2 * Copyright 2017 Google Inc. All rights reserved.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #ifndef FLATBUFFERS_MINIREFLECT_H_
18 #define FLATBUFFERS_MINIREFLECT_H_
20 #include "flatbuffers/flatbuffers.h"
21 #include "flatbuffers/util.h"
23 namespace flatbuffers {
25 // Utilities that can be used with the "mini reflection" tables present
26 // in generated code with --reflect-types (only types) or --reflect-names
28 // This allows basic reflection functionality such as pretty-printing
29 // that does not require the use of the schema parser or loading of binary
30 // schema files at runtime (reflection.h).
32 // For any of the functions below that take `const TypeTable *`, you pass
33 // `FooTypeTable()` if the type of the root is `Foo`.
35 // First, a generic iterator that can be used by multiple algorithms.
37 struct IterationVisitor {
38 // These mark the scope of a table or struct.
39 virtual void StartSequence() {}
40 virtual void EndSequence() {}
41 // Called for each field regardless of wether it is present or not.
42 // If not present, val == nullptr. set_idx is the index of all set fields.
43 virtual void Field(size_t /*field_idx*/, size_t /*set_idx*/,
44 ElementaryType /*type*/, bool /*is_vector*/,
45 const TypeTable * /*type_table*/, const char * /*name*/,
46 const uint8_t * /*val*/) {}
47 // Called for a value that is actually present, after a field, or as part
49 virtual void UType(uint8_t, const char *) {}
50 virtual void Bool(bool) {}
51 virtual void Char(int8_t, const char *) {}
52 virtual void UChar(uint8_t, const char *) {}
53 virtual void Short(int16_t, const char *) {}
54 virtual void UShort(uint16_t, const char *) {}
55 virtual void Int(int32_t, const char *) {}
56 virtual void UInt(uint32_t, const char *) {}
57 virtual void Long(int64_t) {}
58 virtual void ULong(uint64_t) {}
59 virtual void Float(float) {}
60 virtual void Double(double) {}
61 virtual void String(const String *) {}
62 virtual void Unknown(const uint8_t *) {} // From a future version.
63 // These mark the scope of a vector.
64 virtual void StartVector() {}
65 virtual void EndVector() {}
66 virtual void Element(size_t /*i*/, ElementaryType /*type*/,
67 const TypeTable * /*type_table*/,
68 const uint8_t * /*val*/) {}
69 virtual ~IterationVisitor() {}
72 inline size_t InlineSize(ElementaryType type, const TypeTable *type_table) {
77 case ET_UCHAR: return 1;
79 case ET_USHORT: return 2;
83 case ET_STRING: return 4;
86 case ET_DOUBLE: return 8;
88 switch (type_table->st) {
90 case ST_UNION: return 4;
91 case ST_STRUCT: return static_cast<size_t>(type_table->values[type_table->num_elems]);
92 default: FLATBUFFERS_ASSERT(false); return 1;
94 default: FLATBUFFERS_ASSERT(false); return 1;
98 inline int64_t LookupEnum(int64_t enum_val, const int64_t *values,
100 if (!values) return enum_val;
101 for (size_t i = 0; i < num_values; i++) {
102 if (enum_val == values[i]) return static_cast<int64_t>(i);
104 return -1; // Unknown enum value.
107 template<typename T> const char *EnumName(T tval, const TypeTable *type_table) {
108 if (!type_table || !type_table->names) return nullptr;
109 auto i = LookupEnum(static_cast<int64_t>(tval), type_table->values,
110 type_table->num_elems);
111 if (i >= 0 && i < static_cast<int64_t>(type_table->num_elems)) {
112 return type_table->names[i];
117 void IterateObject(const uint8_t *obj, const TypeTable *type_table,
118 IterationVisitor *visitor);
120 inline void IterateValue(ElementaryType type, const uint8_t *val,
121 const TypeTable *type_table, const uint8_t *prev_val,
122 soffset_t vector_index, IterationVisitor *visitor) {
125 auto tval = ReadScalar<uint8_t>(val);
126 visitor->UType(tval, EnumName(tval, type_table));
130 visitor->Bool(ReadScalar<uint8_t>(val) != 0);
134 auto tval = ReadScalar<int8_t>(val);
135 visitor->Char(tval, EnumName(tval, type_table));
139 auto tval = ReadScalar<uint8_t>(val);
140 visitor->UChar(tval, EnumName(tval, type_table));
144 auto tval = ReadScalar<int16_t>(val);
145 visitor->Short(tval, EnumName(tval, type_table));
149 auto tval = ReadScalar<uint16_t>(val);
150 visitor->UShort(tval, EnumName(tval, type_table));
154 auto tval = ReadScalar<int32_t>(val);
155 visitor->Int(tval, EnumName(tval, type_table));
159 auto tval = ReadScalar<uint32_t>(val);
160 visitor->UInt(tval, EnumName(tval, type_table));
164 visitor->Long(ReadScalar<int64_t>(val));
168 visitor->ULong(ReadScalar<uint64_t>(val));
172 visitor->Float(ReadScalar<float>(val));
176 visitor->Double(ReadScalar<double>(val));
180 val += ReadScalar<uoffset_t>(val);
181 visitor->String(reinterpret_cast<const String *>(val));
185 switch (type_table->st) {
187 val += ReadScalar<uoffset_t>(val);
188 IterateObject(val, type_table, visitor);
190 case ST_STRUCT: IterateObject(val, type_table, visitor); break;
192 val += ReadScalar<uoffset_t>(val);
193 FLATBUFFERS_ASSERT(prev_val);
194 auto union_type = *prev_val; // Always a uint8_t.
195 if (vector_index >= 0) {
196 auto type_vec = reinterpret_cast<const Vector<uint8_t> *>(prev_val);
197 union_type = type_vec->Get(static_cast<uoffset_t>(vector_index));
200 LookupEnum(union_type, type_table->values, type_table->num_elems);
201 if (type_code_idx >= 0 &&
202 type_code_idx < static_cast<int32_t>(type_table->num_elems)) {
203 auto type_code = type_table->type_codes[type_code_idx];
204 switch (type_code.base_type) {
206 auto ref = type_table->type_refs[type_code.sequence_ref]();
207 IterateObject(val, ref, visitor);
211 visitor->String(reinterpret_cast<const String *>(val));
213 default: visitor->Unknown(val);
216 visitor->Unknown(val);
220 case ST_ENUM: FLATBUFFERS_ASSERT(false); break;
225 visitor->Unknown(val);
231 inline void IterateObject(const uint8_t *obj, const TypeTable *type_table,
232 IterationVisitor *visitor) {
233 visitor->StartSequence();
234 const uint8_t *prev_val = nullptr;
236 for (size_t i = 0; i < type_table->num_elems; i++) {
237 auto type_code = type_table->type_codes[i];
238 auto type = static_cast<ElementaryType>(type_code.base_type);
239 auto is_vector = type_code.is_vector != 0;
240 auto ref_idx = type_code.sequence_ref;
241 const TypeTable *ref = nullptr;
242 if (ref_idx >= 0) { ref = type_table->type_refs[ref_idx](); }
243 auto name = type_table->names ? type_table->names[i] : nullptr;
244 const uint8_t *val = nullptr;
245 if (type_table->st == ST_TABLE) {
246 val = reinterpret_cast<const Table *>(obj)->GetAddressOf(
247 FieldIndexToOffset(static_cast<voffset_t>(i)));
249 val = obj + type_table->values[i];
251 visitor->Field(i, set_idx, type, is_vector, ref, name, val);
255 val += ReadScalar<uoffset_t>(val);
256 auto vec = reinterpret_cast<const Vector<uint8_t> *>(val);
257 visitor->StartVector();
258 auto elem_ptr = vec->Data();
259 for (size_t j = 0; j < vec->size(); j++) {
260 visitor->Element(j, type, ref, elem_ptr);
261 IterateValue(type, elem_ptr, ref, prev_val, static_cast<soffset_t>(j),
263 elem_ptr += InlineSize(type, ref);
265 visitor->EndVector();
267 IterateValue(type, val, ref, prev_val, -1, visitor);
272 visitor->EndSequence();
275 inline void IterateFlatBuffer(const uint8_t *buffer,
276 const TypeTable *type_table,
277 IterationVisitor *callback) {
278 IterateObject(GetRoot<uint8_t>(buffer), type_table, callback);
281 // Outputting a Flatbuffer to a string. Tries to conform as close to JSON /
282 // the output generated by idl_gen_text.cpp.
284 struct ToStringVisitor : public IterationVisitor {
290 bool vector_delimited;
291 ToStringVisitor(std::string delimiter, bool quotes, std::string indent,
292 bool vdelimited = true)
297 vector_delimited(vdelimited) {}
298 ToStringVisitor(std::string delimiter)
303 vector_delimited(true) {}
305 void append_indent() {
306 for (size_t i = 0; i < indent_level; i++) { s += in; }
309 void StartSequence() {
320 void Field(size_t /*field_idx*/, size_t set_idx, ElementaryType /*type*/,
321 bool /*is_vector*/, const TypeTable * /*type_table*/,
322 const char *name, const uint8_t *val) {
336 template<typename T> void Named(T x, const char *name) {
345 void UType(uint8_t x, const char *name) { Named(x, name); }
346 void Bool(bool x) { s += x ? "true" : "false"; }
347 void Char(int8_t x, const char *name) { Named(x, name); }
348 void UChar(uint8_t x, const char *name) { Named(x, name); }
349 void Short(int16_t x, const char *name) { Named(x, name); }
350 void UShort(uint16_t x, const char *name) { Named(x, name); }
351 void Int(int32_t x, const char *name) { Named(x, name); }
352 void UInt(uint32_t x, const char *name) { Named(x, name); }
353 void Long(int64_t x) { s += NumToString(x); }
354 void ULong(uint64_t x) { s += NumToString(x); }
355 void Float(float x) { s += NumToString(x); }
356 void Double(double x) { s += NumToString(x); }
357 void String(const struct String *str) {
358 EscapeString(str->c_str(), str->size(), &s, true, false);
360 void Unknown(const uint8_t *) { s += "(?)"; }
363 if (vector_delimited) {
372 if (vector_delimited) {
381 void Element(size_t i, ElementaryType /*type*/,
382 const TypeTable * /*type_table*/, const uint8_t * /*val*/) {
385 if (vector_delimited) {
395 inline std::string FlatBufferToString(const uint8_t *buffer,
396 const TypeTable *type_table,
397 bool multi_line = false,
398 bool vector_delimited = true) {
399 ToStringVisitor tostring_visitor(multi_line ? "\n" : " ", false, "",
401 IterateFlatBuffer(buffer, type_table, &tostring_visitor);
402 return tostring_visitor.s;
405 } // namespace flatbuffers
407 #endif // FLATBUFFERS_MINIREFLECT_H_