[antlr-interest] Building an AST Tree?

[Johannes Luber]

Setia, Namit schrieb:
> Thanks for the help.
> 
> Does anyone know of any good tutorials/examples on how to build an AST
> with c#?  When I get the top level tree, it's children are the
> individual characters of the string I passed in.  I'm not quite sure
> what the approach should be to get it to parse into an AST (Maybe my
> understanding is wrong, but I'm trying to get a tree like what you see
> in the antlrworks interpreter).
> 
> I've been trying to find some good examples for the latest version of
> antlr, but none of the csharp samples I could find work.
> 
> Antlr.Runtime.ICharStream str = new
> Antlr.Runtime.ANTLRStringStream("ap=function(\"hello\",4,5);");
> qss_grammarLexer qlex = new qss_grammarLexer(str);
> Antlr.Runtime.CommonTokenStream tokens = new
> Antlr.Runtime.CommonTokenStream(qlex);
> qss_grammarParser grammar = new qss_grammarParser(tokens);
> qss_grammarParser.qexprlist_return ret = grammar.qexprlist();
> CommonTree t = (CommonTree)ret.Tree;
> 
> --> t.Children is an array  of tokens [ {a},{p},{=},{f},{u},{n}....]  

Actually, your grammar below works as expected. You haven't put any 
rewrite rules into the grammar so get always a flat list. I annotate a 
few rules as examples. Those new all uppercase symbols are imaginary 
tokens defined in the tokens section.

tokens {
QEXPR_LIST;
etc.
}

Johannes
> 
> ------------------------------------------------------------------------
> ---
> 
> grammar qss_grammar;
> 
> options
> {
> 	language=CSharp2;
> 	output=AST;
> }
> 
> qexprlist
>   : ( qassignment_statement )* EOF
>   ;
qexprlist
   : ( qassignment_statement )* EOF -> ^(QEXPR_LIST qassignment_statement)
   ;

> 
> qassignment_statement
>   : qassignment SEMI { Console.Write("hello"); }
>   ;

qassignment_statement
   : qassignment SEMI { Console.Write("hello"); } -> qassignment
   ;

> 
> qassignment
>   : (qname ASSIGN )? qexpr
>   ;
qassignment
   : (qname ASSIGN )? qexpr -> ^(QASSIGNMENT ^(OPTIONAL (qname ASSIGN)?) 
qexpr)
   ;
> 
> qprimary_expr
>   : qint
>   | qvname
>   | (LPAREN qexpr RPAREN ) 
>   | qfunction
>   | qarray
>   | qstring
>   ;
> 
> qsign_expr
>   : qprimary_expr
>   ;
> 
> qmul_expr
>   : qsign_expr (( MUL | DIV | MOD ) qsign_expr)*
>   ;
>   
> qexpr
>   	:	 qmul_expr (( PLUS | MINUS ) qmul_expr)*
>   ;
> 
> 
> 
> PLUS	:	'+';
> MINUS	:	'-';
> DIV	:	'/';
> MUL	:	'*';
> MOD	:	'%';
> POW	:	'^';
> LETTER	:	'a'..'z'|'A'..'Z';
> DIGIT	:	'0'..'9';
> PER	:	'.';
> SEMI	:	';';
> ASSIGN	:	'=';
> EQ	:	'=''=';
> NQ	:	'!''=';
> LEQ	:	'<''=';
> GEQ	:	'>''=';
> LPAREN	:	'(';
> RPAREN	:	')';
> 
> qint	:	(DIGIT)*;
> qname	:	LETTER(LETTER|DIGIT)*;
> qstr	:	(LETTER|DIGIT)*;
> qstring	:	'"' (LETTER|DIGIT)* '"';
> qinputval:	(LETTER|DIGIT)*;
> qvname	:	(LETTER(LETTER|DIGIT)*)(':'qinputval('.'qinputval)*)?;
> qarray	:	'{' (qstring|qvname)(','(qstring|qvname))* '}';
> qfunction:	(LETTER(LETTER|DIGIT)*)'('
> qprimary_expr(','qprimary_expr)* ')';
> 
> 
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