Jserv's blog

GCC-XML：GCC 的 XML 輸出

[GCC-XML] 是個相當特別的專案，官方網頁的簡介如下：

Development tools that work with programming languages benefit from their ability to understand the code with which they work at a level comparable to a compiler. C++ has become a popular and powerful language, but parsing it is a very challenging problem. This has discouraged the development of tools meant to work directly with the language.

There is one open-source C++ parser, the C++ front-end to GCC, which is currently able to deal with the language in its entirety. The purpose of the GCC-XML extension is to generate an XML description of a C++ program from GCC's internal representation. Since XML is easy to parse, other development tools will be able to work with C++ programs without the burden of a complicated C++ parser.

依據 [GCC-XML::Links] 所示，至少有兩個專案採用此成果：

• [pyste] - Boost.Python wrapper generator based on GCC-XML.
• [pygccxml] - Python parser for GCC-XML output

在概念上，[GCC-XML] 並不算嶄新，比方說 SWIG 一類的 toolkit 就可以協助開發者跨越諸多程式語言的限制，然而，[GCC-XML] 採用 XML 作為 GCC output 卻是相當特別。相較於 SWIG 以 callback 為基礎的途徑，[GCC-XML] 可更有彈性，並且作為一個 portable intermediate representation，這允許更複雜的語法使用。

Debian 已經有收錄 [Package: gccxml]，我們實地寫一個 C++ 程式來測試：

$ cat example.cpp 
#define _out_ __attribute((gccxml("out")))

class DummyClass {};

int single_function(_out_ float f, DummyClass e)
{
}

int main(void)
{
  return 0;
}

依照 [GCC-XML::Running] 的指示，產生對應的 GCC XML 輸出：

$ gccxml example.cpp -fxml=example.xml

以 mlview (GNOME-based XML viewer) 查看其內容：
我們可以從中窺見 GCC compiled symbols、builtins，以及 C++ mangled，比方說圖中的 mangled 即：

$ c++filt _ZN10DummyClassC1ERKS_
DummyClass::DummyClass(DummyClass const&)

也就是 G++ 所產生的 default copy constructor。
由 jserv 發表於 April 21, 2006 12:06 PM