A stress test for your PGN reader

[sje]

How long of a valid PGN move text can your program load? Here's a random, drawn by insufficient material, 974 ply PGN move text output from Symbolic's test generator:

Code: Select all

1 Nf3 g5 2 Ng1 a6 3 f4 e5 4 g3 f5 5 h4 gxf4 6 d3 h6 7 e4 Kf7 8 Nd2 c5 9 gxf4 Qe7 10 c4 Nc6 11 b3 d5
12 Qc2 Be6 13 a3 h5 14 Be2 Ra7 15 Bd1 Kf6 16 Qb1 Nd8 17 fxe5+ Kg6 18 Ke2 Bf7 19 Ndf3 Qd6 20 Nd2 Kg7
21 Bb2 Qd7 22 Bc1 Kh6 23 exd5 Nc6 24 Nf1+ Kg6 25 Qc2 b5 26 Qa2 Nd4+ 27 Kd2 Qc7 28 a4 Ne6 29 Bxh5+
Kg7 30 Qc2 b4 31 Rb1 Bd6 32 Nh2 Qd7 33 Ng4 Nc7 34 Bxf7 Rh5 35 Bxh5 Nh6 36 Nf3 Qb5 37 Qd1 Kg8 38 Ng1
Qd7 39 Qf3 f4 40 Ke2 Ne8 41 Bxf4 Qg7 42 Qe3 Bf8 43 Ke1 Be7 44 e6 Qxg4 45 Bg5 Qxg5 46 Qe5 Qg2 47 d6
Qe4+ 48 dxe4 Nf7 49 Kf2 Bd8 50 Be2 a5 51 Ra1 Rc7 52 Qd4 Rc8 53 Qd3 Ng5 54 Qd5 Nxe6 55 Qg5+ Kh8 56
Qe7 Ra8 57 Ke1 Bxe7 58 Bh5 Nf4 59 Ne2 Nh3 60 Rh2 Nc7 61 e5 Kh7 62 Nd4 Nd5 63 Nf5 Ng1 64 Be8 Bg5 65
Ng3 Kg7 66 Rh3 Kh6 67 Ra2 Ra6 68 e6 Ne7 69 h5 Ng6 70 Bd7 Nh4 71 e7 Ng6 72 Bf5 Ra7 73 e8=Q Kh7 74
Qe5 Kg8 75 Ra1 Ne2 76 Bc8 Bc1 77 Qf4 Rd7 78 Ne4 Ba3 79 Qf6 Nf8 80 Nd2 Bc1 81 Qf1 Rh7 82 Nb1 Ng1 83
Qf4 Ra7 84 Qg5+ Rg7 85 Rf3 Ng6 86 h6 Ra7 87 Bg4 Ra8 88 Rf7 Rb8 89 d7 Rb6 90 Qxg6+ Kh8 91 Qh5 Bb2 92
Bd1 Rb8 93 Be2 Rb6 94 Rf1 Nf3+ 95 Rxf3 Rg6 96 Rd3 Ba3 97 Rd5 Rb6 98 Qf3 Rb5 99 Qf7 Bb2 100 Nd2 Bf6
101 Bf3 Bd8 102 Qh7+ Kxh7 103 Rd3 Kh8 104 Bd5 Bb6 105 Kf1 Kh7 106 Ra2 Ba7 107 Rf3 Rb7 108 d8=Q Bb8
109 Rf4 Rb6 110 Be4+ Rg6 111 Qf8 Be5 112 Bb7 Rf6 113 Rxf6 Bb2 114 Bd5 Bc3 115 Rb6 Bxd2 116 Rb5 Bc3
117 Qxc5 Bf6 118 Bf3 Bd8 119 Qc8 Kg6 120 Qb7 Bb6 121 Rc5 Kf6 122 Be2 Ke6 123 h7 Bd8 124 Kg2 Kd6 125
Qa6+ Ke7 126 Rg5 Kf7 127 Rxa5 Bc7 128 Bf3 Bh2 129 Kh3 Bc7 130 Be2 Bb8 131 Rg5 Bg3 132 Bf1 Bb8 133
Rd5 Bf4 134 Rb2 Bh6 135 Rd6 Bf8 136 Rd7+ Ke8 137 Kg3 Be7 138 Rdd2 Kf7 139 Qa5 Ke8 140 Rd7 Kf8 141
Rc2 Kg7 142 Rd6 Bf8 143 Qh5 Bxd6+ 144 Kg4 Bc7 145 h8=N Kf8 146 Ng6+ Kg8 147 Be2 Bd8 148 Ne5 Bb6 149
c5 Bd8 150 Rc1 Ba5 151 Kf4 Bc7 152 Rd1 Bxe5+ 153 Kxe5 Kf8 154 Bf3 Kg7 155 Qf7+ Kh6 156 Kd6 Kg5 157
Qg8+ Kf6 158 Ra1 Kf5 159 Qf7+ Kg5 160 Be4 Kh6 161 Qh7+ Kg5 162 Rb1 Kf4 163 Qh5 Kg3 164 Qe2 Kh4 165
Rd1 Kg3 166 Bf3 Kh4 167 Rg1 Kh3 168 Qe1 Kh2 169 Bd1 Kh3 170 Qc3+ Kh2 171 Qc2+ Kxg1 172 Qg2+ Kxg2
173 Bh5 Kh1 174 Kc6 Kg2 175 Bd1 Kg3 176 Bc2 Kg2 177 Bd1 Kh1 178 Kd6 Kg2 179 c6 Kf2 180 Bc2 Ke3 181
Ke6 Kf2 182 Kf6 Kf1 183 a5 Kg2 184 Bf5 Kf3 185 Ke5 Kg2 186 Kd4 Kg3 187 Bc2 Kg4 188 Kd5 Kh3 189 Bh7
Kh2 190 Bd3 Kg2 191 Bc4 Kf3 192 Ba6 Kg4 193 Bc8+ Kg3 194 Ke6 Kg2 195 Kf7 Kg3 196 Ke8 Kh4 197 Be6
Kg3 198 Bh3 Kh2 199 Be6 Kg2 200 Kf7 Kh2 201 Bd7 Kg2 202 Bc8 Kf2 203 Bb7 Kg1 204 c7 Kh2 205 Bg2 Kg1
206 Bf3 Kf1 207 Bg2+ Ke1 208 Kg6 Kd1 209 c8=R Ke1 210 Rg8 Kd1 211 Rb8 Kc1 212 Bc6 Kd1 213 Kf7 Ke1
214 Kg6 Ke2 215 Rb7 Ke3 216 Rb6 Kd3 217 Kg5 Kd4 218 Kh6 Ke5 219 Bg2 Kf5 220 Bd5 Ke5 221 Ra6 Kf5 222
Re6 Kg4 223 Re5 Kg3 224 Rh5 Kf4 225 Kh7 Ke3 226 Bg8 Kf4 227 Rh2 Kf5 228 Kg7 Kg5 229 Rh4 Kxh4 230 a6
Kg4 231 Kh8 Kg3 232 Bh7 Kh3 233 Bc2 Kg2 234 Bg6 Kg1 235 Kg8 Kh2 236 Bb1 Kh1 237 Bc2 Kh2 238 Kh8 Kg1
239 a7 Kf2 240 Kh7 Ke1 241 Bf5 Kf1 242 a8=N Kg2 243 Bc2 Kf3 244 Bf5 Kf4 245 Be4 Kg4 246 Kh6 Kg3 247
Kg6 Kh2 248 Bh1 Kg3 249 Kg5 Kh3 250 Kf5 Kh4 251 Ke5 Kh5 252 Bg2 Kg6 253 Nc7 Kg5 254 Bc6 Kh4 255 Kd4
Kh3 256 Bb7 Kh4 257 Be4 Kh3 258 Bd5 Kg3 259 Bc4 Kh4 260 Nd5 Kg5 261 Ke3 Kh6 262 Kd4 Kg7 263 Ba6 Kh7
264 Bf1 Kg8 265 Bb5 Kf7 266 Ke5 Kg8 267 Nf4 Kg7 268 Ke6 Kh7 269 Kf5 Kg7 270 Ne2 Kh8 271 Ba4 Kg7 272
Kg4 Kh6 273 Kh4 Kg7 274 Nf4 Kf6 275 Nd3 Kg6 276 Nxb4 Kf5 277 Na2 Kf6 278 Nc1 Ke5 279 Kh5 Kf5 280
Kh6 Ke5 281 Be8 Kf5 282 Kh7 Kf6 283 Nd3 Kf5 284 Nb2 Ke4 285 Bd7 Ke5 286 Kg8 Ke4 287 Be6 Kf4 288 Kf7
Kg3 289 Bf5 Kh4 290 Bh7 Kg3 291 Nd3 Kh3 292 Kf8 Kh4 293 Nb4 Kh3 294 Nc6 Kg2 295 Bg8 Kh2 296 Ke8 Kg2
297 Kd8 Kg3 298 Ke8 Kh4 299 b4 Kh5 300 Kf8 Kg5 301 Nd8 Kg4 302 Kg7 Kf5 303 Kf8 Ke4 304 Nc6 Kd3 305
Bc4+ Kc2 306 Kg8 Kb2 307 Bb5 Kc2 308 Kh7 Kc1 309 Na7 Kd1 310 Bd3 Kc1 311 Nb5 Kd2 312 Bc2 Ke3 313
Kg6 Kf3 314 Na3 Kg3 315 Ba4 Kg2 316 Kg5 Kg3 317 Bc6 Kf2 318 Kg6 Ke1 319 Kh5 Ke2 320 Bb5+ Ke3 321
Be8 Ke4 322 Bb5 Kf5 323 Nc2 Kf6 324 Ba6 Ke5 325 Na3 Ke4 326 Bc4 Kf4 327 Bd3 Kg3 328 Kg5 Kg2 329 Nc2
Kf3 330 Kf5 Kg2 331 Nd4 Kf2 332 Ke6 Kg3 333 Kd7 Kh4 334 Bh7 Kg5 335 Ke7 Kg4 336 Bd3 Kg5 337 Ne6+
Kh5 338 Bf1 Kg6 339 Kd7 Kf6 340 Kc8 Ke7 341 Nc5 Kd6 342 Bh3 Ke5 343 Ne6 Kf6 344 Kc7 Kg6 345 Kd6 Kf7
346 Kc6 Kg6 347 b5 Kf6 348 Kc7 Ke7 349 Nf8 Kf6 350 Kb8 Kg5 351 Ka8 Kh5 352 Ne6 Kh6 353 Nf4 Kg5 354
Bd7 Kf6 355 Bc8 Kg5 356 Nd5 Kh5 357 Kb8 Kg6 358 Kc7 Kg7 359 Bb7 Kf7 360 Ne3 Ke6 361 Nc4 Kf6 362 Bc6
Kg5 363 Bd7 Kg6 364 Bc6 Kh6 365 Ne3 Kh7 366 Kc8 Kh8 367 Bd5 Kg7 368 Bc4 Kf6 369 Nc2 Kg5 370 Kb8 Kh4
371 Be6 Kg5 372 Ne1 Kh6 373 Bg8 Kg6 374 Be6 Kh5 375 b6 Kg5 376 Ka8 Kh5 377 Kb7 Kh6 378 Bg4 Kg6 379
Bh5+ Kf5 380 Ka7 Ke5 381 Nd3+ Kf5 382 Ka6 Ke4 383 Kb5 Kf5 384 Kc5 Ke4 385 Be2 Kf5 386 Kd6 Ke4 387
Ne1 Kf4 388 Bb5 Kf5 389 Be8 Ke4 390 Ba4 Ke3 391 Kd5 Kf4 392 Bc2 Ke3 393 Kd6 Kd2 394 Bd1 Ke3 395
Ng2+ Kd2 396 Ba4 Kc3 397 Ne1 Kb2 398 Nf3 Kc1 399 Bd7 Kb1 400 Kc5 Ka1 401 Ba4 Ka2 402 Kd5 Kb2 403
Ke4 Kb1 404 Nh4 Ka2 405 Kd3 Kb1 406 Kc4 Kc1 407 Kd3 Kb2 408 Bc2 Ka1 409 Kc3 Ka2 410 Kc4 Kb2 411 Bg6
Kc1 412 Kc3 Kd1 413 Bc2+ Ke2 414 Bb1 Ke3 415 Bg6 Ke2 416 b7 Kf2 417 Bc2 Kg3 418 Bf5 Kh2 419 Kc2 Kg1
420 Kb2 Kf1 421 Nf3 Kf2 422 Bh3 Kxf3 423 Kb3 Kg3 424 Ka3 Kf2 425 Bd7 Kg3 426 b8=Q+ Kg2 427 Qc7 Kf1
428 Qc6 Kg1 429 Be6 Kf1 430 Bh3+ Kf2 431 Bd7 Ke3 432 Bg4 Kd2 433 Qd7+ Kc2 434 Qc6+ Kd3 435 Bf5+ Ke2
436 Qc1 Kf3 437 Ka4 Kg3 438 Qa1 Kg2 439 Qg7+ Kf2 440 Qh7 Ke1 441 Kb5 Kf2 442 Bd3 Ke3 443 Qb7 Kf4
444 Kc6 Kg5 445 Bg6 Kf6 446 Kd6 Kxg6 447 Ke7 Kf5 448 Ke8 Kg5 449 Ke7 Kf4 450 Ke8 Kg3 451 Kf8 Kg4
452 Qa8 Kh5 453 Ke8 Kh6 454 Qe4 Kg5 455 Qg2+ Kf6 456 Qa2 Kg7 457 Qh2 Kg6 458 Qh5+ Kg7 459 Qc5 Kf6
460 Qc4 Kg7 461 Qb3 Kh7 462 Qd1 Kh6 463 Kd8 Kg6 464 Qa1 Kf5 465 Qb1+ Kg5 466 Qc2 Kg4 467 Qf2 Kg5
468 Qb2 Kf4 469 Qe2 Kf5 470 Kc7 Kf4 471 Qa6 Kg3 472 Qe6 Kf2 473 Qd5 Kg3 474 Qd4 Kg2 475 Qe5 Kf1 476
Qa1+ Kf2 477 Qd4+ Ke2 478 Kc6 Ke1 479 Qc4 Kd1 480 Qb5 Kd2 481 Qb4+ Ke2 482 Qb3 Ke1 483 Kc7 Kd2 484
Qa2+ Kd1 485 Qb1+ Ke2 486 Kb7 Ke3 487 Qd3+ Kxd3 1/2-1/2

Your program should detect the draw after the last move and not before.

[sje]

After 5,000,000+ random games, a 1,063 ply new longest example has appeared. I'll let the test generator run for a few days to see if an even longer game will show up.

Some three decades ago when I wrote my first C language chess program, I set its game length limit to 200 full moves. I justified this at the time as the limit was big enough to cover nearly every practical game. But in truth, I was just lazy. Allocating a large but fixed length wastes space nearly always, and the program will still break if the limit is exceeded.

Today, with C++ and its standard library templates, there's no excuse to have arbitrary fixed limits for data structures with an indefinite element count. And if you're not wholly pleased with some of the standard templates, you can write replacements as I have.

[bob]

After 5,000,000+ random games, a 1,063 ply new longest example has appeared. I'll let the test generator run for a few days to see if an even longer game will show up.

Some three decades ago when I wrote my first C language chess program, I set its game length limit to 200 full moves. I justified this at the time as the limit was big enough to cover nearly every practical game. But in truth, I was just lazy. Allocating a large but fixed length wastes space nearly always, and the program will still break if the limit is exceeded.

Today, with C++ and its standard library templates, there's no excuse to have arbitrary fixed limits for data structures with an indefinite element count. And if you're not wholly pleased with some of the standard templates, you can write replacements as I have.

That's a trivial test. I had a game in my old enormous.pgn that had comments nested 17 levels deep.. THAT was a PGN reader stress test...

[mvk]

Some three decades ago when I wrote my first C language chess program, I set its game length limit to 200 full moves. I justified this at the time as the limit was big enough to cover nearly every practical game. But in truth, I was just lazy. Allocating a large but fixed length wastes space nearly always, and the program will still break if the limit is exceeded.

Today, with C++ and its standard library templates, there's no excuse to have arbitrary fixed limits for data structures with an indefinite element count. And if you're not wholly pleased with some of the standard templates, you can write replacements as I have.

Why not use realloc() to solve your C programming problem?

[sje]

Why not use realloc() to solve your C programming problem?

Because realloc() can move previously written data.

[mvk]

Why not use realloc() to solve your C programming problem?

Because realloc() can move previously written data.

Why is that an issue for a move list?

[bob]

Why not use realloc() to solve your C programming problem?

Because realloc() can move previously written data.

Why is that an issue for a move list?

Pointers to existing data?

That are now wrong...

[mvk]

Why not use realloc() to solve your C programming problem?

Because realloc() can move previously written data.

Why is that an issue for a move list?

Pointers to existing data?

That are now wrong...

So update them after realloc, or recalculate them whenever needed (i.e. keep indexes instead of pre-calculated pointers deep into the data structure's guts).

I mean, this is not a C problem, but a problem of a linear address space.

[sje]

US General George S. Patton once said:

I don't want to pay twice for the same real estate.

Think about it.

[mvk]

US General George S. Patton once said:

I don't want to pay twice for the same real estate.

Think about it.

The authors of pgn-extract use C and realloc BTW. They must have it all wrong.