1 // Copyright (c) 2012 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.
6 This file contains the declaration for CppVariant, a type used by C++ classes
7 that are to be bound to JavaScript objects.
9 CppVariant exists primarily as an interface between C++ callers and the
10 corresponding NPVariant type. CppVariant also provides a number of
11 convenience constructors and accessors, so that the NPVariantType values
12 don't need to be exposed, and a destructor to free any memory allocated for
15 For a usage example, see cpp_binding_example.{h|cc}.
18 #ifndef WEBKIT_RENDERER_CPP_VARIANT_H__
19 #define WEBKIT_RENDERER_CPP_VARIANT_H__
24 #include "base/basictypes.h"
25 #include "third_party/npapi/bindings/npruntime.h"
26 #include "webkit/renderer/webkit_renderer_export.h"
28 namespace webkit_glue {
30 class WEBKIT_RENDERER_EXPORT CppVariant : public NPVariant {
36 void Set(int32_t value);
37 void Set(double value);
39 // Note that setting a CppVariant to a string value involves copying the
40 // string data, which must be freed with a call to FreeData() when the
41 // CppVariant is set to a different value or is no longer needed. Normally
42 // this is handled by the other Set() methods and by the destructor.
43 void Set(const char* value); // Must be a null-terminated string.
44 void Set(const std::string& value);
45 void Set(const NPString& new_value);
46 void Set(const NPVariant& new_value);
48 // Note that setting a CppVariant to an NPObject involves ref-counting
49 // the actual object. FreeData() should only be called if the CppVariant
50 // is no longer needed. The other Set() methods handle this internally.
51 // Also, the object's NPClass is expected to be a static object: neither
52 // the NP runtime nor CPPVariant will ever free it.
53 void Set(NPObject* new_value);
55 // These three methods all perform deep copies of any string data. This
56 // allows local CppVariants to be released by the destructor without
57 // corrupting their sources. In performance-critical code, or when strings
58 // are very long, avoid creating new CppVariants.
59 // In case of NPObject as the data, the copying involves ref-counting
60 // as opposed to deep-copying. The ref-counting ensures that sources don't
61 // get corrupted when the copies get destroyed.
62 void CopyToNPVariant(NPVariant* result) const;
63 CppVariant& operator=(const CppVariant& original);
64 CppVariant(const CppVariant& original);
66 // Calls NPN_ReleaseVariantValue, which frees any string data
67 // held by the object and sets its type to null.
68 // In case of NPObject, the NPN_ReleaseVariantValue decrements
69 // the ref-count (releases when ref-count becomes 0)
72 // Compares this CppVariant's type and value to another's. They must be
73 // identical in both type and value to be considered equal. For string and
74 // object types, a deep comparison is performed; that is, the contents of the
75 // strings, or the classes and refcounts of the objects, must be the same,
76 // but they need not be the same pointers.
77 bool isEqual(const CppVariant& other) const;
79 // The value of a CppVariant may be read directly from its NPVariant (but
80 // should only be set using one of the Set() methods above). Although the
81 // type of a CppVariant is likewise public, it can be accessed through these
82 // functions rather than directly if a caller wishes to avoid dependence on
83 // the NPVariantType values.
84 bool isBool() const { return (type == NPVariantType_Bool); }
85 bool isInt32() const { return (type == NPVariantType_Int32); }
86 bool isDouble() const { return (type == NPVariantType_Double); }
87 bool isNumber() const { return (isInt32() || isDouble()); }
88 bool isString() const { return (type == NPVariantType_String); }
89 bool isVoid() const { return (type == NPVariantType_Void); }
90 bool isNull() const { return (type == NPVariantType_Null); }
91 bool isEmpty() const { return (isVoid() || isNull()); }
92 bool isObject() const { return (type == NPVariantType_Object); }
94 // Converters. The CppVariant must be of a type convertible to these values.
95 // For example, ToInt32() works only if isNumber() is true.
96 std::string ToString() const;
97 int32_t ToInt32() const;
98 double ToDouble() const;
99 bool ToBoolean() const;
100 // Returns a vector of CppVariant for the specified variant. This should only
101 // be called on an Object. If the object has no "length" property an empty
102 // vector is returned.
103 std::vector<CppVariant> ToVector() const;
105 // Invoke method of the given name on an object with the supplied arguments.
106 // The first argument should be the object on which the method is to be
107 // invoked. Returns whether the method was successfully invoked. If the
108 // method was invoked successfully, any return value is stored in the
109 // CppVariant specified by result.
110 bool Invoke(const std::string& method, const CppVariant* args,
111 uint32 arg_count, CppVariant& result) const;
114 } // namespace webkit_glue
116 #endif // WEBKIT_RENDERER_CPP_VARIANT_H__