bin/zxdb/expr/template_type_extractor.h

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#pragma once

#include <string>
#include <vector>

#include "garnet/bin/zxdb/common/err.h"

namespace zxdb {

class ExprToken;

// C++ template types are mostly opaque to the debugger and we can't do many
// transformations on them. We don't attempt to fully parse or understand types
// and require the user to input things according to how the symbols represent
// the names.
//
// But one thing we do need to do is find where the end of a type is for
// certain expressions such as template parameters, and to perform limited
// canonicalization of those types.
//
// For example, to do a cast:
//   static_cast<Foo::Bar<Something*>>(a)
// We need only understand what the type is enough to look it up in the
// symbols, and would prefer to allow the user flexibility in exactly matching
// the whitespace generated by the compiler.
//
// There are two parts:
//
//  1. Finding the end of a template type. This tracks things like brackets,
//     parens, and quotes so we know where the end token of the type is. In the
//     above example, this means knowing the second '>' is the terminator.
//
//  2. Canonicalization. The only canonicalization we do is whitespace
//     canonicalization. This comes up most often in spaces after commas in
//     type lists, and whether the ">>" at the end of the above example needs
//     a space separating them or not.

struct TemplateTypeResult {
  bool success = false;

  // When success = false, this is the index of the token for which a
  // terminator was not found. So if there was a '[" with no ']', this will
  // reference the '[' token.
  size_t unmatched_error_token = 0;

  // Token immediately following the extracted type on success. Will be one
  // past the end of the input tokens if everything was consumed.
  size_t end_token = 0;

  // Valid on success.
  std::string canonical_name;
};

TemplateTypeResult ExtractTemplateType(const std::vector<ExprToken>& tokens,
                                       size_t begin_token);

}  // namespace zxdb