UNIX

extern prexpr();

extern gt(), lt(), eq(), ge(), le(), ne(), and(), or(), not();

extern ifcode(), whilecode();

3.6.5 hoc.y

%{

#include "hoc.h"

#define code2(c1,c2) code(c1); code(c2)

#define code3(c1,c2,c3) code(c1); code(c2); code(c3)

%}

%union {

 Symbol *sym; /* symbol table pointer */

 Inst *inst; /* machine instruction */

}

%token NUMBER PRINT VAR BLTIN UNDEF WHILE IF ELSE

%type stmt asgn expr stmtlist cond while if end

%right '='

%left OR

%left AND

%left GT GE LT LE EQ NE

%left '+' '-'

%left '*' '/'

%left UNARYMINUS NOT

%right

%%

list: /* nothing */

 | list '\n'

 | list asgn '\n' { code2(pop, STOP); return 1; }

 | list stmt '\n' { code(STOP); return 1; }

 | list expr '\n' { code2(print, STOP); return 1; }

 | list error '\n' { yyerrok; }

 ;

asgn: VAR '=' expr { $$=$3; code3(varpush,(Inst)$1.assign); }

 ;

stmt: expr { code(pop); }

 | PRINT expr { code(prexpr); $$ = $2; }

 | while cond stmt end {

  ($1)[1] = (Inst)$3; /* body of loop */

  ($1)[2] = (Inst)$4;

 } /* end, if cond fails */

 | if cond stmt end { /* else-less if */

  ($1)[1] = (Inst)$3; /* thenpart */

  ($1)[2] = (Inst)$4;

 } /* end, if cond fails */

 | if cond stmt end ELSE stmt end { /* if with else */

  ($1)[1] = (Inst)$3; /* thenpart */

  ($1)[2] = (Inst)$6; /* elsepart */

  ($1)[3] = (Inst)$7;

 } /* end, if cond fails */

 | '{' stmtlist '}' { $$ = $2; }

 ;

cond: '(' expr ')' { code(STOP); $$ = $2; }

 ;

while: WHILE { $$ = code3(whilecode, STOP, STOP); }

 ;

if: IF { $$=code(ifcode); code3(STOP, STOP, STOP); }

 ;

end: /* nothing */ { code(STOP); $$ = progp; }

 ;

stmtlist: /* nothing */ { $$ = progp; }

 | stmtlist '\n'

 | stmtlist stmt

 ;

expr: NUMBER { $$ = code2(constpush, (Inst)$1); }

 | VAR { $$ = code3(varpush, (Inst)$1, eval); }

 | asgn

 | BLTIN '(' expr ')'

  { $$ = $3; code2(bltin,(Inst)$1->u.ptr); }

 | '(' expr ')' { $$ = $2; }

 | expr '+' expr { code(add); }

 | expr '-' expr { code(sub); }

 | expr '*' expr { code(mul); }

 | expr '/' expr { code(div); }

 | expr '^' expr { code (power); }

 | '-' expr %prec UNARYMINUS { $$ = $2; code(negate); }

 | expr GT expr { code(gt); }

 | expr GE expr { code(ge); }

 | expr LT expr { code(lt); }

 | expr LE expr { code(le); }

 | expr EQ expr { code(eq); }

 | expr NE expr { code(ne); }

 | expr AND expr { code(and); }

 | expr OR expr { code(or); }

 | NOT expr { $$ = $2; code(not); }

 ;

%%

/* end of grammar */

#include

#include

char *progname;

int lineno = 1;

#include

#include

jmp_buf begin;

int defining;

int c; /* global for use by warning() */

yylex() /* hoc5 */

{

 while ((c=getchar()) == ' ' || c == '\t')

  ;

 if (c == EOF)

  return 0;

 if (c == '.' || isdigit(c)) { /* number */

  double d;

  ungetc(c, stdin);