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// 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_writer.h"
#include <stdint.h>
#include <cmath>
#include <limits>
#include "base/json/string_escape.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/utf_string_conversion_utils.h"
#include "base/values.h"
#include "build/build_config.h"
namespace base {
#if defined(OS_WIN)
const char kPrettyPrintLineEnding[] = "\r\n";
#else
const char kPrettyPrintLineEnding[] = "\n";
#endif
// static
bool JSONWriter::Write(const Value& node, std::string* json) {
return WriteWithOptions(node, 0, json);
}
// static
bool JSONWriter::WriteWithOptions(const Value& node,
int options,
std::string* json) {
json->clear();
// Is there a better way to estimate the size of the output?
json->reserve(1024);
JSONWriter writer(options, json);
bool result = writer.BuildJSONString(node, 0U);
if (options & OPTIONS_PRETTY_PRINT)
json->append(kPrettyPrintLineEnding);
return result;
}
JSONWriter::JSONWriter(int options, std::string* json)
: omit_binary_values_((options & OPTIONS_OMIT_BINARY_VALUES) != 0),
omit_double_type_preservation_(
(options & OPTIONS_OMIT_DOUBLE_TYPE_PRESERVATION) != 0),
pretty_print_((options & OPTIONS_PRETTY_PRINT) != 0),
json_string_(json) {
DCHECK(json);
}
bool JSONWriter::BuildJSONString(const Value& node, size_t depth) {
switch (node.GetType()) {
case Value::TYPE_NULL: {
json_string_->append("null");
return true;
}
case Value::TYPE_BOOLEAN: {
bool value;
bool result = node.GetAsBoolean(&value);
DCHECK(result);
json_string_->append(value ? "true" : "false");
return result;
}
case Value::TYPE_INTEGER: {
int value;
bool result = node.GetAsInteger(&value);
DCHECK(result);
json_string_->append(IntToString(value));
return result;
}
case Value::TYPE_DOUBLE: {
double value;
bool result = node.GetAsDouble(&value);
DCHECK(result);
if (omit_double_type_preservation_ &&
value <= std::numeric_limits<int64_t>::max() &&
value >= std::numeric_limits<int64_t>::min() &&
std::floor(value) == value) {
json_string_->append(Int64ToString(static_cast<int64_t>(value)));
return result;
}
std::string real = DoubleToString(value);
// Ensure that the number has a .0 if there's no decimal or 'e'. This
// makes sure that when we read the JSON back, it's interpreted as a
// real rather than an int.
if (real.find('.') == std::string::npos &&
real.find('e') == std::string::npos &&
real.find('E') == std::string::npos) {
real.append(".0");
}
// The JSON spec requires that non-integer values in the range (-1,1)
// have a zero before the decimal point - ".52" is not valid, "0.52" is.
if (real[0] == '.') {
real.insert(static_cast<size_t>(0), static_cast<size_t>(1), '0');
} else if (real.length() > 1 && real[0] == '-' && real[1] == '.') {
// "-.1" bad "-0.1" good
real.insert(static_cast<size_t>(1), static_cast<size_t>(1), '0');
}
json_string_->append(real);
return result;
}
case Value::TYPE_STRING: {
std::string value;
bool result = node.GetAsString(&value);
DCHECK(result);
EscapeJSONString(value, true, json_string_);
return result;
}
case Value::TYPE_LIST: {
json_string_->push_back('[');
if (pretty_print_)
json_string_->push_back(' ');
const ListValue* list = NULL;
bool first_value_has_been_output = false;
bool result = node.GetAsList(&list);
DCHECK(result);
for (ListValue::const_iterator it = list->begin(); it != list->end();
++it) {
const Value* value = *it;
if (omit_binary_values_ && value->GetType() == Value::TYPE_BINARY)
continue;
if (first_value_has_been_output) {
json_string_->push_back(',');
if (pretty_print_)
json_string_->push_back(' ');
}
if (!BuildJSONString(*value, depth))
result = false;
first_value_has_been_output = true;
}
if (pretty_print_)
json_string_->push_back(' ');
json_string_->push_back(']');
return result;
}
case Value::TYPE_DICTIONARY: {
json_string_->push_back('{');
if (pretty_print_)
json_string_->append(kPrettyPrintLineEnding);
const DictionaryValue* dict = NULL;
bool first_value_has_been_output = false;
bool result = node.GetAsDictionary(&dict);
DCHECK(result);
for (DictionaryValue::Iterator itr(*dict); !itr.IsAtEnd();
itr.Advance()) {
if (omit_binary_values_ &&
itr.value().GetType() == Value::TYPE_BINARY) {
continue;
}
if (first_value_has_been_output) {
json_string_->push_back(',');
if (pretty_print_)
json_string_->append(kPrettyPrintLineEnding);
}
if (pretty_print_)
IndentLine(depth + 1U);
EscapeJSONString(itr.key(), true, json_string_);
json_string_->push_back(':');
if (pretty_print_)
json_string_->push_back(' ');
if (!BuildJSONString(itr.value(), depth + 1U))
result = false;
first_value_has_been_output = true;
}
if (pretty_print_) {
json_string_->append(kPrettyPrintLineEnding);
IndentLine(depth);
}
json_string_->push_back('}');
return result;
}
case Value::TYPE_BINARY:
// Successful only if we're allowed to omit it.
DLOG_IF(ERROR, !omit_binary_values_) << "Cannot serialize binary value.";
return omit_binary_values_;
}
NOTREACHED();
return false;
}
void JSONWriter::IndentLine(size_t depth) {
json_string_->append(depth * 3U, ' ');
}
} // namespace base
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