grammar miniC;

options {
    language=Java;
}

// START:scope
// rules prog, func, and block share the same global scope
// and, therefore, push their scopes onto the same stack
// of scopes as you would expect for C (a code block's
// scope hides the function scope, which in turn, hides
// the global scope).
scope CScope {
    String name;
    List symbols;
}
// END:scope

@header { package edu.lantoniak.minic; }
@lexer::header { package edu.lantoniak.minic; }

// START:members
@members {
int loopCounter = 5;
boolean evaluate = true;
boolean isLoop = false;

/** Is id defined in a CScope?  Walk from top of stack
 *  downwards looking for a symbols list containing id.
 */
boolean isDefined(String id) {
    for (int s=$CScope.size()-1; s>=0; s--) {
        if ( $CScope[s]::symbols.contains(id) ) {
            System.out.println(id+" found in "+$CScope[s]::name);
            return true;
        }
    }
    return false;
}
}
// END:members

// START:augment
prog
scope CScope;
@init {
    // initialize a scope for overall C program
    $CScope::symbols = new ArrayList();
    $CScope::name = "global";
    System.out.println("Begin program");
}
@after {
    // dump global symbols after matching entire program
    System.out.println("End of program. Global symbols = "+$CScope::symbols);
}
    :   prog_content*
    ;

prog_content 
	:	decl
	|	func
	;

func
scope CScope;
@init {
    // initialize a scope for this function
    $CScope::symbols = new ArrayList();
}

@after {
    // dump variables defined within the function itself
    System.out.println("End function "+$CScope::name+" symbols = "+
                       $CScope::symbols);
}
    :   'void' ID {$CScope::name=$ID.text; System.out.println("Begin function: " + $ID.text);} '(' ')' block //'{' decl* stat+ cond* loop* '}'
    ;

block
scope CScope;
@init {
    // initialize a scope for this code block
    $CScope::symbols = new ArrayList();
    $CScope::name = "level "+$CScope.size();
    System.out.println("Begin block: " + $CScope::name);
}
@after {
    // dump variables defined within this code block
    System.out.println("End code block level "+$CScope.size()+" = "+
                       $CScope::symbols);
}
    :   '{' block_content* '}' //decl* stat+ loop* cond* '}'
    ;
// END:augment

block_content 
	:	decl
	|	stat
	|	loop
	|	cond
	|	'{' {System.out.println("Blok anonimowy");} block_content* '}'
	;

/** Match a declaration and had the variable name to the current scope */
decl:   'int' ID {if (evaluate) { $CScope::symbols.add($ID.text); System.out.println("Decalred variable: " + $ID.text);}} ';'
    ;

/** Match an assignment and call isDefined to ensure that the variable
 *  is defined by looking it up in the stack of scopes.
 */
stat:   ID '=' INT ';'
        {
        if ( !isDefined($ID.text) ) {
            System.err.println("undefined variable level "+
                $CScope.size()+": "+$ID.text);
        }
        }
// TODO why?    |   block
    ;

loop
@init {
    int start = -1;
}
@after {
    if (--loopCounter > 0) {
       System.out.println("rewinding: " + loopCounter);
       input.rewind(start);
    } else {
       System.out.println("End loop block.");
    }
}
     : 'for' val=ID 'in' set=ID {start = input.mark(); System.out.println("start: " + start);} block {if (--loopCounter > 0) {
       System.out.println("rewinding: " + loopCounter);
       input.rewind(start);
    }}
     ;

cond
//scope CScope;
@init {
//    $CScope::symbols = new ArrayList();
//    $CScope::name = "if block "+$CScope.size();
}
@after {
    evaluate = true;
}
    :   'if' condition=ID {if (true) { evaluate = true; } else { evaluate = false; }} block
    ;

ID  :   'a'..'z'+ ;
INT :   '0'..'9'+ ;
WS  :   (' '|'\n'|'\r')+ {$channel = HIDDEN;} ;

COMMENT : '//' (~('\n'|'\r'))*
          {$channel = HIDDEN;}
;

ML_COMMENT : '/*' ( options {greedy=false;} : . )* '*/'
;