1// Copyright 2013 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5// This file provides a builders for DictionaryValue and ListValue.  These
6// aren't specific to extensions and could move up to base/ if there's interest
7// from other sub-projects.
8//
9// The general pattern is to write:
10//
11//  scoped_ptr<BuiltType> result(FooBuilder()
12//                               .Set(args)
13//                               .Set(args)
14//                               .Build());
15//
16// For methods that take other built types, you can pass the builder directly
17// to the setter without calling Build():
18//
19// DictionaryBuilder().Set("key", ListBuilder()
20//                         .Append("foo").Append("bar") /* No .Build() */);
21//
22// Because of limitations in C++03, and to avoid extra copies, you can't pass a
23// just-constructed Builder into another Builder's method directly. Use the
24// Pass() method.
25//
26// The Build() method invalidates its builder, and returns ownership of the
27// built value.
28//
29// These objects are intended to be used as temporaries rather than stored
30// anywhere, so the use of non-const reference parameters is likely to cause
31// less confusion than usual.
32
33#ifndef EXTENSIONS_COMMON_VALUE_BUILDER_H_
34#define EXTENSIONS_COMMON_VALUE_BUILDER_H_
35
36#include <string>
37
38#include "base/memory/scoped_ptr.h"
39#include "base/strings/string16.h"
40#include "base/values.h"
41
42namespace extensions {
43
44class ListBuilder;
45
46class DictionaryBuilder {
47 public:
48  DictionaryBuilder();
49  explicit DictionaryBuilder(const base::DictionaryValue& init);
50  ~DictionaryBuilder();
51
52  // Workaround to allow you to pass rvalue ExtensionBuilders by reference to
53  // other functions.
54  DictionaryBuilder& Pass() { return *this; }
55
56  // Can only be called once, after which it's invalid to use the builder.
57  scoped_ptr<base::DictionaryValue> Build() { return dict_.Pass(); }
58
59  DictionaryBuilder& Set(const std::string& path, int in_value);
60  DictionaryBuilder& Set(const std::string& path, double in_value);
61  DictionaryBuilder& Set(const std::string& path, const std::string& in_value);
62  DictionaryBuilder& Set(const std::string& path,
63                         const base::string16& in_value);
64  DictionaryBuilder& Set(const std::string& path, DictionaryBuilder& in_value);
65  DictionaryBuilder& Set(const std::string& path, ListBuilder& in_value);
66
67  // Named differently because overload resolution is too eager to
68  // convert implicitly to bool.
69  DictionaryBuilder& SetBoolean(const std::string& path, bool in_value);
70
71 private:
72  scoped_ptr<base::DictionaryValue> dict_;
73};
74
75class ListBuilder {
76 public:
77  ListBuilder();
78  explicit ListBuilder(const base::ListValue& init);
79  ~ListBuilder();
80
81  // Workaround to allow you to pass rvalue ExtensionBuilders by reference to
82  // other functions.
83  ListBuilder& Pass() { return *this; }
84
85  // Can only be called once, after which it's invalid to use the builder.
86  scoped_ptr<base::ListValue> Build() { return list_.Pass(); }
87
88  ListBuilder& Append(int in_value);
89  ListBuilder& Append(double in_value);
90  ListBuilder& Append(const std::string& in_value);
91  ListBuilder& Append(const base::string16& in_value);
92  ListBuilder& Append(DictionaryBuilder& in_value);
93  ListBuilder& Append(ListBuilder& in_value);
94
95  // Named differently because overload resolution is too eager to
96  // convert implicitly to bool.
97  ListBuilder& AppendBoolean(bool in_value);
98
99 private:
100  scoped_ptr<base::ListValue> list_;
101};
102
103}  // namespace extensions
104
105#endif  // EXTENSIONS_COMMON_VALUE_BUILDER_H_
106