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. 4 5 /* 6 This file contains the declaration for CppVariant, a type used by C++ classes 7 that are to be bound to JavaScript objects. 8 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 13 string values. 14 15 For a usage example, see cpp_binding_example.{h|cc}. 16 */ 17 18 #ifndef WEBKIT_RENDERER_CPP_VARIANT_H__ 19 #define WEBKIT_RENDERER_CPP_VARIANT_H__ 20 21 #include <string> 22 #include <vector> 23 24 #include "base/basictypes.h" 25 #include "third_party/npapi/bindings/npruntime.h" 26 #include "webkit/renderer/webkit_renderer_export.h" 27 28 namespace webkit_glue { 29 30 class WEBKIT_RENDERER_EXPORT CppVariant : public NPVariant { 31 public: 32 CppVariant(); 33 ~CppVariant(); 34 void SetNull(); 35 void Set(bool value); 36 void Set(int32_t value); 37 void Set(double value); 38 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); 47 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); 54 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); 65 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) 70 void FreeData(); 71 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; 78 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); } 93 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; 104 105 // 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; 112 }; 113 114 } // namespace webkit_glue 115 116 #endif // WEBKIT_RENDERER_CPP_VARIANT_H__ 117
