blob: 848e1684ea9845e9d61b9bda4c9dbe2ef5fc8f3e [file] [log] [blame]
// Copyright (c) 2020 The Chromium Embedded Framework 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 "base/strings/string_piece.h"
namespace devtools_util {
// Fast parser for DevTools JSON protocol messages. This implementation makes
// certain assumptions about the JSON object structure (value order and
// formatting) to avoid stateful parsing of messages that may be large
// (sometimes > 1MB in size). The message must be a JSON dictionary that starts
// with a "method" or "id" value which is non-empty and of the expected data
// type. Messages that have a "method" value (event message) may optionally have
// a "params" dictionary. Messages that have an "id" value (result message) must
// have a "result" or "error" dictionary. The dictionary contents are not
// validated and may be empty ("{}").
// Example event message:
// {"method":"Target.targetDestroyed","params":{"targetId":"1234..."}}
// Example result messages:
// {"id":3,"result":{}}
// {"id":4,"result":{"debuggerId":"-2193881606781505058.81393575456727957"}}
// {"id":5,"error":{"code":-32000,"message":"Not supported"}}
struct ProtocolParser {
ProtocolParser() = default;
// Checks for a non-empty JSON dictionary.
static bool IsValidMessage(const base::StringPiece& message);
// Returns false if already initialized.
bool Initialize(const base::StringPiece& message);
bool IsInitialized() const { return status_ != UNINITIALIZED; }
bool IsEvent() const { return status_ == EVENT; }
bool IsResult() const { return status_ == RESULT; }
bool IsFailure() const { return status_ == FAILURE; }
void Reset() { status_ = UNINITIALIZED; }
// For event messages:
// "method" string:
base::StringPiece method_;
// For result messages:
// "id" int:
int message_id_ = 0;
// true if "result" value, false if "error" value:
bool success_ = false;
// For both:
// "params", "result" or "error" dictionary:
base::StringPiece params_;
enum Status {
EVENT, // Event message.
RESULT, // Result message.
FAILURE, // Parsing failure.
Status status_ = UNINITIALIZED;
} // namespace devtools_util