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value.h
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1 //
2 // Copyright 2016 Pixar
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5 // with the following modification; you may not use this file except in
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24 #ifndef PXR_BASE_JS_VALUE_H
25 #define PXR_BASE_JS_VALUE_H
26 
27 /// \file js/value.h
28 
29 #include "pxr/pxr.h"
30 #include "pxr/base/js/api.h"
31 #include "pxr/base/js/types.h"
32 
33 #include <algorithm>
34 #include <cstdint>
35 #include <memory>
36 #include <string>
37 #include <type_traits>
38 #include <vector>
39 
41 
42 // Value API Version
43 // 1 (or undefined) - Initial version.
44 // 2 - Changed Get{Array,Object} to GetJs{Array,Object}.
45 #define JS_VALUE_API_VERSION 2
46 
47 /// \class JsValue
48 ///
49 /// A discriminated union type for JSON values. A JsValue may contain one of
50 /// the following types:
51 ///
52 /// \li JsObject, a dictionary type
53 /// \li JsArray, a vector type
54 /// \li std::string
55 /// \li bool
56 /// \li int64_t
57 /// \li uint64_t
58 /// \li double
59 /// \li null
60 ///
61 class JsValue
62 {
63 public:
64  /// Type held by this JSON value.
65  enum Type {
73  };
74 
75  /// Constructs a null value.
76  JS_API JsValue();
77 
78  /// Constructs a value holding the given object.
79  JS_API JsValue(const JsObject& value);
80 
81  /// Constructs a value holding the given object rvalue reference.
83 
84  /// Constructs a value holding the given array.
85  JS_API JsValue(const JsArray& value);
86 
87  /// Constructs a value holding the given array rvalue reference.
89 
90  /// Constructs a value holding the given char array as a std::string.
91  JS_API explicit JsValue(const char* value);
92 
93  /// Constructs a value holding the given std::string.
94  JS_API explicit JsValue(const std::string& value);
95 
96  /// Constructs a value holding the given std::string rvalue reference.
97  JS_API explicit JsValue(std::string&& value);
98 
99  /// Constructs a value holding a bool.
100  JS_API explicit JsValue(bool value);
101 
102  /// Constructs a value holding a signed integer.
103  JS_API explicit JsValue(int value);
104 
105  /// Constructs a value holding a 64-bit signed integer.
106  JS_API explicit JsValue(int64_t value);
107 
108  /// Constructs a value holding a 64-bit unsigned integer.
109  JS_API explicit JsValue(uint64_t value);
110 
111  /// Constructs a value holding a double.
112  JS_API explicit JsValue(double value);
113 
114  /// Returns the object held by this value. If this value is not holding an
115  /// object, this method raises a coding error and an empty object is
116  /// returned.
117  JS_API const JsObject& GetJsObject() const;
118 
119  /// Returns the array held by this value. If this value is not holding an
120  /// array, this method raises a coding error and an empty array is
121  /// returned.
122  JS_API const JsArray& GetJsArray() const;
123 
124  /// Returns the string held by this value. If this value is not holding a
125  /// string, this method raises a coding error and an empty string is
126  /// returned.
127  JS_API const std::string& GetString() const;
128 
129  /// Returns the bool held by this value. If this value is not holding a
130  /// bool, this method raises a coding error and false is returned.
131  JS_API bool GetBool() const;
132 
133  /// Returns the integer held by this value. If this value is not holding
134  /// an int, this method raises a coding error and zero is returned. If the
135  /// value is holding a 64-bit integer larger than the platform int may
136  /// hold, the value is truncated.
137  JS_API int GetInt() const;
138 
139  /// Returns the 64-bit integer held by this value. If this value is not
140  /// holding a 64-bit integer, this method raises a coding error and zero
141  /// is returned.
142  JS_API int64_t GetInt64() const;
143 
144  /// Returns the 64-bit unsigned integer held by this value. If this value
145  /// is not holding a 64-bit unsigned integer, this method raises a coding
146  /// error and zero is returned.
147  JS_API uint64_t GetUInt64() const;
148 
149  /// Returns the double held by this value. If this value is not holding a
150  /// double, this method raises a coding error and zero is returned.
151  JS_API double GetReal() const;
152 
153  /// Returns the value corresponding to the C++ type specified in the
154  /// template parameter if it is holding such a value. Calling this
155  /// function with C++ type T is equivalent to calling the specific Get
156  /// function above that returns a value or reference to a type T.
157  ///
158  /// If a value corresponding to the C++ type is not being held, this
159  /// method raises a coding error. See Get functions above for default
160  /// value returned in this case.
161  template <typename T,
162  typename ReturnType = typename std::conditional<
166  const T&, T>::type>
167  ReturnType Get() const {
168  return _Get(static_cast<T*>(nullptr));
169  }
170 
171  /// Returns a vector holding the elements of this value's array that
172  /// correspond to the C++ type specified as the template parameter.
173  /// If this value is not holding an array, an empty vector is returned.
174  /// If any of the array's elements does not correspond to the C++ type,
175  /// it is replaced with the default value used by the Get functions above.
176  /// In both cases, a coding error will be raised.
177  template <typename T>
178  std::vector<T> GetArrayOf() const;
179 
180  /// Returns the type of this value.
181  JS_API Type GetType() const;
182 
183  /// Returns a display name for the type of this value.
185 
186  /// Returns true if this value is holding an object type.
187  JS_API bool IsObject() const;
188 
189  /// Returns true if this value is holding an array type.
190  JS_API bool IsArray() const;
191 
192  /// Returns true if this value is holding a string type.
193  JS_API bool IsString() const;
194 
195  /// Returns true if this value is holding a boolean type.
196  JS_API bool IsBool() const;
197 
198  /// Returns true if this value is holding an integer type.
199  JS_API bool IsInt() const;
200 
201  /// Returns true if this value is holding a real type.
202  JS_API bool IsReal() const;
203 
204  /// Returns true if this value is holding a 64-bit unsigned integer.
205  JS_API bool IsUInt64() const;
206 
207  /// Returns true if this value is holding a type that corresponds
208  /// to the C++ type specified as the template parameter.
209  template <typename T>
210  bool Is() const {
211  return _Is(static_cast<T*>(nullptr));
212  }
213 
214  /// Returns true if this value is holding an array whose elements all
215  /// correspond to the C++ type specified as the template parameter.
216  template <typename T>
217  bool IsArrayOf() const;
218 
219  /// Returns true if this value is null, false otherwise.
220  JS_API bool IsNull() const;
221 
222  /// Evaluates to true if this value is not null.
223  JS_API explicit operator bool() const;
224 
225  /// Returns true of both values hold the same type and the underlying held
226  /// values are equal.
227  JS_API bool operator==(const JsValue& other) const;
228 
229  /// Returns true if values are of different type, or the underlying held
230  /// values are not equal.
231  JS_API bool operator!=(const JsValue& other) const;
232 
233 private:
234  template <typename T>
235  struct _InvalidTypeHelper : public std::false_type { };
236 
237  template <class T>
238  T _Get(T*) const {
239  static_assert(_InvalidTypeHelper<T>::value,
240  "Invalid type for JsValue");
241  return T();
242  }
243 
244  const JsObject& _Get(JsObject*) const { return GetJsObject(); }
245  const JsArray& _Get(JsArray*) const { return GetJsArray(); }
246  const std::string& _Get(std::string*) const { return GetString(); }
247  bool _Get(bool*) const { return GetBool(); }
248  int _Get(int*) const { return GetInt(); }
249  int64_t _Get(int64_t*) const { return GetInt64(); }
250  uint64_t _Get(uint64_t*) const { return GetUInt64(); }
251  double _Get(double*) const { return GetReal(); }
252 
253  template <class T>
254  bool _Is(T*) const {
255  static_assert(_InvalidTypeHelper<T>::value,
256  "Invalid type for JsValue");
257  return false;
258  }
259 
260  bool _Is(JsObject*) const { return IsObject(); }
261  bool _Is(JsArray*) const { return IsArray(); }
262  bool _Is(std::string*) const { return IsString(); }
263  bool _Is(bool*) const { return IsBool(); }
264  bool _Is(int*) const { return IsInt(); }
265  bool _Is(int64_t*) const { return IsInt(); }
266  bool _Is(uint64_t*) const { return IsUInt64(); }
267  bool _Is(double*) const { return IsReal(); }
268 
269  struct _Holder;
270  std::shared_ptr<_Holder> _holder;
271 };
272 
273 template <typename T>
274 inline std::vector<T> JsValue::GetArrayOf() const
275 {
276  const JsArray& array = GetJsArray();
277  std::vector<T> result(array.size());
278  std::transform(array.begin(), array.end(), result.begin(),
279  [](const JsValue& v) { return v.Get<T>(); });
280  return result;
281 }
282 
283 template <typename T>
284 inline bool JsValue::IsArrayOf() const
285 {
286  if (!IsArray()) {
287  return false;
288  }
289  const JsArray& array = GetJsArray();
290  return std::all_of(array.begin(), array.end(),
291  [](const JsValue& v) { return v.Is<T>(); });
292 }
293 
295 
296 #endif // PXR_BASE_JS_VALUE_H
JS_API int GetInt() const
JS_API int64_t GetInt64() const
JS_API bool IsString() const
Returns true if this value is holding a string type.
ReturnType Get() const
Definition: value.h:167
JS_API bool IsObject() const
Returns true if this value is holding an object type.
const GLdouble * v
Definition: glcorearb.h:837
GLsizei const GLchar *const * string
Definition: glcorearb.h:814
GLsizei const GLfloat * value
Definition: glcorearb.h:824
JS_API bool operator!=(const JsValue &other) const
JS_API bool IsArray() const
Returns true if this value is holding an array type.
JS_API double GetReal() const
**But if you need a result
Definition: thread.h:613
std::vector< JsValue > JsArray
Definition: types.h:39
JS_API const std::string & GetString() const
JS_API bool IsInt() const
Returns true if this value is holding an integer type.
Definition: value.h:61
JS_API bool IsBool() const
Returns true if this value is holding a boolean type.
#define JS_API
Definition: api.h:40
JS_API bool operator==(const JsValue &other) const
JS_API JsValue()
Constructs a null value.
std::map< std::string, JsValue > JsObject
Definition: types.h:37
GA_API const UT_StringHolder transform
JS_API bool IsNull() const
Returns true if this value is null, false otherwise.
JS_API Type GetType() const
Returns the type of this value.
PXR_NAMESPACE_CLOSE_SCOPE PXR_NAMESPACE_OPEN_SCOPE
Definition: path.h:1432
JS_API bool IsReal() const
Returns true if this value is holding a real type.
JS_API uint64_t GetUInt64() const
JS_API bool GetBool() const
JS_API const JsArray & GetJsArray() const
#define PXR_NAMESPACE_CLOSE_SCOPE
Definition: pxr.h:91
Type
Type held by this JSON value.
Definition: value.h:65
bool IsArrayOf() const
Definition: value.h:284
JS_API std::string GetTypeName() const
Returns a display name for the type of this value.
Definition: core.h:1131
type
Definition: core.h:1059
JS_API const JsObject & GetJsObject() const
std::vector< T > GetArrayOf() const
Definition: value.h:274
JS_API bool IsUInt64() const
Returns true if this value is holding a 64-bit unsigned integer.
bool Is() const
Definition: value.h:210