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/* SI 413 Fall 2012
 * Lab 7
 * Parser for SPL that just shows the parse tree
 * This parser uses a simpler grammar with assoc/prec specifications.
 */
 
// This code is included in the spl.tab.hpp header file
%code requires {
 
#include <cstdlib>
#include <iostream>
using namespace std;
 
#include "ast.hpp"
 
int yylex(); 
 
} // end header file part
 
// This code is only included in the parser file spl.tab.cpp
%code {
 
// These are the colored output streams to make things all pretty.
colorout resout(1, 'u');
colorout errout(2, 'r');
 
// Global variable will be set to the entire AST.
Stmt* tree;
 
// Global variable to indicate if an error has occurred.
bool error;
 
// Global variable to indicate that terminal input is "live" and
// so prompts should be displayed.
bool showPrompt;
 
// This is the C file that flex reads from for scanning.
extern FILE* yyin;
 
void yyerror(const char *p) { 
  if (! error) {
    errout << "Parser error: " << p << endl; 
    error = true;
  }
}
 
} // end top of parser part
 
  /* Tell bison to give descriptive error mesages. */
%error-verbose
 
%union {
  Block* block;
  Stmt* stmt;
  Exp* exp;
  Id* id;
  Oper op;
};
 
%left<op> BOP
%right<op> NOTTOK
%left<op> COMP
%left<op> OPA
%left<op> OPM
%right POSNEG
%left FUNARG
 
%token LC RC LP RP LAMBDA IF IFELSE WHILE READ WRITE NEW ASN STOP
%token<id> ID
%token<exp> NUM BOOL
%type<stmt> stmt stmtlist
%type<block> block
%type<exp> exp
 
%%
  /*Note: YYACCEPT is a bison macro that just tells it to quit parsing.*/
res: stmt { tree = $1; YYACCEPT; }
|         { tree = NULL; }
 
block: LC stmtlist RC { $$ = new Block($2); }
 
stmtlist: stmtlist stmt { $$ = Stmt::append($1,$2); }
|                       { $$ = new NullStmt; }
 
stmt: NEW ID ASN exp STOP    {$$ = new NewStmt($2,$4);}
|     ID ASN exp STOP        {$$ = new Asn($1,$3);}
|     WRITE exp STOP         {$$ = new Write($2);}
|     IF exp block           {$$ = new IfStmt($2,$3,new NullStmt());}
|     IFELSE exp block block {$$ = new IfStmt($2,$3,$4);}
|     WHILE exp block        {$$ = new WhileStmt($2,$3);}
|     block                  {$$ = $1;}
 
exp: exp BOP exp          {$$ = new BoolOp($1,$2,$3);}
|    NOTTOK exp           {$$ = new NotOp($2);}
|    exp COMP exp         {$$ = new CompOp($1,$2,$3);}
|    exp OPA exp          {$$ = new ArithOp($1,$2,$3);}
|    exp OPM exp          {$$ = new ArithOp($1,$2,$3);}
|    OPA exp %prec POSNEG {$$ = ($1 == ADD ? $2 : new NegOp($2));}
|    READ                 {$$ = new Read();}
|    LAMBDA ID block      {$$ = new Lambda($2,$3);}
|    exp FUNARG exp       {$$ = new Funcall($1,$3);}
|    LP exp RP            {$$ = $2;}
|    ID                   {$$ = $1;}
|    NUM                  {$$ = $1;}
|    BOOL                 {$$ = $1;}
 
%%
int main(int argc, char** argv) {
  showPrompt = isatty(0) && isatty(2);
  bool interactive = showPrompt;
 
  if (argc >= 2) {
    if (!(yyin = fopen(argv[1],"r"))) {
      cerr << "Could not open input file \"" << argv[1] << "\"!" << endl;
      exit(2);
    }
    interactive = false;
  }
 
  if (interactive) {
    bool showAST = true; // set to false to stop the AST from popping up.
    // This is the "interactive" version of the interpreter.
    // It keeps going, even if there are errors, and prints out
    // prompts and such.
    while(true) {
      tree = NULL;
      error = false;
      cerr << "spl> ";
      yyparse();
      if (tree == NULL && ! error) break;
      else if (tree != NULL) {
        tree->writeDot("spl.dot");
        system("dot -Tpdf spl.dot > spl.pdf");
        if (showAST) system("evince spl.pdf > /dev/null 2>&1 &");
        tree->exec();
      }
    }
    cerr << "Goodbye" << endl;
  }
  else {
    // This is the non-interactive version of the interpreter.
    // It exits with return code 5 if there is any kind of error,
    // and doesn't display prompts or other niceties.
    error = false;
    while(! error) {
      tree = NULL;
      if (yyparse() != 0 || error || tree == NULL) break;
      tree->writeDot("spl.dot");
      system("dot -Tpdf spl.dot > spl.pdf");
      tree->exec();
    }
    if (error) return 5;
  }
 
  return 0;
}