util.c

编译器的一个部分,只负责扫描输入的原文件,以后会把其余部分上传

/****************************************************/
/* File: util.c                                     */
/* Utility function implementation                  */
/* for the TINY compiler                            */
/* Compiler Construction: Principles and Practice   */
/* Kenneth C. Louden                                */
/****************************************************/

#include "globals.h"
#include "util.h"

/* Procedure printToken prints a token 
 * and its lexeme to the listing file
 */
void printToken( TokenType token, const char* tokenString )
{ switch (token)
  { case IF:
    case THEN:
    case ELSE:
    case END:
    case REPEAT:
    case UNTIL:
    case READ:
    case WRITE:
      fprintf(listing,
         "reserved word: %s\n",tokenString);
      break;
    case ASSIGN: fprintf(listing,":=\n"); break;
    case LT: fprintf(listing,"<\n"); break;
    case EQ: fprintf(listing,"=\n"); break;
    case LPAREN: fprintf(listing,"(\n"); break;
    case RPAREN: fprintf(listing,")\n"); break;
    case SEMI: fprintf(listing,";\n"); break;
    case PLUS: fprintf(listing,"+\n"); break;
    case MINUS: fprintf(listing,"-\n"); break;
    case TIMES: fprintf(listing,"*\n"); break;
    case OVER: fprintf(listing,"/\n"); break;
    case ENDFILE: fprintf(listing,"EOF\n"); break;
    case NUM:
      fprintf(listing,
          "NUM, val= %s\n",tokenString);
      break;
    case ID:
      fprintf(listing,
          "ID, name= %s\n",tokenString);
      break;
    case ERROR:
      fprintf(listing,
          "ERROR: %s\n",tokenString);
      break;
    default: /* should never happen */
      fprintf(listing,"Unknown token: %d\n",token);
  }
}

/* Function newStmtNode creates a new statement
 * node for syntax tree construction
 */

char * copyString(char * s)
{ int n;
  char * t;
  if (s==NULL) return NULL;
  n = strlen(s)+1;
  t = malloc(n);
  if (t==NULL)
    fprintf(listing,"Out of memory error at line %d\n",lineno);
  else strcpy(t,s);
  return t;
}

/* Variable indentno is used by printTree to
 * store current number of spaces to indent
 */
static indentno = 0;

/* macros to increase/decrease indentation */
#define INDENT indentno+=2
#define UNINDENT indentno-=2

/* printSpaces indents by printing spaces */
static void printSpaces(void)
{ int i;
  for (i=0;i<indentno;i++)
    fprintf(listing," ");
}