缥缈峰

News from http://www.freepascal.org/
引用
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August 22, 2005 The ARM port of Free Pascal can now be used to develop games for the Gameboy Advance.
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For details: http://fpc4gba.pascalgamedevelopment.com/

1)支持文法格式有： ''?' 0个或者1个, +' 1个或多个, '*' 0个或者多个, '|' 并列选择结构. '' 空串, 'A' 单个字符, \"string\" 字符串
2)自动展开文法，自动合并相同文法项
3)生成单一一个ANSI C的标准c文件，任何编译器均可以编译通过


TODO:
1)支持ASCII的字符，比如  '\n', \"hello\250\"
2)支持字符的范围格式，比如'0'-'9'
3)需要把空串文法放在并列选择的最后，比如 A : | B ; 应该调整为 A : B | ;


源程序： http://down.turbozv.com/PIG/PIG.dpr  (Delphi 7.0编译通过)


还是举个例子吧，输入exp.txt
===============exp.txt=============
exp : [ '+' | '-' ] ? term [ [ '+' | '-' ] term ] * ;
term : factor [ [ '*' | '/' ] factor ] * ;
factor : uint | '(' exp ')' ;
uint : number + ;
number : '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ;
=================================


输出exp.c
/* Generated by PIG version 1.0 (turbozv@uestc.edu.cn)
$Id: PIG.dpr,v 1.4 2005/09/19 17:15:51 ZV Exp $
DateTime: 2005-9-20 15:23:21
===================== Orignal Rules ===================
1) exp : [ '+' | '-' ] ? term [ [ '+' | '-' ] term ] * ;
2) term : factor [ [ '*' | '/' ] factor ] * ;
3) factor : uint | '(' exp ')' ;
4) uint : number + ;
5) number : '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ;
===================Processed to Rules==================
1) exp : exp_1 ? term exp_2 * ;
2) term : factor term_1 * ;
3) factor : uint | '(' exp ')' ;
4) uint : number + ;
5) number : '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ;
6) exp_1 : '+' | '-' ;
7) exp_2 : exp_1 term ;
8) term_1 : term_2 factor ;
9) term_2 : '*' | '/' ;
*/
#include <stdio.h>

typedef void Parser;

static int is_exp(Parser * pVar, char *buf);
static int is_term(Parser * pVar, char *buf);
static int is_factor(Parser * pVar, char *buf);
static int is_uint(Parser * pVar, char *buf);
static int is_number(Parser * pVar, char *buf);
static int is_exp_1(Parser * pVar, char *buf);
static int is_exp_2(Parser * pVar, char *buf);
static int is_term_1(Parser * pVar, char *buf);
static int is_term_2(Parser * pVar, char *buf);

/* 1) exp : exp_1 ? term exp_2 * ; */
static int is_exp(Parser * pVar, char *buf)
{
  int ret, sum = 0;

  // exp_1 ?
  if (-1 != (ret = is_exp_1(pVar, buf))) {
      sum += ret;
      buf += ret;
   }
  // term
  if (-1 == (ret = is_term(pVar, buf)))
      return -1;
  sum += ret;
  buf += ret;
  // exp_2 *
  while (-1 != (ret = is_exp_2(pVar, buf))) {
      sum += ret;
      buf += ret;
   }
  return sum;
}

/* 2) term : factor term_1 * ; */
static int is_term(Parser * pVar, char *buf)
{
  int ret, sum = 0;

  // factor
  if (-1 == (ret = is_factor(pVar, buf)))
      return -1;
  sum += ret;
  buf += ret;
  // term_1 *
  while (-1 != (ret = is_term_1(pVar, buf))) {
      sum += ret;
      buf += ret;
   }
  return sum;
}

/* 3) factor : uint | '(' exp ')' ; */
static int is_factor(Parser * pVar, char *buf)
{
  int ret, sum = 0;

  // uint
  if (-1 != (ret = is_uint(pVar, buf))) {
      sum += ret;
      buf += ret;
      return sum;
   }
  // '('
  if ('(' != *buf)
      return -1;
  sum++;
  buf++;
  // exp
  if (-1 == (ret = is_exp(pVar, buf)))
      return -1;
  sum += ret;
  buf += ret;
  // ')'
  if (')' != *buf)
      return -1;
  sum++;
  buf++;
  return sum;
}

/* 4) uint : number + ; */
static int is_uint(Parser * pVar, char *buf)
{
  int ret, sum = 0;

  // number +
  if (-1 == (ret = is_number(pVar, buf)))
      return -1;
  do {
      sum += ret;
      buf += ret;
   } while (-1 != (ret = is_number(pVar, buf)));
  return sum;
}

/* 5) number : '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ; */
static int is_number(Parser * pVar, char *buf)
{
  int sum = 0;

  // '0'
  if ('0' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '1'
  if ('1' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '2'
  if ('2' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '3'
  if ('3' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '4'
  if ('4' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '5'
  if ('5' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '6'
  if ('6' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '7'
  if ('7' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '8'
  if ('8' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '9'
  if ('9' != *buf)
      return -1;
  sum++;
  buf++;
  return sum;
}

/* 6) exp_1 : '+' | '-' ; */
static int is_exp_1(Parser * pVar, char *buf)
{
  int sum = 0;

  // '+'
  if ('+' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '-'
  if ('-' != *buf)
      return -1;
  sum++;
  buf++;
  return sum;
}

/* 7) exp_2 : exp_1 term ; */
static int is_exp_2(Parser * pVar, char *buf)
{
  int ret, sum = 0;

  // exp_1
  if (-1 == (ret = is_exp_1(pVar, buf)))
      return -1;
  sum += ret;
  buf += ret;
  // term
  if (-1 == (ret = is_term(pVar, buf)))
      return -1;
  sum += ret;
  buf += ret;
  return sum;
}

/* 8) term_1 : term_2 factor ; */
static int is_term_1(Parser * pVar, char *buf)
{
  int ret, sum = 0;

  // term_2
  if (-1 == (ret = is_term_2(pVar, buf)))
      return -1;
  sum += ret;
  buf += ret;
  // factor
  if (-1 == (ret = is_factor(pVar, buf)))
      return -1;
  sum += ret;
  buf += ret;
  return sum;
}

/* 9) term_2 : '*' | '/' ; */
static int is_term_2(Parser * pVar, char *buf)
{
  int sum = 0;

  // '*'
  if ('*' == *buf) {
      sum++;
      buf++;
      return sum;
   }
  // '/'
  if ('/' != *buf)
      return -1;
  sum++;
  buf++;
  return sum;
}

void main()
{
}

Q: What is PIG?
A: PIG is the short form of Parser Interface Generator. It turns the grammar and token scripts to a Parser.C file which can interpret the just language.


Q: Why made another YACC/LEX?
A: Because I find YACC/LEX is too difficult to learn (maybe only for me), and I also want to practice in such field. By the way, my recent work is related to it.


Q: What language do you want to use to implement PIG?
A: I want to use Delphi (Pascal) first, because it's my favorite language. Then, I'd like to port it to Python, and then C/C++ for wilder support.


Q: What’s the plan, when can the first version be released?
A: As I said, I am now using Delphi7.0. Well, the first version may be released in a week or less, because my work needs a common CSS2-parser very soon. In the following week, I will do PIG full-time. lol


Q:How can I contact with you?
A:Many ways, but I think email is best. Email me at: turbozv_AT_uestc_DOT_edu_DOT_cn

掌心万年历 1.2 QVGA：http://www.onlinedown.net/soft/38528.htm


掌心万年历 1.2 VGA：http://www.onlinedown.net/soft/42306.htm