\documentclass{beamer}
%include lhs2TeX.fmt
\author{Piyush P Kurur\\
  Office no: 224\\
  Dept. of Comp. Sci. and Engg.\\
  IIT Kanpur}

\usepackage{tikz}
\usepgfmodule{matrix}
\usetikzlibrary{chains}
\newcommand{\Token}[2][]{\node(#2#1)[token]{#2};}
\newcommand{\Symbol}[2][]{\node(#2#1)[symbol]{#2};}
\newcommand{\Point}[1]{\node(#1)[point]{#1};}
\usepackage{multicol}

\usetikzlibrary{positioning,shapes,chains}
\usetikzlibrary{shapes.symbols}
\usetikzlibrary{matrix}
\usepackage{dot2texi}
\input{../include/grammar.tex}
\title{Fundamentals of Computing: Lecture 5}
\date{August 5, 2009}
\begin{document}
\begin{frame}
\maketitle
\end{frame}

\begin{frame}
  \frametitle{Summary of previous lecture}
  \begin{block}{Expressions}
    \begin{itemize}
    \item Integer expressions.
    \item Floating point expressions |float| and |double|.
    \item Boolean expressions (or rather the lack of boolean expressions)
    \end{itemize}
  \end{block}
  \begin{block}{Assignment}
    \begin{itemize}
    \item Assignment is also an expression
    \item Special assignements liket |i++| and |m *= 4|
    \item Problem with |==| and |=|. 
    \end{itemize}
  \end{block}
\end{frame}

\begin{frame}
  \frametitle{Statement}
  \begin{block}{Simple statement}
    A simple statement is just an expression followed by |;| (semicolon).
    eg

    |x = 100;|
    \pause
    |f(x);|
  \end{block}
  \pause
  \begin{block}{Compound statement}
    A sequence of statements enclosed in a pair of braces
    eg
    \begin{spec}
      {
        foo = x;
        bar = y;
      }
    \end{spec}
  \end{block}
\end{frame}
\begin{frame}
  \frametitle{Control flow statements}
  Normally statements are executed in the sequence in which 
  they are given.

  What if we want to change ?

  \begin{itemize}
  \item Conditional statements
  \item Loop statements.
  \end{itemize}

\end{frame}
\begin{frame}
  \frametitle{Conditional statement}
  \begin{spec}
    if ( expression ) statement
    if ( expression ) statement1 else statement2
  \end{spec}
  \pause
  eg
  \begin{spec}
    if ( x > 42 ) {
      printf("Value too large");
    }
    else {
      printf("just right")
    }
  \end{spec}
\end{frame}

\begin{frame}
  \frametitle{While loop}
  \begin{spec}
    while( expression ) statement
  \end{spec}
  \pause
  Example summing numbers till |n|
  \begin{spec}
    sum = 0;
    i = 0;
    while( i < n )
    { 
      sum += i;
      i++;
    }
    printf("sum till %d is %d",n,sum);
  \end{spec}
\end{frame}
\begin{frame}
  \frametitle{For loop}
  \begin{spec}
      for( initialisation ; condition; update) statement
  \end{spec}
  eg
  \begin{spec}
    for(int i = 0; i <= n; i++)
    {
      sum +=i;
    }
    printf("Sum till %d is %d",n,sum);
    
  \end{spec}
  \pause
  \newpage
  \begin{spec}
    for(int i = 0; i <= n; i++) sum +=i;
    printf("Sum till %d is %d",n,sum);
  \end{spec}
\end{frame}
\end{document}

%[start chain, every node/.style={on chain, join},every join/.style={->}]
      % %   \&              \& |[symbol]|{expr} \& |[symbol]{binary op} \& \node[symbol]{expr}\\
      % %   \&              \& \node[symbol]{unary op} \& \node[symbol]{expr} \\



\begin{frame}
  \frametitle{Grammar of expressions}
  \begin{tikzpicture}[tip/.style={->},join/.style={rounded corners},
      thick,draw=black!50,
      
      hv path/.style={to path={-|(\tikztotarget)}},
      vh path/.style={to path={|-(\tikztotarget)}}]
    \matrix[ampersand replacement =\&, row sep=0.25cm, column sep=0.5cm]
    {
      %%% Constant line
       \& \& \Point{c1}\& \Token{constant} \& \Point{c2}\\
       \& \& \Point{v1}\& \Symbol{variable} \& \Point{v2}\\
       \Point{p0}\& \Point{p1} \& \& \& \&
       \Point{p2} \& \Point{p3} \\
       \& \& \Symbol[1]{expr} \& \Symbol{bin-op} \& \Symbol[2]{expr}\\
       \& \& \Symbol{un-op} \& \Symbol[3]{expr}\\
    };
    \begin{scope}
      [start chain];
      \chainin(p0);
      \chainin(p1);
      \begin{scope}[start branch=const]
        \chainin(c1)[join =by {vh path,tip}];
        \chainin(constant);
        \chainin(c2);
        \chainin(p2)[join =by {hv path, tip}];
      \end{scope};
    \end{scope}
  \end{tikzpicture}
\end{frame}