1 /*
2 * Copyright 2017 Google Inc. All rights reserved.
3 *
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
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17 #ifndef FLATBUFFERS_MINIREFLECT_H_
18 #define FLATBUFFERS_MINIREFLECT_H_
19
20 #include "flatbuffers/flatbuffers.h"
21 #include "flatbuffers/util.h"
22
23 namespace flatbuffers {
24
25 // Utilities that can be used with the "mini reflection" tables present
26 // in generated code with --reflect-types (only types) or --reflect-names
27 // (also 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).
31
32 // For any of the functions below that take `const TypeTable *`, you pass
33 // `FooTypeTable()` if the type of the root is `Foo`.
34
35 // First, a generic iterator that can be used by multiple algorithms.
36
37 struct IterationVisitor {
38 // These mark the scope of a table or struct.
StartSequenceIterationVisitor39 virtual void StartSequence() {}
EndSequenceIterationVisitor40 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.
FieldIterationVisitor43 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
48 // of a vector.
UTypeIterationVisitor49 virtual void UType(uint8_t, const char *) {}
BoolIterationVisitor50 virtual void Bool(bool) {}
CharIterationVisitor51 virtual void Char(int8_t, const char *) {}
UCharIterationVisitor52 virtual void UChar(uint8_t, const char *) {}
ShortIterationVisitor53 virtual void Short(int16_t, const char *) {}
UShortIterationVisitor54 virtual void UShort(uint16_t, const char *) {}
IntIterationVisitor55 virtual void Int(int32_t, const char *) {}
UIntIterationVisitor56 virtual void UInt(uint32_t, const char *) {}
LongIterationVisitor57 virtual void Long(int64_t) {}
ULongIterationVisitor58 virtual void ULong(uint64_t) {}
FloatIterationVisitor59 virtual void Float(float) {}
DoubleIterationVisitor60 virtual void Double(double) {}
StringIterationVisitor61 virtual void String(const String *) {}
UnknownIterationVisitor62 virtual void Unknown(const uint8_t *) {} // From a future version.
63 // These mark the scope of a vector.
StartVectorIterationVisitor64 virtual void StartVector() {}
EndVectorIterationVisitor65 virtual void EndVector() {}
ElementIterationVisitor66 virtual void Element(size_t /*i*/, ElementaryType /*type*/,
67 const TypeTable * /*type_table*/,
68 const uint8_t * /*val*/) {}
~IterationVisitorIterationVisitor69 virtual ~IterationVisitor() {}
70 };
71
InlineSize(ElementaryType type,const TypeTable * type_table)72 inline size_t InlineSize(ElementaryType type, const TypeTable *type_table) {
73 switch (type) {
74 case ET_UTYPE:
75 case ET_BOOL:
76 case ET_CHAR:
77 case ET_UCHAR: return 1;
78 case ET_SHORT:
79 case ET_USHORT: return 2;
80 case ET_INT:
81 case ET_UINT:
82 case ET_FLOAT:
83 case ET_STRING: return 4;
84 case ET_LONG:
85 case ET_ULONG:
86 case ET_DOUBLE: return 8;
87 case ET_SEQUENCE:
88 switch (type_table->st) {
89 case ST_TABLE:
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;
93 }
94 default: FLATBUFFERS_ASSERT(false); return 1;
95 }
96 }
97
LookupEnum(int64_t enum_val,const int64_t * values,size_t num_values)98 inline int64_t LookupEnum(int64_t enum_val, const int64_t *values,
99 size_t num_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);
103 }
104 return -1; // Unknown enum value.
105 }
106
EnumName(T tval,const TypeTable * type_table)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];
113 }
114 return nullptr;
115 }
116
117 void IterateObject(const uint8_t *obj, const TypeTable *type_table,
118 IterationVisitor *visitor);
119
IterateValue(ElementaryType type,const uint8_t * val,const TypeTable * type_table,const uint8_t * prev_val,soffset_t vector_index,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) {
123 switch (type) {
124 case ET_UTYPE: {
125 auto tval = ReadScalar<uint8_t>(val);
126 visitor->UType(tval, EnumName(tval, type_table));
127 break;
128 }
129 case ET_BOOL: {
130 visitor->Bool(ReadScalar<uint8_t>(val) != 0);
131 break;
132 }
133 case ET_CHAR: {
134 auto tval = ReadScalar<int8_t>(val);
135 visitor->Char(tval, EnumName(tval, type_table));
136 break;
137 }
138 case ET_UCHAR: {
139 auto tval = ReadScalar<uint8_t>(val);
140 visitor->UChar(tval, EnumName(tval, type_table));
141 break;
142 }
143 case ET_SHORT: {
144 auto tval = ReadScalar<int16_t>(val);
145 visitor->Short(tval, EnumName(tval, type_table));
146 break;
147 }
148 case ET_USHORT: {
149 auto tval = ReadScalar<uint16_t>(val);
150 visitor->UShort(tval, EnumName(tval, type_table));
151 break;
152 }
153 case ET_INT: {
154 auto tval = ReadScalar<int32_t>(val);
155 visitor->Int(tval, EnumName(tval, type_table));
156 break;
157 }
158 case ET_UINT: {
159 auto tval = ReadScalar<uint32_t>(val);
160 visitor->UInt(tval, EnumName(tval, type_table));
161 break;
162 }
163 case ET_LONG: {
164 visitor->Long(ReadScalar<int64_t>(val));
165 break;
166 }
167 case ET_ULONG: {
168 visitor->ULong(ReadScalar<uint64_t>(val));
169 break;
170 }
171 case ET_FLOAT: {
172 visitor->Float(ReadScalar<float>(val));
173 break;
174 }
175 case ET_DOUBLE: {
176 visitor->Double(ReadScalar<double>(val));
177 break;
178 }
179 case ET_STRING: {
180 val += ReadScalar<uoffset_t>(val);
181 visitor->String(reinterpret_cast<const String *>(val));
182 break;
183 }
184 case ET_SEQUENCE: {
185 switch (type_table->st) {
186 case ST_TABLE:
187 val += ReadScalar<uoffset_t>(val);
188 IterateObject(val, type_table, visitor);
189 break;
190 case ST_STRUCT: IterateObject(val, type_table, visitor); break;
191 case ST_UNION: {
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));
198 }
199 auto type_code_idx =
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) {
205 case ET_SEQUENCE: {
206 auto ref = type_table->type_refs[type_code.sequence_ref]();
207 IterateObject(val, ref, visitor);
208 break;
209 }
210 case ET_STRING:
211 visitor->String(reinterpret_cast<const String *>(val));
212 break;
213 default: visitor->Unknown(val);
214 }
215 } else {
216 visitor->Unknown(val);
217 }
218 break;
219 }
220 case ST_ENUM: FLATBUFFERS_ASSERT(false); break;
221 }
222 break;
223 }
224 default: {
225 visitor->Unknown(val);
226 break;
227 }
228 }
229 }
230
IterateObject(const uint8_t * obj,const TypeTable * type_table,IterationVisitor * visitor)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;
235 size_t set_idx = 0;
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)));
248 } else {
249 val = obj + type_table->values[i];
250 }
251 visitor->Field(i, set_idx, type, is_vector, ref, name, val);
252 if (val) {
253 set_idx++;
254 if (is_vector) {
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),
262 visitor);
263 elem_ptr += InlineSize(type, ref);
264 }
265 visitor->EndVector();
266 } else {
267 IterateValue(type, val, ref, prev_val, -1, visitor);
268 }
269 }
270 prev_val = val;
271 }
272 visitor->EndSequence();
273 }
274
IterateFlatBuffer(const uint8_t * buffer,const TypeTable * type_table,IterationVisitor * callback)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);
279 }
280
281 // Outputting a Flatbuffer to a string. Tries to conform as close to JSON /
282 // the output generated by idl_gen_text.cpp.
283
284 struct ToStringVisitor : public IterationVisitor {
285 std::string s;
286 std::string d;
287 bool q;
288 std::string in;
289 size_t indent_level;
ToStringVisitorToStringVisitor290 ToStringVisitor(std::string delimiter, bool quotes, std::string indent)
291 : d(delimiter), q(quotes), in(indent), indent_level(0) {}
ToStringVisitorToStringVisitor292 ToStringVisitor(std::string delimiter)
293 : d(delimiter), q(false), in(""), indent_level(0) {}
294
append_indentToStringVisitor295 void append_indent() {
296 for (size_t i = 0; i < indent_level; i++) { s += in; }
297 }
298
StartSequenceToStringVisitor299 void StartSequence() {
300 s += "{";
301 s += d;
302 indent_level++;
303 }
EndSequenceToStringVisitor304 void EndSequence() {
305 s += d;
306 indent_level--;
307 append_indent();
308 s += "}";
309 }
FieldToStringVisitor310 void Field(size_t /*field_idx*/, size_t set_idx, ElementaryType /*type*/,
311 bool /*is_vector*/, const TypeTable * /*type_table*/,
312 const char *name, const uint8_t *val) {
313 if (!val) return;
314 if (set_idx) {
315 s += ",";
316 s += d;
317 }
318 append_indent();
319 if (name) {
320 if (q) s += "\"";
321 s += name;
322 if (q) s += "\"";
323 s += ": ";
324 }
325 }
NamedToStringVisitor326 template<typename T> void Named(T x, const char *name) {
327 if (name) {
328 if (q) s += "\"";
329 s += name;
330 if (q) s += "\"";
331 } else {
332 s += NumToString(x);
333 }
334 }
UTypeToStringVisitor335 void UType(uint8_t x, const char *name) { Named(x, name); }
BoolToStringVisitor336 void Bool(bool x) { s += x ? "true" : "false"; }
CharToStringVisitor337 void Char(int8_t x, const char *name) { Named(x, name); }
UCharToStringVisitor338 void UChar(uint8_t x, const char *name) { Named(x, name); }
ShortToStringVisitor339 void Short(int16_t x, const char *name) { Named(x, name); }
UShortToStringVisitor340 void UShort(uint16_t x, const char *name) { Named(x, name); }
IntToStringVisitor341 void Int(int32_t x, const char *name) { Named(x, name); }
UIntToStringVisitor342 void UInt(uint32_t x, const char *name) { Named(x, name); }
LongToStringVisitor343 void Long(int64_t x) { s += NumToString(x); }
ULongToStringVisitor344 void ULong(uint64_t x) { s += NumToString(x); }
FloatToStringVisitor345 void Float(float x) { s += NumToString(x); }
DoubleToStringVisitor346 void Double(double x) { s += NumToString(x); }
StringToStringVisitor347 void String(const struct String *str) {
348 EscapeString(str->c_str(), str->size(), &s, true, false);
349 }
UnknownToStringVisitor350 void Unknown(const uint8_t *) { s += "(?)"; }
StartVectorToStringVisitor351 void StartVector() {
352 s += "[";
353 s += d;
354 indent_level++;
355 append_indent();
356 }
EndVectorToStringVisitor357 void EndVector() {
358 s += d;
359 indent_level--;
360 append_indent();
361 s += "]";
362 }
ElementToStringVisitor363 void Element(size_t i, ElementaryType /*type*/,
364 const TypeTable * /*type_table*/, const uint8_t * /*val*/) {
365 if (i) {
366 s += ",";
367 s += d;
368 append_indent();
369 }
370 }
371 };
372
373 inline std::string FlatBufferToString(const uint8_t *buffer,
374 const TypeTable *type_table,
375 bool multi_line = false) {
376 ToStringVisitor tostring_visitor(multi_line ? "\n" : " ");
377 IterateFlatBuffer(buffer, type_table, &tostring_visitor);
378 return tostring_visitor.s;
379 }
380
381 } // namespace flatbuffers
382
383 #endif // FLATBUFFERS_MINIREFLECT_H_
384