推荐保留预处理器指令的 C 前端答案

【问题标题】：Recommend C front-end that preserves preprocessor directives推荐保留预处理器指令的 C 前端
【发布时间】：2010-01-26 23:41:42
【问题描述】：

我想启动一个涉及转换C 代码的项目，但我想包含预处理器指令。我不想通过编写自己的 C 解析器来重新发明轮子，所以有人知道可以解析 C 预处理器和 C 代码，并生成可用于重新生成（或漂亮打印）原始源代码的 AST？

例如：

#define FILENAME "filename"
#include <stdio.h>

FILE *f=0;
...
if (file_is_open) {
#ifdef CAN_OPEN_IT
    f = fopen(FILENAME, "r");
#else
    printf("Unable to open file.\n");
#endif
}

上面的代码应该被解析成一些内存中的表示，可以用来重新生成源代码。换句话说，它不应该像普通的 C 那样分两个阶段处理，首先处理 PP 指令，然后解析纯 C 代码。相反，它应该代表整个编译时逻辑，包括预处理器变量。

【问题讨论】：

标签： c compiler-construction c-preprocessor abstract-syntax-tree

【解决方案1】：

看看Clang。（见http://clang.llvm.org/features.html#applications。）

【讨论】：

我不相信 Clang 在其 AST 中捕获预处理器指令。

【解决方案2】：

我们的DMS Software Reengineering Toolkit 有a C front end（和一个C++ 前端）：

将各种方言中的 C 源代码解析（可编译）为 AST，
在大多数情况下将预处理器指令保留为 AST 节点
可以从 AST 重新生成可编译的 C 代码（使用 cmets 和预处理器指令）
可以在单个图像中收集数千个文件以允许跨文件分析和转换
提供完整的符号表构造和访问
通过大型 AST 操作库提供对 AST 的过程访问，包括导航、检查、插入、删除、替换、匹配......
使用与 AST 匹配的 C 表示法编写的模式提供源到源的转换

对于 C（尚不支持 C++），DMS 还提供：

控制和数据流分析
本地和全局指向分析
全局调用图构建

DMS 已被用于处理超大型 C 应用程序，以提取事实并从原始源代码库生成新的派生代码。

（编辑：2016 年 2 月）

它可以处理 OP 的示例（稍作修正以使其有效）。这是稍作修改的来源：

#define FILENAME "filename"
#include <stdio.h>

FILE *f;
main() {
  f=0;
if (file_is_open) {
#ifdef CAN_OPEN_IT
f = fopen(FILENAME, "r");
#else
printf("Unable to open file.\n");
#endif
}

}

这是生成的 AST：

C~GCC4 Domain Parser Version 3.0.1(28449)
Copyright (C) 1996-2013 Semantic Designs, Inc; All Rights Reserved; SD Confidential
Powered by DMS (R) Software Reengineering Toolkit
AST Optimizations: remove constant tokens, remove unary productions, compact sequences
Using encoding Unicode-UTF-8?ANSI +CRLF +1 /^I
(translation_unit@C~GCC4=2#4a7e0e0^0 Line 1 Column 1 File C:/temp/test.c
 (declaration_seq@C~GCC4=605#4a77580^1#4a7e0e0:1 {4} Line 1 Column 1 File C:/temp/test.c
  (control_line@C~GCC4=1094#4a775c0^1#4a77580:1 Line 1 Column 1 File C:/temp/test.c
   ('#'@C~GCC4=1548#4a771c0^1#4a775c0:1[Keyword:0] Line 1 Column 1 File C:/temp/test.c)'#'
   (IDENTIFIER@C~GCC4=1531#4a77200^1#4a775c0:2[`FILENAME'] Line 1 Column 9 File C:/temp/test.c)IDENTIFIER
   (<!MacroDefinition>@C~GCC4=1603#4a77180^2#4a775c0:3#4a7f300:1[`FILENAME'] Line 1 Column 18 File C:/temp/test.c
$VOID$ [Child 1]
   |(STRING_LITERAL@C~GCC4=1525#4a77160^2#4a77180:2#4a7f300:2[`filename'] Line 1 Column 18 File C:/temp/test.c)STRING_LITERAL
$VOID$ [Child 3]
   )<!MacroDefinition>#4a77180
   (new_line@C~GCC4=1578#4a77260^1#4a775c0:4[Keyword:0] Line 1 Column 28 File C:/temp/test.c)new_line
  )control_line#4a775c0
  (control_line@C~GCC4=1104#4a77460^1#4a77580:2 Line 2 Column 1 File C:/temp/test.c
   ('#'@C~GCC4=1548#4a77340^1#4a77460:1[Keyword:0] Line 2 Column 1 File C:/temp/test.c)'#'
   (ANGLED_HEADER_NAME@C~GCC4=1589#4a77380^1#4a77460:2[`stdio.h'] Line 2 Column 10 File C:/temp/test.c)ANGLED_HEADER_NAME
   (new_line@C~GCC4=1578#4a773c0^1#4a77460:3[Keyword:0] Line 2 Column 19 File C:/temp/test.c)new_line
  )control_line#4a77460
  (simple_declaration@C~GCC4=631#4a774c0^1#4a77580:3 Line 4 Column 1 File C:/temp/test.c
   (IDENTIFIER@C~GCC4=1531#4a77360^1#4a774c0:1[`FILE'] Line 4 Column 1 File C:/temp/test.c)IDENTIFIER
   (declarator@C~GCC4=850#4a77520^1#4a774c0:2 Line 4 Column 6 File C:/temp/test.c
   |(ptr_operator@C~GCC4=866#4a77560^1#4a77520:1 Line 4 Column 6 File C:/temp/test.c)ptr_operator
   |(IDENTIFIER@C~GCC4=1531#4a77480^1#4a77520:2[`f'] Line 4 Column 7 File C:/temp/test.c)IDENTIFIER
   )declarator#4a77520
  )simple_declaration#4a774c0
  (function_definition@C~GCC4=966#4a77be0^1#4a77580:4 Line 5 Column 1 File C:/temp/test.c
   (direct_declarator@C~GCC4=852#4a77440^1#4a77be0:1 Line 5 Column 1 File C:/temp/test.c
   |(IDENTIFIER@C~GCC4=1531#4a774e0^1#4a77440:1[`main'] Line 5 Column 1 File C:/temp/test.c)IDENTIFIER
   |(parameter_declaration_clause@C~GCC4=900#4a77220^1#4a77440:2 Line 5 Column 6 File C:/temp/test.c)parameter_declaration_clause
   )direct_declarator#4a77440
   (compound_statement@C~GCC4=507#4a77b20^1#4a77be0:2 Line 5 Column 8 File C:/temp/test.c
   |(statement_seq@C~GCC4=511#4a77d20^1#4a77b20:1 {2} Line 6 Column 3 File C:/temp/test.c
   | (AMBIGUITY<statement=358>@C~GCC4=1602#4a77680^1#4a77d20:1{2} Line 6 Column 3 File C:/temp/test.c
   |  (expression_statement@C~GCC4=503#4a7e040^1#4a77680:1 Line 6 Column 3 File C:/temp/test.c
   |   (assignment_expression@C~GCC4=457#4a77f00^1#4a7e040:1 Line 6 Column 3 File C:/temp/test.c
   |   |(assignment_target@C~GCC4=470#4a77a00^1#4a77f00:1 Line 6 Column 3 File C:/temp/test.c
   |   | (IDENTIFIER@C~GCC4=1531#4a77400^2#4a77a00:1#4a77fc0:1[`f'] Line 6 Column 3 File C:/temp/test.c)IDENTIFIER
   |   |)assignment_target#4a77a00
   |   |(INT_LITERAL@C~GCC4=1471#4a77a60^2#4a77f00:2#4a77f60:1[0] Line 6 Column 5 File C:/temp/test.c)INT_LITERAL
   |   )assignment_expression#4a77f00
   |  )expression_statement#4a7e040
   |  (simple_declaration@C~GCC4=630#4a7e060^1#4a77680:2 Line 6 Column 3 File C:/temp/test.c
   |   (init_declarator@C~GCC4=835#4a77fc0^1#4a7e060:1 Line 6 Column 3 File C:/temp/test.c
   |   |(IDENTIFIER@C~GCC4=1531#4a77400^2... [ALREADY PRINTED] ...)
   |   |(initializer@C~GCC4=983#4a77f60^1#4a77fc0:2 Line 6 Column 4 File C:/temp/test.c
   |   | (INT_LITERAL@C~GCC4=1471#4a77a60^2... [ALREADY PRINTED] ...)
   |   |)initializer#4a77f60
   |   )init_declarator#4a77fc0
   |  )simple_declaration#4a7e060
   | )AMBIGUITY#4a77680
   | (selection_statement@C~GCC4=527#4a77b40^1#4a77d20:2 Line 7 Column 1 File C:/temp/test.c
   |  (IDENTIFIER@C~GCC4=1531#4a7e0c0^1#4a77b40:1[`file_is_open'] Line 7 Column 5 File C:/temp/test.c)IDENTIFIER
   |  (compound_statement@C~GCC4=507#4a77ae0^1#4a77b40:2 Line 7 Column 19 File C:/temp/test.c
   |   (statement@C~GCC4=490#4a7f840^1#4a77ae0:1 Line 8 Column 1 File C:/temp/test.c
   |   |(if_directive@C~GCC4=1088#4a7f1c0^1#4a7f840:1 Line 8 Column 1 File C:/temp/test.c
   |   | ('#'@C~GCC4=1548#4a7f240^1#4a7f1c0:1[Keyword:0] Line 8 Column 1 File C:/temp/test.c)'#'
   |   | (IDENTIFIER@C~GCC4=1531#4a7ee60^1#4a7f1c0:2[`CAN_OPEN_IT'] Line 8 Column 8 File C:/temp/test.c)IDENTIFIER
   |   | (new_line@C~GCC4=1578#4a7f1e0^1#4a7f1c0:3[Keyword:0] Line 8 Column 19 File C:/temp/test.c)new_line
   |   |)if_directive#4a7f1c0
   |   |(AMBIGUITY<statement=358>@C~GCC4=1602#4a77d40^1#4a7f840:2{2} Line 9 Column 5 File C:/temp/test.c
   |   | (expression_statement@C~GCC4=503#4a7f4a0^1#4a77d40:1 Line 9 Column 5 File C:/temp/test.c
   |   |  (assignment_expression@C~GCC4=457#4a7f3c0^1#4a7f4a0:1 Line 9 Column 5 File C:/temp/test.c
   |   |   (assignment_target@C~GCC4=470#4a7eec0^1#4a7f3c0:1 Line 9 Column 5 File C:/temp/test.c
   |   |   |(IDENTIFIER@C~GCC4=1531#4a7eee0^2#4a7eec0:1#4a7f400:1[`f'] Line 9 Column 5 File C:/temp/test.c)IDENTIFIER
   |   |   )assignment_target#4a7eec0
   |   |   (postfix_expression@C~GCC4=201#4a7f2e0^1#4a7f3c0:2 Line 9 Column 9 File C:/temp/test.c
   |   |   |(IDENTIFIER@C~GCC4=1531#4a7f120^2#4a7f2e0:1#4a7f160:1[`fopen'] Line 9 Column 9 File C:/temp/test.c)IDENTIFIER
   |   |   |(expression_list@C~GCC4=228#4a7f260^2#4a7f2e0:2#4a7f160:2 Line 9 Column 15 File C:/temp/test.c
   |   |   | (<!MacroCall>@C~GCC4=1607#4a7f300^1#4a7f260:1[`FILENAME'] Line 9 Column 15 File C:/temp/test.c
   |   |   |  (<!MacroDefinition>@C~GCC4=1603#4a77180^2... [ALREADY PRINTED] ...)
   |   |   |  (STRING_LITERAL@C~GCC4=1525#4a77160^2... [ALREADY PRINTED] ...)
   |   |   |  $VOID$ [Child 3]
   |   |   |  (STRING_LITERAL@C~GCC4=1525#4a7f2c0^1#4a7f300:4[`filename'] Line 1 Column 18 File C:/temp/test.c)STRING_LITERAL
   |   |   |  $VOID$ [Child 5]
   |   |   | )<!MacroCall>#4a7f300
   |   |   | (STRING_LITERAL@C~GCC4=1525#4a7f140^1#4a7f260:2[`r'] Line 9 Column 25 File C:/temp/test.c)STRING_LITERAL
   |   |   |)expression_list#4a7f260
   |   |   )postfix_expression#4a7f2e0
   |   |  )assignment_expression#4a7f3c0
   |   | )expression_statement#4a7f4a0
   |   | (simple_declaration@C~GCC4=630#4a7f480^1#4a77d40:2 Line 9 Column 5 File C:/temp/test.c
   |   |  (init_declarator@C~GCC4=835#4a7f400^1#4a7f480:1 Line 9 Column 5 File C:/temp/test.c
   |   |   (IDENTIFIER@C~GCC4=1531#4a7eee0^2... [ALREADY PRINTED] ...)
   |   |   (initializer@C~GCC4=983#4a7f3e0^1#4a7f400:2 Line 9 Column 7 File C:/temp/test.c
   |   |   |(postfix_expression@C~GCC4=201#4a7f160^1#4a7f3e0:1 Line 9 Column 9 File C:/temp/test.c
   |   |   | (IDENTIFIER@C~GCC4=1531#4a7f120^2... [ALREADY PRINTED] ...)
   |   |   | (expression_list@C~GCC4=228#4a7f260^2... [ALREADY PRINTED] ...)
   |   |   |)postfix_expression#4a7f160
   |   |   )initializer#4a7f3e0
   |   |  )init_declarator#4a7f400
   |   | )simple_declaration#4a7f480
   |   |)AMBIGUITY#4a77d40
   |   |(else_directive@C~GCC4=1091#4a7f4c0^1#4a7f840:3 Line 10 Column 1 File C:/temp/test.c
   |   | ('#'@C~GCC4=1548#4a7f500^1#4a7f4c0:1[Keyword:0] Line 10 Column 1 File C:/temp/test.c)'#'
   |   | (new_line@C~GCC4=1578#4a7f4e0^1#4a7f4c0:2[Keyword:0] Line 10 Column 6 File C:/temp/test.c)new_line
   |   |)else_directive#4a7f4c0
   |   |(expression_statement@C~GCC4=503#4a7f7c0^1#4a7f840:4 Line 11 Column 5 File C:/temp/test.c
   |   | (postfix_expression@C~GCC4=201#4a77ba0^1#4a7f7c0:1 Line 11 Column 5 File C:/temp/test.c
   |   |  (IDENTIFIER@C~GCC4=1531#4a7f640^1#4a77ba0:1[`printf'] Line 11 Column 5 File C:/temp/test.c)IDENTIFIER
   |   |  (STRING_LITERAL@C~GCC4=1525#4a77c20^1#4a77ba0:2[`Unable to open file.
'] Line 11 Column 12 File C:/temp/test.c)STRING_LITERAL
   |   | )postfix_expression#4a77ba0
   |   |)expression_statement#4a7f7c0
   |   |(endif_directive@C~GCC4=1092#4a7f7e0^1#4a7f840:5 Line 12 Column 1 File C:/temp/test.c
   |   | ('#'@C~GCC4=1548#4a7f720^1#4a7f7e0:1[Keyword:0] Line 12 Column 1 File C:/temp/test.c)'#'
   |   | (new_line@C~GCC4=1578#4a7f700^1#4a7f7e0:2[Keyword:0] Line 12 Column 7 File C:/temp/test.c)new_line
   |   |)endif_directive#4a7f7e0
   |   )statement#4a7f840
   |  )compound_statement#4a77ae0
   | )selection_statement#4a77b40
   |)statement_seq#4a77d20
   )compound_statement#4a77b20
  )function_definition#4a77be0
 )declaration_seq#4a77580
)translation_unit#4a7e0e0

您可以在第 8 行看到预处理器指令为“if_directive”。

是的，DMS 也可以漂亮地打印这棵树。以下命令运行解析器以生成 AST，然后运行 DMS 漂亮打印机以仅从树中重新生成源。往返准确；您可以重新编译并获得相同的结果。评论也会被保留。

C:\DMS\Domains\C\GCC4\Tools\PrettyPrinter>run domainprettyprinter \temp\test.c
C~GCC4 PrettyPrinter Version 1.2.13
Copyright (C) 2004-2013 Semantic Designs, Inc; All Rights Reserved; SD Confidential
Powered by DMS (R) Software Reengineering Toolkit

#define FILENAME "filename"
#include <stdio.h>
FILE *f;

main()
{
  f = 0;
  if (file_is_open)
    {
      #ifdef CAN_OPEN_IT
        f = fopen(FILENAME, "r");
      #else
        printf("Unable to open file.\n");
      #endif
    }
}

You can see how DMS handles C++。在这一点上，它处理了 GCC 和 MS 方言的所有 C++14。

【讨论】：

【解决方案3】：

以 GNU gcc 编译器为例，预处理源代码所需的标志是gcc -E mysource.c，更多信息请参见here。至于漂亮的打印，有indent，这解释了here的用法，这有点旧，但仍然值得一提。还有cflow可以生成源图。

抱歉，如果我误解了您要查找的内容...

【讨论】：

为什么投反对票？我提到了缩进和 cflow ......但是当问题的上下文包括“漂亮的打印”时，为什么需要 AST 的问题完全不清楚。如果投反对票，最好发表评论解释为什么而不是忽略它，这违背了 SO 的精神。
投反对票；他们很讨厌。通常，它们不会对您的声誉造成无法弥补的损害。
@Jonathan：快速提问，之前我对stackoverflow.com/questions/2142796/… 投了 3 票，但现在显示为 5，而不是 30，为什么？
对不起，如果不清楚，我正在寻找可以解析 C 和预处理器代码的东西，不一定是漂亮的打印机，但我提到这个的原因是漂亮的打印机可能会解析 CPP代码。我想要的是能够生成包含 CPP 逻辑的 AST 的东西。我不关心漂亮的印刷本身。
@Steve：好的，我能给出的最好的答案是看Antlr的语法在这里解析...antlr.org/grammar/list...usingAntlr 你可以生成一个AST并且有多种语言接口，即C#、C , CPP, Java 可以使用 Antlr 库进行解析，如果这就是你要找的... :)

【解决方案4】：

你可以看看http://www.antlr.org/wiki/display/ANTLR3/ANTLR3+Code+Generation+-+C

【讨论】：

这似乎是关于（ANTLR）解析器生成器，它产生用 C 实现的解析器。OP 想要 parses C 的东西。我错过了什么吗？