diff -r 610f14009c0b -r cd0ceaf89c1d slides01.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/slides01.tex Sun May 05 22:02:29 2019 +0100 @@ -0,0 +1,914 @@ +\documentclass[dvipsnames,14pt,t,xelatex]{beamer} +\usepackage{./slides} +\usepackage{./graph} +\usepackage{./langs} +\usepackage{./data} + +\hfuzz=220pt + +\lstset{language=Scala, + style=mystyle, + numbersep=0pt, + numbers=none, + xleftmargin=0mm} + +\newcommand{\bl}[1]{\textcolor{blue}{#1}} + +% beamer stuff +\renewcommand{\slidecaption}{CFL 01, King's College London} + + +\begin{filecontents}{re-python2.data} +1 0.033 +5 0.036 +10 0.034 +15 0.036 +18 0.059 +19 0.084 +20 0.141 +21 0.248 +22 0.485 +23 0.878 +24 1.71 +25 3.40 +26 7.08 +27 14.12 +28 26.69 +\end{filecontents} + +\begin{filecontents}{re-java.data} +5 0.00298 +10 0.00418 +15 0.00996 +16 0.01710 +17 0.03492 +18 0.03303 +19 0.05084 +20 0.10177 +21 0.19960 +22 0.41159 +23 0.82234 +24 1.70251 +25 3.36112 +26 6.63998 +27 13.35120 +28 29.81185 +\end{filecontents} + +\begin{filecontents}{re-java9.data} +1000 0.01410 +2000 0.04882 +3000 0.10609 +4000 0.17456 +5000 0.27530 +6000 0.41116 +7000 0.53741 +8000 0.70261 +9000 0.93981 +10000 0.97419 +11000 1.28697 +12000 1.51387 +14000 2.07079 +16000 2.69846 +20000 4.41823 +24000 6.46077 +26000 7.64373 +30000 9.99446 +34000 12.966885 +38000 16.281621 +42000 19.180228 +46000 21.984721 +50000 26.950203 +60000 43.0327746 +\end{filecontents} + + + +\begin{document} + + + + + + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[t] +\frametitle{% + \begin{tabular}{@ {}c@ {}} + \\[-3mm] + \LARGE Compilers and \\[-1mm] + \LARGE Formal Languages (1)\\[-3mm] + \end{tabular}} + + \begin{center} + %\includegraphics[scale=0.3]{pics/ante1.jpg}\hspace{5mm} + %\includegraphics[scale=0.31]{pics/ante2.jpg}\\ + %\footnotesize\textcolor{gray}{Antikythera automaton, 100 BC (Archimedes?)} + \end{center} + + \normalsize + \begin{center} + \begin{tabular}{ll} + Email: & christian.urban at kcl.ac.uk\\ + Office: & N\liningnums{7.07} (North Wing, Bush House)\\ + Slides: & KEATS + \end{tabular} + \end{center} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[t] +\frametitle{Why Study Compilers?} + +John Regehr {\small(Univ.~Utah, LLVM compiler hacker)}\smallskip\\ + +\begin{bubble}[10.5cm] + \bf ``\ldots{}It’s effectively a perpetual + employment act for solid compiler hackers.'' +\end{bubble} + +\onslide<1->{ +\only<2>{ +\begin{itemize} +\item {\bf Hardware is getting weirder + rather than getting clocked faster} + +\begin{itemize} +\item Almost all processors are + multicores nowadays and it looks like there is increasing asymmetry in + resources across cores. Processors come with vector units, crypto + accelerators etc. We have DSPs, GPUs, + ARM big.little, and Xeon Phi. This is only scratching the + surface. +\end{itemize} +\end{itemize}} +\only<3>{ +\begin{itemize} +\item {\bf We’re getting tired of low-level languages and + their associated security disasters} + +\begin{itemize} +\item + We want to write new code, to + whatever extent possible, in safer, higher-level + languages. Compilers are caught right in the middle of these + opposing trends: one of their main jobs is to help bridge the large + and growing gap between increasingly high-level languages and + increasingly wacky platforms. +\end{itemize} +\end{itemize}}} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{Why Bother?} + +\begin{columns}[t] +\begin{column}{.5\textwidth} +Ruby, Python, Java 8\medskip\\ +\begin{tikzpicture}\footnotesize +\begin{axis}[ + xlabel={$n$}, + x label style={at={(1.05,0.0)}}, + ylabel={time in secs}, + enlargelimits=false, + xtick={0,5,...,30}, + xmax=33, + ymax=35, + ytick={0,5,...,30}, + scaled ticks=false, + axis lines=left, + width=5.5cm, + height=4cm, + legend entries={Python,Ruby}, + legend pos=north west, + legend cell align=left] +\addplot[blue,mark=*, mark options={fill=white}] table {re-python.data}; +\addplot[brown,mark=triangle*, mark options={fill=white}] table {re-ruby.data}; +\end{axis} +\end{tikzpicture} +\begin{tikzpicture}\footnotesize +\begin{axis}[ + xlabel={$n$}, + x label style={at={(1.05,0.0)}}, + ylabel={time in secs}, + enlargelimits=false, + xtick={0,5,...,30}, + xmax=33, + ymax=35, + ytick={0,5,...,30}, + scaled ticks=false, + axis lines=left, + width=5.5cm, + height=4cm, + legend entries={Python, Java 8}, + legend pos=north west, + legend cell align=left] +\addplot[blue,mark=*, mark options={fill=white}] table {re-python2.data}; +\addplot[cyan,mark=*, mark options={fill=white}] table {re-java.data}; +\end{axis} +\end{tikzpicture} + +\end{column} +\begin{column}{.5\textwidth} +Us (after next lecture)\medskip\\ +\begin{tikzpicture}\footnotesize +\begin{axis}[ + xlabel={$n$}, + x label style={at={(1.07,0.0)}}, + ylabel={time in secs}, + enlargelimits=false, + xtick={0,5000,...,10000}, + xmax=11000, + ymax=35, + ytick={0,5,...,30}, + scaled ticks=false, + axis lines=left, + width=5.5cm, + height=4cm] +\addplot[green,mark=square*,mark options={fill=white}] table {re2.data}; +\addplot[black,mark=square*,mark options={fill=white}] table {re3.data}; +\end{axis} +\end{tikzpicture} +\begin{tikzpicture}\footnotesize +\begin{axis}[ + xlabel={$n$}, + x label style={at={(1.07,0.0)}}, + ylabel={time in secs}, + enlargelimits=false, + ymax=35, + ytick={0,5,...,30}, + scaled ticks=false, + axis lines=left, + width=5.5cm, + height=4cm] +\addplot[black,mark=square*,mark options={fill=white}] table {re3a.data}; +\end{axis} +\end{tikzpicture} +\end{column} +\end{columns}\bigskip + +\small\centering +matching \texttt{[a?]\{n\}[a]\{n\}} and \texttt{(a*)*b} +against $\underbrace{\texttt{a}...\texttt{a}}_n$ +\end{frame} + +\begin{frame} +\begin{column}{.5\textwidth} +\begin{tikzpicture} +\begin{axis}[ + xlabel={$n$}, + x label style={at={(1.05,0.0)}}, + ylabel={time in secs}, + y label style={at={(0.06,0.5)}}, + enlargelimits=false, + xtick={0,5,...,30}, + xmax=33, + ymax=45, + ytick={0,10,...,40}, + scaled ticks=false, + axis lines=left, + width=6cm, + height=4.5cm, + legend entries={Python, Java 8}, + legend pos=north west] +\addplot[blue,mark=*, mark options={fill=white}] table {re-python2.data}; +\addplot[cyan,mark=*, mark options={fill=white}] table {re-java.data}; +\end{axis} +\end{tikzpicture} +\begin{tikzpicture} +\begin{axis}[ + xlabel={$n$}, + x label style={at={(1.05,0.0)}}, + ylabel={time in secs}, + y label style={at={(0.06,0.5)}}, + %enlargelimits=false, + %xtick={0,5000,...,30000}, + xmax=65000, + ymax=45, + ytick={0,10,...,40}, + scaled ticks=false, + axis lines=left, + width=6cm, + height=4.5cm, + legend entries={Java 9}, + legend pos=north west] +\addplot[cyan,mark=*, mark options={fill=white}] table {re-java9.data}; +\end{axis} +\end{tikzpicture} +\end{column} +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{Evil Regular Expressions} + +\begin{itemize} +\item \alert{R}egular \alert{e}xpression \alert{D}enial \alert{o}f \alert{S}ervice (ReDoS)\medskip +\item Evil regular expressions\medskip +\begin{itemize} +\item \bl{$(a^{?\{n\}}) \cdot a^{\{n\}}$} +\item \bl{$(a^*)^*\cdot b$} +\item \bl{$([a$\,-\,$z]^+)^*$} +\item \bl{$(a + a \cdot a)^*$} +\item \bl{$(a + a^?)^*$} +\end{itemize} + +\item sometimes also called \alert{catastrophic backtracking} +\item this is a problem for \alert{N}etwork \alert{I}ntrusion + \alert{D}etection systems, StackExchange, Atom editor +\item \url{https://vimeo.com/112065252} +\end{itemize} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{The Goal of this Module} + +\begin{center} + \begin{tikzpicture}[scale=1, + node/.style={ + rectangle,rounded corners=3mm, + very thick,draw=black!50,minimum height=18mm, minimum width=20mm, + top color=white,bottom color=black!20}] + + \node at (3.05, 1.8) {\Large\bf write a compiler}; + + \node (0) at (-2.3,0) {}; + \node [above=5mm of 0] + {\makebox[0mm]{\footnotesize + \begin{tabular}{@{}l@{}}input\\[-1mm]program\end{tabular}}}; + + \node (A) at (0,0) [node] {}; + \node [below right] at (A.north west) {lexer}; + + \node (B) at (3,0) [node] {}; + \node [below right=1mm] at (B.north west) {\mbox{}\hspace{-1mm}parser}; + + \node (C) at (6,0) [node] {}; + \node [below right] at (C.north west) {\mbox{}\hspace{-1mm}code gen}; + + \node (1) at (8.4,0) {}; + \node [above=5mm of 1] + {\makebox[0mm]{\footnotesize + \begin{tabular}{@{}r@{}}binary\\[-1mm]code\end{tabular}}}; + + \draw [->,line width=4mm] (0) -- (A); + \draw [->,line width=4mm] (A) -- (B); + \draw [->,line width=4mm] (B) -- (C); + \draw [->,line width=4mm] (C) -- (1); + \end{tikzpicture} + \end{center} + +\only<2,3,4>{ +\begin{textblock}{1}(1,2.1) +\begin{bubble}[9.8cm] +\normalsize +lexer input: a string\smallskip\\ +\hspace{5mm}\code{"read(n);"}\medskip\\ +lexer output: a sequence of tokens\smallskip\\ +\hspace{5mm}\code{key(read) lpar id(n) rpar semi} +\end{bubble} +\end{textblock}} + +\only<3,4>{ +\begin{textblock}{1}(6,7.8) +\begin{tabular}{c} +\includegraphics[scale=0.2]{rosetta.jpg}\\[-2mm] +\footnotesize lexing $\Rightarrow$ recognising words (Stone of Rosetta) +\end{tabular} +\end{textblock}} + +\only<4>{ +\begin{textblock}{1}(0.5,12)\small +\begin{tabular}{l@{}c@{}l} + \pcode{if} & $\;\Rightarrow\;$ & keyword\\ + \pcode{iffoo} & $\;\Rightarrow\;$ & identifier\\ +\end{tabular} +\end{textblock}} + +\only<5>{ +\begin{textblock}{1}(1,1.5) +\begin{bubble}[8.5cm] +\normalsize +parser input: a sequence of tokens\smallskip\\ + +{\small\hspace{5mm}\code{key(read) lpar id(n) rpar semi}}\smallskip\\ + +parser output: an abstract syntax tree\smallskip\\ +\footnotesize +\hspace{2cm}\begin{tikzpicture} + \node {\code{read}} + child {node {\code{lpar}}} + child {node {\code{n}}} + child {node {\code{rpar}}}; +\end{tikzpicture} +\end{bubble} +\end{textblock}} + +\only<6,7>{ +\begin{textblock}{1}(1,1.5) +\begin{bubble}[4cm] +\normalsize +code generator:\smallskip\\ +\hspace{5mm}\code{istore 2}\\ +\hspace{5mm}\code{iload 2}\\ +\hspace{5mm}\code{ldc 10}\\ +\hspace{5mm}\code{isub}\\ +\hspace{5mm}\code{ifeq Label2}\\ +\hspace{5mm}\code{iload 2}\\ +\hspace{5mm}\code{...}\\ +\end{bubble} +\end{textblock}} + +\only<7>{ +\begin{textblock}{6}(8.4,7) +\begin{bubble}[5cm] +\mbox{\begin{tikzpicture}[scale=0.58,rounded corners=0mm] +\begin{axis}[axis x line=bottom, axis y line=left, ylabel=secs, + xlabel=n, + enlargelimits=0.05, + ybar interval=0.7, legend style=small] +\addplot file {interpreted2.data}; +\addplot file {compiled2.data}; +%\legend{interpreted, compiled} +\end{axis} +\end{tikzpicture}} +\end{bubble} +\end{textblock}} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{The Acad.~Subject is Mature} + +\begin{itemize} +\item Turing Machines, 1936 +\item Regular Expressions, 1956\\ +\item The first compiler for COBOL, 1957\\ (Grace Hopper) +\item But surprisingly research papers are still published nowadays\\ +\item ``Parsing: The Solved Problem That Isn't'' +\end{itemize} + +\begin{flushright} +\includegraphics[scale=0.3]{hopper.jpg}\\ +\footnotesize\textcolor{gray}{Grace Hopper} +\end{flushright} + + +\begin{flushright} +\mbox{}\\[-6mm] +{\footnotesize\textcolor{gray}{(she made it to David Letterman's Tonight Show,\\[-2mm] + \url{http://www.youtube.com/watch?v=aZOxtURhfEU})}} +\end{flushright} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{Lectures 1 - 5} + +transforming strings into structured data\\[10mm] + +{\LARGE\bf Lexing} {\hfill{}based on regular expressions}\medskip\\ +\hspace{5mm}(recognising ``words'')\\[6mm] + +{\LARGE\bf Parsing}\medskip\\ +\hspace{5mm}(recognising ``sentences'') + +\begin{textblock}{1}(10,9.1) +\begin{tabular}{c} +\includegraphics[scale=0.1]{rosetta.jpg}\\[-2mm] +\footnotesize Stone of Rosetta +\end{tabular} +\end{textblock} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[t] +\frametitle{Familiar Regular Expr.} +\small +\begin{center} +\texttt{[a-z0-9\_$\backslash{}$.-]+ @ [a-z0-9$\backslash{}$.-]+ . [a-z$\backslash{}$.]\{2,6\}} +\end{center}\smallskip + +\begin{center} +\begin{tabular}{@{}lp{8.5cm}@{}} +\pcode{re*} & matches 0 or more times\\ +\pcode{re+} & matches 1 or more times\\ +\pcode{re?} & matches 0 or 1 times\\ +\pcode{re\{n\}} & matches exactly \pcode{n} number of times\\ +\pcode{re\{n,m\}} & matches at least \pcode{n} and at most {\tt m} times\\ +\pcode{[...]} & matches any single character inside the brackets\\ +\pcode{[^...]} & matches any single character not inside the +brackets\\ +\pcode{a-z A-Z} & character ranges\\ +\pcode{\\d} & matches digits; equivalent to \pcode{[0-9]}\\ +\pcode{.} & matches every character except newline\\ +\pcode{(re)} & groups regular expressions and remembers +the matched text +\end{tabular} +\end{center} + + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{Today} + +\begin{itemize} +\item While the ultimate goal is to implement a small compiler for the JVM + \ldots\bigskip +\end{itemize} + +Let's start with: + +\begin{itemize} +\item a web-crawler +\item an email harvester +%\item \textcolor{gray}{(a web-scraper)} +\end{itemize} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[t] +\frametitle{A Web-Crawler} + +\mbox{}\\[10mm] + +\begin{enumerate} +\item given an URL, read the corresponding webpage +\item extract all links from it +\item call the web-crawler again for all these links +\end{enumerate} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[t] +\frametitle{A Web-Crawler} + +\mbox{}\\[10mm] + + +\begin{enumerate} +\item given an URL, read the corresponding webpage +\item if not possible print, out a problem +\item if possible, extract all links from it +\item call the web-crawler again for all these links +\end{enumerate}\bigskip\pause + +\small (we need a bound for the number of recursive calls) + +\small (the purpose is to check all links on my own webpage) +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] + +\begin{textblock}{1}(2,5) +\begin{tabular}{c} +\includegraphics[scale=0.15]{servers.png}\\[-2mm] +\small Server +\end{tabular} +\end{textblock} + +\begin{textblock}{1}(5.6,4) + \begin{tikzpicture}[scale=1.1] + \draw[white] (0,1) node (X) {}; + \draw[white] (2,1) node (Y) {}; + \draw[white] (0,0) node (X1) {}; + \draw[white] (2,0) node (Y1) {}; + \draw[white] (0,-1) node (X2) {}; + \draw[white] (2,-1) node (Y2) {}; + \draw[red, <-, line width = 2mm] (X) -- (Y); + \node [inner sep=5pt,label=above:\textcolor{black}{GET request}] at ($ (X)!.5!(Y) $) {}; + \draw[red, ->, line width = 2mm] (X1) -- (Y1); + \node [inner sep=5pt,label=above:\textcolor{black}{webpage}] at ($ (X1)!.5!(Y1) $) {}; + \draw[red, <-, line width = 2mm] (X2) -- (Y2); + \node [inner sep=7pt,label=above:\textcolor{black}{POST data}] at ($ (X2)!.5!(Y2) $) {}; + \end{tikzpicture} +\end{textblock} + + +\begin{textblock}{1}(9,5.5) +\begin{tabular}{c} +\includegraphics[scale=0.15]{laptop.png}\\[-2mm] +\small Browser +\end{tabular} +\end{textblock} +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + + + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[t] +\frametitle{A Regular Expression} + +\begin{itemize} +\item \ldots{} is a pattern or template for specifying strings +\end{itemize}\bigskip + +\begin{center} +\only<1>{\scode{"https?://[^"]*"}}% +\only<2>{\scode{""""https?://[^"]*"""".r}} +\end{center}\bigskip\bigskip + +matches for example\smallskip\\ +\hspace{2mm}\code{"http://www.foobar.com"}\\ +\hspace{2mm}\code{"https://www.tls.org"}\smallskip\\ + +but not\smallskip\\ +\hspace{2mm}\code{"http://www."foo"bar.com"}\\ + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{Finding Operations in Scala} + +{\bf\code{rexp.findAllIn(string)}}\medskip + +returns a list of all (sub)strings that match the +regular expression +\bigskip\bigskip + + +{\bf\code{rexp.findFirstIn(string)}}\medskip + +returns either + +\begin{itemize} +\item \code{None} if no (sub)string matches or +\item \code{Some(s)} with the first (sub)string +\end{itemize} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[t] +\frametitle{Regular Expressions} + +Their inductive definition: + + +\begin{textblock}{6}(2,7.5) + \begin{tabular}{@ {}rrl@ {\hspace{13mm}}l} + \bl{$r$} & \bl{$::=$} & \bl{$\ZERO$} & nothing\\ + & \bl{$\mid$} & \bl{$\ONE$} & empty string / \pcode{""} / $[]$\\ + & \bl{$\mid$} & \bl{$c$} & character\\ + & \bl{$\mid$} & \bl{$r_1 + r_2$} & alternative / choice\\ + & \bl{$\mid$} & \bl{$r_1 \cdot r_2$} & sequence\\ + & \bl{$\mid$} & \bl{$r^*$} & star (zero or more)\\ + \end{tabular} + \end{textblock} + + + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%\begin{frame}[t] +%\frametitle{Regular Expressions} +% +%\small +%In Scala:\bigskip +% +%\footnotesize +%\lstinputlisting{../progs/app51.scala} +% +% +%\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[t] +\frametitle{Strings} + +\ldots are lists of characters. For example \code{"hello"} + +\begin{center} +\bl{$[h, e, l, l, o]$} or just \bl{$hello$} +\end{center} + +the empty string: \bl{$[]$} or \bl{\pcode{""}}\bigskip\\ + +the concatenation of two strings: + +\begin{center} +\bl{$s_1 \,@\, s_2$} +\end{center} + +\bl{\textit{foo $@$ bar = foobar}, \textit{baz $@\, []$ = baz}} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{Languages, Strings} + +\begin{itemize} +\item \alert{\bf Strings} are lists of characters, for example +\begin{center} +\bl{$[]$},\;\bl{$abc$} \hspace{2cm}(Pattern match: \bl{$c\!::\!s$}) +\end{center}\bigskip + + +\item A \alert{\bf language} is a set of strings, for example\medskip +\begin{center} +\bl{$\{[], hello, \textit{foobar}, a, abc\}$} +\end{center}\bigskip + +\item \alert{\bf Concatenation} of strings and languages + +\begin{center} +\begin{tabular}{rcl} +\bl{$\textit{foo}\;@\;bar$} & \bl{$=$} & \bl{$\textit{foobar}$}\medskip\\ +\bl{$A\;@\;B$} & \bl{$\dn$} & \bl{$\{ s_1\,@\,s_2 \;\mid\; s_1 \in A \wedge s_2 \in B\}$} +\end{tabular} +\end{center} + +%\item The \alert{\bf meaning} of a regular expression is a set of +% strings, or language. +\end{itemize} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\mode{ +\begin{frame}[c] +\frametitle{\begin{tabular}{c}The Meaning of a\\[-2mm] + Regular Expression\end{tabular}} + +\begin{textblock}{15}(1,4) + \begin{tabular}{rcl} + \bl{$L(\ZERO)$} & \bl{$\dn$} & \bl{$\{\}$}\\ + \bl{$L(\ONE)$} & \bl{$\dn$} & \bl{$\{[]\}$}\\ + \bl{$L(c)$} & \bl{$\dn$} & \bl{$\{[c]\}$}\\ + \bl{$L(r_1 + r_2)$} & \bl{$\dn$} & \bl{$L(r_1) \cup L(r_2)$}\\ + \bl{$L(r_1 \cdot r_2)$} & \bl{$\dn$} & \bl{$\{ s_1 \,@\, s_2 \;|\; s_1 \in L(r_1) \wedge s_2 \in L(r_2) \}$}\\ + \bl{$L(r^*)$} & \bl{$\dn$} & \onslide<4->{\bl{$\bigcup_{0 \le n} L(r)^n$}}\\ + \end{tabular}\bigskip + +\onslide<2->{ +\hspace{5mm}\bl{$L(r)^0 \;\dn\; \{[]\}$}\\ +\bl{$L(r)^{n+1} \;\dn\; L(r) \,@\, L(r)^n$}\hspace{9mm}\onslide<3->{\small\textcolor{gray}{(append on sets)}\\ +\small\hspace{5cm}\textcolor{gray}{$\{ s_1 @ s_2 \;|\; s_1\in L(r) \wedge s_2 \in L(r)^n \}$}} +} + \end{textblock} + +\end{frame}} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{The Meaning of Matching} + +\begin{bubble}[10cm] +\large\bf +A regular expression \bl{$r$} matches a string~\bl{$s$} +provided + +\begin{center} +\bl{$s \in L(r)$}\\ +\end{center} +\end{bubble}\bigskip\bigskip + +\ldots and the point of the next lecture is +to decide this problem as fast as possible (unlike Python, +Ruby, Java) + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{Written Exam} + +\begin{itemize} +\item Accounts for 80\%.\bigskip + +\item The question ``\textit{Is this relevant for + the exam?}'' is very demotivating for the lecturer!\bigskip\\ + +\item Deal: Whatever is in the homework (and is not marked + ``\textit{optional}'') is relevant for the exam.\bigskip + +\item Each lecture has also a handout. There are also handouts about +notation and Scala. +\end{itemize} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[t] +\frametitle{Coursework} + +\begin{itemize} +\item Accounts for 20\%. Two strands. Choose \alert{\bf one}!\bigskip +\end{itemize} + +\begin{columns}[t] +\begin{column}{.5\textwidth} +\underline{\bf Strand 1}\medskip +\begin{itemize} +\item four programming tasks: +\begin{itemize} +\item matcher (4\%, 12.10.) +\item lexer (5\%, 02.11.) +\item parser (5\%, 23.11.) +\item compiler (6\%, 14.12.) +\end{itemize} +\item in any lang.~you like,\\ but I want to see the code +\end{itemize} +\end{column} + +\hspace{-45pt}\vrule{}\hspace{10pt} +\begin{column}{.5\textwidth} +\underline{\bf Strand 2}\smallskip\begin{itemize} +\item one task: prove the correctness of a regular expression matcher in +the \underline{Isabelle} theorem prover +\item 20\%, submission on~14.12.\hspace{-5mm}\mbox{} +\end{itemize} +\end{column} +\end{columns}\medskip + +\small +\begin{itemize} +\item Solving more than one strand will {\bf not} give you more +marks. + +\end{itemize} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{Lecture Capture} + +\begin{itemize} +\item Hope it works\ldots\pause actually no, it does not!\medskip\pause +\item It is important to use lecture capture wisely\\ (it is only the ``baseline''): +\begin{itemize} +\item Lecture recordings are a study and revision aid. +\item Statistically, there is a clear and direct link between attendance and + attainment: Students who do not attend lectures, do less well in exams. +\end{itemize} + +\item Attending a lecture is more than watching it online -- if you do not +attend, you miss out! + +\end{itemize} + +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\begin{frame}[c] +\frametitle{\begin{tabular}{c}\\[3cm]\alert{Questions?}\end{tabular}} + +\mbox{} +\end{frame} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\end{document} + +%%% Local Variables: +%%% mode: latex +%%% TeX-master: t +%%% End: +