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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 <cmath>
#include "base/json/string_escape.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/values.h"
namespace base {
#if defined(OS_WIN)
static const char kPrettyPrintLineEnding[] = "\r\n";
#else
static const char kPrettyPrintLineEnding[] = "\n";
#endif
// static
void JSONWriter::Write(const Value* const node, std::string* json) {
WriteWithOptions(node, 0, json);
}
// static
void JSONWriter::WriteWithOptions(const Value* const node, int options,
std::string* json) {
json->clear();
// Is there a better way to estimate the size of the output?
json->reserve(1024);
bool omit_binary_values = !!(options & OPTIONS_OMIT_BINARY_VALUES);
bool omit_double_type_preservation =
!!(options & OPTIONS_OMIT_DOUBLE_TYPE_PRESERVATION);
bool pretty_print = !!(options & OPTIONS_PRETTY_PRINT);
JSONWriter writer(omit_binary_values, omit_double_type_preservation,
pretty_print, json);
writer.BuildJSONString(node, 0);
if (pretty_print)
json->append(kPrettyPrintLineEnding);
}
JSONWriter::JSONWriter(bool omit_binary_values,
bool omit_double_type_preservation, bool pretty_print,
std::string* json)
: omit_binary_values_(omit_binary_values),
omit_double_type_preservation_(omit_double_type_preservation),
pretty_print_(pretty_print),
json_string_(json) {
DCHECK(json);
}
void JSONWriter::BuildJSONString(const Value* const node, int depth) {
switch (node->GetType()) {
case Value::TYPE_NULL:
json_string_->append("null");
break;
case Value::TYPE_BOOLEAN:
{
bool value;
bool result = node->GetAsBoolean(&value);
DCHECK(result);
json_string_->append(value ? "true" : "false");
break;
}
case Value::TYPE_INTEGER:
{
int value;
bool result = node->GetAsInteger(&value);
DCHECK(result);
base::StringAppendF(json_string_, "%d", value);
break;
}
case Value::TYPE_DOUBLE:
{
double value;
bool result = node->GetAsDouble(&value);
DCHECK(result);
if (omit_double_type_preservation_ &&
value <= kint64max &&
value >= kint64min &&
std::floor(value) == value) {
json_string_->append(Int64ToString(static_cast<int64>(value)));
break;
}
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(0, "0");
} else if (real.length() > 1 && real[0] == '-' && real[1] == '.') {
// "-.1" bad "-0.1" good
real.insert(1, "0");
}
json_string_->append(real);
break;
}
case Value::TYPE_STRING:
{
std::string value;
bool result = node->GetAsString(&value);
DCHECK(result);
EscapeJSONString(value, true, json_string_);
break;
}
case Value::TYPE_LIST:
{
json_string_->append("[");
if (pretty_print_)
json_string_->append(" ");
const ListValue* list = static_cast<const ListValue*>(node);
for (size_t i = 0; i < list->GetSize(); ++i) {
const Value* value = NULL;
bool result = list->Get(i, &value);
DCHECK(result);
if (omit_binary_values_ && value->GetType() == Value::TYPE_BINARY) {
continue;
}
if (i != 0) {
json_string_->append(",");
if (pretty_print_)
json_string_->append(" ");
}
BuildJSONString(value, depth);
}
if (pretty_print_)
json_string_->append(" ");
json_string_->append("]");
break;
}
case Value::TYPE_DICTIONARY:
{
json_string_->append("{");
if (pretty_print_)
json_string_->append(kPrettyPrintLineEnding);
const DictionaryValue* dict =
static_cast<const DictionaryValue*>(node);
bool first_entry = true;
for (DictionaryValue::Iterator itr(*dict); !itr.IsAtEnd();
itr.Advance(), first_entry = false) {
if (omit_binary_values_ &&
itr.value().GetType() == Value::TYPE_BINARY) {
continue;
}
if (!first_entry) {
json_string_->append(",");
if (pretty_print_)
json_string_->append(kPrettyPrintLineEnding);
}
if (pretty_print_)
IndentLine(depth + 1);
EscapeJSONString(itr.key(), true, json_string_);
if (pretty_print_) {
json_string_->append(": ");
} else {
json_string_->append(":");
}
BuildJSONString(&itr.value(), depth + 1);
}
if (pretty_print_) {
json_string_->append(kPrettyPrintLineEnding);
IndentLine(depth);
json_string_->append("}");
} else {
json_string_->append("}");
}
break;
}
case Value::TYPE_BINARY:
{
if (!omit_binary_values_) {
NOTREACHED() << "Cannot serialize binary value.";
}
break;
}
default:
NOTREACHED() << "unknown json type";
}
}
void JSONWriter::IndentLine(int depth) {
// It may be faster to keep an indent string so we don't have to keep
// reallocating.
json_string_->append(std::string(depth * 3, ' '));
}
} // namespace base
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