demangle.h

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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// An async-signal-safe and thread-safe demangler for Itanium C++ ABI
// (aka G++ V3 ABI).
//
// The demangler is implemented to be used in async signal handlers to
// symbolize stack traces.  We cannot use libstdc++'s
// abi::__cxa_demangle() in such signal handlers since it's not async
// signal safe (it uses malloc() internally).
//
// Note that this demangler doesn't support full demangling.  More
// specifically, it doesn't print types of function parameters and
// types of template arguments.  It just skips them.  However, it's
// still very useful to extract basic information such as class,
// function, constructor, destructor, and operator names.
//
// See the implementation note in demangle.cc if you are interested.
//
// Example:
//
// | Mangled Name  | The Demangler | abi::__cxa_demangle()
// |---------------|---------------|-----------------------
// | _Z1fv         | f()           | f()
// | _Z1fi         | f()           | f(int)
// | _Z3foo3bar    | foo()         | foo(bar)
// | _Z1fIiEvi     | f<>()         | void f<int>(int)
// | _ZN1N1fE      | N::f          | N::f
// | _ZN3Foo3BarEv | Foo::Bar()    | Foo::Bar()
// | _Zrm1XS_"     | operator%()   | operator%(X, X)
// | _ZN3FooC1Ev   | Foo::Foo()    | Foo::Foo()
// | _Z1fSs        | f()           | f(std::basic_string<char,
// |               |               |   std::char_traits<char>,
// |               |               |   std::allocator<char> >)
//
// See the unit test for more examples.
//
// Note: we might want to write demanglers for ABIs other than Itanium
// C++ ABI in the future.
//

#ifndef ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_
#define ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_

namespace absl {
namespace debugging_internal {

// Demangle `mangled`.  On success, return true and write the
// demangled symbol name to `out`.  Otherwise, return false.
// `out` is modified even if demangling is unsuccessful.
bool Demangle(const char *mangled, char *out, int out_size);

}  // namespace debugging_internal
}  // namespace absl

#endif  // ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_