Создание парсеров на основе GPLEX+GPPG

К основной странице курса

Комплект разработчика парсеров

SimpleLex.lex

%namespace LexScanner

Alpha 	[a-zA-Z_]
INTNUM  [0-9]+
REALNUM {INTNUM}\.{INTNUM}
ID [a-zA-Z_][a-zA-Z0-9_]* 

%%

":=" { return (int)Tokens.ASSIGN; }
";" { return (int)Tokens.SEMICOLON; }
"-=" { return (int)Tokens.ASSIGNMINUS; }
"+=" { return (int)Tokens.ASSIGNPLUS; }
"*=" { return (int)Tokens.ASSIGNMULT; }

{ID}  { 
  int res = ScannerHelper.GetIDToken(yytext);
  if (res == (int)Tokens.ID)
	yylval.sVal = yytext;
  return res;
}

{INTNUM} { 
  yylval.iVal = int.Parse(yytext); 
  return (int)Tokens.INTNUM; 
}

{REALNUM} { 
  yylval.dVal = double.Parse(yytext,new System.Globalization.CultureInfo("en-US")); 
  return (int)Tokens.REALNUM; 
}

%{
  yylloc = new LexLocation(tokLin, tokCol, tokELin, tokECol);
%}

%%

class ScannerHelper 
{
  private static Dictionary<string,int> keywords;

  static ScannerHelper() 
  {
    keywords = new Dictionary<string,int>();
    keywords.Add("begin",(int)Tokens.kBEGIN);
    keywords.Add("end",(int)Tokens.kEND);
    keywords.Add("cycle",(int)Tokens.kIF);
  }
  public static int GetIDToken(string s)
  {
	if (keywords.ContainsKey(s.ToLower()))
	  return keywords[s];
	else
      return (int)Tokens.ID;
  }
  
}

SimpleYacc.yacc

%{
    Dictionary<string,double> vars = new Dictionary<string,double>();
%}

%output = SimpleYacc.cs

%union { public double dVal; 
         public int iVal; 
         public ExprNode eVal;
         public List<ExprNode> elVal;
         public TreeNode tVal;
         public BlockNode lVal;
         }

%using System.IO


%namespace LexScanner

%start progr

%token BEGIN END CYCLE ASSIGN SEMICOLON
%token <iVal> INTNUM 
%token <sVal> ID

%%

progr   : stlist
	;

stlist	: st
	| stlist SEMICOLON st
	;

st	: assign
	| comp
	| cycl
	;

assign 	: ID ASSIGN expr
	;

expr	: ID
	| INTNUM
	;

comp	: BEGIN stlist END
	;

cycl	: CYCLE expr st
	;

%%