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        <a href="https://xerckm.github.io/Python-Lexer-and-Parser/">
          <h1>Python-Lexer-and-Parser</h1>
        </a>
        <h2>A Lexical Analyzer and Parser Written in Python</h2>

          <a href="https://github.com/XerckM/Python-Lexer-and-Parser" class="button"><small>View project on</small> GitHub</a>


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          <h1 id="python-lexer-and-parser">Python-Lexer-and-Parser</h1>
<p>This is a project to create a lexer and parser using python without using libraries like ‘re’.</p>

<p>Project information is in its respective folder.</p>

<p>This project is for learning purposes only.</p>

<p>Project is written in Python 3.10 (to work with match case)</p>

<h2 id="the-syntax">The syntax</h2>

<p>Program  =  “program”  Identifier  “:”  Body  “end” .</p>

<p>Body  =  [ Declarations ]  Statements .</p>

<p>Declarations  =  Declaration { Declaration } .</p>

<p>Declaration  =  ( “bool” | “int” )  Identifier “;” .</p>

<p>Statements  =  Statement { “;” Statement } .</p>

<p>Statement  =  AssignmentStatement
           |  ConditionalStatement
           |  IterativeStatement
           |  PrintStatement .</p>

<p>AssignmentStatement  =  Identifier “:=” Expression .</p>

<p>ConditionalStatement  =  “if”  Expression
                         “then”  Body
                         [ “else” Body ]
                         “fi” .</p>

<p>IterativeStatement  =  “while”  Expression  “do”  Body  “od” .</p>

<p>PrintStatement  =  “print”  Expression .</p>

<p>Expression  =  SimpleExpression [ RelationalOperator SimpleExpression ] .</p>

<p>RelationalOperator  =  “&lt;” | “=&lt;” | “=” | “!=” | “&gt;=” | “&gt;” .</p>

<p>SimpleExpression  =  Term { AdditiveOperator Term } .</p>

<p>AdditiveOperator  =  “+” | “-“ | “or” .</p>

<p>Term  =  Factor { MultiplicativeOperator Factor } .</p>

<p>MultiplicativeOperator  =  “*” | “/” | “and” .</p>

<p>Factor  =  [ UnaryOperator ] ( Literal  |  Identifier  | “(“ Expression “)” ) .</p>

<p>UnaryOperator  =  “-“ | “not” .</p>

<p>Literal  =  BooleanLiteral  |  IntegerLiteral .</p>

<p>BooleanLiteral  =  “false”  |  “true” .</p>

<p>IntegerLiteral  =  Digit { Digit } .</p>

<p>Identifier  =  Letter { Letter | Digit | “_” }.</p>

<p>Digit  =  “0” | “1” | “2” | “3” | “4” | “5” | “6” | “7” | “8” | “9” .</p>

<p>Letter  = “a” | “b” | “c” | “d” | “e” | “f” | “g” | “h” | “i” | “j” | “k”
        | “l” | “m” | “n” | “o” | “p” | “q” | “u” | “r” | “s” | “t” | “u”
        | “v” | “w” | “x” | “y” | “z”
        | “A” | “B” | “C” | “D” | “E” | “F” | “G” | “H” | “I” | “J” | “K”
        | “L” | “M” | “N” | “O” | “P” | “Q” | “U” | “R” | “S” | “T” | “U”
        | “V” | “W” | “X” | “Y” | “Z” .</p>

<h2 id="comments">Comments:</h2>

<ol>
  <li>
    <p>Integer literals and identifiers are treated as terminal symbols.</p>
  </li>
  <li>
    <p>White space is allowed anywhere, except within terminal symbols.</p>
  </li>
  <li>
    <p>A comment begins with a double slash (“//”) and terminates at the end of
the line.</p>
  </li>
  <li>
    <p>“Maximum munch” applies. For example, “if1” is an identifier, not an “if”
followed by a “1”.</p>
  </li>
  <li>
    <p>The scope of a variable is from its declaration to the end of the nearest
enclosing body.  Standard rules for hiding apply.</p>
  </li>
</ol>


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            <p class="repo-owner"><a href="https://github.com/XerckM/Python-Lexer-and-Parser">Python-Lexer-and-Parser</a> is maintained by <a href="https://github.com/XerckM">XerckM</a>.</p>


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