Rewrite base::JSONReader to be 35-40% faster, depending on the input string.

base/json/json_parser_unittest.cc

Index: base/json/json_parser_unittest.cc
diff --git a/base/json/json_parser_unittest.cc b/base/json/json_parser_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..206ef4c0ef599104c643387c3d65da59c862e6d2
--- /dev/null
+++ b/base/json/json_parser_unittest.cc
@@ -0,0 +1,293 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/json/json_parser.h"
+
+#include "base/json/json_reader.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/values.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace internal {
+
+class JSONParserTest : public testing::Test {
+ public:
+  JSONParser* NewTestParser(const std::string& input) {
+    JSONParser* parser = new JSONParser(JSON_PARSE_RFC);
+    parser->start_pos_ = input.data();
+    parser->pos_ = parser->start_pos_;
+    parser->end_pos_ = parser->start_pos_ + input.length();
+    return parser;
+  }
+
+  void TestLastThree(JSONParser* parser) {
+    EXPECT_EQ(',', *parser->NextChar());
+    EXPECT_EQ('|', *parser->NextChar());
+    EXPECT_EQ('\0', *parser->NextChar());
+    EXPECT_EQ(parser->end_pos_, parser->pos_);
+  }
+};
+
+TEST_F(JSONParserTest, NextChar) {
+  std::string input("Hello world");
+  scoped_ptr<JSONParser> parser(NewTestParser(input));
+
+  EXPECT_EQ('H', *parser->pos_);
+  for (size_t i = 1; i < input.length(); ++i) {
+    EXPECT_EQ(input[i], *parser->NextChar());
+  }
+  EXPECT_EQ(parser->end_pos_, parser->NextChar());
+}
+
+TEST_F(JSONParserTest, ConsumeString) {
+  std::string input("\"test\",|");
+  scoped_ptr<JSONParser> parser(NewTestParser(input));
+  scoped_ptr<Value> value(parser->ConsumeString());
+  EXPECT_EQ('"', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  std::string str;
+  EXPECT_TRUE(value->GetAsString(&str));
+  EXPECT_EQ("test", str);
+}
+
+TEST_F(JSONParserTest, ConsumeList) {
+  std::string input("[true, false],|");
+  scoped_ptr<JSONParser> parser(NewTestParser(input));
+  scoped_ptr<Value> value(parser->ConsumeList());
+  EXPECT_EQ(']', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  base::ListValue* list;
+  EXPECT_TRUE(value->GetAsList(&list));
+  EXPECT_EQ(2u, list->GetSize());
+}
+
+TEST_F(JSONParserTest, ConsumeDictionary) {
+  std::string input("{\"abc\":\"def\"},|");
+  scoped_ptr<JSONParser> parser(NewTestParser(input));
+  scoped_ptr<Value> value(parser->ConsumeDictionary());
+  EXPECT_EQ('}', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  base::DictionaryValue* dict;
+  EXPECT_TRUE(value->GetAsDictionary(&dict));
+  std::string str;
+  EXPECT_TRUE(dict->GetString("abc", &str));
+  EXPECT_EQ("def", str);
+}
+
+TEST_F(JSONParserTest, ConsumeLiterals) {
+  // Literal |true|.
+  std::string input("true,|");
+  scoped_ptr<JSONParser> parser(NewTestParser(input));
+  scoped_ptr<Value> value(parser->ConsumeLiteral());
+  EXPECT_EQ('e', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  bool bool_value = false;
+  EXPECT_TRUE(value->GetAsBoolean(&bool_value));
+  EXPECT_TRUE(bool_value);
+
+  // Literal |false|.
+  input = "false,|";
+  parser.reset(NewTestParser(input));
+  value.reset(parser->ConsumeLiteral());
+  EXPECT_EQ('e', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  EXPECT_TRUE(value->GetAsBoolean(&bool_value));
+  EXPECT_FALSE(bool_value);
+
+  // Literal |null|.
+  input = "null,|";
+  parser.reset(NewTestParser(input));
+  value.reset(parser->ConsumeLiteral());
+  EXPECT_EQ('l', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  EXPECT_TRUE(value->IsType(Value::TYPE_NULL));
+}
+
+TEST_F(JSONParserTest, ConsumeNumbers) {
+  // Integer.
+  std::string input("1234,|");
+  scoped_ptr<JSONParser> parser(NewTestParser(input));
+  scoped_ptr<Value> value(parser->ConsumeNumber());
+  EXPECT_EQ('4', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  int number_i;
+  EXPECT_TRUE(value->GetAsInteger(&number_i));
+  EXPECT_EQ(1234, number_i);
+
+  // Negative integer.
+  input = "-1234,|";
+  parser.reset(NewTestParser(input));
+  value.reset(parser->ConsumeNumber());
+  EXPECT_EQ('4', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  EXPECT_TRUE(value->GetAsInteger(&number_i));
+  EXPECT_EQ(-1234, number_i);
+
+  // Double.
+  input = "12.34,|";
+  parser.reset(NewTestParser(input));
+  value.reset(parser->ConsumeNumber());
+  EXPECT_EQ('4', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  double number_d;
+  EXPECT_TRUE(value->GetAsDouble(&number_d));
+  EXPECT_EQ(12.34, number_d);
+
+  // Scientific.
+  input = "42e3,|";
+  parser.reset(NewTestParser(input));
+  value.reset(parser->ConsumeNumber());
+  EXPECT_EQ('3', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  EXPECT_TRUE(value->GetAsDouble(&number_d));
+  EXPECT_EQ(42000, number_d);
+
+  // Negative scientific.
+  input = "314159e-5,|";
+  parser.reset(NewTestParser(input));
+  value.reset(parser->ConsumeNumber());
+  EXPECT_EQ('5', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  EXPECT_TRUE(value->GetAsDouble(&number_d));
+  EXPECT_EQ(3.14159, number_d);
+
+  // Positive scientific.
+  input = "0.42e+3,|";
+  parser.reset(NewTestParser(input));
+  value.reset(parser->ConsumeNumber());
+  EXPECT_EQ('3', *parser->pos_);
+
+  TestLastThree(parser.get());
+
+  ASSERT_TRUE(value.get());
+  EXPECT_TRUE(value->GetAsDouble(&number_d));
+  EXPECT_EQ(420, number_d);
+}
+
+TEST_F(JSONParserTest, ErrorMessages) {
+  // Error strings should not be modified in case of success.
+  std::string error_message;
+  int error_code = 0;
+  scoped_ptr<Value> root;
+  root.reset(JSONReader::ReadAndReturnError("[42]", JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_TRUE(error_message.empty());
+  EXPECT_EQ(0, error_code);
+
+  // Test line and column counting
+  const char* big_json = "[\n0,\n1,\n2,\n3,4,5,6 7,\n8,\n9\n]";
+  // error here ---------------------------------^
+  root.reset(JSONReader::ReadAndReturnError(big_json, JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(5, 10, JSONReader::kSyntaxError),
+            error_message);
+  EXPECT_EQ(JSONReader::JSON_SYNTAX_ERROR, error_code);
+
+  // Test each of the error conditions
+  root.reset(JSONReader::ReadAndReturnError("{},{}", JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(1, 3,
+      JSONReader::kUnexpectedDataAfterRoot), error_message);
+  EXPECT_EQ(JSONReader::JSON_UNEXPECTED_DATA_AFTER_ROOT, error_code);
+
+  std::string nested_json;
+  for (int i = 0; i < 101; ++i) {
+    nested_json.insert(nested_json.begin(), '[');
+    nested_json.append(1, ']');
+  }
+  root.reset(JSONReader::ReadAndReturnError(nested_json, JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(1, 100, JSONReader::kTooMuchNesting),
+            error_message);
+  EXPECT_EQ(JSONReader::JSON_TOO_MUCH_NESTING, error_code);
+
+  root.reset(JSONReader::ReadAndReturnError("[1,]", JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(1, 4, JSONReader::kTrailingComma),
+            error_message);
+  EXPECT_EQ(JSONReader::JSON_TRAILING_COMMA, error_code);
+
+  root.reset(JSONReader::ReadAndReturnError("{foo:\"bar\"}", JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(1, 2,
+      JSONReader::kUnquotedDictionaryKey), error_message);
+  EXPECT_EQ(JSONReader::JSON_UNQUOTED_DICTIONARY_KEY, error_code);
+
+  root.reset(JSONReader::ReadAndReturnError("{\"foo\":\"bar\",}",
+                                            JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(1, 14, JSONReader::kTrailingComma),
+            error_message);
+
+  root.reset(JSONReader::ReadAndReturnError("[nu]", JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(1, 2, JSONReader::kSyntaxError),
+            error_message);
+  EXPECT_EQ(JSONReader::JSON_SYNTAX_ERROR, error_code);
+
+  root.reset(JSONReader::ReadAndReturnError("[\"xxx\\xq\"]", JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(1, 7, JSONReader::kInvalidEscape),
+            error_message);
+  EXPECT_EQ(JSONReader::JSON_INVALID_ESCAPE, error_code);
+
+  root.reset(JSONReader::ReadAndReturnError("[\"xxx\\uq\"]", JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(1, 7, JSONReader::kInvalidEscape),
+            error_message);
+  EXPECT_EQ(JSONReader::JSON_INVALID_ESCAPE, error_code);
+
+  root.reset(JSONReader::ReadAndReturnError("[\"xxx\\q\"]", JSON_PARSE_RFC,
+                                            &error_code, &error_message));
+  EXPECT_FALSE(root.get());
+  EXPECT_EQ(JSONParser::FormatErrorMessage(1, 7, JSONReader::kInvalidEscape),
+            error_message);
+  EXPECT_EQ(JSONReader::JSON_INVALID_ESCAPE, error_code);
+}
+
+}  // namespace internal
+}  // namespace base