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| 1 // Copyright 2011 Google Inc. All Rights Reserved. | |
| 2 // Copyright 1996 John Maloney and Mario Wolczko | |
| 3 // | |
| 4 // This file is part of GNU Smalltalk. | |
| 5 // | |
| 6 // GNU Smalltalk is free software; you can redistribute it and/or modify it | |
| 7 // under the terms of the GNU General Public License as published by the Free | |
| 8 // Software Foundation; either version 2, or (at your option) any later version. | |
| 9 // | |
| 10 // GNU Smalltalk is distributed in the hope that it will be useful, but WITHOUT | |
| 11 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
| 12 // FOR A PARTICULAR PURPOSE. See the GNU General Public License for more | |
| 13 // details. | |
| 14 // | |
| 15 // You should have received a copy of the GNU General Public License along with | |
| 16 // GNU Smalltalk; see the file COPYING. If not, write to the Free Software | |
| 17 // Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | |
| 18 // | |
| 19 // Translated first from Smalltalk to JavaScript, and finally to | |
| 20 // Dart by Google 2008-2010. | |
| 21 | |
| 22 /** | |
| 23 * A Dart implementation of the DeltaBlue constraint-solving | |
| 24 * algorithm, as described in: | |
| 25 * | |
| 26 * "The DeltaBlue Algorithm: An Incremental Constraint Hierarchy Solver" | |
| 27 * Bjorn N. Freeman-Benson and John Maloney | |
| 28 * January 1990 Communications of the ACM, | |
| 29 * also available as University of Washington TR 89-08-06. | |
| 30 * | |
| 31 * Beware: this benchmark is written in a grotesque style where | |
| 32 * the constraint model is built by side-effects from constructors. | |
| 33 * I've kept it this way to avoid deviating too much from the original | |
| 34 * implementation. | |
| 35 */ | |
| 36 | |
| 37 import "BenchmarkBase.dart"; | |
| 38 | |
| 39 main() { | |
| 40 new DeltaBlue().report(); | |
| 41 } | |
| 42 | |
| 43 /// Benchmark class required to report results. | |
| 44 class DeltaBlue extends BenchmarkBase { | |
| 45 const DeltaBlue() : super("DeltaBlue"); | |
| 46 | |
| 47 void run() { | |
| 48 chainTest(100); | |
| 49 projectionTest(100); | |
| 50 } | |
| 51 } | |
| 52 | |
| 53 /** | |
| 54 * Strengths are used to measure the relative importance of constraints. | |
| 55 * New strengths may be inserted in the strength hierarchy without | |
| 56 * disrupting current constraints. Strengths cannot be created outside | |
| 57 * this class, so == can be used for value comparison. | |
| 58 */ | |
| 59 class Strength { | |
| 60 final int value; | |
| 61 final String name; | |
| 62 | |
| 63 const Strength(this.value, this.name); | |
| 64 | |
| 65 Strength nextWeaker() => const <Strength>[ | |
| 66 STRONG_PREFERRED, | |
| 67 PREFERRED, | |
| 68 STRONG_DEFAULT, | |
| 69 NORMAL, | |
| 70 WEAK_DEFAULT, | |
| 71 WEAKEST | |
| 72 ][value]; | |
| 73 | |
| 74 static bool stronger(Strength s1, Strength s2) { | |
| 75 return s1.value < s2.value; | |
| 76 } | |
| 77 | |
| 78 static bool weaker(Strength s1, Strength s2) { | |
| 79 return s1.value > s2.value; | |
| 80 } | |
| 81 | |
| 82 static Strength weakest(Strength s1, Strength s2) { | |
| 83 return weaker(s1, s2) ? s1 : s2; | |
| 84 } | |
| 85 | |
| 86 static Strength strongest(Strength s1, Strength s2) { | |
| 87 return stronger(s1, s2) ? s1 : s2; | |
| 88 } | |
| 89 } | |
| 90 | |
| 91 // Compile time computed constants. | |
| 92 const REQUIRED = const Strength(0, "required"); | |
| 93 const STRONG_PREFERRED = const Strength(1, "strongPreferred"); | |
| 94 const PREFERRED = const Strength(2, "preferred"); | |
| 95 const STRONG_DEFAULT = const Strength(3, "strongDefault"); | |
| 96 const NORMAL = const Strength(4, "normal"); | |
| 97 const WEAK_DEFAULT = const Strength(5, "weakDefault"); | |
| 98 const WEAKEST = const Strength(6, "weakest"); | |
| 99 | |
| 100 abstract class Constraint { | |
| 101 final Strength strength; | |
| 102 | |
| 103 const Constraint(this.strength); | |
| 104 | |
| 105 bool isSatisfied(); | |
| 106 void markUnsatisfied(); | |
| 107 void addToGraph(); | |
| 108 void removeFromGraph(); | |
| 109 void chooseMethod(int mark); | |
| 110 void markInputs(int mark); | |
| 111 bool inputsKnown(int mark); | |
| 112 Variable output(); | |
| 113 void execute(); | |
| 114 void recalculate(); | |
| 115 | |
| 116 /// Activate this constraint and attempt to satisfy it. | |
| 117 void addConstraint() { | |
| 118 addToGraph(); | |
| 119 planner.incrementalAdd(this); | |
| 120 } | |
| 121 | |
| 122 /** | |
| 123 * Attempt to find a way to enforce this constraint. If successful, | |
| 124 * record the solution, perhaps modifying the current dataflow | |
| 125 * graph. Answer the constraint that this constraint overrides, if | |
| 126 * there is one, or nil, if there isn't. | |
| 127 * Assume: I am not already satisfied. | |
| 128 */ | |
| 129 Constraint satisfy(mark) { | |
| 130 chooseMethod(mark); | |
| 131 if (!isSatisfied()) { | |
| 132 if (strength == REQUIRED) { | |
| 133 print("Could not satisfy a required constraint!"); | |
| 134 } | |
| 135 return null; | |
| 136 } | |
| 137 markInputs(mark); | |
| 138 Variable out = output(); | |
| 139 Constraint overridden = out.determinedBy; | |
| 140 if (overridden != null) overridden.markUnsatisfied(); | |
| 141 out.determinedBy = this; | |
| 142 if (!planner.addPropagate(this, mark)) print("Cycle encountered"); | |
| 143 out.mark = mark; | |
| 144 return overridden; | |
| 145 } | |
| 146 | |
| 147 void destroyConstraint() { | |
| 148 if (isSatisfied()) planner.incrementalRemove(this); | |
| 149 removeFromGraph(); | |
| 150 } | |
| 151 | |
| 152 /** | |
| 153 * Normal constraints are not input constraints. An input constraint | |
| 154 * is one that depends on external state, such as the mouse, the | |
| 155 * keybord, a clock, or some arbitraty piece of imperative code. | |
| 156 */ | |
| 157 bool isInput() => false; | |
| 158 } | |
| 159 | |
| 160 /** | |
| 161 * Abstract superclass for constraints having a single possible output variable. | |
| 162 */ | |
| 163 abstract class UnaryConstraint extends Constraint { | |
| 164 final Variable myOutput; | |
| 165 bool satisfied = false; | |
| 166 | |
| 167 UnaryConstraint(this.myOutput, Strength strength) : super(strength) { | |
| 168 addConstraint(); | |
| 169 } | |
| 170 | |
| 171 /// Adds this constraint to the constraint graph | |
| 172 void addToGraph() { | |
| 173 myOutput.addConstraint(this); | |
| 174 satisfied = false; | |
| 175 } | |
| 176 | |
| 177 /// Decides if this constraint can be satisfied and records that decision. | |
| 178 void chooseMethod(int mark) { | |
| 179 satisfied = (myOutput.mark != mark) && | |
| 180 Strength.stronger(strength, myOutput.walkStrength); | |
| 181 } | |
| 182 | |
| 183 /// Returns true if this constraint is satisfied in the current solution. | |
| 184 bool isSatisfied() => satisfied; | |
| 185 | |
| 186 void markInputs(int mark) { | |
| 187 // has no inputs. | |
| 188 } | |
| 189 | |
| 190 /// Returns the current output variable. | |
| 191 Variable output() => myOutput; | |
| 192 | |
| 193 /** | |
| 194 * Calculate the walkabout strength, the stay flag, and, if it is | |
| 195 * 'stay', the value for the current output of this constraint. Assume | |
| 196 * this constraint is satisfied. | |
| 197 */ | |
| 198 void recalculate() { | |
| 199 myOutput.walkStrength = strength; | |
| 200 myOutput.stay = !isInput(); | |
| 201 if (myOutput.stay) execute(); // Stay optimization. | |
| 202 } | |
| 203 | |
| 204 /// Records that this constraint is unsatisfied. | |
| 205 void markUnsatisfied() { | |
| 206 satisfied = false; | |
| 207 } | |
| 208 | |
| 209 bool inputsKnown(int mark) => true; | |
| 210 | |
| 211 void removeFromGraph() { | |
| 212 if (myOutput != null) myOutput.removeConstraint(this); | |
| 213 satisfied = false; | |
| 214 } | |
| 215 } | |
| 216 | |
| 217 /** | |
| 218 * Variables that should, with some level of preference, stay the same. | |
| 219 * Planners may exploit the fact that instances, if satisfied, will not | |
| 220 * change their output during plan execution. This is called "stay | |
| 221 * optimization". | |
| 222 */ | |
| 223 class StayConstraint extends UnaryConstraint { | |
| 224 StayConstraint(Variable v, Strength str) : super(v, str); | |
| 225 | |
| 226 void execute() { | |
| 227 // Stay constraints do nothing. | |
| 228 } | |
| 229 } | |
| 230 | |
| 231 /** | |
| 232 * A unary input constraint used to mark a variable that the client | |
| 233 * wishes to change. | |
| 234 */ | |
| 235 class EditConstraint extends UnaryConstraint { | |
| 236 EditConstraint(Variable v, Strength str) : super(v, str); | |
| 237 | |
| 238 /// Edits indicate that a variable is to be changed by imperative code. | |
| 239 bool isInput() => true; | |
| 240 | |
| 241 void execute() { | |
| 242 // Edit constraints do nothing. | |
| 243 } | |
| 244 } | |
| 245 | |
| 246 // Directions. | |
| 247 const int NONE = 1; | |
| 248 const int FORWARD = 2; | |
| 249 const int BACKWARD = 0; | |
| 250 | |
| 251 /** | |
| 252 * Abstract superclass for constraints having two possible output | |
| 253 * variables. | |
| 254 */ | |
| 255 abstract class BinaryConstraint extends Constraint { | |
| 256 Variable v1; | |
| 257 Variable v2; | |
| 258 int direction = NONE; | |
| 259 | |
| 260 BinaryConstraint(this.v1, this.v2, Strength strength) : super(strength) { | |
| 261 addConstraint(); | |
| 262 } | |
| 263 | |
| 264 /** | |
| 265 * Decides if this constraint can be satisfied and which way it | |
| 266 * should flow based on the relative strength of the variables related, | |
| 267 * and record that decision. | |
| 268 */ | |
| 269 void chooseMethod(int mark) { | |
| 270 if (v1.mark == mark) { | |
| 271 direction = (v2.mark != mark && | |
| 272 Strength.stronger(strength, v2.walkStrength)) ? FORWARD : NONE; | |
| 273 } | |
| 274 if (v2.mark == mark) { | |
| 275 direction = (v1.mark != mark && | |
| 276 Strength.stronger(strength, v1.walkStrength)) ? BACKWARD : NONE; | |
| 277 } | |
| 278 if (Strength.weaker(v1.walkStrength, v2.walkStrength)) { | |
| 279 direction = | |
| 280 Strength.stronger(strength, v1.walkStrength) ? BACKWARD : NONE; | |
| 281 } else { | |
| 282 direction = | |
| 283 Strength.stronger(strength, v2.walkStrength) ? FORWARD : BACKWARD; | |
| 284 } | |
| 285 } | |
| 286 | |
| 287 /// Add this constraint to the constraint graph. | |
| 288 void addToGraph() { | |
| 289 v1.addConstraint(this); | |
| 290 v2.addConstraint(this); | |
| 291 direction = NONE; | |
| 292 } | |
| 293 | |
| 294 /// Answer true if this constraint is satisfied in the current solution. | |
| 295 bool isSatisfied() => direction != NONE; | |
| 296 | |
| 297 /// Mark the input variable with the given mark. | |
| 298 void markInputs(int mark) { | |
| 299 input().mark = mark; | |
| 300 } | |
| 301 | |
| 302 /// Returns the current input variable | |
| 303 Variable input() => direction == FORWARD ? v1 : v2; | |
| 304 | |
| 305 /// Returns the current output variable. | |
| 306 Variable output() => direction == FORWARD ? v2 : v1; | |
| 307 | |
| 308 /** | |
| 309 * Calculate the walkabout strength, the stay flag, and, if it is | |
| 310 * 'stay', the value for the current output of this | |
| 311 * constraint. Assume this constraint is satisfied. | |
| 312 */ | |
| 313 void recalculate() { | |
| 314 Variable ihn = input(), | |
| 315 out = output(); | |
| 316 out.walkStrength = Strength.weakest(strength, ihn.walkStrength); | |
| 317 out.stay = ihn.stay; | |
| 318 if (out.stay) execute(); | |
| 319 } | |
| 320 | |
| 321 /// Record the fact that this constraint is unsatisfied. | |
| 322 void markUnsatisfied() { | |
| 323 direction = NONE; | |
| 324 } | |
| 325 | |
| 326 bool inputsKnown(int mark) { | |
| 327 Variable i = input(); | |
| 328 return i.mark == mark || i.stay || i.determinedBy == null; | |
| 329 } | |
| 330 | |
| 331 void removeFromGraph() { | |
| 332 if (v1 != null) v1.removeConstraint(this); | |
| 333 if (v2 != null) v2.removeConstraint(this); | |
| 334 direction = NONE; | |
| 335 } | |
| 336 } | |
| 337 | |
| 338 /** | |
| 339 * Relates two variables by the linear scaling relationship: "v2 = | |
| 340 * (v1 * scale) + offset". Either v1 or v2 may be changed to maintain | |
| 341 * this relationship but the scale factor and offset are considered | |
| 342 * read-only. | |
| 343 */ | |
| 344 | |
| 345 class ScaleConstraint extends BinaryConstraint { | |
| 346 final Variable scale; | |
| 347 final Variable offset; | |
| 348 | |
| 349 ScaleConstraint( | |
| 350 Variable src, this.scale, this.offset, Variable dest, Strength strength) | |
| 351 : super(src, dest, strength); | |
| 352 | |
| 353 /// Adds this constraint to the constraint graph. | |
| 354 void addToGraph() { | |
| 355 super.addToGraph(); | |
| 356 scale.addConstraint(this); | |
| 357 offset.addConstraint(this); | |
| 358 } | |
| 359 | |
| 360 void removeFromGraph() { | |
| 361 super.removeFromGraph(); | |
| 362 if (scale != null) scale.removeConstraint(this); | |
| 363 if (offset != null) offset.removeConstraint(this); | |
| 364 } | |
| 365 | |
| 366 void markInputs(int mark) { | |
| 367 super.markInputs(mark); | |
| 368 scale.mark = offset.mark = mark; | |
| 369 } | |
| 370 | |
| 371 /// Enforce this constraint. Assume that it is satisfied. | |
| 372 void execute() { | |
| 373 if (direction == FORWARD) { | |
| 374 v2.value = v1.value * scale.value + offset.value; | |
| 375 } else { | |
| 376 v1.value = (v2.value - offset.value) ~/ scale.value; | |
| 377 } | |
| 378 } | |
| 379 | |
| 380 /** | |
| 381 * Calculate the walkabout strength, the stay flag, and, if it is | |
| 382 * 'stay', the value for the current output of this constraint. Assume | |
| 383 * this constraint is satisfied. | |
| 384 */ | |
| 385 void recalculate() { | |
| 386 Variable ihn = input(), | |
| 387 out = output(); | |
| 388 out.walkStrength = Strength.weakest(strength, ihn.walkStrength); | |
| 389 out.stay = ihn.stay && scale.stay && offset.stay; | |
| 390 if (out.stay) execute(); | |
| 391 } | |
| 392 } | |
| 393 | |
| 394 /** | |
| 395 * Constrains two variables to have the same value. | |
| 396 */ | |
| 397 class EqualityConstraint extends BinaryConstraint { | |
| 398 EqualityConstraint(Variable v1, Variable v2, Strength strength) | |
| 399 : super(v1, v2, strength); | |
| 400 | |
| 401 /// Enforce this constraint. Assume that it is satisfied. | |
| 402 void execute() { | |
| 403 output().value = input().value; | |
| 404 } | |
| 405 } | |
| 406 | |
| 407 /** | |
| 408 * A constrained variable. In addition to its value, it maintain the | |
| 409 * structure of the constraint graph, the current dataflow graph, and | |
| 410 * various parameters of interest to the DeltaBlue incremental | |
| 411 * constraint solver. | |
| 412 **/ | |
| 413 class Variable { | |
| 414 List<Constraint> constraints = <Constraint>[]; | |
| 415 Constraint determinedBy; | |
| 416 int mark = 0; | |
| 417 Strength walkStrength = WEAKEST; | |
| 418 bool stay = true; | |
| 419 int value; | |
| 420 final String name; | |
| 421 | |
| 422 Variable(this.name, this.value); | |
| 423 | |
| 424 /** | |
| 425 * Add the given constraint to the set of all constraints that refer | |
| 426 * this variable. | |
| 427 */ | |
| 428 void addConstraint(Constraint c) { | |
| 429 constraints.add(c); | |
| 430 } | |
| 431 | |
| 432 /// Removes all traces of c from this variable. | |
| 433 void removeConstraint(Constraint c) { | |
| 434 constraints.remove(c); | |
| 435 if (determinedBy == c) determinedBy = null; | |
| 436 } | |
| 437 } | |
| 438 | |
| 439 class Planner { | |
| 440 int currentMark = 0; | |
| 441 | |
| 442 /** | |
| 443 * Attempt to satisfy the given constraint and, if successful, | |
| 444 * incrementally update the dataflow graph. Details: If satifying | |
| 445 * the constraint is successful, it may override a weaker constraint | |
| 446 * on its output. The algorithm attempts to resatisfy that | |
| 447 * constraint using some other method. This process is repeated | |
| 448 * until either a) it reaches a variable that was not previously | |
| 449 * determined by any constraint or b) it reaches a constraint that | |
| 450 * is too weak to be satisfied using any of its methods. The | |
| 451 * variables of constraints that have been processed are marked with | |
| 452 * a unique mark value so that we know where we've been. This allows | |
| 453 * the algorithm to avoid getting into an infinite loop even if the | |
| 454 * constraint graph has an inadvertent cycle. | |
| 455 */ | |
| 456 void incrementalAdd(Constraint c) { | |
| 457 int mark = newMark(); | |
| 458 for (Constraint overridden = c.satisfy(mark); | |
| 459 overridden != null; | |
| 460 overridden = overridden.satisfy(mark)); | |
| 461 } | |
| 462 | |
| 463 /** | |
| 464 * Entry point for retracting a constraint. Remove the given | |
| 465 * constraint and incrementally update the dataflow graph. | |
| 466 * Details: Retracting the given constraint may allow some currently | |
| 467 * unsatisfiable downstream constraint to be satisfied. We therefore collect | |
| 468 * a list of unsatisfied downstream constraints and attempt to | |
| 469 * satisfy each one in turn. This list is traversed by constraint | |
| 470 * strength, strongest first, as a heuristic for avoiding | |
| 471 * unnecessarily adding and then overriding weak constraints. | |
| 472 * Assume: [c] is satisfied. | |
| 473 */ | |
| 474 void incrementalRemove(Constraint c) { | |
| 475 Variable out = c.output(); | |
| 476 c.markUnsatisfied(); | |
| 477 c.removeFromGraph(); | |
| 478 List<Constraint> unsatisfied = removePropagateFrom(out); | |
| 479 Strength strength = REQUIRED; | |
| 480 do { | |
| 481 for (int i = 0; i < unsatisfied.length; i++) { | |
| 482 Constraint u = unsatisfied[i]; | |
| 483 if (u.strength == strength) incrementalAdd(u); | |
| 484 } | |
| 485 strength = strength.nextWeaker(); | |
| 486 } while (strength != WEAKEST); | |
| 487 } | |
| 488 | |
| 489 /// Select a previously unused mark value. | |
| 490 int newMark() => ++currentMark; | |
| 491 | |
| 492 /** | |
| 493 * Extract a plan for resatisfaction starting from the given source | |
| 494 * constraints, usually a set of input constraints. This method | |
| 495 * assumes that stay optimization is desired; the plan will contain | |
| 496 * only constraints whose output variables are not stay. Constraints | |
| 497 * that do no computation, such as stay and edit constraints, are | |
| 498 * not included in the plan. | |
| 499 * Details: The outputs of a constraint are marked when it is added | |
| 500 * to the plan under construction. A constraint may be appended to | |
| 501 * the plan when all its input variables are known. A variable is | |
| 502 * known if either a) the variable is marked (indicating that has | |
| 503 * been computed by a constraint appearing earlier in the plan), b) | |
| 504 * the variable is 'stay' (i.e. it is a constant at plan execution | |
| 505 * time), or c) the variable is not determined by any | |
| 506 * constraint. The last provision is for past states of history | |
| 507 * variables, which are not stay but which are also not computed by | |
| 508 * any constraint. | |
| 509 * Assume: [sources] are all satisfied. | |
| 510 */ | |
| 511 Plan makePlan(List<Constraint> sources) { | |
| 512 int mark = newMark(); | |
| 513 Plan plan = new Plan(); | |
| 514 List<Constraint> todo = sources; | |
| 515 while (todo.length > 0) { | |
| 516 Constraint c = todo.removeLast(); | |
| 517 if (c.output().mark != mark && c.inputsKnown(mark)) { | |
| 518 plan.addConstraint(c); | |
| 519 c.output().mark = mark; | |
| 520 addConstraintsConsumingTo(c.output(), todo); | |
| 521 } | |
| 522 } | |
| 523 return plan; | |
| 524 } | |
| 525 | |
| 526 /** | |
| 527 * Extract a plan for resatisfying starting from the output of the | |
| 528 * given [constraints], usually a set of input constraints. | |
| 529 */ | |
| 530 Plan extractPlanFromConstraints(List<Constraint> constraints) { | |
| 531 List<Constraint> sources = <Constraint>[]; | |
| 532 for (int i = 0; i < constraints.length; i++) { | |
| 533 Constraint c = constraints[i]; | |
| 534 // if not in plan already and eligible for inclusion. | |
| 535 if (c.isInput() && c.isSatisfied()) sources.add(c); | |
| 536 } | |
| 537 return makePlan(sources); | |
| 538 } | |
| 539 | |
| 540 /** | |
| 541 * Recompute the walkabout strengths and stay flags of all variables | |
| 542 * downstream of the given constraint and recompute the actual | |
| 543 * values of all variables whose stay flag is true. If a cycle is | |
| 544 * detected, remove the given constraint and answer | |
| 545 * false. Otherwise, answer true. | |
| 546 * Details: Cycles are detected when a marked variable is | |
| 547 * encountered downstream of the given constraint. The sender is | |
| 548 * assumed to have marked the inputs of the given constraint with | |
| 549 * the given mark. Thus, encountering a marked node downstream of | |
| 550 * the output constraint means that there is a path from the | |
| 551 * constraint's output to one of its inputs. | |
| 552 */ | |
| 553 bool addPropagate(Constraint c, int mark) { | |
| 554 List<Constraint> todo = <Constraint>[c]; | |
| 555 while (todo.length > 0) { | |
| 556 Constraint d = todo.removeLast(); | |
| 557 if (d.output().mark == mark) { | |
| 558 incrementalRemove(c); | |
| 559 return false; | |
| 560 } | |
| 561 d.recalculate(); | |
| 562 addConstraintsConsumingTo(d.output(), todo); | |
| 563 } | |
| 564 return true; | |
| 565 } | |
| 566 | |
| 567 /** | |
| 568 * Update the walkabout strengths and stay flags of all variables | |
| 569 * downstream of the given constraint. Answer a collection of | |
| 570 * unsatisfied constraints sorted in order of decreasing strength. | |
| 571 */ | |
| 572 List<Constraint> removePropagateFrom(Variable out) { | |
| 573 out.determinedBy = null; | |
| 574 out.walkStrength = WEAKEST; | |
| 575 out.stay = true; | |
| 576 List<Constraint> unsatisfied = <Constraint>[]; | |
| 577 List<Variable> todo = <Variable>[out]; | |
| 578 while (todo.length > 0) { | |
| 579 Variable v = todo.removeLast(); | |
| 580 for (int i = 0; i < v.constraints.length; i++) { | |
| 581 Constraint c = v.constraints[i]; | |
| 582 if (!c.isSatisfied()) unsatisfied.add(c); | |
| 583 } | |
| 584 Constraint determining = v.determinedBy; | |
| 585 for (int i = 0; i < v.constraints.length; i++) { | |
| 586 Constraint next = v.constraints[i]; | |
| 587 if (next != determining && next.isSatisfied()) { | |
| 588 next.recalculate(); | |
| 589 todo.add(next.output()); | |
| 590 } | |
| 591 } | |
| 592 } | |
| 593 return unsatisfied; | |
| 594 } | |
| 595 | |
| 596 void addConstraintsConsumingTo(Variable v, List<Constraint> coll) { | |
| 597 Constraint determining = v.determinedBy; | |
| 598 for (int i = 0; i < v.constraints.length; i++) { | |
| 599 Constraint c = v.constraints[i]; | |
| 600 if (c != determining && c.isSatisfied()) coll.add(c); | |
| 601 } | |
| 602 } | |
| 603 } | |
| 604 | |
| 605 /** | |
| 606 * A Plan is an ordered list of constraints to be executed in sequence | |
| 607 * to resatisfy all currently satisfiable constraints in the face of | |
| 608 * one or more changing inputs. | |
| 609 */ | |
| 610 class Plan { | |
| 611 List<Constraint> list = <Constraint>[]; | |
| 612 | |
| 613 void addConstraint(Constraint c) { | |
| 614 list.add(c); | |
| 615 } | |
| 616 | |
| 617 int size() => list.length; | |
| 618 | |
| 619 void execute() { | |
| 620 for (int i = 0; i < list.length; i++) { | |
| 621 list[i].execute(); | |
| 622 } | |
| 623 } | |
| 624 } | |
| 625 | |
| 626 /** | |
| 627 * This is the standard DeltaBlue benchmark. A long chain of equality | |
| 628 * constraints is constructed with a stay constraint on one end. An | |
| 629 * edit constraint is then added to the opposite end and the time is | |
| 630 * measured for adding and removing this constraint, and extracting | |
| 631 * and executing a constraint satisfaction plan. There are two cases. | |
| 632 * In case 1, the added constraint is stronger than the stay | |
| 633 * constraint and values must propagate down the entire length of the | |
| 634 * chain. In case 2, the added constraint is weaker than the stay | |
| 635 * constraint so it cannot be accomodated. The cost in this case is, | |
| 636 * of course, very low. Typical situations lie somewhere between these | |
| 637 * two extremes. | |
| 638 */ | |
| 639 void chainTest(int n) { | |
| 640 planner = new Planner(); | |
| 641 Variable prev = null, | |
| 642 first = null, | |
| 643 last = null; | |
| 644 // Build chain of n equality constraints. | |
| 645 for (int i = 0; i <= n; i++) { | |
| 646 Variable v = new Variable("v", 0); | |
| 647 if (prev != null) new EqualityConstraint(prev, v, REQUIRED); | |
| 648 if (i == 0) first = v; | |
| 649 if (i == n) last = v; | |
| 650 prev = v; | |
| 651 } | |
| 652 new StayConstraint(last, STRONG_DEFAULT); | |
| 653 EditConstraint edit = new EditConstraint(first, PREFERRED); | |
| 654 Plan plan = planner.extractPlanFromConstraints(<Constraint>[edit]); | |
| 655 for (int i = 0; i < 100; i++) { | |
| 656 first.value = i; | |
| 657 plan.execute(); | |
| 658 if (last.value != i) { | |
| 659 print("Chain test failed:"); | |
| 660 print("Expected last value to be $i but it was ${last.value}."); | |
| 661 } | |
| 662 } | |
| 663 } | |
| 664 | |
| 665 /** | |
| 666 * This test constructs a two sets of variables related to each | |
| 667 * other by a simple linear transformation (scale and offset). The | |
| 668 * time is measured to change a variable on either side of the | |
| 669 * mapping and to change the scale and offset factors. | |
| 670 */ | |
| 671 void projectionTest(int n) { | |
| 672 planner = new Planner(); | |
| 673 Variable scale = new Variable("scale", 10); | |
| 674 Variable offset = new Variable("offset", 1000); | |
| 675 Variable src = null, | |
| 676 dst = null; | |
| 677 | |
| 678 List<Variable> dests = <Variable>[]; | |
| 679 for (int i = 0; i < n; i++) { | |
| 680 src = new Variable("src", i); | |
| 681 dst = new Variable("dst", i); | |
| 682 dests.add(dst); | |
| 683 new StayConstraint(src, NORMAL); | |
| 684 new ScaleConstraint(src, scale, offset, dst, REQUIRED); | |
| 685 } | |
| 686 change(src, 17); | |
| 687 if (dst.value != 1170) print("Projection 1 failed"); | |
| 688 change(dst, 1050); | |
| 689 if (src.value != 5) print("Projection 2 failed"); | |
| 690 change(scale, 5); | |
| 691 for (int i = 0; i < n - 1; i++) { | |
| 692 if (dests[i].value != i * 5 + 1000) print("Projection 3 failed"); | |
| 693 } | |
| 694 change(offset, 2000); | |
| 695 for (int i = 0; i < n - 1; i++) { | |
| 696 if (dests[i].value != i * 5 + 2000) print("Projection 4 failed"); | |
| 697 } | |
| 698 } | |
| 699 | |
| 700 void change(Variable v, int newValue) { | |
| 701 EditConstraint edit = new EditConstraint(v, PREFERRED); | |
| 702 Plan plan = planner.extractPlanFromConstraints(<EditConstraint>[edit]); | |
| 703 for (int i = 0; i < 10; i++) { | |
| 704 v.value = newValue; | |
| 705 plan.execute(); | |
| 706 } | |
| 707 edit.destroyConstraint(); | |
| 708 } | |
| 709 | |
| 710 Planner planner; | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 1988503002:
Move generated files to gen/. (Closed)
Base URL: https://github.com/dart-lang/dev_compiler.git@master