parse.c

/*
** Input file parser for the LEMON parser generator.
*/

/* The state of the parser */
enum e_state {
  INITIALIZE,
  WAITING_FOR_DECL_OR_RULE,
  WAITING_FOR_DECL_KEYWORD,
  WAITING_FOR_DECL_ARG,
  WAITING_FOR_PRECEDENCE_SYMBOL,
  WAITING_FOR_ARROW,
  IN_RHS,
  LHS_ALIAS_1,
  LHS_ALIAS_2,
  LHS_ALIAS_3,
  RHS_ALIAS_1,
  RHS_ALIAS_2,
  PRECEDENCE_MARK_1,
  PRECEDENCE_MARK_2,
  RESYNC_AFTER_RULE_ERROR,
  RESYNC_AFTER_DECL_ERROR,
  WAITING_FOR_DESTRUCTOR_SYMBOL,
  WAITING_FOR_DATATYPE_SYMBOL,
  WAITING_FOR_FALLBACK_ID,
  WAITING_FOR_WILDCARD_ID,
  WAITING_FOR_CLASS_ID,
  WAITING_FOR_CLASS_TOKEN,
  WAITING_FOR_TOKEN_NAME
};
struct pstate {
  char *filename;       /* Name of the input file */
  int tokenlineno;      /* Linenumber at which current token starts */
  int errorcnt;         /* Number of errors so far */
  char *tokenstart;     /* Text of current token */
  struct lemon *gp;     /* Global state vector */
  enum e_state state;        /* The state of the parser */
  struct symbol *fallback;   /* The fallback token */
  struct symbol *tkclass;    /* Token class symbol */
  struct symbol *lhs;        /* Left-hand side of current rule */
  const char *lhsalias;      /* Alias for the LHS */
  int nrhs;                  /* Number of right-hand side symbols seen */
  struct symbol *rhs[MAXRHS];  /* RHS symbols */
  const char *alias[MAXRHS]; /* Aliases for each RHS symbol (or NULL) */
  struct rule *prevrule;     /* Previous rule parsed */
  const char *declkeyword;   /* Keyword of a declaration */
  char **declargslot;        /* Where the declaration argument should be put */
  int insertLineMacro;       /* Add #line before declaration insert */
  int *decllinenoslot;       /* Where to write declaration line number */
  enum e_assoc declassoc;    /* Assign this association to decl arguments */
  int preccounter;           /* Assign this precedence to decl arguments */
  struct rule *firstrule;    /* Pointer to first rule in the grammar */
  struct rule *lastrule;     /* Pointer to the most recently parsed rule */
};

/* Parse a single token */
static void parseonetoken(struct pstate *psp)
{
  const char *x;
  x = Strsafe(psp->tokenstart);     /* Save the token permanently */
#if 0
  printf("%s:%d: Token=[%s] state=%d\n",psp->filename,psp->tokenlineno,
    x,psp->state);
#endif
  switch( psp->state ){
    case INITIALIZE:
      psp->prevrule = 0;
      psp->preccounter = 0;
      psp->firstrule = psp->lastrule = 0;
      psp->gp->nrule = 0;
      /* fall through */
    case WAITING_FOR_DECL_OR_RULE:
      if( x[0]=='%' ){
        psp->state = WAITING_FOR_DECL_KEYWORD;
      }else if( ISLOWER(x[0]) ){
        psp->lhs = Symbol_new(x);
        psp->nrhs = 0;
        psp->lhsalias = 0;
        psp->state = WAITING_FOR_ARROW;
      }else if( x[0]=='{' ){
        if( psp->prevrule==0 ){
          ErrorMsg(psp->filename,psp->tokenlineno,
            "There is no prior rule upon which to attach the code "
            "fragment which begins on this line.");
          psp->errorcnt++;
        }else if( psp->prevrule->code!=0 ){
          ErrorMsg(psp->filename,psp->tokenlineno,
            "Code fragment beginning on this line is not the first "
            "to follow the previous rule.");
          psp->errorcnt++;
        }else if( strcmp(x, "{NEVER-REDUCE")==0 ){
          psp->prevrule->neverReduce = 1;
        }else{
          psp->prevrule->line = psp->tokenlineno;
          psp->prevrule->code = &x[1];
          psp->prevrule->noCode = 0;
        }
      }else if( x[0]=='[' ){
        psp->state = PRECEDENCE_MARK_1;
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Token \"%s\" should be either \"%%\" or a nonterminal name.",
          x);
        psp->errorcnt++;
      }
      break;
    case PRECEDENCE_MARK_1:
      if( !ISUPPER(x[0]) ){
        ErrorMsg(psp->filename,psp->tokenlineno,
          "The precedence symbol must be a terminal.");
        psp->errorcnt++;
      }else if( psp->prevrule==0 ){
        ErrorMsg(psp->filename,psp->tokenlineno,
          "There is no prior rule to assign precedence \"[%s]\".",x);
        psp->errorcnt++;
      }else if( psp->prevrule->precsym!=0 ){
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Precedence mark on this line is not the first "
          "to follow the previous rule.");
        psp->errorcnt++;
      }else{
        psp->prevrule->precsym = Symbol_new(x);
      }
      psp->state = PRECEDENCE_MARK_2;
      break;
    case PRECEDENCE_MARK_2:
      if( x[0]!=']' ){
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Missing \"]\" on precedence mark.");
        psp->errorcnt++;
      }
      psp->state = WAITING_FOR_DECL_OR_RULE;
      break;
    case WAITING_FOR_ARROW:
      if( x[0]==':' && x[1]==':' && x[2]=='=' ){
        psp->state = IN_RHS;
      }else if( x[0]=='(' ){
        psp->state = LHS_ALIAS_1;
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Expected to see a \":\" following the LHS symbol \"%s\".",
          psp->lhs->name);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_RULE_ERROR;
      }
      break;
    case LHS_ALIAS_1:
      if( ISALPHA(x[0]) ){
        psp->lhsalias = x;
        psp->state = LHS_ALIAS_2;
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "\"%s\" is not a valid alias for the LHS \"%s\"\n",
          x,psp->lhs->name);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_RULE_ERROR;
      }
      break;
    case LHS_ALIAS_2:
      if( x[0]==')' ){
        psp->state = LHS_ALIAS_3;
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Missing \")\" following LHS alias name \"%s\".",psp->lhsalias);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_RULE_ERROR;
      }
      break;
    case LHS_ALIAS_3:
      if( x[0]==':' && x[1]==':' && x[2]=='=' ){
        psp->state = IN_RHS;
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Missing \"->\" following: \"%s(%s)\".",
           psp->lhs->name,psp->lhsalias);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_RULE_ERROR;
      }
      break;
    case IN_RHS:
      if( x[0]=='.' ){
        struct rule *rp;
        rp = (struct rule *)calloc( sizeof(struct rule) +
             sizeof(struct symbol*)*psp->nrhs + sizeof(char*)*psp->nrhs, 1);
        if( rp==0 ){
          ErrorMsg(psp->filename,psp->tokenlineno,
            "Can't allocate enough memory for this rule.");
          psp->errorcnt++;
          psp->prevrule = 0;
        }else{
          int i;
          rp->ruleline = psp->tokenlineno;
          rp->rhs = (struct symbol**)&rp[1];
          rp->rhsalias = (const char**)&(rp->rhs[psp->nrhs]);
          for(i=0; i<psp->nrhs; i++){
            rp->rhs[i] = psp->rhs[i];
            rp->rhsalias[i] = psp->alias[i];
            if( rp->rhsalias[i]!=0 ){ rp->rhs[i]->bContent = 1; }
          }
          rp->lhs = psp->lhs;
          rp->lhsalias = psp->lhsalias;
          rp->nrhs = psp->nrhs;
          rp->code = 0;
          rp->noCode = 1;
          rp->precsym = 0;
          rp->index = psp->gp->nrule++;
          rp->nextlhs = rp->lhs->rule;
          rp->lhs->rule = rp;
          rp->next = 0;
          if( psp->firstrule==0 ){
            psp->firstrule = psp->lastrule = rp;
          }else{
            psp->lastrule->next = rp;
            psp->lastrule = rp;
          }
          psp->prevrule = rp;
        }
        psp->state = WAITING_FOR_DECL_OR_RULE;
      }else if( ISALPHA(x[0]) ){
        if( psp->nrhs>=MAXRHS ){
          ErrorMsg(psp->filename,psp->tokenlineno,
            "Too many symbols on RHS of rule beginning at \"%s\".",
            x);
          psp->errorcnt++;
          psp->state = RESYNC_AFTER_RULE_ERROR;
        }else{
          psp->rhs[psp->nrhs] = Symbol_new(x);
          psp->alias[psp->nrhs] = 0;
          psp->nrhs++;
        }
      }else if( (x[0]=='|' || x[0]=='/') && psp->nrhs>0 && ISUPPER(x[1]) ){
        struct symbol *msp = psp->rhs[psp->nrhs-1];
        if( msp->type!=MULTITERMINAL ){
          struct symbol *origsp = msp;
          msp = (struct symbol *) calloc(1,sizeof(*msp));
          memset(msp, 0, sizeof(*msp));
          msp->type = MULTITERMINAL;
          msp->nsubsym = 1;
          msp->subsym = (struct symbol **) calloc(1,sizeof(struct symbol*));
          msp->subsym[0] = origsp;
          msp->name = origsp->name;
          psp->rhs[psp->nrhs-1] = msp;
        }
        msp->nsubsym++;
        msp->subsym = (struct symbol **) realloc(msp->subsym,
          sizeof(struct symbol*)*msp->nsubsym);
        msp->subsym[msp->nsubsym-1] = Symbol_new(&x[1]);
        if( ISLOWER(x[1]) || ISLOWER(msp->subsym[0]->name[0]) ){
          ErrorMsg(psp->filename,psp->tokenlineno,
            "Cannot form a compound containing a non-terminal");
          psp->errorcnt++;
        }
      }else if( x[0]=='(' && psp->nrhs>0 ){
        psp->state = RHS_ALIAS_1;
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Illegal character on RHS of rule: \"%s\".",x);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_RULE_ERROR;
      }
      break;
    case RHS_ALIAS_1:
      if( ISALPHA(x[0]) ){
        psp->alias[psp->nrhs-1] = x;
        psp->state = RHS_ALIAS_2;
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "\"%s\" is not a valid alias for the RHS symbol \"%s\"\n",
          x,psp->rhs[psp->nrhs-1]->name);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_RULE_ERROR;
      }
      break;
    case RHS_ALIAS_2:
      if( x[0]==')' ){
        psp->state = IN_RHS;
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Missing \")\" following LHS alias name \"%s\".",psp->lhsalias);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_RULE_ERROR;
      }
      break;
    case WAITING_FOR_DECL_KEYWORD:
      if( ISALPHA(x[0]) ){
        psp->declkeyword = x;
        psp->declargslot = 0;
        psp->decllinenoslot = 0;
        psp->insertLineMacro = 1;
        psp->state = WAITING_FOR_DECL_ARG;
        if( strcmp(x,"name")==0 ){
          psp->declargslot = &(psp->gp->name);
          psp->insertLineMacro = 0;
        }else if( strcmp(x,"include")==0 ){
          psp->declargslot = &(psp->gp->include);
        }else if( strcmp(x,"code")==0 ){
          psp->declargslot = &(psp->gp->extracode);
        }else if( strcmp(x,"token_destructor")==0 ){
          psp->declargslot = &psp->gp->tokendest;
        }else if( strcmp(x,"default_destructor")==0 ){
          psp->declargslot = &psp->gp->vardest;
        }else if( strcmp(x,"token_prefix")==0 ){
          psp->declargslot = &psp->gp->tokenprefix;
          psp->insertLineMacro = 0;
        }else if( strcmp(x,"syntax_error")==0 ){
          psp->declargslot = &(psp->gp->error);
        }else if( strcmp(x,"parse_accept")==0 ){
          psp->declargslot = &(psp->gp->accept);
        }else if( strcmp(x,"parse_failure")==0 ){
          psp->declargslot = &(psp->gp->failure);
        }else if( strcmp(x,"stack_overflow")==0 ){
          psp->declargslot = &(psp->gp->overflow);
        }else if( strcmp(x,"extra_argument")==0 ){
          psp->declargslot = &(psp->gp->arg);
          psp->insertLineMacro = 0;
        }else if( strcmp(x,"extra_context")==0 ){
          psp->declargslot = &(psp->gp->ctx);
          psp->insertLineMacro = 0;
        }else if( strcmp(x,"token_type")==0 ){
          psp->declargslot = &(psp->gp->tokentype);
          psp->insertLineMacro = 0;
        }else if( strcmp(x,"default_type")==0 ){
          psp->declargslot = &(psp->gp->vartype);
          psp->insertLineMacro = 0;
        }else if( strcmp(x,"stack_size")==0 ){
          psp->declargslot = &(psp->gp->stacksize);
          psp->insertLineMacro = 0;
        }else if( strcmp(x,"start_symbol")==0 ){
          psp->declargslot = &(psp->gp->start);
          psp->insertLineMacro = 0;
        }else if( strcmp(x,"left")==0 ){
          psp->preccounter++;
          psp->declassoc = LEFT;
          psp->state = WAITING_FOR_PRECEDENCE_SYMBOL;
        }else if( strcmp(x,"right")==0 ){
          psp->preccounter++;
          psp->declassoc = RIGHT;
          psp->state = WAITING_FOR_PRECEDENCE_SYMBOL;
        }else if( strcmp(x,"nonassoc")==0 ){
          psp->preccounter++;
          psp->declassoc = NONE;
          psp->state = WAITING_FOR_PRECEDENCE_SYMBOL;
        }else if( strcmp(x,"destructor")==0 ){
          psp->state = WAITING_FOR_DESTRUCTOR_SYMBOL;
        }else if( strcmp(x,"type")==0 ){
          psp->state = WAITING_FOR_DATATYPE_SYMBOL;
        }else if( strcmp(x,"fallback")==0 ){
          psp->fallback = 0;
          psp->state = WAITING_FOR_FALLBACK_ID;
        }else if( strcmp(x,"token")==0 ){
          psp->state = WAITING_FOR_TOKEN_NAME;
        }else if( strcmp(x,"wildcard")==0 ){
          psp->state = WAITING_FOR_WILDCARD_ID;
        }else if( strcmp(x,"token_class")==0 ){
          psp->state = WAITING_FOR_CLASS_ID;
        }else{
          ErrorMsg(psp->filename,psp->tokenlineno,
            "Unknown declaration keyword: \"%%%s\".",x);
          psp->errorcnt++;
          psp->state = RESYNC_AFTER_DECL_ERROR;
        }
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Illegal declaration keyword: \"%s\".",x);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_DECL_ERROR;
      }
      break;
    case WAITING_FOR_DESTRUCTOR_SYMBOL:
      if( !ISALPHA(x[0]) ){
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Symbol name missing after %%destructor keyword");
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_DECL_ERROR;
      }else{
        struct symbol *sp = Symbol_new(x);
        psp->declargslot = &sp->destructor;
        psp->decllinenoslot = &sp->destLineno;
        psp->insertLineMacro = 1;
        psp->state = WAITING_FOR_DECL_ARG;
      }
      break;
    case WAITING_FOR_DATATYPE_SYMBOL:
      if( !ISALPHA(x[0]) ){
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Symbol name missing after %%type keyword");
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_DECL_ERROR;
      }else{
        struct symbol *sp = Symbol_find(x);
        if((sp) && (sp->datatype)){
          ErrorMsg(psp->filename,psp->tokenlineno,
            "Symbol %%type \"%s\" already defined", x);
          psp->errorcnt++;
          psp->state = RESYNC_AFTER_DECL_ERROR;
        }else{
          if (!sp){
            sp = Symbol_new(x);
          }
          psp->declargslot = &sp->datatype;
          psp->insertLineMacro = 0;
          psp->state = WAITING_FOR_DECL_ARG;
        }
      }
      break;
    case WAITING_FOR_PRECEDENCE_SYMBOL:
      if( x[0]=='.' ){
        psp->state = WAITING_FOR_DECL_OR_RULE;
      }else if( ISUPPER(x[0]) ){
        struct symbol *sp;
        sp = Symbol_new(x);
        if( sp->prec>=0 ){
          ErrorMsg(psp->filename,psp->tokenlineno,
            "Symbol \"%s\" has already be given a precedence.",x);
          psp->errorcnt++;
        }else{
          sp->prec = psp->preccounter;
          sp->assoc = psp->declassoc;
        }
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Can't assign a precedence to \"%s\".",x);
        psp->errorcnt++;
      }
      break;
    case WAITING_FOR_DECL_ARG:
      if( x[0]=='{' || x[0]=='\"' || ISALNUM(x[0]) ){
        const char *zOld, *zNew;
        char *zBuf, *z;
        int nOld, n, nLine = 0, nNew, nBack;
        int addLineMacro;
        char zLine[50];
        zNew = x;
        if( zNew[0]=='"' || zNew[0]=='{' ) zNew++;
        nNew = lemonStrlen(zNew);
        if( *psp->declargslot ){
          zOld = *psp->declargslot;
        }else{
          zOld = "";
        }
        nOld = lemonStrlen(zOld);
        n = nOld + nNew + 20;
        addLineMacro = !psp->gp->nolinenosflag
                       && psp->insertLineMacro
                       && psp->tokenlineno>1
                       && (psp->decllinenoslot==0 || psp->decllinenoslot[0]!=0);
        if( addLineMacro ){
          for(z=psp->filename, nBack=0; *z; z++){
            if( *z=='\\' ) nBack++;
          }
          lemon_sprintf(zLine, "#line %d ", psp->tokenlineno);
          nLine = lemonStrlen(zLine);
          n += nLine + lemonStrlen(psp->filename) + nBack;
        }
        *psp->declargslot = (char *) realloc(*psp->declargslot, n);
        zBuf = *psp->declargslot + nOld;
        if( addLineMacro ){
          if( nOld && zBuf[-1]!='\n' ){
            *(zBuf++) = '\n';
          }
          memcpy(zBuf, zLine, nLine);
          zBuf += nLine;
          *(zBuf++) = '"';
          for(z=psp->filename; *z; z++){
            if( *z=='\\' ){
              *(zBuf++) = '\\';
            }
            *(zBuf++) = *z;
          }
          *(zBuf++) = '"';
          *(zBuf++) = '\n';
        }
        if( psp->decllinenoslot && psp->decllinenoslot[0]==0 ){
          psp->decllinenoslot[0] = psp->tokenlineno;
        }
        memcpy(zBuf, zNew, nNew);
        zBuf += nNew;
        *zBuf = 0;
        psp->state = WAITING_FOR_DECL_OR_RULE;
      }else{
        ErrorMsg(psp->filename,psp->tokenlineno,
          "Illegal argument to %%%s: %s",psp->declkeyword,x);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_DECL_ERROR;
      }
      break;
    case WAITING_FOR_FALLBACK_ID:
      if( x[0]=='.' ){
        psp->state = WAITING_FOR_DECL_OR_RULE;
      }else if( !ISUPPER(x[0]) ){
        ErrorMsg(psp->filename, psp->tokenlineno,
          "%%fallback argument \"%s\" should be a token", x);
        psp->errorcnt++;
      }else{
        struct symbol *sp = Symbol_new(x);
        if( psp->fallback==0 ){
          psp->fallback = sp;
        }else if( sp->fallback ){
          ErrorMsg(psp->filename, psp->tokenlineno,
            "More than one fallback assigned to token %s", x);
          psp->errorcnt++;
        }else{
          sp->fallback = psp->fallback;
          psp->gp->has_fallback = 1;
        }
      }
      break;
    case WAITING_FOR_TOKEN_NAME:
      /* Tokens do not have to be declared before use.  But they can be
      ** in order to control their assigned integer number.  The number for
      ** each token is assigned when it is first seen.  So by including
      **
      **     %token ONE TWO THREE.
      **
      ** early in the grammar file, that assigns small consecutive values
      ** to each of the tokens ONE TWO and THREE.
      */
      if( x[0]=='.' ){
        psp->state = WAITING_FOR_DECL_OR_RULE;
      }else if( !ISUPPER(x[0]) ){
        ErrorMsg(psp->filename, psp->tokenlineno,
          "%%token argument \"%s\" should be a token", x);
        psp->errorcnt++;
      }else{
        (void)Symbol_new(x);
      }
      break;
    case WAITING_FOR_WILDCARD_ID:
      if( x[0]=='.' ){
        psp->state = WAITING_FOR_DECL_OR_RULE;
      }else if( !ISUPPER(x[0]) ){
        ErrorMsg(psp->filename, psp->tokenlineno,
          "%%wildcard argument \"%s\" should be a token", x);
        psp->errorcnt++;
      }else{
        struct symbol *sp = Symbol_new(x);
        if( psp->gp->wildcard==0 ){
          psp->gp->wildcard = sp;
        }else{
          ErrorMsg(psp->filename, psp->tokenlineno,
            "Extra wildcard to token: %s", x);
          psp->errorcnt++;
        }
      }
      break;
    case WAITING_FOR_CLASS_ID:
      if( !ISLOWER(x[0]) ){
        ErrorMsg(psp->filename, psp->tokenlineno,
          "%%token_class must be followed by an identifier: %s", x);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_DECL_ERROR;
     }else if( Symbol_find(x) ){
        ErrorMsg(psp->filename, psp->tokenlineno,
          "Symbol \"%s\" already used", x);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_DECL_ERROR;
      }else{
        psp->tkclass = Symbol_new(x);
        psp->tkclass->type = MULTITERMINAL;
        psp->state = WAITING_FOR_CLASS_TOKEN;
      }
      break;
    case WAITING_FOR_CLASS_TOKEN:
      if( x[0]=='.' ){
        psp->state = WAITING_FOR_DECL_OR_RULE;
      }else if( ISUPPER(x[0]) || ((x[0]=='|' || x[0]=='/') && ISUPPER(x[1])) ){
        struct symbol *msp = psp->tkclass;
        msp->nsubsym++;
        msp->subsym = (struct symbol **) realloc(msp->subsym,
          sizeof(struct symbol*)*msp->nsubsym);
        if( !ISUPPER(x[0]) ) x++;
        msp->subsym[msp->nsubsym-1] = Symbol_new(x);
      }else{
        ErrorMsg(psp->filename, psp->tokenlineno,
          "%%token_class argument \"%s\" should be a token", x);
        psp->errorcnt++;
        psp->state = RESYNC_AFTER_DECL_ERROR;
      }
      break;
    case RESYNC_AFTER_RULE_ERROR:
/*      if( x[0]=='.' ) psp->state = WAITING_FOR_DECL_OR_RULE;
**      break; */
    case RESYNC_AFTER_DECL_ERROR:
      if( x[0]=='.' ) psp->state = WAITING_FOR_DECL_OR_RULE;
      if( x[0]=='%' ) psp->state = WAITING_FOR_DECL_KEYWORD;
      break;
  }
}

/* The text in the input is part of the argument to an %ifdef or %ifndef.
** Evaluate the text as a boolean expression.  Return true or false.
*/
static int eval_preprocessor_boolean(char *z, int lineno){
  int neg = 0;
  int res = 0;
  int okTerm = 1;
  int i;
  for(i=0; z[i]!=0; i++){
    if( ISSPACE(z[i]) ) continue;
    if( z[i]=='!' ){
      if( !okTerm ) goto pp_syntax_error;
      neg = !neg;
      continue;
    }
    if( z[i]=='|' && z[i+1]=='|' ){
      if( okTerm ) goto pp_syntax_error;
      if( res ) return 1;
      i++;
      okTerm = 1;
      continue;
    }
    if( z[i]=='&' && z[i+1]=='&' ){
      if( okTerm ) goto pp_syntax_error;
      if( !res ) return 0;
      i++;
      okTerm = 1;
      continue;
    }
    if( z[i]=='(' ){
      int k;
      int n = 1;
      if( !okTerm ) goto pp_syntax_error;
      for(k=i+1; z[k]; k++){
        if( z[k]==')' ){
          n--;
          if( n==0 ){
            z[k] = 0;
            res = eval_preprocessor_boolean(&z[i+1], -1);
            z[k] = ')';
            if( res<0 ){
              i = i-res;
              goto pp_syntax_error;
            }
            i = k;
            break;
          }
        }else if( z[k]=='(' ){
          n++;
        }else if( z[k]==0 ){
          i = k;
          goto pp_syntax_error;
        }
      }
      if( neg ){
        res = !res;
        neg = 0;
      }
      okTerm = 0;
      continue;
    }
    if( ISALPHA(z[i]) ){
      int j, k, n;
      if( !okTerm ) goto pp_syntax_error;
      for(k=i+1; ISALNUM(z[k]) || z[k]=='_'; k++){}
      n = k - i;
      res = 0;
      for(j=0; j<nDefine; j++){
        if( strncmp(azDefine[j],&z[i],n)==0 && azDefine[j][n]==0 ){
          res = 1;
          break;
        }
      }
      i = k-1;
      if( neg ){
        res = !res;
        neg = 0;
      }
      okTerm = 0;
      continue;
    }
    goto pp_syntax_error;
  }
  return res;

pp_syntax_error:
  if( lineno>0 ){
    fprintf(stderr, "%%if syntax error on line %d.\n", lineno);
    fprintf(stderr, "  %.*s <-- syntax error here\n", i+1, z);
    exit(1);
  }else{
    return -(i+1);
  }
}

/* Run the preprocessor over the input file text.  The global variables
** azDefine[0] through azDefine[nDefine-1] contains the names of all defined
** macros.  This routine looks for "%ifdef" and "%ifndef" and "%endif" and
** comments them out.  Text in between is also commented out as appropriate.
*/
static void preprocess_input(char *z){
  int i, j, k;
  int exclude = 0;
  int start = 0;
  int lineno = 1;
  int start_lineno = 1;
  for(i=0; z[i]; i++){
    if( z[i]=='\n' ) lineno++;
    if( z[i]!='%' || (i>0 && z[i-1]!='\n') ) continue;
    if( strncmp(&z[i],"%endif",6)==0 && ISSPACE(z[i+6]) ){
      if( exclude ){
        exclude--;
        if( exclude==0 ){
          for(j=start; j<i; j++) if( z[j]!='\n' ) z[j] = ' ';
        }
      }
      for(j=i; z[j] && z[j]!='\n'; j++) z[j] = ' ';
    }else if( strncmp(&z[i],"%else",5)==0 && ISSPACE(z[i+5]) ){
      if( exclude==1){
        exclude = 0;
        for(j=start; j<i; j++) if( z[j]!='\n' ) z[j] = ' ';
      }else if( exclude==0 ){
        exclude = 1;
        start = i;
        start_lineno = lineno;
      }
      for(j=i; z[j] && z[j]!='\n'; j++) z[j] = ' ';
    }else if( strncmp(&z[i],"%ifdef ",7)==0
          || strncmp(&z[i],"%if ",4)==0
          || strncmp(&z[i],"%ifndef ",8)==0 ){
      if( exclude ){
        exclude++;
      }else{
        int isNot;
        int iBool;
        for(j=i; z[j] && !ISSPACE(z[j]); j++){}
        iBool = j;
        isNot = (j==i+7);
        while( z[j] && z[j]!='\n' ){ j++; }
        k = z[j];
        z[j] = 0;
        exclude = eval_preprocessor_boolean(&z[iBool], lineno);
        z[j] = k;
        if( !isNot ) exclude = !exclude;
        if( exclude ){
          start = i;
          start_lineno = lineno;
        }
      }
      for(j=i; z[j] && z[j]!='\n'; j++) z[j] = ' ';
    }
  }
  if( exclude ){
    fprintf(stderr,"unterminated %%ifdef starting on line %d\n", start_lineno);
    exit(1);
  }
}

/* In spite of its name, this function is really a scanner.  It read
** in the entire input file (all at once) then tokenizes it.  Each
** token is passed to the function "parseonetoken" which builds all
** the appropriate data structures in the global state vector "gp".
*/
void Parse(struct lemon *gp)
{
  struct pstate ps;
  FILE *fp;
  char *filebuf;
  unsigned int filesize;
  int lineno;
  int c;
  char *cp, *nextcp;
  int startline = 0;

  memset(&ps, '\0', sizeof(ps));
  ps.gp = gp;
  ps.filename = gp->filename;
  ps.errorcnt = 0;
  ps.state = INITIALIZE;

  /* Begin by reading the input file */
  fp = fopen(ps.filename,"rb");
  if( fp==0 ){
    ErrorMsg(ps.filename,0,"Can't open this file for reading.");
    gp->errorcnt++;
    return;
  }
  fseek(fp,0,2);
  filesize = ftell(fp);
  rewind(fp);
  filebuf = (char *)malloc( filesize+1 );
  if( filesize>100000000 || filebuf==0 ){
    ErrorMsg(ps.filename,0,"Input file too large.");
    free(filebuf);
    gp->errorcnt++;
    fclose(fp);
    return;
  }
  if( fread(filebuf,1,filesize,fp)!=filesize ){
    ErrorMsg(ps.filename,0,"Can't read in all %d bytes of this file.",
      filesize);
    free(filebuf);
    gp->errorcnt++;
    fclose(fp);
    return;
  }
  fclose(fp);
  filebuf[filesize] = 0;

  /* Make an initial pass through the file to handle %ifdef and %ifndef */
  preprocess_input(filebuf);
  if( gp->printPreprocessed ){
    printf("%s\n", filebuf);
    return;
  }

  /* Now scan the text of the input file */
  lineno = 1;
  for(cp=filebuf; (c= *cp)!=0; ){
    if( c=='\n' ) lineno++;              /* Keep track of the line number */
    if( ISSPACE(c) ){ cp++; continue; }  /* Skip all white space */
    if( c=='/' && cp[1]=='/' ){          /* Skip C++ style comments */
      cp+=2;
      while( (c= *cp)!=0 && c!='\n' ) cp++;
      continue;
    }
    if( c=='/' && cp[1]=='*' ){          /* Skip C style comments */
      cp+=2;
      while( (c= *cp)!=0 && (c!='/' || cp[-1]!='*') ){
        if( c=='\n' ) lineno++;
        cp++;
      }
      if( c ) cp++;
      continue;
    }
    ps.tokenstart = cp;                /* Mark the beginning of the token */
    ps.tokenlineno = lineno;           /* Linenumber on which token begins */
    if( c=='\"' ){                     /* String literals */
      cp++;
      while( (c= *cp)!=0 && c!='\"' ){
        if( c=='\n' ) lineno++;
        cp++;
      }
      if( c==0 ){
        ErrorMsg(ps.filename,startline,
            "String starting on this line is not terminated before "
            "the end of the file.");
        ps.errorcnt++;
        nextcp = cp;
      }else{
        nextcp = cp+1;
      }
    }else if( c=='{' ){               /* A block of C code */
      int level;
      cp++;
      for(level=1; (c= *cp)!=0 && (level>1 || c!='}'); cp++){
        if( c=='\n' ) lineno++;
        else if( c=='{' ) level++;
        else if( c=='}' ) level--;
        else if( c=='/' && cp[1]=='*' ){  /* Skip comments */
          int prevc;
          cp = &cp[2];
          prevc = 0;
          while( (c= *cp)!=0 && (c!='/' || prevc!='*') ){
            if( c=='\n' ) lineno++;
            prevc = c;
            cp++;
          }
        }else if( c=='/' && cp[1]=='/' ){  /* Skip C++ style comments too */
          cp = &cp[2];
          while( (c= *cp)!=0 && c!='\n' ) cp++;
          if( c ) lineno++;
        }else if( c=='\'' || c=='\"' ){    /* String a character literals */
          int startchar, prevc;
          startchar = c;
          prevc = 0;
          for(cp++; (c= *cp)!=0 && (c!=startchar || prevc=='\\'); cp++){
            if( c=='\n' ) lineno++;
            if( prevc=='\\' ) prevc = 0;
            else              prevc = c;
          }
        }
      }
      if( c==0 ){
        ErrorMsg(ps.filename,ps.tokenlineno,
          "C code starting on this line is not terminated before "
          "the end of the file.");
        ps.errorcnt++;
        nextcp = cp;
      }else{
        nextcp = cp+1;
      }
    }else if( ISALNUM(c) ){          /* Identifiers */
      while( (c= *cp)!=0 && (ISALNUM(c) || c=='_') ) cp++;
      nextcp = cp;
    }else if( c==':' && cp[1]==':' && cp[2]=='=' ){ /* The operator "::=" */
      cp += 3;
      nextcp = cp;
    }else if( (c=='/' || c=='|') && ISALPHA(cp[1]) ){
      cp += 2;
      while( (c = *cp)!=0 && (ISALNUM(c) || c=='_') ) cp++;
      nextcp = cp;
    }else{                          /* All other (one character) operators */
      cp++;
      nextcp = cp;
    }
    c = *cp;
    *cp = 0;                        /* Null terminate the token */
    parseonetoken(&ps);             /* Parse the token */
    *cp = (char)c;                  /* Restore the buffer */
    cp = nextcp;
  }
  free(filebuf);                    /* Release the buffer after parsing */
  gp->rule = ps.firstrule;
  gp->errorcnt = ps.errorcnt;
}