| 1 |
424 |
jeremybenn |
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
| 2 |
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
| 3 |
|
|
<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 40. Demangling</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><meta name="keywords" content=" ISO C++ , library " /><link rel="home" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="extensions.html" title="Part XII. Extensions" /><link rel="prev" href="ext_io.html" title="Chapter 39. Input and Output" /><link rel="next" href="ext_concurrency.html" title="Chapter 41. Concurrency" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 40. Demangling</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ext_io.html">Prev</a> </td><th width="60%" align="center">Part XII.
|
| 4 |
|
|
Extensions
|
| 5 |
|
|
|
| 6 |
|
|
</th><td width="20%" align="right"> <a accesskey="n" href="ext_concurrency.html">Next</a></td></tr></table><hr /></div><div class="chapter" title="Chapter 40. Demangling"><div class="titlepage"><div><div><h2 class="title"><a id="manual.ext.demangle"></a>Chapter 40. Demangling</h2></div></div></div><p>
|
| 7 |
|
|
Transforming C++ ABI identifiers (like RTTI symbols) into the
|
| 8 |
|
|
original C++ source identifiers is called
|
| 9 |
|
|
<span class="quote">“<span class="quote">demangling.</span>”</span>
|
| 10 |
|
|
</p><p>
|
| 11 |
|
|
If you have read the <a class="ulink" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01115.html" target="_top">source
|
| 12 |
|
|
documentation for <code class="code">namespace abi</code></a> then you are
|
| 13 |
|
|
aware of the cross-vendor C++ ABI in use by GCC. One of the
|
| 14 |
|
|
exposed functions is used for demangling,
|
| 15 |
|
|
<code class="code">abi::__cxa_demangle</code>.
|
| 16 |
|
|
</p><p>
|
| 17 |
|
|
In programs like <span class="command"><strong>c++filt</strong></span>, the linker, and other tools
|
| 18 |
|
|
have the ability to decode C++ ABI names, and now so can you.
|
| 19 |
|
|
</p><p>
|
| 20 |
|
|
(The function itself might use different demanglers, but that's the
|
| 21 |
|
|
whole point of abstract interfaces. If we change the implementation,
|
| 22 |
|
|
you won't notice.)
|
| 23 |
|
|
</p><p>
|
| 24 |
|
|
Probably the only times you'll be interested in demangling at runtime
|
| 25 |
|
|
are when you're seeing <code class="code">typeid</code> strings in RTTI, or when
|
| 26 |
|
|
you're handling the runtime-support exception classes. For example:
|
| 27 |
|
|
</p><pre class="programlisting">
|
| 28 |
|
|
#include <exception>
|
| 29 |
|
|
#include <iostream>
|
| 30 |
|
|
#include <cxxabi.h>
|
| 31 |
|
|
|
| 32 |
|
|
struct empty { };
|
| 33 |
|
|
|
| 34 |
|
|
template <typename T, int N>
|
| 35 |
|
|
struct bar { };
|
| 36 |
|
|
|
| 37 |
|
|
|
| 38 |
|
|
int main()
|
| 39 |
|
|
{
|
| 40 |
|
|
int status;
|
| 41 |
|
|
char *realname;
|
| 42 |
|
|
|
| 43 |
|
|
// exception classes not in <stdexcept>, thrown by the implementation
|
| 44 |
|
|
// instead of the user
|
| 45 |
|
|
std::bad_exception e;
|
| 46 |
|
|
realname = abi::__cxa_demangle(e.what(), 0, 0, &status);
|
| 47 |
|
|
std::cout << e.what() << "\t=> " << realname << "\t: " << status << '\n';
|
| 48 |
|
|
free(realname);
|
| 49 |
|
|
|
| 50 |
|
|
|
| 51 |
|
|
// typeid
|
| 52 |
|
|
bar<empty,17> u;
|
| 53 |
|
|
const std::type_info &ti = typeid(u);
|
| 54 |
|
|
|
| 55 |
|
|
realname = abi::__cxa_demangle(ti.name(), 0, 0, &status);
|
| 56 |
|
|
std::cout << ti.name() << "\t=> " << realname << "\t: " << status << '\n';
|
| 57 |
|
|
free(realname);
|
| 58 |
|
|
|
| 59 |
|
|
return 0;
|
| 60 |
|
|
}
|
| 61 |
|
|
</pre><p>
|
| 62 |
|
|
This prints
|
| 63 |
|
|
</p><pre class="screen">
|
| 64 |
|
|
<code class="computeroutput">
|
| 65 |
|
|
St13bad_exception => std::bad_exception : 0
|
| 66 |
|
|
3barI5emptyLi17EE => bar<empty, 17> : 0
|
| 67 |
|
|
</code>
|
| 68 |
|
|
</pre><p>
|
| 69 |
|
|
The demangler interface is described in the source documentation
|
| 70 |
|
|
linked to above. It is actually written in C, so you don't need to
|
| 71 |
|
|
be writing C++ in order to demangle C++. (That also means we have to
|
| 72 |
|
|
use crummy memory management facilities, so don't forget to free()
|
| 73 |
|
|
the returned char array.)
|
| 74 |
|
|
</p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ext_io.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="extensions.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ext_concurrency.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 39. Input and Output </td><td width="20%" align="center"><a accesskey="h" href="../spine.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 41. Concurrency</td></tr></table></div></body></html>
|
