There are plenty of resources available on KEATS, but is there
|
|
|
1723 |
anything else you'd recommend us to study? Although (just by skimming
|
|
|
1724 |
the headings) the module seems to be a combination of practical and
|
|
|
1725 |
theoretical matters, exactly in what field would the syllabus be
|
|
|
1726 |
applied? Besides these questions and the ones other students asked, is
|
|
|
1727 |
there anything else we should know? Thank you!
|
|
|
1728 |
\end{mybox3}
|
|
|
1729 |
\end{frame}
|
|
|
1730 |
|
|
|
1731 |
|
|
|
1732 |
\begin{frame}[c]
|
|
|
1733 |
\end{frame}
|
|
|
1734 |
|
|
|
1735 |
\begin{frame}[c]
|
|
|
1736 |
\end{frame}
|
|
|
1737 |
|
|
|
1738 |
\begin{frame}[c]
|
|
|
1739 |
\end{frame}
|
|
|
1740 |
|
|
|
1741 |
\begin{frame}[c]
|
|
|
1742 |
\end{frame}
|
|
|
1743 |
|
|
|
1744 |
\begin{frame}[c,fragile]
|
|
|
1745 |
|
|
|
1746 |
\end{frame}
|
|
|
1747 |
|
|
|
1748 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
1749 |
\end{document}
|
|
|
1750 |
|
|
|
1751 |
%%% Local Variables:
|
|
|
1752 |
%%% mode: latex
|
|
|
1753 |
%%% TeX-master: t
|
|
|
1754 |
%%% End:
|
|
|
1755 |
|