1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/src/v8/deltablue.js Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,880 @@
1.4 +// Copyright 2008 the V8 project authors. All rights reserved.
1.5 +// Copyright 1996 John Maloney and Mario Wolczko.
1.6 +
1.7 +// This program is free software; you can redistribute it and/or modify
1.8 +// it under the terms of the GNU General Public License as published by
1.9 +// the Free Software Foundation; either version 2 of the License, or
1.10 +// (at your option) any later version.
1.11 +//
1.12 +// This program is distributed in the hope that it will be useful,
1.13 +// but WITHOUT ANY WARRANTY; without even the implied warranty of
1.14 +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
1.15 +// GNU General Public License for more details.
1.16 +//
1.17 +// You should have received a copy of the GNU General Public License
1.18 +// along with this program; if not, write to the Free Software
1.19 +// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
1.20 +
1.21 +
1.22 +// This implementation of the DeltaBlue benchmark is derived
1.23 +// from the Smalltalk implementation by John Maloney and Mario
1.24 +// Wolczko. Some parts have been translated directly, whereas
1.25 +// others have been modified more aggresively to make it feel
1.26 +// more like a JavaScript program.
1.27 +
1.28 +
1.29 +var DeltaBlue = new BenchmarkSuite('DeltaBlue', 66118, [
1.30 + new Benchmark('DeltaBlue', deltaBlue)
1.31 +]);
1.32 +
1.33 +
1.34 +/**
1.35 + * A JavaScript implementation of the DeltaBlue constraint-solving
1.36 + * algorithm, as described in:
1.37 + *
1.38 + * "The DeltaBlue Algorithm: An Incremental Constraint Hierarchy Solver"
1.39 + * Bjorn N. Freeman-Benson and John Maloney
1.40 + * January 1990 Communications of the ACM,
1.41 + * also available as University of Washington TR 89-08-06.
1.42 + *
1.43 + * Beware: this benchmark is written in a grotesque style where
1.44 + * the constraint model is built by side-effects from constructors.
1.45 + * I've kept it this way to avoid deviating too much from the original
1.46 + * implementation.
1.47 + */
1.48 +
1.49 +
1.50 +/* --- O b j e c t M o d e l --- */
1.51 +
1.52 +Object.prototype.inheritsFrom = function (shuper) {
1.53 + function Inheriter() { }
1.54 + Inheriter.prototype = shuper.prototype;
1.55 + this.prototype = new Inheriter();
1.56 + this.superConstructor = shuper;
1.57 +}
1.58 +
1.59 +function OrderedCollection() {
1.60 + this.elms = new Array();
1.61 +}
1.62 +
1.63 +OrderedCollection.prototype.add = function (elm) {
1.64 + this.elms.push(elm);
1.65 +}
1.66 +
1.67 +OrderedCollection.prototype.at = function (index) {
1.68 + return this.elms[index];
1.69 +}
1.70 +
1.71 +OrderedCollection.prototype.size = function () {
1.72 + return this.elms.length;
1.73 +}
1.74 +
1.75 +OrderedCollection.prototype.removeFirst = function () {
1.76 + return this.elms.pop();
1.77 +}
1.78 +
1.79 +OrderedCollection.prototype.remove = function (elm) {
1.80 + var index = 0, skipped = 0;
1.81 + for (var i = 0; i < this.elms.length; i++) {
1.82 + var value = this.elms[i];
1.83 + if (value != elm) {
1.84 + this.elms[index] = value;
1.85 + index++;
1.86 + } else {
1.87 + skipped++;
1.88 + }
1.89 + }
1.90 + for (var i = 0; i < skipped; i++)
1.91 + this.elms.pop();
1.92 +}
1.93 +
1.94 +/* --- *
1.95 + * S t r e n g t h
1.96 + * --- */
1.97 +
1.98 +/**
1.99 + * Strengths are used to measure the relative importance of constraints.
1.100 + * New strengths may be inserted in the strength hierarchy without
1.101 + * disrupting current constraints. Strengths cannot be created outside
1.102 + * this class, so pointer comparison can be used for value comparison.
1.103 + */
1.104 +function Strength(strengthValue, name) {
1.105 + this.strengthValue = strengthValue;
1.106 + this.name = name;
1.107 +}
1.108 +
1.109 +Strength.stronger = function (s1, s2) {
1.110 + return s1.strengthValue < s2.strengthValue;
1.111 +}
1.112 +
1.113 +Strength.weaker = function (s1, s2) {
1.114 + return s1.strengthValue > s2.strengthValue;
1.115 +}
1.116 +
1.117 +Strength.weakestOf = function (s1, s2) {
1.118 + return this.weaker(s1, s2) ? s1 : s2;
1.119 +}
1.120 +
1.121 +Strength.strongest = function (s1, s2) {
1.122 + return this.stronger(s1, s2) ? s1 : s2;
1.123 +}
1.124 +
1.125 +Strength.prototype.nextWeaker = function () {
1.126 + switch (this.strengthValue) {
1.127 + case 0: return Strength.WEAKEST;
1.128 + case 1: return Strength.WEAK_DEFAULT;
1.129 + case 2: return Strength.NORMAL;
1.130 + case 3: return Strength.STRONG_DEFAULT;
1.131 + case 4: return Strength.PREFERRED;
1.132 + case 5: return Strength.REQUIRED;
1.133 + }
1.134 +}
1.135 +
1.136 +// Strength constants.
1.137 +Strength.REQUIRED = new Strength(0, "required");
1.138 +Strength.STONG_PREFERRED = new Strength(1, "strongPreferred");
1.139 +Strength.PREFERRED = new Strength(2, "preferred");
1.140 +Strength.STRONG_DEFAULT = new Strength(3, "strongDefault");
1.141 +Strength.NORMAL = new Strength(4, "normal");
1.142 +Strength.WEAK_DEFAULT = new Strength(5, "weakDefault");
1.143 +Strength.WEAKEST = new Strength(6, "weakest");
1.144 +
1.145 +/* --- *
1.146 + * C o n s t r a i n t
1.147 + * --- */
1.148 +
1.149 +/**
1.150 + * An abstract class representing a system-maintainable relationship
1.151 + * (or "constraint") between a set of variables. A constraint supplies
1.152 + * a strength instance variable; concrete subclasses provide a means
1.153 + * of storing the constrained variables and other information required
1.154 + * to represent a constraint.
1.155 + */
1.156 +function Constraint(strength) {
1.157 + this.strength = strength;
1.158 +}
1.159 +
1.160 +/**
1.161 + * Activate this constraint and attempt to satisfy it.
1.162 + */
1.163 +Constraint.prototype.addConstraint = function () {
1.164 + this.addToGraph();
1.165 + planner.incrementalAdd(this);
1.166 +}
1.167 +
1.168 +/**
1.169 + * Attempt to find a way to enforce this constraint. If successful,
1.170 + * record the solution, perhaps modifying the current dataflow
1.171 + * graph. Answer the constraint that this constraint overrides, if
1.172 + * there is one, or nil, if there isn't.
1.173 + * Assume: I am not already satisfied.
1.174 + */
1.175 +Constraint.prototype.satisfy = function (mark) {
1.176 + this.chooseMethod(mark);
1.177 + if (!this.isSatisfied()) {
1.178 + if (this.strength == Strength.REQUIRED)
1.179 + alert("Could not satisfy a required constraint!");
1.180 + return null;
1.181 + }
1.182 + this.markInputs(mark);
1.183 + var out = this.output();
1.184 + var overridden = out.determinedBy;
1.185 + if (overridden != null) overridden.markUnsatisfied();
1.186 + out.determinedBy = this;
1.187 + if (!planner.addPropagate(this, mark))
1.188 + alert("Cycle encountered");
1.189 + out.mark = mark;
1.190 + return overridden;
1.191 +}
1.192 +
1.193 +Constraint.prototype.destroyConstraint = function () {
1.194 + if (this.isSatisfied()) planner.incrementalRemove(this);
1.195 + else this.removeFromGraph();
1.196 +}
1.197 +
1.198 +/**
1.199 + * Normal constraints are not input constraints. An input constraint
1.200 + * is one that depends on external state, such as the mouse, the
1.201 + * keybord, a clock, or some arbitraty piece of imperative code.
1.202 + */
1.203 +Constraint.prototype.isInput = function () {
1.204 + return false;
1.205 +}
1.206 +
1.207 +/* --- *
1.208 + * U n a r y C o n s t r a i n t
1.209 + * --- */
1.210 +
1.211 +/**
1.212 + * Abstract superclass for constraints having a single possible output
1.213 + * variable.
1.214 + */
1.215 +function UnaryConstraint(v, strength) {
1.216 + UnaryConstraint.superConstructor.call(this, strength);
1.217 + this.myOutput = v;
1.218 + this.satisfied = false;
1.219 + this.addConstraint();
1.220 +}
1.221 +
1.222 +UnaryConstraint.inheritsFrom(Constraint);
1.223 +
1.224 +/**
1.225 + * Adds this constraint to the constraint graph
1.226 + */
1.227 +UnaryConstraint.prototype.addToGraph = function () {
1.228 + this.myOutput.addConstraint(this);
1.229 + this.satisfied = false;
1.230 +}
1.231 +
1.232 +/**
1.233 + * Decides if this constraint can be satisfied and records that
1.234 + * decision.
1.235 + */
1.236 +UnaryConstraint.prototype.chooseMethod = function (mark) {
1.237 + this.satisfied = (this.myOutput.mark != mark)
1.238 + && Strength.stronger(this.strength, this.myOutput.walkStrength);
1.239 +}
1.240 +
1.241 +/**
1.242 + * Returns true if this constraint is satisfied in the current solution.
1.243 + */
1.244 +UnaryConstraint.prototype.isSatisfied = function () {
1.245 + return this.satisfied;
1.246 +}
1.247 +
1.248 +UnaryConstraint.prototype.markInputs = function (mark) {
1.249 + // has no inputs
1.250 +}
1.251 +
1.252 +/**
1.253 + * Returns the current output variable.
1.254 + */
1.255 +UnaryConstraint.prototype.output = function () {
1.256 + return this.myOutput;
1.257 +}
1.258 +
1.259 +/**
1.260 + * Calculate the walkabout strength, the stay flag, and, if it is
1.261 + * 'stay', the value for the current output of this constraint. Assume
1.262 + * this constraint is satisfied.
1.263 + */
1.264 +UnaryConstraint.prototype.recalculate = function () {
1.265 + this.myOutput.walkStrength = this.strength;
1.266 + this.myOutput.stay = !this.isInput();
1.267 + if (this.myOutput.stay) this.execute(); // Stay optimization
1.268 +}
1.269 +
1.270 +/**
1.271 + * Records that this constraint is unsatisfied
1.272 + */
1.273 +UnaryConstraint.prototype.markUnsatisfied = function () {
1.274 + this.satisfied = false;
1.275 +}
1.276 +
1.277 +UnaryConstraint.prototype.inputsKnown = function () {
1.278 + return true;
1.279 +}
1.280 +
1.281 +UnaryConstraint.prototype.removeFromGraph = function () {
1.282 + if (this.myOutput != null) this.myOutput.removeConstraint(this);
1.283 + this.satisfied = false;
1.284 +}
1.285 +
1.286 +/* --- *
1.287 + * S t a y C o n s t r a i n t
1.288 + * --- */
1.289 +
1.290 +/**
1.291 + * Variables that should, with some level of preference, stay the same.
1.292 + * Planners may exploit the fact that instances, if satisfied, will not
1.293 + * change their output during plan execution. This is called "stay
1.294 + * optimization".
1.295 + */
1.296 +function StayConstraint(v, str) {
1.297 + StayConstraint.superConstructor.call(this, v, str);
1.298 +}
1.299 +
1.300 +StayConstraint.inheritsFrom(UnaryConstraint);
1.301 +
1.302 +StayConstraint.prototype.execute = function () {
1.303 + // Stay constraints do nothing
1.304 +}
1.305 +
1.306 +/* --- *
1.307 + * E d i t C o n s t r a i n t
1.308 + * --- */
1.309 +
1.310 +/**
1.311 + * A unary input constraint used to mark a variable that the client
1.312 + * wishes to change.
1.313 + */
1.314 +function EditConstraint(v, str) {
1.315 + EditConstraint.superConstructor.call(this, v, str);
1.316 +}
1.317 +
1.318 +EditConstraint.inheritsFrom(UnaryConstraint);
1.319 +
1.320 +/**
1.321 + * Edits indicate that a variable is to be changed by imperative code.
1.322 + */
1.323 +EditConstraint.prototype.isInput = function () {
1.324 + return true;
1.325 +}
1.326 +
1.327 +EditConstraint.prototype.execute = function () {
1.328 + // Edit constraints do nothing
1.329 +}
1.330 +
1.331 +/* --- *
1.332 + * B i n a r y C o n s t r a i n t
1.333 + * --- */
1.334 +
1.335 +var Direction = new Object();
1.336 +Direction.NONE = 0;
1.337 +Direction.FORWARD = 1;
1.338 +Direction.BACKWARD = -1;
1.339 +
1.340 +/**
1.341 + * Abstract superclass for constraints having two possible output
1.342 + * variables.
1.343 + */
1.344 +function BinaryConstraint(var1, var2, strength) {
1.345 + BinaryConstraint.superConstructor.call(this, strength);
1.346 + this.v1 = var1;
1.347 + this.v2 = var2;
1.348 + this.direction = Direction.NONE;
1.349 + this.addConstraint();
1.350 +}
1.351 +
1.352 +BinaryConstraint.inheritsFrom(Constraint);
1.353 +
1.354 +/**
1.355 + * Decides if this constraint can be satisfied and which way it
1.356 + * should flow based on the relative strength of the variables related,
1.357 + * and record that decision.
1.358 + */
1.359 +BinaryConstraint.prototype.chooseMethod = function (mark) {
1.360 + if (this.v1.mark == mark) {
1.361 + this.direction = (this.v2.mark != mark && Strength.stronger(this.strength, this.v2.walkStrength))
1.362 + ? Direction.FORWARD
1.363 + : Direction.NONE;
1.364 + }
1.365 + if (this.v2.mark == mark) {
1.366 + this.direction = (this.v1.mark != mark && Strength.stronger(this.strength, this.v1.walkStrength))
1.367 + ? Direction.BACKWARD
1.368 + : Direction.NONE;
1.369 + }
1.370 + if (Strength.weaker(this.v1.walkStrength, this.v2.walkStrength)) {
1.371 + this.direction = Strength.stronger(this.strength, this.v1.walkStrength)
1.372 + ? Direction.BACKWARD
1.373 + : Direction.NONE;
1.374 + } else {
1.375 + this.direction = Strength.stronger(this.strength, this.v2.walkStrength)
1.376 + ? Direction.FORWARD
1.377 + : Direction.BACKWARD
1.378 + }
1.379 +}
1.380 +
1.381 +/**
1.382 + * Add this constraint to the constraint graph
1.383 + */
1.384 +BinaryConstraint.prototype.addToGraph = function () {
1.385 + this.v1.addConstraint(this);
1.386 + this.v2.addConstraint(this);
1.387 + this.direction = Direction.NONE;
1.388 +}
1.389 +
1.390 +/**
1.391 + * Answer true if this constraint is satisfied in the current solution.
1.392 + */
1.393 +BinaryConstraint.prototype.isSatisfied = function () {
1.394 + return this.direction != Direction.NONE;
1.395 +}
1.396 +
1.397 +/**
1.398 + * Mark the input variable with the given mark.
1.399 + */
1.400 +BinaryConstraint.prototype.markInputs = function (mark) {
1.401 + this.input().mark = mark;
1.402 +}
1.403 +
1.404 +/**
1.405 + * Returns the current input variable
1.406 + */
1.407 +BinaryConstraint.prototype.input = function () {
1.408 + return (this.direction == Direction.FORWARD) ? this.v1 : this.v2;
1.409 +}
1.410 +
1.411 +/**
1.412 + * Returns the current output variable
1.413 + */
1.414 +BinaryConstraint.prototype.output = function () {
1.415 + return (this.direction == Direction.FORWARD) ? this.v2 : this.v1;
1.416 +}
1.417 +
1.418 +/**
1.419 + * Calculate the walkabout strength, the stay flag, and, if it is
1.420 + * 'stay', the value for the current output of this
1.421 + * constraint. Assume this constraint is satisfied.
1.422 + */
1.423 +BinaryConstraint.prototype.recalculate = function () {
1.424 + var ihn = this.input(), out = this.output();
1.425 + out.walkStrength = Strength.weakestOf(this.strength, ihn.walkStrength);
1.426 + out.stay = ihn.stay;
1.427 + if (out.stay) this.execute();
1.428 +}
1.429 +
1.430 +/**
1.431 + * Record the fact that this constraint is unsatisfied.
1.432 + */
1.433 +BinaryConstraint.prototype.markUnsatisfied = function () {
1.434 + this.direction = Direction.NONE;
1.435 +}
1.436 +
1.437 +BinaryConstraint.prototype.inputsKnown = function (mark) {
1.438 + var i = this.input();
1.439 + return i.mark == mark || i.stay || i.determinedBy == null;
1.440 +}
1.441 +
1.442 +BinaryConstraint.prototype.removeFromGraph = function () {
1.443 + if (this.v1 != null) this.v1.removeConstraint(this);
1.444 + if (this.v2 != null) this.v2.removeConstraint(this);
1.445 + this.direction = Direction.NONE;
1.446 +}
1.447 +
1.448 +/* --- *
1.449 + * S c a l e C o n s t r a i n t
1.450 + * --- */
1.451 +
1.452 +/**
1.453 + * Relates two variables by the linear scaling relationship: "v2 =
1.454 + * (v1 * scale) + offset". Either v1 or v2 may be changed to maintain
1.455 + * this relationship but the scale factor and offset are considered
1.456 + * read-only.
1.457 + */
1.458 +function ScaleConstraint(src, scale, offset, dest, strength) {
1.459 + this.direction = Direction.NONE;
1.460 + this.scale = scale;
1.461 + this.offset = offset;
1.462 + ScaleConstraint.superConstructor.call(this, src, dest, strength);
1.463 +}
1.464 +
1.465 +ScaleConstraint.inheritsFrom(BinaryConstraint);
1.466 +
1.467 +/**
1.468 + * Adds this constraint to the constraint graph.
1.469 + */
1.470 +ScaleConstraint.prototype.addToGraph = function () {
1.471 + ScaleConstraint.superConstructor.prototype.addToGraph.call(this);
1.472 + this.scale.addConstraint(this);
1.473 + this.offset.addConstraint(this);
1.474 +}
1.475 +
1.476 +ScaleConstraint.prototype.removeFromGraph = function () {
1.477 + ScaleConstraint.superConstructor.prototype.removeFromGraph.call(this);
1.478 + if (this.scale != null) this.scale.removeConstraint(this);
1.479 + if (this.offset != null) this.offset.removeConstraint(this);
1.480 +}
1.481 +
1.482 +ScaleConstraint.prototype.markInputs = function (mark) {
1.483 + ScaleConstraint.superConstructor.prototype.markInputs.call(this, mark);
1.484 + this.scale.mark = this.offset.mark = mark;
1.485 +}
1.486 +
1.487 +/**
1.488 + * Enforce this constraint. Assume that it is satisfied.
1.489 + */
1.490 +ScaleConstraint.prototype.execute = function () {
1.491 + if (this.direction == Direction.FORWARD) {
1.492 + this.v2.value = this.v1.value * this.scale.value + this.offset.value;
1.493 + } else {
1.494 + this.v1.value = (this.v2.value - this.offset.value) / this.scale.value;
1.495 + }
1.496 +}
1.497 +
1.498 +/**
1.499 + * Calculate the walkabout strength, the stay flag, and, if it is
1.500 + * 'stay', the value for the current output of this constraint. Assume
1.501 + * this constraint is satisfied.
1.502 + */
1.503 +ScaleConstraint.prototype.recalculate = function () {
1.504 + var ihn = this.input(), out = this.output();
1.505 + out.walkStrength = Strength.weakestOf(this.strength, ihn.walkStrength);
1.506 + out.stay = ihn.stay && this.scale.stay && this.offset.stay;
1.507 + if (out.stay) this.execute();
1.508 +}
1.509 +
1.510 +/* --- *
1.511 + * E q u a l i t y C o n s t r a i n t
1.512 + * --- */
1.513 +
1.514 +/**
1.515 + * Constrains two variables to have the same value.
1.516 + */
1.517 +function EqualityConstraint(var1, var2, strength) {
1.518 + EqualityConstraint.superConstructor.call(this, var1, var2, strength);
1.519 +}
1.520 +
1.521 +EqualityConstraint.inheritsFrom(BinaryConstraint);
1.522 +
1.523 +/**
1.524 + * Enforce this constraint. Assume that it is satisfied.
1.525 + */
1.526 +EqualityConstraint.prototype.execute = function () {
1.527 + this.output().value = this.input().value;
1.528 +}
1.529 +
1.530 +/* --- *
1.531 + * V a r i a b l e
1.532 + * --- */
1.533 +
1.534 +/**
1.535 + * A constrained variable. In addition to its value, it maintain the
1.536 + * structure of the constraint graph, the current dataflow graph, and
1.537 + * various parameters of interest to the DeltaBlue incremental
1.538 + * constraint solver.
1.539 + **/
1.540 +function Variable(name, initialValue) {
1.541 + this.value = initialValue || 0;
1.542 + this.constraints = new OrderedCollection();
1.543 + this.determinedBy = null;
1.544 + this.mark = 0;
1.545 + this.walkStrength = Strength.WEAKEST;
1.546 + this.stay = true;
1.547 + this.name = name;
1.548 +}
1.549 +
1.550 +/**
1.551 + * Add the given constraint to the set of all constraints that refer
1.552 + * this variable.
1.553 + */
1.554 +Variable.prototype.addConstraint = function (c) {
1.555 + this.constraints.add(c);
1.556 +}
1.557 +
1.558 +/**
1.559 + * Removes all traces of c from this variable.
1.560 + */
1.561 +Variable.prototype.removeConstraint = function (c) {
1.562 + this.constraints.remove(c);
1.563 + if (this.determinedBy == c) this.determinedBy = null;
1.564 +}
1.565 +
1.566 +/* --- *
1.567 + * P l a n n e r
1.568 + * --- */
1.569 +
1.570 +/**
1.571 + * The DeltaBlue planner
1.572 + */
1.573 +function Planner() {
1.574 + this.currentMark = 0;
1.575 +}
1.576 +
1.577 +/**
1.578 + * Attempt to satisfy the given constraint and, if successful,
1.579 + * incrementally update the dataflow graph. Details: If satifying
1.580 + * the constraint is successful, it may override a weaker constraint
1.581 + * on its output. The algorithm attempts to resatisfy that
1.582 + * constraint using some other method. This process is repeated
1.583 + * until either a) it reaches a variable that was not previously
1.584 + * determined by any constraint or b) it reaches a constraint that
1.585 + * is too weak to be satisfied using any of its methods. The
1.586 + * variables of constraints that have been processed are marked with
1.587 + * a unique mark value so that we know where we've been. This allows
1.588 + * the algorithm to avoid getting into an infinite loop even if the
1.589 + * constraint graph has an inadvertent cycle.
1.590 + */
1.591 +Planner.prototype.incrementalAdd = function (c) {
1.592 + var mark = this.newMark();
1.593 + var overridden = c.satisfy(mark);
1.594 + while (overridden != null)
1.595 + overridden = overridden.satisfy(mark);
1.596 +}
1.597 +
1.598 +/**
1.599 + * Entry point for retracting a constraint. Remove the given
1.600 + * constraint and incrementally update the dataflow graph.
1.601 + * Details: Retracting the given constraint may allow some currently
1.602 + * unsatisfiable downstream constraint to be satisfied. We therefore collect
1.603 + * a list of unsatisfied downstream constraints and attempt to
1.604 + * satisfy each one in turn. This list is traversed by constraint
1.605 + * strength, strongest first, as a heuristic for avoiding
1.606 + * unnecessarily adding and then overriding weak constraints.
1.607 + * Assume: c is satisfied.
1.608 + */
1.609 +Planner.prototype.incrementalRemove = function (c) {
1.610 + var out = c.output();
1.611 + c.markUnsatisfied();
1.612 + c.removeFromGraph();
1.613 + var unsatisfied = this.removePropagateFrom(out);
1.614 + var strength = Strength.REQUIRED;
1.615 + do {
1.616 + for (var i = 0; i < unsatisfied.size(); i++) {
1.617 + var u = unsatisfied.at(i);
1.618 + if (u.strength == strength)
1.619 + this.incrementalAdd(u);
1.620 + }
1.621 + strength = strength.nextWeaker();
1.622 + } while (strength != Strength.WEAKEST);
1.623 +}
1.624 +
1.625 +/**
1.626 + * Select a previously unused mark value.
1.627 + */
1.628 +Planner.prototype.newMark = function () {
1.629 + return ++this.currentMark;
1.630 +}
1.631 +
1.632 +/**
1.633 + * Extract a plan for resatisfaction starting from the given source
1.634 + * constraints, usually a set of input constraints. This method
1.635 + * assumes that stay optimization is desired; the plan will contain
1.636 + * only constraints whose output variables are not stay. Constraints
1.637 + * that do no computation, such as stay and edit constraints, are
1.638 + * not included in the plan.
1.639 + * Details: The outputs of a constraint are marked when it is added
1.640 + * to the plan under construction. A constraint may be appended to
1.641 + * the plan when all its input variables are known. A variable is
1.642 + * known if either a) the variable is marked (indicating that has
1.643 + * been computed by a constraint appearing earlier in the plan), b)
1.644 + * the variable is 'stay' (i.e. it is a constant at plan execution
1.645 + * time), or c) the variable is not determined by any
1.646 + * constraint. The last provision is for past states of history
1.647 + * variables, which are not stay but which are also not computed by
1.648 + * any constraint.
1.649 + * Assume: sources are all satisfied.
1.650 + */
1.651 +Planner.prototype.makePlan = function (sources) {
1.652 + var mark = this.newMark();
1.653 + var plan = new Plan();
1.654 + var todo = sources;
1.655 + while (todo.size() > 0) {
1.656 + var c = todo.removeFirst();
1.657 + if (c.output().mark != mark && c.inputsKnown(mark)) {
1.658 + plan.addConstraint(c);
1.659 + c.output().mark = mark;
1.660 + this.addConstraintsConsumingTo(c.output(), todo);
1.661 + }
1.662 + }
1.663 + return plan;
1.664 +}
1.665 +
1.666 +/**
1.667 + * Extract a plan for resatisfying starting from the output of the
1.668 + * given constraints, usually a set of input constraints.
1.669 + */
1.670 +Planner.prototype.extractPlanFromConstraints = function (constraints) {
1.671 + var sources = new OrderedCollection();
1.672 + for (var i = 0; i < constraints.size(); i++) {
1.673 + var c = constraints.at(i);
1.674 + if (c.isInput() && c.isSatisfied())
1.675 + // not in plan already and eligible for inclusion
1.676 + sources.add(c);
1.677 + }
1.678 + return this.makePlan(sources);
1.679 +}
1.680 +
1.681 +/**
1.682 + * Recompute the walkabout strengths and stay flags of all variables
1.683 + * downstream of the given constraint and recompute the actual
1.684 + * values of all variables whose stay flag is true. If a cycle is
1.685 + * detected, remove the given constraint and answer
1.686 + * false. Otherwise, answer true.
1.687 + * Details: Cycles are detected when a marked variable is
1.688 + * encountered downstream of the given constraint. The sender is
1.689 + * assumed to have marked the inputs of the given constraint with
1.690 + * the given mark. Thus, encountering a marked node downstream of
1.691 + * the output constraint means that there is a path from the
1.692 + * constraint's output to one of its inputs.
1.693 + */
1.694 +Planner.prototype.addPropagate = function (c, mark) {
1.695 + var todo = new OrderedCollection();
1.696 + todo.add(c);
1.697 + while (todo.size() > 0) {
1.698 + var d = todo.removeFirst();
1.699 + if (d.output().mark == mark) {
1.700 + this.incrementalRemove(c);
1.701 + return false;
1.702 + }
1.703 + d.recalculate();
1.704 + this.addConstraintsConsumingTo(d.output(), todo);
1.705 + }
1.706 + return true;
1.707 +}
1.708 +
1.709 +
1.710 +/**
1.711 + * Update the walkabout strengths and stay flags of all variables
1.712 + * downstream of the given constraint. Answer a collection of
1.713 + * unsatisfied constraints sorted in order of decreasing strength.
1.714 + */
1.715 +Planner.prototype.removePropagateFrom = function (out) {
1.716 + out.determinedBy = null;
1.717 + out.walkStrength = Strength.WEAKEST;
1.718 + out.stay = true;
1.719 + var unsatisfied = new OrderedCollection();
1.720 + var todo = new OrderedCollection();
1.721 + todo.add(out);
1.722 + while (todo.size() > 0) {
1.723 + var v = todo.removeFirst();
1.724 + for (var i = 0; i < v.constraints.size(); i++) {
1.725 + var c = v.constraints.at(i);
1.726 + if (!c.isSatisfied())
1.727 + unsatisfied.add(c);
1.728 + }
1.729 + var determining = v.determinedBy;
1.730 + for (var i = 0; i < v.constraints.size(); i++) {
1.731 + var next = v.constraints.at(i);
1.732 + if (next != determining && next.isSatisfied()) {
1.733 + next.recalculate();
1.734 + todo.add(next.output());
1.735 + }
1.736 + }
1.737 + }
1.738 + return unsatisfied;
1.739 +}
1.740 +
1.741 +Planner.prototype.addConstraintsConsumingTo = function (v, coll) {
1.742 + var determining = v.determinedBy;
1.743 + var cc = v.constraints;
1.744 + for (var i = 0; i < cc.size(); i++) {
1.745 + var c = cc.at(i);
1.746 + if (c != determining && c.isSatisfied())
1.747 + coll.add(c);
1.748 + }
1.749 +}
1.750 +
1.751 +/* --- *
1.752 + * P l a n
1.753 + * --- */
1.754 +
1.755 +/**
1.756 + * A Plan is an ordered list of constraints to be executed in sequence
1.757 + * to resatisfy all currently satisfiable constraints in the face of
1.758 + * one or more changing inputs.
1.759 + */
1.760 +function Plan() {
1.761 + this.v = new OrderedCollection();
1.762 +}
1.763 +
1.764 +Plan.prototype.addConstraint = function (c) {
1.765 + this.v.add(c);
1.766 +}
1.767 +
1.768 +Plan.prototype.size = function () {
1.769 + return this.v.size();
1.770 +}
1.771 +
1.772 +Plan.prototype.constraintAt = function (index) {
1.773 + return this.v.at(index);
1.774 +}
1.775 +
1.776 +Plan.prototype.execute = function () {
1.777 + for (var i = 0; i < this.size(); i++) {
1.778 + var c = this.constraintAt(i);
1.779 + c.execute();
1.780 + }
1.781 +}
1.782 +
1.783 +/* --- *
1.784 + * M a i n
1.785 + * --- */
1.786 +
1.787 +/**
1.788 + * This is the standard DeltaBlue benchmark. A long chain of equality
1.789 + * constraints is constructed with a stay constraint on one end. An
1.790 + * edit constraint is then added to the opposite end and the time is
1.791 + * measured for adding and removing this constraint, and extracting
1.792 + * and executing a constraint satisfaction plan. There are two cases.
1.793 + * In case 1, the added constraint is stronger than the stay
1.794 + * constraint and values must propagate down the entire length of the
1.795 + * chain. In case 2, the added constraint is weaker than the stay
1.796 + * constraint so it cannot be accomodated. The cost in this case is,
1.797 + * of course, very low. Typical situations lie somewhere between these
1.798 + * two extremes.
1.799 + */
1.800 +function chainTest(n) {
1.801 + planner = new Planner();
1.802 + var prev = null, first = null, last = null;
1.803 +
1.804 + // Build chain of n equality constraints
1.805 + for (var i = 0; i <= n; i++) {
1.806 + var name = "v" + i;
1.807 + var v = new Variable(name);
1.808 + if (prev != null)
1.809 + new EqualityConstraint(prev, v, Strength.REQUIRED);
1.810 + if (i == 0) first = v;
1.811 + if (i == n) last = v;
1.812 + prev = v;
1.813 + }
1.814 +
1.815 + new StayConstraint(last, Strength.STRONG_DEFAULT);
1.816 + var edit = new EditConstraint(first, Strength.PREFERRED);
1.817 + var edits = new OrderedCollection();
1.818 + edits.add(edit);
1.819 + var plan = planner.extractPlanFromConstraints(edits);
1.820 + for (var i = 0; i < 100; i++) {
1.821 + first.value = i;
1.822 + plan.execute();
1.823 + if (last.value != i)
1.824 + alert("Chain test failed.");
1.825 + }
1.826 +}
1.827 +
1.828 +/**
1.829 + * This test constructs a two sets of variables related to each
1.830 + * other by a simple linear transformation (scale and offset). The
1.831 + * time is measured to change a variable on either side of the
1.832 + * mapping and to change the scale and offset factors.
1.833 + */
1.834 +function projectionTest(n) {
1.835 + planner = new Planner();
1.836 + var scale = new Variable("scale", 10);
1.837 + var offset = new Variable("offset", 1000);
1.838 + var src = null, dst = null;
1.839 +
1.840 + var dests = new OrderedCollection();
1.841 + for (var i = 0; i < n; i++) {
1.842 + src = new Variable("src" + i, i);
1.843 + dst = new Variable("dst" + i, i);
1.844 + dests.add(dst);
1.845 + new StayConstraint(src, Strength.NORMAL);
1.846 + new ScaleConstraint(src, scale, offset, dst, Strength.REQUIRED);
1.847 + }
1.848 +
1.849 + change(src, 17);
1.850 + if (dst.value != 1170) alert("Projection 1 failed");
1.851 + change(dst, 1050);
1.852 + if (src.value != 5) alert("Projection 2 failed");
1.853 + change(scale, 5);
1.854 + for (var i = 0; i < n - 1; i++) {
1.855 + if (dests.at(i).value != i * 5 + 1000)
1.856 + alert("Projection 3 failed");
1.857 + }
1.858 + change(offset, 2000);
1.859 + for (var i = 0; i < n - 1; i++) {
1.860 + if (dests.at(i).value != i * 5 + 2000)
1.861 + alert("Projection 4 failed");
1.862 + }
1.863 +}
1.864 +
1.865 +function change(v, newValue) {
1.866 + var edit = new EditConstraint(v, Strength.PREFERRED);
1.867 + var edits = new OrderedCollection();
1.868 + edits.add(edit);
1.869 + var plan = planner.extractPlanFromConstraints(edits);
1.870 + for (var i = 0; i < 10; i++) {
1.871 + v.value = newValue;
1.872 + plan.execute();
1.873 + }
1.874 + edit.destroyConstraint();
1.875 +}
1.876 +
1.877 +// Global variable holding the current planner.
1.878 +var planner = null;
1.879 +
1.880 +function deltaBlue() {
1.881 + chainTest(100);
1.882 + projectionTest(100);
1.883 +}
