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// Copyright (c) 2010 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 "base/json/string_escape.h"
#include "base/logging.h"
#include "base/stringprintf.h"
#include "base/string_number_conversions.h"
#include "base/values.h"
#include "base/utf_string_conversions.h"
namespace base {
#if defined(OS_WIN)
static const char kPrettyPrintLineEnding[] = "\r\n";
#else
static const char kPrettyPrintLineEnding[] = "\n";
#endif
/* static */
const char* JSONWriter::kEmptyArray = "[]";
/* static */
void JSONWriter::Write(const Value* const node,
bool pretty_print,
std::string* json) {
WriteWithOptionalEscape(node, pretty_print, true, json);
}
/* static */
void JSONWriter::WriteWithOptionalEscape(const Value* const node,
bool pretty_print,
bool escape,
std::string* json) {
json->clear();
// Is there a better way to estimate the size of the output?
json->reserve(1024);
JSONWriter writer(pretty_print, json);
writer.BuildJSONString(node, 0, escape);
if (pretty_print)
json->append(kPrettyPrintLineEnding);
}
JSONWriter::JSONWriter(bool pretty_print, std::string* json)
: json_string_(json),
pretty_print_(pretty_print) {
DCHECK(json);
}
void JSONWriter::BuildJSONString(const Value* const node,
int depth,
bool escape) {
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);
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);
if (escape) {
JsonDoubleQuote(UTF8ToUTF16(value), true, json_string_);
} else {
JsonDoubleQuote(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) {
if (i != 0) {
json_string_->append(",");
if (pretty_print_)
json_string_->append(" ");
}
Value* value = NULL;
bool result = list->Get(i, &value);
DCHECK(result);
BuildJSONString(value, depth, escape);
}
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);
for (DictionaryValue::key_iterator key_itr = dict->begin_keys();
key_itr != dict->end_keys();
++key_itr) {
if (key_itr != dict->begin_keys()) {
json_string_->append(",");
if (pretty_print_)
json_string_->append(kPrettyPrintLineEnding);
}
Value* value = NULL;
bool result = dict->GetWithoutPathExpansion(*key_itr, &value);
DCHECK(result);
if (pretty_print_)
IndentLine(depth + 1);
AppendQuotedString(*key_itr);
if (pretty_print_) {
json_string_->append(": ");
} else {
json_string_->append(":");
}
BuildJSONString(value, depth + 1, escape);
}
if (pretty_print_) {
json_string_->append(kPrettyPrintLineEnding);
IndentLine(depth);
json_string_->append("}");
} else {
json_string_->append("}");
}
break;
}
default:
// TODO(jhughes): handle TYPE_BINARY
NOTREACHED() << "unknown json type";
}
}
void JSONWriter::AppendQuotedString(const std::string& str) {
// TODO(viettrungluu): |str| is UTF-8, not ASCII, so to properly escape it we
// have to convert it to UTF-16. This round-trip is suboptimal.
JsonDoubleQuote(UTF8ToUTF16(str), true, json_string_);
}
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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