Building a compiler

Hi

I'm in the middle of contruction a compiler for new programming language.

I have managed to build a basic compiler consisting of the following:

[code]
/********************global.h**************************/

#include <stdio.h>
#include <ctype.h>

#define BSIZE 128
#define NONE -1
#define EOS '\0'

#define NUM 256
#define DIV 257
#define MOD 258
#define ID 259
#define DONE 260

int tokenval;
int lineno;

struct entry {
  char *lexptr;
  int token;
};

struct entry symtable[100];

/***************************emitter.c*******************************/

#include "global.h"

emit(t, tval)
     int t, tval;
{
  switch(t) {
  case '+': case '-': case '*': case '/':
    printf("%c\n", t); break;
  case DIV:
    printf("DIV\n"); break;
  case NUM:
    printf("%d\n", tval); break;
  case ID:
    printf("%s\n", symtable[tval].lexptr); break;
  default:
    printf("token %d, tokenval %d\n", t, tval);
  }
}

/******************error.c***************************/

#include "global.h"

error(m)
     char *m;
{
  fprintf(stderr, "line %d: %s\n", lineno, m);
  exit(1);
}

/**************************init.c************************************/

#include "global.h"

struct entry keywords[] = {
  "div", DIV,
  "mod", MOD,
  0, 0
};

init()
{
  struct entry *p;
  for (p = keywords; p->token; p++)
    insert(p->lexptr, p->token);
}

/*****************************lexer************************/
#include "global.h"

char lexbuf[BSIZE];
int lineno = 1;
int tokenval = NONE;

int lexan()
{
  int t;
  while(1) {
    t = getchar();
    if (t == ' ' || t == '\t');
    else if (t == '\n')
      lineno = lineno + 1;
    else if (isdigit(t)) {
      ungetc(t, stdin);
      scanf("%d", &tokenval);
      return NUM;
    }
    else if (isalpha(t)) {
      int p, b = 0;
      while (isalnum(t)) {
      lexbuf[b] = t;
      t = getchar();
      b = b + 1;
      if (b >= BSIZE)
        error("We have a compiler error ha ha");
      }
      lexbuf[b] = EOS;
      if (t != EOF)
      ungetc (t, stdin);
      p = lookup(lexbuf);
      if( p == 0)
      p = insert(lexbuf, ID);
      tokenval = p;
      return symtable[p].token;
    }
    else if ( t == EOF)
      return DONE;

    else {
      tokenval = NONE;
      return t;
    }
  }
}

#include "global.h"

main()
{
  init();
  parse();
  exit(0);
}

/*********************************parser************************/
#include "global.h"

int lookahead;

parse()
{
  lookahead = lexan();
  while (lookahead != DONE ) {
    expr(); match(';');
  }
}
expr()
{
  int t;
  term();
  while(1)
    switch (lookahead) {
    case '+': case '-':
      t = lookahead;
      match(lookahead); term(); emit(t, NONE);
      continue;
    default:
      return;
    }
}
term()
{
  int t;
  factor();
  while(1)
    switch(lookahead) {
    case '*': case '/': case DIV: case MOD:
      t = lookahead;
      match(lookahead); factor(); emit(t,NONE);
      continue;
    default:
      return;
    }
}
factor()
{
  switch(lookahead) {
  case '(':
    match('('); expr(); match(')'); break;
  case NUM:
    emit(NUM, tokenval); match(NUM); break;
  case ID:
    emit(ID, tokenval); match(ID); break;
  default:
    error("syntax error ha ha");
  }
}
match(t)
     int t;
{
  if (lookahead == t)
    lookahead = lexan();
  else error("syntax error again haha");
}

/******************************symbol.c***********************************/

#include "global.h"

#define STRMAX 999
#define SYMMAX 100

char lexemes[STRMAX];
int lastchar = -1;
struct entry symtable[SYMMAX];
int lastentry = 0;

int lookup(s)
     char s[];
{
  int p;
  for (p = lastentry; p > 0; p = p - 1)
    if (strcmp(symtable[p].lexptr, s) == 0)
      return p;
  return 0;
}
int insert(s, tok)
char s[];
int tok;
{
  int len;
  len = strlen(s);
  if (lastentry + 1 >= SYMMAX)
    error("symbol table full");
  if (lastchar + len + 1 >= STRMAX)
    error("lexemes array is full");
  lastentry = lastentry + 1;
  symtable[lastentry].token = tok;
  symtable[lastentry].lexptr = &lexemes[lastchar + 1];
  lastchar = lastchar + len + 1;
  strcpy(symtable[lastentry].lexptr, s);
  return lastentry;
}

[/code]

I have a couple of questions: How do I make the compiler read-in keywords and statement from a specific file-format .oebj ?

Secondly then programming I have noticed that keywords are highlighted after they have been typed-in. Do I need implement anything specific in-order to get this to work in my programming language ?

Sincerely Frank