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dynamicFileFormatContext.h
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1 //
2 // Copyright 2019 Pixar
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24 #ifndef PXR_USD_PCP_DYNAMIC_FILE_FORMAT_CONTEXT_H
25 #define PXR_USD_PCP_DYNAMIC_FILE_FORMAT_CONTEXT_H
26 
27 #include "pxr/pxr.h"
28 #include "pxr/usd/pcp/api.h"
29 #include "pxr/usd/pcp/node.h"
30 
32 
33 class PcpPrimIndex_StackFrame;
34 class PcpCache;
35 
36 /// \class PcpDynamicFileFormatContext
37 ///
38 /// Context object for the current state of a prim index that is being built
39 /// that allows implementations of PcpDynamicFileFormatInterface to compose
40 /// field values when generating dynamic file format arguments. The context
41 /// allows us to iterate over all nodes that have already been composed looking
42 /// for the strongest opinion for a relevant field.
44 {
45 public:
46  using VtValueVector = std::vector<VtValue>;
47 
48  PCP_API
49  ~PcpDynamicFileFormatContext() = default;
50 
51  /// Compose the \p value of the given \p field and return its current
52  /// strongest opinion. For dictionary valued fields this will be a
53  /// dictionary containing the strongest value for each individual key.
54  /// Returns true if a value for the field was found.
55  PCP_API
56  bool ComposeValue(const TfToken &field, VtValue *value) const;
57 
58  /// Compose the \p values of the given \p field returning all available
59  /// opinions ordered from strongest to weakest. For dictionary valued
60  /// fields, the dictionaries from each opinion are not composed together
61  /// at each step and are instead returned in the list as is.
62  /// Returns true if a value for the field was found.
63  ///
64  /// Note that this is slower than ComposeValue, especially for
65  /// non-dictionary valued fields, and should only be used if knowing more
66  /// than just the strongest value is necessary.
67  PCP_API
68  bool ComposeValueStack(const TfToken &field,
69  VtValueVector *values) const;
70 
71 private:
72  // Callback function for ComposeValue. This callback function will
73  // be passed values for the field given to ComposeValue from
74  // strongest to weakest available opinion and is free to copy or
75  // swap out the value as desired.
76  using _ComposeFunction = std::function<void(VtValue &&)>;
77 
78  /// Constructs a context.
79  /// \p parentNode and \p previousFrame are used to traverse the
80  /// current state of the prim index graph when composing the opinions on
81  /// fields. \p composedFieldNames is the set of field names that is
82  /// to be updated with the names of fields that ComposeValue and
83  /// ComposeValueStack are called on for dependency tracking.
85  const PcpNodeRef &parentNode,
86  PcpPrimIndex_StackFrame *previousFrame,
87  TfToken::Set *composedFieldNames);
88  /// Access to private constructor. Should only be called by prim indexing.
90  const PcpNodeRef &, PcpPrimIndex_StackFrame *, TfToken::Set *);
91 
92  /// Returns whether the given \p field is allowed to be used to generate
93  /// file format arguments. It can also return whether the value type of
94  /// the field is a dictionary if needed.
95  bool _IsAllowedFieldForArguments(
96  const TfToken &field, bool *fieldValueIsDictionary = nullptr) const;
97 
98 private:
99  PcpNodeRef _parentNode;
100  PcpPrimIndex_StackFrame *_previousStackFrame;
101 
102  // Cached names of fields that had values composed by this context.
103  TfToken::Set *_composedFieldNames;
104 };
105 
107 
108 #endif // PXR_USD_PCP_DYNAMIC_FILE_FORMAT_CONTEXT_H
PCP_API bool ComposeValue(const TfToken &field, VtValue *value) const
GLint GLsizei const GLuint64 * values
Definition: glew.h:3612
Definition: cache.h:91
friend PcpDynamicFileFormatContext Pcp_CreateDynamicFileFormatContext(const PcpNodeRef &, PcpPrimIndex_StackFrame *, TfToken::Set *)
Access to private constructor. Should only be called by prim indexing.
std::vector< VtValue > VtValueVector
Definition: token.h:87
PCP_API ~PcpDynamicFileFormatContext()=default
PCP_API bool ComposeValueStack(const TfToken &field, VtValueVector *values) const
PXR_NAMESPACE_CLOSE_SCOPE PXR_NAMESPACE_OPEN_SCOPE
Definition: path.h:1346
#define PXR_NAMESPACE_CLOSE_SCOPE
Definition: pxr.h:91
GLsizei const GLfloat * value
Definition: glew.h:1849
Definition: value.h:174
std::set< TfToken, TfTokenFastArbitraryLessThan > Set
Definition: token.h:183
#define PCP_API
Definition: api.h:40