xref: /aosp_15_r20/external/flatbuffers/reflection/reflection.fbs (revision 890232f25432b36107d06881e0a25aaa6b473652) 
1// This schema defines objects that represent a parsed schema, like
2// the binary version of a .fbs file.
3// This could be used to operate on unknown FlatBuffers at runtime.
4// It can even ... represent itself (!)
5
6namespace reflection;
7
8// These must correspond to the enum in idl.h.
9enum BaseType : byte {
10    None,
11    UType,
12    Bool,
13    Byte,
14    UByte,
15    Short,
16    UShort,
17    Int,
18    UInt,
19    Long,
20    ULong,
21    Float,
22    Double,
23    String,
24    Vector,
25    Obj,     // Used for tables & structs.
26    Union,
27    Array,
28
29    // Add any new type above this value.
30    MaxBaseType
31}
32
33table Type {
34    base_type:BaseType;
35    element:BaseType = None;  // Only if base_type == Vector
36                              // or base_type == Array.
37    index:int = -1;  // If base_type == Object, index into "objects" below.
38                     // If base_type == Union, UnionType, or integral derived
39                     // from an enum, index into "enums" below.
40                     // If base_type == Vector && element == Union or UnionType.
41    fixed_length:uint16 = 0;  // Only if base_type == Array.
42    /// The size (octets) of the `base_type` field.
43    base_size:uint = 4; // 4 Is a common size due to offsets being that size.
44    /// The size (octets) of the `element` field, if present.
45    element_size:uint = 0;
46}
47
48table KeyValue {
49    key:string (required, key);
50    value:string;
51}
52
53table EnumVal {
54    name:string (required);
55    value:long (key);
56    object:Object (deprecated);
57    union_type:Type;
58    documentation:[string];
59}
60
61table Enum {
62    name:string (required, key);
63    values:[EnumVal] (required);  // In order of their values.
64    is_union:bool = false;
65    underlying_type:Type (required);
66    attributes:[KeyValue];
67    documentation:[string];
68    /// File that this Enum is declared in.
69    declaration_file: string;
70}
71
72table Field {
73    name:string (required, key);
74    type:Type (required);
75    id:ushort;
76    offset:ushort;  // Offset into the vtable for tables, or into the struct.
77    default_integer:long = 0;
78    default_real:double = 0.0;
79    deprecated:bool = false;
80    required:bool = false;
81    key:bool = false;
82    attributes:[KeyValue];
83    documentation:[string];
84    optional:bool = false;
85    /// Number of padding octets to always add after this field. Structs only.
86    padding:uint16 = 0;
87}
88
89table Object {  // Used for both tables and structs.
90    name:string (required, key);
91    fields:[Field] (required);  // Sorted.
92    is_struct:bool = false;
93    minalign:int;
94    bytesize:int;  // For structs.
95    attributes:[KeyValue];
96    documentation:[string];
97    /// File that this Object is declared in.
98    declaration_file: string;
99}
100
101table RPCCall {
102    name:string (required, key);
103    request:Object (required);      // must be a table (not a struct)
104    response:Object (required);     // must be a table (not a struct)
105    attributes:[KeyValue];
106    documentation:[string];
107}
108
109table Service {
110    name:string (required, key);
111    calls:[RPCCall];
112    attributes:[KeyValue];
113    documentation:[string];
114    /// File that this Service is declared in.
115    declaration_file: string;
116}
117
118/// New schema language features that are not supported by old code generators.
119enum AdvancedFeatures : ulong (bit_flags) {
120    AdvancedArrayFeatures,
121    AdvancedUnionFeatures,
122    OptionalScalars,
123    DefaultVectorsAndStrings,
124}
125
126/// File specific information.
127/// Symbols declared within a file may be recovered by iterating over all
128/// symbols and examining the `declaration_file` field.
129table SchemaFile {
130  /// Filename, relative to project root.
131  filename:string (required, key);
132  /// Names of included files, relative to project root.
133  included_filenames:[string];
134}
135
136table Schema {
137    objects:[Object] (required);    // Sorted.
138    enums:[Enum] (required);        // Sorted.
139    file_ident:string;
140    file_ext:string;
141    root_table:Object;
142    services:[Service];             // Sorted.
143    advanced_features:AdvancedFeatures;
144    /// All the files used in this compilation. Files are relative to where
145    /// flatc was invoked.
146    fbs_files:[SchemaFile];         // Sorted.
147}
148
149root_type Schema;
150
151file_identifier "BFBS";
152file_extension "bfbs";
153