temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 1 | # Protocol Buffers - Google's data interchange format |
kenton@google.com | 24bf56f | 2008-09-24 20:31:01 +0000 | [diff] [blame] | 2 | # Copyright 2008 Google Inc. All rights reserved. |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 3 | # http://code.google.com/p/protobuf/ |
| 4 | # |
kenton@google.com | 24bf56f | 2008-09-24 20:31:01 +0000 | [diff] [blame] | 5 | # Redistribution and use in source and binary forms, with or without |
| 6 | # modification, are permitted provided that the following conditions are |
| 7 | # met: |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 8 | # |
kenton@google.com | 24bf56f | 2008-09-24 20:31:01 +0000 | [diff] [blame] | 9 | # * Redistributions of source code must retain the above copyright |
| 10 | # notice, this list of conditions and the following disclaimer. |
| 11 | # * Redistributions in binary form must reproduce the above |
| 12 | # copyright notice, this list of conditions and the following disclaimer |
| 13 | # in the documentation and/or other materials provided with the |
| 14 | # distribution. |
| 15 | # * Neither the name of Google Inc. nor the names of its |
| 16 | # contributors may be used to endorse or promote products derived from |
| 17 | # this software without specific prior written permission. |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 18 | # |
kenton@google.com | 24bf56f | 2008-09-24 20:31:01 +0000 | [diff] [blame] | 19 | # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 20 | # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 21 | # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 22 | # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 23 | # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 24 | # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 25 | # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 26 | # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 27 | # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 28 | # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 29 | # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 30 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 31 | """Code for encoding protocol message primitives. |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 32 | |
| 33 | Contains the logic for encoding every logical protocol field type |
| 34 | into one of the 5 physical wire types. |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 35 | |
| 36 | This code is designed to push the Python interpreter's performance to the |
| 37 | limits. |
| 38 | |
| 39 | The basic idea is that at startup time, for every field (i.e. every |
| 40 | FieldDescriptor) we construct two functions: a "sizer" and an "encoder". The |
| 41 | sizer takes a value of this field's type and computes its byte size. The |
| 42 | encoder takes a writer function and a value. It encodes the value into byte |
| 43 | strings and invokes the writer function to write those strings. Typically the |
| 44 | writer function is the write() method of a cStringIO. |
| 45 | |
| 46 | We try to do as much work as possible when constructing the writer and the |
| 47 | sizer rather than when calling them. In particular: |
| 48 | * We copy any needed global functions to local variables, so that we do not need |
| 49 | to do costly global table lookups at runtime. |
| 50 | * Similarly, we try to do any attribute lookups at startup time if possible. |
| 51 | * Every field's tag is encoded to bytes at startup, since it can't change at |
| 52 | runtime. |
| 53 | * Whatever component of the field size we can compute at startup, we do. |
| 54 | * We *avoid* sharing code if doing so would make the code slower and not sharing |
| 55 | does not burden us too much. For example, encoders for repeated fields do |
| 56 | not just call the encoders for singular fields in a loop because this would |
| 57 | add an extra function call overhead for every loop iteration; instead, we |
| 58 | manually inline the single-value encoder into the loop. |
| 59 | * If a Python function lacks a return statement, Python actually generates |
| 60 | instructions to pop the result of the last statement off the stack, push |
| 61 | None onto the stack, and then return that. If we really don't care what |
| 62 | value is returned, then we can save two instructions by returning the |
| 63 | result of the last statement. It looks funny but it helps. |
| 64 | * We assume that type and bounds checking has happened at a higher level. |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 65 | """ |
| 66 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 67 | __author__ = 'kenton@google.com (Kenton Varda)' |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 68 | |
| 69 | import struct |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 70 | from google.protobuf.internal import wire_format |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 71 | |
| 72 | |
liujisi@google.com | 33165fe | 2010-11-02 13:14:58 +0000 | [diff] [blame^] | 73 | # This will overflow and thus become IEEE-754 "infinity". We would use |
| 74 | # "float('inf')" but it doesn't work on Windows pre-Python-2.6. |
| 75 | _POS_INF = 1e10000 |
| 76 | _NEG_INF = -_POS_INF |
| 77 | |
| 78 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 79 | def _VarintSize(value): |
| 80 | """Compute the size of a varint value.""" |
| 81 | if value <= 0x7f: return 1 |
| 82 | if value <= 0x3fff: return 2 |
| 83 | if value <= 0x1fffff: return 3 |
| 84 | if value <= 0xfffffff: return 4 |
| 85 | if value <= 0x7ffffffff: return 5 |
| 86 | if value <= 0x3ffffffffff: return 6 |
| 87 | if value <= 0x1ffffffffffff: return 7 |
| 88 | if value <= 0xffffffffffffff: return 8 |
| 89 | if value <= 0x7fffffffffffffff: return 9 |
| 90 | return 10 |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 91 | |
| 92 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 93 | def _SignedVarintSize(value): |
| 94 | """Compute the size of a signed varint value.""" |
| 95 | if value < 0: return 10 |
| 96 | if value <= 0x7f: return 1 |
| 97 | if value <= 0x3fff: return 2 |
| 98 | if value <= 0x1fffff: return 3 |
| 99 | if value <= 0xfffffff: return 4 |
| 100 | if value <= 0x7ffffffff: return 5 |
| 101 | if value <= 0x3ffffffffff: return 6 |
| 102 | if value <= 0x1ffffffffffff: return 7 |
| 103 | if value <= 0xffffffffffffff: return 8 |
| 104 | if value <= 0x7fffffffffffffff: return 9 |
| 105 | return 10 |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 106 | |
| 107 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 108 | def _TagSize(field_number): |
| 109 | """Returns the number of bytes required to serialize a tag with this field |
| 110 | number.""" |
| 111 | # Just pass in type 0, since the type won't affect the tag+type size. |
| 112 | return _VarintSize(wire_format.PackTag(field_number, 0)) |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 113 | |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 114 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 115 | # -------------------------------------------------------------------- |
| 116 | # In this section we define some generic sizers. Each of these functions |
| 117 | # takes parameters specific to a particular field type, e.g. int32 or fixed64. |
| 118 | # It returns another function which in turn takes parameters specific to a |
| 119 | # particular field, e.g. the field number and whether it is repeated or packed. |
| 120 | # Look at the next section to see how these are used. |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 121 | |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 122 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 123 | def _SimpleSizer(compute_value_size): |
| 124 | """A sizer which uses the function compute_value_size to compute the size of |
| 125 | each value. Typically compute_value_size is _VarintSize.""" |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 126 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 127 | def SpecificSizer(field_number, is_repeated, is_packed): |
| 128 | tag_size = _TagSize(field_number) |
| 129 | if is_packed: |
| 130 | local_VarintSize = _VarintSize |
| 131 | def PackedFieldSize(value): |
| 132 | result = 0 |
| 133 | for element in value: |
| 134 | result += compute_value_size(element) |
| 135 | return result + local_VarintSize(result) + tag_size |
| 136 | return PackedFieldSize |
| 137 | elif is_repeated: |
| 138 | def RepeatedFieldSize(value): |
| 139 | result = tag_size * len(value) |
| 140 | for element in value: |
| 141 | result += compute_value_size(element) |
| 142 | return result |
| 143 | return RepeatedFieldSize |
| 144 | else: |
| 145 | def FieldSize(value): |
| 146 | return tag_size + compute_value_size(value) |
| 147 | return FieldSize |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 148 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 149 | return SpecificSizer |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 150 | |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 151 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 152 | def _ModifiedSizer(compute_value_size, modify_value): |
| 153 | """Like SimpleSizer, but modify_value is invoked on each value before it is |
| 154 | passed to compute_value_size. modify_value is typically ZigZagEncode.""" |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 155 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 156 | def SpecificSizer(field_number, is_repeated, is_packed): |
| 157 | tag_size = _TagSize(field_number) |
| 158 | if is_packed: |
| 159 | local_VarintSize = _VarintSize |
| 160 | def PackedFieldSize(value): |
| 161 | result = 0 |
| 162 | for element in value: |
| 163 | result += compute_value_size(modify_value(element)) |
| 164 | return result + local_VarintSize(result) + tag_size |
| 165 | return PackedFieldSize |
| 166 | elif is_repeated: |
| 167 | def RepeatedFieldSize(value): |
| 168 | result = tag_size * len(value) |
| 169 | for element in value: |
| 170 | result += compute_value_size(modify_value(element)) |
| 171 | return result |
| 172 | return RepeatedFieldSize |
| 173 | else: |
| 174 | def FieldSize(value): |
| 175 | return tag_size + compute_value_size(modify_value(value)) |
| 176 | return FieldSize |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 177 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 178 | return SpecificSizer |
kenton@google.com | 2d6daa7 | 2009-01-22 01:27:00 +0000 | [diff] [blame] | 179 | |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 180 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 181 | def _FixedSizer(value_size): |
| 182 | """Like _SimpleSizer except for a fixed-size field. The input is the size |
| 183 | of one value.""" |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 184 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 185 | def SpecificSizer(field_number, is_repeated, is_packed): |
| 186 | tag_size = _TagSize(field_number) |
| 187 | if is_packed: |
| 188 | local_VarintSize = _VarintSize |
| 189 | def PackedFieldSize(value): |
| 190 | result = len(value) * value_size |
| 191 | return result + local_VarintSize(result) + tag_size |
| 192 | return PackedFieldSize |
| 193 | elif is_repeated: |
| 194 | element_size = value_size + tag_size |
| 195 | def RepeatedFieldSize(value): |
| 196 | return len(value) * element_size |
| 197 | return RepeatedFieldSize |
| 198 | else: |
| 199 | field_size = value_size + tag_size |
| 200 | def FieldSize(value): |
| 201 | return field_size |
| 202 | return FieldSize |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 203 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 204 | return SpecificSizer |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 205 | |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 206 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 207 | # ==================================================================== |
| 208 | # Here we declare a sizer constructor for each field type. Each "sizer |
| 209 | # constructor" is a function that takes (field_number, is_repeated, is_packed) |
| 210 | # as parameters and returns a sizer, which in turn takes a field value as |
| 211 | # a parameter and returns its encoded size. |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 212 | |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 213 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 214 | Int32Sizer = Int64Sizer = EnumSizer = _SimpleSizer(_SignedVarintSize) |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 215 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 216 | UInt32Sizer = UInt64Sizer = _SimpleSizer(_VarintSize) |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 217 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 218 | SInt32Sizer = SInt64Sizer = _ModifiedSizer( |
| 219 | _SignedVarintSize, wire_format.ZigZagEncode) |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 220 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 221 | Fixed32Sizer = SFixed32Sizer = FloatSizer = _FixedSizer(4) |
| 222 | Fixed64Sizer = SFixed64Sizer = DoubleSizer = _FixedSizer(8) |
| 223 | |
| 224 | BoolSizer = _FixedSizer(1) |
| 225 | |
| 226 | |
| 227 | def StringSizer(field_number, is_repeated, is_packed): |
| 228 | """Returns a sizer for a string field.""" |
| 229 | |
| 230 | tag_size = _TagSize(field_number) |
| 231 | local_VarintSize = _VarintSize |
| 232 | local_len = len |
| 233 | assert not is_packed |
| 234 | if is_repeated: |
| 235 | def RepeatedFieldSize(value): |
| 236 | result = tag_size * len(value) |
| 237 | for element in value: |
| 238 | l = local_len(element.encode('utf-8')) |
| 239 | result += local_VarintSize(l) + l |
| 240 | return result |
| 241 | return RepeatedFieldSize |
| 242 | else: |
| 243 | def FieldSize(value): |
| 244 | l = local_len(value.encode('utf-8')) |
| 245 | return tag_size + local_VarintSize(l) + l |
| 246 | return FieldSize |
| 247 | |
| 248 | |
| 249 | def BytesSizer(field_number, is_repeated, is_packed): |
| 250 | """Returns a sizer for a bytes field.""" |
| 251 | |
| 252 | tag_size = _TagSize(field_number) |
| 253 | local_VarintSize = _VarintSize |
| 254 | local_len = len |
| 255 | assert not is_packed |
| 256 | if is_repeated: |
| 257 | def RepeatedFieldSize(value): |
| 258 | result = tag_size * len(value) |
| 259 | for element in value: |
| 260 | l = local_len(element) |
| 261 | result += local_VarintSize(l) + l |
| 262 | return result |
| 263 | return RepeatedFieldSize |
| 264 | else: |
| 265 | def FieldSize(value): |
| 266 | l = local_len(value) |
| 267 | return tag_size + local_VarintSize(l) + l |
| 268 | return FieldSize |
| 269 | |
| 270 | |
| 271 | def GroupSizer(field_number, is_repeated, is_packed): |
| 272 | """Returns a sizer for a group field.""" |
| 273 | |
| 274 | tag_size = _TagSize(field_number) * 2 |
| 275 | assert not is_packed |
| 276 | if is_repeated: |
| 277 | def RepeatedFieldSize(value): |
| 278 | result = tag_size * len(value) |
| 279 | for element in value: |
| 280 | result += element.ByteSize() |
| 281 | return result |
| 282 | return RepeatedFieldSize |
| 283 | else: |
| 284 | def FieldSize(value): |
| 285 | return tag_size + value.ByteSize() |
| 286 | return FieldSize |
| 287 | |
| 288 | |
| 289 | def MessageSizer(field_number, is_repeated, is_packed): |
| 290 | """Returns a sizer for a message field.""" |
| 291 | |
| 292 | tag_size = _TagSize(field_number) |
| 293 | local_VarintSize = _VarintSize |
| 294 | assert not is_packed |
| 295 | if is_repeated: |
| 296 | def RepeatedFieldSize(value): |
| 297 | result = tag_size * len(value) |
| 298 | for element in value: |
| 299 | l = element.ByteSize() |
| 300 | result += local_VarintSize(l) + l |
| 301 | return result |
| 302 | return RepeatedFieldSize |
| 303 | else: |
| 304 | def FieldSize(value): |
| 305 | l = value.ByteSize() |
| 306 | return tag_size + local_VarintSize(l) + l |
| 307 | return FieldSize |
| 308 | |
| 309 | |
| 310 | # -------------------------------------------------------------------- |
| 311 | # MessageSet is special. |
| 312 | |
| 313 | |
| 314 | def MessageSetItemSizer(field_number): |
| 315 | """Returns a sizer for extensions of MessageSet. |
| 316 | |
| 317 | The message set message looks like this: |
| 318 | message MessageSet { |
| 319 | repeated group Item = 1 { |
| 320 | required int32 type_id = 2; |
| 321 | required string message = 3; |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 322 | } |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 323 | } |
| 324 | """ |
| 325 | static_size = (_TagSize(1) * 2 + _TagSize(2) + _VarintSize(field_number) + |
| 326 | _TagSize(3)) |
| 327 | local_VarintSize = _VarintSize |
temporal | 40ee551 | 2008-07-10 02:12:20 +0000 | [diff] [blame] | 328 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 329 | def FieldSize(value): |
| 330 | l = value.ByteSize() |
| 331 | return static_size + local_VarintSize(l) + l |
| 332 | |
| 333 | return FieldSize |
| 334 | |
| 335 | |
| 336 | # ==================================================================== |
| 337 | # Encoders! |
| 338 | |
| 339 | |
| 340 | def _VarintEncoder(): |
| 341 | """Return an encoder for a basic varint value (does not include tag).""" |
| 342 | |
| 343 | local_chr = chr |
| 344 | def EncodeVarint(write, value): |
| 345 | bits = value & 0x7f |
| 346 | value >>= 7 |
| 347 | while value: |
| 348 | write(local_chr(0x80|bits)) |
| 349 | bits = value & 0x7f |
| 350 | value >>= 7 |
| 351 | return write(local_chr(bits)) |
| 352 | |
| 353 | return EncodeVarint |
| 354 | |
| 355 | |
| 356 | def _SignedVarintEncoder(): |
| 357 | """Return an encoder for a basic signed varint value (does not include |
| 358 | tag).""" |
| 359 | |
| 360 | local_chr = chr |
| 361 | def EncodeSignedVarint(write, value): |
| 362 | if value < 0: |
| 363 | value += (1 << 64) |
| 364 | bits = value & 0x7f |
| 365 | value >>= 7 |
| 366 | while value: |
| 367 | write(local_chr(0x80|bits)) |
| 368 | bits = value & 0x7f |
| 369 | value >>= 7 |
| 370 | return write(local_chr(bits)) |
| 371 | |
| 372 | return EncodeSignedVarint |
| 373 | |
| 374 | |
| 375 | _EncodeVarint = _VarintEncoder() |
| 376 | _EncodeSignedVarint = _SignedVarintEncoder() |
| 377 | |
| 378 | |
| 379 | def _VarintBytes(value): |
| 380 | """Encode the given integer as a varint and return the bytes. This is only |
| 381 | called at startup time so it doesn't need to be fast.""" |
| 382 | |
| 383 | pieces = [] |
| 384 | _EncodeVarint(pieces.append, value) |
| 385 | return "".join(pieces) |
| 386 | |
| 387 | |
| 388 | def TagBytes(field_number, wire_type): |
| 389 | """Encode the given tag and return the bytes. Only called at startup.""" |
| 390 | |
| 391 | return _VarintBytes(wire_format.PackTag(field_number, wire_type)) |
| 392 | |
| 393 | # -------------------------------------------------------------------- |
| 394 | # As with sizers (see above), we have a number of common encoder |
| 395 | # implementations. |
| 396 | |
| 397 | |
| 398 | def _SimpleEncoder(wire_type, encode_value, compute_value_size): |
| 399 | """Return a constructor for an encoder for fields of a particular type. |
| 400 | |
| 401 | Args: |
| 402 | wire_type: The field's wire type, for encoding tags. |
| 403 | encode_value: A function which encodes an individual value, e.g. |
| 404 | _EncodeVarint(). |
| 405 | compute_value_size: A function which computes the size of an individual |
| 406 | value, e.g. _VarintSize(). |
| 407 | """ |
| 408 | |
| 409 | def SpecificEncoder(field_number, is_repeated, is_packed): |
| 410 | if is_packed: |
| 411 | tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED) |
| 412 | local_EncodeVarint = _EncodeVarint |
| 413 | def EncodePackedField(write, value): |
| 414 | write(tag_bytes) |
| 415 | size = 0 |
| 416 | for element in value: |
| 417 | size += compute_value_size(element) |
| 418 | local_EncodeVarint(write, size) |
| 419 | for element in value: |
| 420 | encode_value(write, element) |
| 421 | return EncodePackedField |
| 422 | elif is_repeated: |
| 423 | tag_bytes = TagBytes(field_number, wire_type) |
| 424 | def EncodeRepeatedField(write, value): |
| 425 | for element in value: |
| 426 | write(tag_bytes) |
| 427 | encode_value(write, element) |
| 428 | return EncodeRepeatedField |
| 429 | else: |
| 430 | tag_bytes = TagBytes(field_number, wire_type) |
| 431 | def EncodeField(write, value): |
| 432 | write(tag_bytes) |
| 433 | return encode_value(write, value) |
| 434 | return EncodeField |
| 435 | |
| 436 | return SpecificEncoder |
| 437 | |
| 438 | |
| 439 | def _ModifiedEncoder(wire_type, encode_value, compute_value_size, modify_value): |
| 440 | """Like SimpleEncoder but additionally invokes modify_value on every value |
| 441 | before passing it to encode_value. Usually modify_value is ZigZagEncode.""" |
| 442 | |
| 443 | def SpecificEncoder(field_number, is_repeated, is_packed): |
| 444 | if is_packed: |
| 445 | tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED) |
| 446 | local_EncodeVarint = _EncodeVarint |
| 447 | def EncodePackedField(write, value): |
| 448 | write(tag_bytes) |
| 449 | size = 0 |
| 450 | for element in value: |
| 451 | size += compute_value_size(modify_value(element)) |
| 452 | local_EncodeVarint(write, size) |
| 453 | for element in value: |
| 454 | encode_value(write, modify_value(element)) |
| 455 | return EncodePackedField |
| 456 | elif is_repeated: |
| 457 | tag_bytes = TagBytes(field_number, wire_type) |
| 458 | def EncodeRepeatedField(write, value): |
| 459 | for element in value: |
| 460 | write(tag_bytes) |
| 461 | encode_value(write, modify_value(element)) |
| 462 | return EncodeRepeatedField |
| 463 | else: |
| 464 | tag_bytes = TagBytes(field_number, wire_type) |
| 465 | def EncodeField(write, value): |
| 466 | write(tag_bytes) |
| 467 | return encode_value(write, modify_value(value)) |
| 468 | return EncodeField |
| 469 | |
| 470 | return SpecificEncoder |
| 471 | |
| 472 | |
| 473 | def _StructPackEncoder(wire_type, format): |
| 474 | """Return a constructor for an encoder for a fixed-width field. |
| 475 | |
| 476 | Args: |
| 477 | wire_type: The field's wire type, for encoding tags. |
| 478 | format: The format string to pass to struct.pack(). |
| 479 | """ |
| 480 | |
| 481 | value_size = struct.calcsize(format) |
| 482 | |
| 483 | def SpecificEncoder(field_number, is_repeated, is_packed): |
| 484 | local_struct_pack = struct.pack |
| 485 | if is_packed: |
| 486 | tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED) |
| 487 | local_EncodeVarint = _EncodeVarint |
| 488 | def EncodePackedField(write, value): |
| 489 | write(tag_bytes) |
| 490 | local_EncodeVarint(write, len(value) * value_size) |
| 491 | for element in value: |
| 492 | write(local_struct_pack(format, element)) |
| 493 | return EncodePackedField |
| 494 | elif is_repeated: |
| 495 | tag_bytes = TagBytes(field_number, wire_type) |
| 496 | def EncodeRepeatedField(write, value): |
| 497 | for element in value: |
| 498 | write(tag_bytes) |
| 499 | write(local_struct_pack(format, element)) |
| 500 | return EncodeRepeatedField |
| 501 | else: |
| 502 | tag_bytes = TagBytes(field_number, wire_type) |
| 503 | def EncodeField(write, value): |
| 504 | write(tag_bytes) |
| 505 | return write(local_struct_pack(format, value)) |
| 506 | return EncodeField |
| 507 | |
| 508 | return SpecificEncoder |
| 509 | |
| 510 | |
liujisi@google.com | 33165fe | 2010-11-02 13:14:58 +0000 | [diff] [blame^] | 511 | def _FloatingPointEncoder(wire_type, format): |
| 512 | """Return a constructor for an encoder for float fields. |
| 513 | |
| 514 | This is like StructPackEncoder, but catches errors that may be due to |
| 515 | passing non-finite floating-point values to struct.pack, and makes a |
| 516 | second attempt to encode those values. |
| 517 | |
| 518 | Args: |
| 519 | wire_type: The field's wire type, for encoding tags. |
| 520 | format: The format string to pass to struct.pack(). |
| 521 | """ |
| 522 | |
| 523 | value_size = struct.calcsize(format) |
| 524 | if value_size == 4: |
| 525 | def EncodeNonFiniteOrRaise(write, value): |
| 526 | # Remember that the serialized form uses little-endian byte order. |
| 527 | if value == _POS_INF: |
| 528 | write('\x00\x00\x80\x7F') |
| 529 | elif value == _NEG_INF: |
| 530 | write('\x00\x00\x80\xFF') |
| 531 | elif value != value: # NaN |
| 532 | write('\x00\x00\xC0\x7F') |
| 533 | else: |
| 534 | raise |
| 535 | elif value_size == 8: |
| 536 | def EncodeNonFiniteOrRaise(write, value): |
| 537 | if value == _POS_INF: |
| 538 | write('\x00\x00\x00\x00\x00\x00\xF0\x7F') |
| 539 | elif value == _NEG_INF: |
| 540 | write('\x00\x00\x00\x00\x00\x00\xF0\xFF') |
| 541 | elif value != value: # NaN |
| 542 | write('\x00\x00\x00\x00\x00\x00\xF8\x7F') |
| 543 | else: |
| 544 | raise |
| 545 | else: |
| 546 | raise ValueError('Can\'t encode floating-point values that are ' |
| 547 | '%d bytes long (only 4 or 8)' % value_size) |
| 548 | |
| 549 | def SpecificEncoder(field_number, is_repeated, is_packed): |
| 550 | local_struct_pack = struct.pack |
| 551 | if is_packed: |
| 552 | tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED) |
| 553 | local_EncodeVarint = _EncodeVarint |
| 554 | def EncodePackedField(write, value): |
| 555 | write(tag_bytes) |
| 556 | local_EncodeVarint(write, len(value) * value_size) |
| 557 | for element in value: |
| 558 | # This try/except block is going to be faster than any code that |
| 559 | # we could write to check whether element is finite. |
| 560 | try: |
| 561 | write(local_struct_pack(format, element)) |
| 562 | except SystemError: |
| 563 | EncodeNonFiniteOrRaise(write, element) |
| 564 | return EncodePackedField |
| 565 | elif is_repeated: |
| 566 | tag_bytes = TagBytes(field_number, wire_type) |
| 567 | def EncodeRepeatedField(write, value): |
| 568 | for element in value: |
| 569 | write(tag_bytes) |
| 570 | try: |
| 571 | write(local_struct_pack(format, element)) |
| 572 | except SystemError: |
| 573 | EncodeNonFiniteOrRaise(write, element) |
| 574 | return EncodeRepeatedField |
| 575 | else: |
| 576 | tag_bytes = TagBytes(field_number, wire_type) |
| 577 | def EncodeField(write, value): |
| 578 | write(tag_bytes) |
| 579 | try: |
| 580 | write(local_struct_pack(format, value)) |
| 581 | except SystemError: |
| 582 | EncodeNonFiniteOrRaise(write, value) |
| 583 | return EncodeField |
| 584 | |
| 585 | return SpecificEncoder |
| 586 | |
| 587 | |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 588 | # ==================================================================== |
| 589 | # Here we declare an encoder constructor for each field type. These work |
| 590 | # very similarly to sizer constructors, described earlier. |
| 591 | |
| 592 | |
| 593 | Int32Encoder = Int64Encoder = EnumEncoder = _SimpleEncoder( |
| 594 | wire_format.WIRETYPE_VARINT, _EncodeSignedVarint, _SignedVarintSize) |
| 595 | |
| 596 | UInt32Encoder = UInt64Encoder = _SimpleEncoder( |
| 597 | wire_format.WIRETYPE_VARINT, _EncodeVarint, _VarintSize) |
| 598 | |
| 599 | SInt32Encoder = SInt64Encoder = _ModifiedEncoder( |
| 600 | wire_format.WIRETYPE_VARINT, _EncodeVarint, _VarintSize, |
| 601 | wire_format.ZigZagEncode) |
| 602 | |
| 603 | # Note that Python conveniently guarantees that when using the '<' prefix on |
| 604 | # formats, they will also have the same size across all platforms (as opposed |
| 605 | # to without the prefix, where their sizes depend on the C compiler's basic |
| 606 | # type sizes). |
| 607 | Fixed32Encoder = _StructPackEncoder(wire_format.WIRETYPE_FIXED32, '<I') |
| 608 | Fixed64Encoder = _StructPackEncoder(wire_format.WIRETYPE_FIXED64, '<Q') |
| 609 | SFixed32Encoder = _StructPackEncoder(wire_format.WIRETYPE_FIXED32, '<i') |
| 610 | SFixed64Encoder = _StructPackEncoder(wire_format.WIRETYPE_FIXED64, '<q') |
liujisi@google.com | 33165fe | 2010-11-02 13:14:58 +0000 | [diff] [blame^] | 611 | FloatEncoder = _FloatingPointEncoder(wire_format.WIRETYPE_FIXED32, '<f') |
| 612 | DoubleEncoder = _FloatingPointEncoder(wire_format.WIRETYPE_FIXED64, '<d') |
kenton@google.com | fccb146 | 2009-12-18 02:11:36 +0000 | [diff] [blame] | 613 | |
| 614 | |
| 615 | def BoolEncoder(field_number, is_repeated, is_packed): |
| 616 | """Returns an encoder for a boolean field.""" |
| 617 | |
| 618 | false_byte = chr(0) |
| 619 | true_byte = chr(1) |
| 620 | if is_packed: |
| 621 | tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED) |
| 622 | local_EncodeVarint = _EncodeVarint |
| 623 | def EncodePackedField(write, value): |
| 624 | write(tag_bytes) |
| 625 | local_EncodeVarint(write, len(value)) |
| 626 | for element in value: |
| 627 | if element: |
| 628 | write(true_byte) |
| 629 | else: |
| 630 | write(false_byte) |
| 631 | return EncodePackedField |
| 632 | elif is_repeated: |
| 633 | tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_VARINT) |
| 634 | def EncodeRepeatedField(write, value): |
| 635 | for element in value: |
| 636 | write(tag_bytes) |
| 637 | if element: |
| 638 | write(true_byte) |
| 639 | else: |
| 640 | write(false_byte) |
| 641 | return EncodeRepeatedField |
| 642 | else: |
| 643 | tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_VARINT) |
| 644 | def EncodeField(write, value): |
| 645 | write(tag_bytes) |
| 646 | if value: |
| 647 | return write(true_byte) |
| 648 | return write(false_byte) |
| 649 | return EncodeField |
| 650 | |
| 651 | |
| 652 | def StringEncoder(field_number, is_repeated, is_packed): |
| 653 | """Returns an encoder for a string field.""" |
| 654 | |
| 655 | tag = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED) |
| 656 | local_EncodeVarint = _EncodeVarint |
| 657 | local_len = len |
| 658 | assert not is_packed |
| 659 | if is_repeated: |
| 660 | def EncodeRepeatedField(write, value): |
| 661 | for element in value: |
| 662 | encoded = element.encode('utf-8') |
| 663 | write(tag) |
| 664 | local_EncodeVarint(write, local_len(encoded)) |
| 665 | write(encoded) |
| 666 | return EncodeRepeatedField |
| 667 | else: |
| 668 | def EncodeField(write, value): |
| 669 | encoded = value.encode('utf-8') |
| 670 | write(tag) |
| 671 | local_EncodeVarint(write, local_len(encoded)) |
| 672 | return write(encoded) |
| 673 | return EncodeField |
| 674 | |
| 675 | |
| 676 | def BytesEncoder(field_number, is_repeated, is_packed): |
| 677 | """Returns an encoder for a bytes field.""" |
| 678 | |
| 679 | tag = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED) |
| 680 | local_EncodeVarint = _EncodeVarint |
| 681 | local_len = len |
| 682 | assert not is_packed |
| 683 | if is_repeated: |
| 684 | def EncodeRepeatedField(write, value): |
| 685 | for element in value: |
| 686 | write(tag) |
| 687 | local_EncodeVarint(write, local_len(element)) |
| 688 | write(element) |
| 689 | return EncodeRepeatedField |
| 690 | else: |
| 691 | def EncodeField(write, value): |
| 692 | write(tag) |
| 693 | local_EncodeVarint(write, local_len(value)) |
| 694 | return write(value) |
| 695 | return EncodeField |
| 696 | |
| 697 | |
| 698 | def GroupEncoder(field_number, is_repeated, is_packed): |
| 699 | """Returns an encoder for a group field.""" |
| 700 | |
| 701 | start_tag = TagBytes(field_number, wire_format.WIRETYPE_START_GROUP) |
| 702 | end_tag = TagBytes(field_number, wire_format.WIRETYPE_END_GROUP) |
| 703 | assert not is_packed |
| 704 | if is_repeated: |
| 705 | def EncodeRepeatedField(write, value): |
| 706 | for element in value: |
| 707 | write(start_tag) |
| 708 | element._InternalSerialize(write) |
| 709 | write(end_tag) |
| 710 | return EncodeRepeatedField |
| 711 | else: |
| 712 | def EncodeField(write, value): |
| 713 | write(start_tag) |
| 714 | value._InternalSerialize(write) |
| 715 | return write(end_tag) |
| 716 | return EncodeField |
| 717 | |
| 718 | |
| 719 | def MessageEncoder(field_number, is_repeated, is_packed): |
| 720 | """Returns an encoder for a message field.""" |
| 721 | |
| 722 | tag = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED) |
| 723 | local_EncodeVarint = _EncodeVarint |
| 724 | assert not is_packed |
| 725 | if is_repeated: |
| 726 | def EncodeRepeatedField(write, value): |
| 727 | for element in value: |
| 728 | write(tag) |
| 729 | local_EncodeVarint(write, element.ByteSize()) |
| 730 | element._InternalSerialize(write) |
| 731 | return EncodeRepeatedField |
| 732 | else: |
| 733 | def EncodeField(write, value): |
| 734 | write(tag) |
| 735 | local_EncodeVarint(write, value.ByteSize()) |
| 736 | return value._InternalSerialize(write) |
| 737 | return EncodeField |
| 738 | |
| 739 | |
| 740 | # -------------------------------------------------------------------- |
| 741 | # As before, MessageSet is special. |
| 742 | |
| 743 | |
| 744 | def MessageSetItemEncoder(field_number): |
| 745 | """Encoder for extensions of MessageSet. |
| 746 | |
| 747 | The message set message looks like this: |
| 748 | message MessageSet { |
| 749 | repeated group Item = 1 { |
| 750 | required int32 type_id = 2; |
| 751 | required string message = 3; |
| 752 | } |
| 753 | } |
| 754 | """ |
| 755 | start_bytes = "".join([ |
| 756 | TagBytes(1, wire_format.WIRETYPE_START_GROUP), |
| 757 | TagBytes(2, wire_format.WIRETYPE_VARINT), |
| 758 | _VarintBytes(field_number), |
| 759 | TagBytes(3, wire_format.WIRETYPE_LENGTH_DELIMITED)]) |
| 760 | end_bytes = TagBytes(1, wire_format.WIRETYPE_END_GROUP) |
| 761 | local_EncodeVarint = _EncodeVarint |
| 762 | |
| 763 | def EncodeField(write, value): |
| 764 | write(start_bytes) |
| 765 | local_EncodeVarint(write, value.ByteSize()) |
| 766 | value._InternalSerialize(write) |
| 767 | return write(end_bytes) |
| 768 | |
| 769 | return EncodeField |