The Tor Browser: js/src/v8/deltablue.js@129ffea94266 (annotated)

js/src/v8/deltablue.js@129ffea94266 (annotated)

js/src/v8/deltablue.js

Sat, 03 Jan 2015 20:18:00 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Sat, 03 Jan 2015 20:18:00 +0100
branch: TOR_BUG_3246
changeset 7: 129ffea94266
permissions: -rw-r--r--

Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.

 // Copyright 2008 the V8 project authors. All rights reserved.
 // Copyright 1996 John Maloney and Mario Wolczko.
 // This program is free software; you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
 // the Free Software Foundation; either version 2 of the License, or
 // (at your option) any later version.
 //
 // This program is distributed in the hope that it will be useful,
 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 // GNU General Public License for more details.
 //
 // You should have received a copy of the GNU General Public License
 // along with this program; if not, write to the Free Software
 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 // This implementation of the DeltaBlue benchmark is derived
 // from the Smalltalk implementation by John Maloney and Mario
 // Wolczko. Some parts have been translated directly, whereas
 // others have been modified more aggresively to make it feel
 // more like a JavaScript program.
 var DeltaBlue = new BenchmarkSuite('DeltaBlue', 66118, [
   new Benchmark('DeltaBlue', deltaBlue)
 ]);
 /**
  * A JavaScript implementation of the DeltaBlue constraint-solving
  * algorithm, as described in:
  *
  * "The DeltaBlue Algorithm: An Incremental Constraint Hierarchy Solver"
  *   Bjorn N. Freeman-Benson and John Maloney
  *   January 1990 Communications of the ACM,
  *   also available as University of Washington TR 89-08-06.
  *
  * Beware: this benchmark is written in a grotesque style where
  * the constraint model is built by side-effects from constructors.
  * I've kept it this way to avoid deviating too much from the original
  * implementation.
  */
 /* --- O b j e c t   M o d e l --- */
 Object.prototype.inheritsFrom = function (shuper) {
   function Inheriter() { }
   Inheriter.prototype = shuper.prototype;
   this.prototype = new Inheriter();
   this.superConstructor = shuper;
 }
 function OrderedCollection() {
   this.elms = new Array();
 }
 OrderedCollection.prototype.add = function (elm) {
   this.elms.push(elm);
 }
 OrderedCollection.prototype.at = function (index) {
   return this.elms[index];
 }
 OrderedCollection.prototype.size = function () {
   return this.elms.length;
 }
 OrderedCollection.prototype.removeFirst = function () {
   return this.elms.pop();
 }
 OrderedCollection.prototype.remove = function (elm) {
   var index = 0, skipped = 0;
   for (var i = 0; i < this.elms.length; i++) {
     var value = this.elms[i];
     if (value != elm) {
       this.elms[index] = value;
       index++;
     } else {
       skipped++;
     }
   }
   for (var i = 0; i < skipped; i++)
     this.elms.pop();
 }
 /* --- *
  * S t r e n g t h
  * --- */
 /**
  * Strengths are used to measure the relative importance of constraints.
  * New strengths may be inserted in the strength hierarchy without
  * disrupting current constraints.  Strengths cannot be created outside
  * this class, so pointer comparison can be used for value comparison.
  */
 function Strength(strengthValue, name) {
   this.strengthValue = strengthValue;
   this.name = name;
 }
 Strength.stronger = function (s1, s2) {
   return s1.strengthValue < s2.strengthValue;
 }
 Strength.weaker = function (s1, s2) {
   return s1.strengthValue > s2.strengthValue;
 }
 Strength.weakestOf = function (s1, s2) {
   return this.weaker(s1, s2) ? s1 : s2;
 }
 Strength.strongest = function (s1, s2) {
   return this.stronger(s1, s2) ? s1 : s2;
 }
 Strength.prototype.nextWeaker = function () {
   switch (this.strengthValue) {
     case 0: return Strength.WEAKEST;
     case 1: return Strength.WEAK_DEFAULT;
     case 2: return Strength.NORMAL;
     case 3: return Strength.STRONG_DEFAULT;
     case 4: return Strength.PREFERRED;
     case 5: return Strength.REQUIRED;
   }
 }
 // Strength constants.
 Strength.REQUIRED        = new Strength(0, "required");
 Strength.STONG_PREFERRED = new Strength(1, "strongPreferred");
 Strength.PREFERRED       = new Strength(2, "preferred");
 Strength.STRONG_DEFAULT  = new Strength(3, "strongDefault");
 Strength.NORMAL          = new Strength(4, "normal");
 Strength.WEAK_DEFAULT    = new Strength(5, "weakDefault");
 Strength.WEAKEST         = new Strength(6, "weakest");
 /* --- *
  * C o n s t r a i n t
  * --- */
 /**
  * An abstract class representing a system-maintainable relationship
  * (or "constraint") between a set of variables. A constraint supplies
  * a strength instance variable; concrete subclasses provide a means
  * of storing the constrained variables and other information required
  * to represent a constraint.
  */
 function Constraint(strength) {
   this.strength = strength;
 }
 /**
  * Activate this constraint and attempt to satisfy it.
  */
 Constraint.prototype.addConstraint = function () {
   this.addToGraph();
   planner.incrementalAdd(this);
 }
 /**
  * Attempt to find a way to enforce this constraint. If successful,
  * record the solution, perhaps modifying the current dataflow
  * graph. Answer the constraint that this constraint overrides, if
  * there is one, or nil, if there isn't.
  * Assume: I am not already satisfied.
  */
 Constraint.prototype.satisfy = function (mark) {
   this.chooseMethod(mark);
   if (!this.isSatisfied()) {
     if (this.strength == Strength.REQUIRED)
       alert("Could not satisfy a required constraint!");
     return null;
   }
   this.markInputs(mark);
   var out = this.output();
   var overridden = out.determinedBy;
   if (overridden != null) overridden.markUnsatisfied();
   out.determinedBy = this;
   if (!planner.addPropagate(this, mark))
     alert("Cycle encountered");
   out.mark = mark;
   return overridden;
 }
 Constraint.prototype.destroyConstraint = function () {
   if (this.isSatisfied()) planner.incrementalRemove(this);
   else this.removeFromGraph();
 }
 /**
  * Normal constraints are not input constraints.  An input constraint
  * is one that depends on external state, such as the mouse, the
  * keybord, a clock, or some arbitraty piece of imperative code.
  */
 Constraint.prototype.isInput = function () {
   return false;
 }
 /* --- *
  * U n a r y   C o n s t r a i n t
  * --- */
 /**
  * Abstract superclass for constraints having a single possible output
  * variable.
  */
 function UnaryConstraint(v, strength) {
   UnaryConstraint.superConstructor.call(this, strength);
   this.myOutput = v;
   this.satisfied = false;
   this.addConstraint();
 }
 UnaryConstraint.inheritsFrom(Constraint);
 /**
  * Adds this constraint to the constraint graph
  */
 UnaryConstraint.prototype.addToGraph = function () {
   this.myOutput.addConstraint(this);
   this.satisfied = false;
 }
 /**
  * Decides if this constraint can be satisfied and records that
  * decision.
  */
 UnaryConstraint.prototype.chooseMethod = function (mark) {
   this.satisfied = (this.myOutput.mark != mark)
     && Strength.stronger(this.strength, this.myOutput.walkStrength);
 }
 /**
  * Returns true if this constraint is satisfied in the current solution.
  */
 UnaryConstraint.prototype.isSatisfied = function () {
   return this.satisfied;
 }
 UnaryConstraint.prototype.markInputs = function (mark) {
   // has no inputs
 }
 /**
  * Returns the current output variable.
  */
 UnaryConstraint.prototype.output = function () {
   return this.myOutput;
 }
 /**
  * Calculate the walkabout strength, the stay flag, and, if it is
  * 'stay', the value for the current output of this constraint. Assume
  * this constraint is satisfied.
  */
 UnaryConstraint.prototype.recalculate = function () {
   this.myOutput.walkStrength = this.strength;
   this.myOutput.stay = !this.isInput();
   if (this.myOutput.stay) this.execute(); // Stay optimization
 }
 /**
  * Records that this constraint is unsatisfied
  */
 UnaryConstraint.prototype.markUnsatisfied = function () {
   this.satisfied = false;
 }
 UnaryConstraint.prototype.inputsKnown = function () {
   return true;
 }
 UnaryConstraint.prototype.removeFromGraph = function () {
   if (this.myOutput != null) this.myOutput.removeConstraint(this);
   this.satisfied = false;
 }
 /* --- *
  * S t a y   C o n s t r a i n t
  * --- */
 /**
  * Variables that should, with some level of preference, stay the same.
  * Planners may exploit the fact that instances, if satisfied, will not
  * change their output during plan execution.  This is called "stay
  * optimization".
  */
 function StayConstraint(v, str) {
   StayConstraint.superConstructor.call(this, v, str);
 }
 StayConstraint.inheritsFrom(UnaryConstraint);
 StayConstraint.prototype.execute = function () {
   // Stay constraints do nothing
 }
 /* --- *
  * E d i t   C o n s t r a i n t
  * --- */
 /**
  * A unary input constraint used to mark a variable that the client
  * wishes to change.
  */
 function EditConstraint(v, str) {
   EditConstraint.superConstructor.call(this, v, str);
 }
 EditConstraint.inheritsFrom(UnaryConstraint);
 /**
  * Edits indicate that a variable is to be changed by imperative code.
  */
 EditConstraint.prototype.isInput = function () {
   return true;
 }
 EditConstraint.prototype.execute = function () {
   // Edit constraints do nothing
 }
 /* --- *
  * B i n a r y   C o n s t r a i n t
  * --- */
 var Direction = new Object();
 Direction.NONE     = 0;
 Direction.FORWARD  = 1;
 Direction.BACKWARD = -1;
 /**
  * Abstract superclass for constraints having two possible output
  * variables.
  */
 function BinaryConstraint(var1, var2, strength) {
   BinaryConstraint.superConstructor.call(this, strength);
   this.v1 = var1;
   this.v2 = var2;
   this.direction = Direction.NONE;
   this.addConstraint();
 }
 BinaryConstraint.inheritsFrom(Constraint);
 /**
  * Decides if this constraint can be satisfied and which way it
  * should flow based on the relative strength of the variables related,
  * and record that decision.
  */
 BinaryConstraint.prototype.chooseMethod = function (mark) {
   if (this.v1.mark == mark) {
     this.direction = (this.v2.mark != mark && Strength.stronger(this.strength, this.v2.walkStrength))
       ? Direction.FORWARD
       : Direction.NONE;
   }
   if (this.v2.mark == mark) {
     this.direction = (this.v1.mark != mark && Strength.stronger(this.strength, this.v1.walkStrength))
       ? Direction.BACKWARD
       : Direction.NONE;
   }
   if (Strength.weaker(this.v1.walkStrength, this.v2.walkStrength)) {
     this.direction = Strength.stronger(this.strength, this.v1.walkStrength)
       ? Direction.BACKWARD
       : Direction.NONE;
   } else {
     this.direction = Strength.stronger(this.strength, this.v2.walkStrength)
       ? Direction.FORWARD
       : Direction.BACKWARD
   }
 }
 /**
  * Add this constraint to the constraint graph
  */
 BinaryConstraint.prototype.addToGraph = function () {
   this.v1.addConstraint(this);
   this.v2.addConstraint(this);
   this.direction = Direction.NONE;
 }
 /**
  * Answer true if this constraint is satisfied in the current solution.
  */
 BinaryConstraint.prototype.isSatisfied = function () {
   return this.direction != Direction.NONE;
 }
 /**
  * Mark the input variable with the given mark.
  */
 BinaryConstraint.prototype.markInputs = function (mark) {
   this.input().mark = mark;
 }
 /**
  * Returns the current input variable
  */
 BinaryConstraint.prototype.input = function () {
   return (this.direction == Direction.FORWARD) ? this.v1 : this.v2;
 }
 /**
  * Returns the current output variable
  */
 BinaryConstraint.prototype.output = function () {
   return (this.direction == Direction.FORWARD) ? this.v2 : this.v1;
 }
 /**
  * Calculate the walkabout strength, the stay flag, and, if it is
  * 'stay', the value for the current output of this
  * constraint. Assume this constraint is satisfied.
  */
 BinaryConstraint.prototype.recalculate = function () {
   var ihn = this.input(), out = this.output();
   out.walkStrength = Strength.weakestOf(this.strength, ihn.walkStrength);
   out.stay = ihn.stay;
   if (out.stay) this.execute();
 }
 /**
  * Record the fact that this constraint is unsatisfied.
  */
 BinaryConstraint.prototype.markUnsatisfied = function () {
   this.direction = Direction.NONE;
 }
 BinaryConstraint.prototype.inputsKnown = function (mark) {
   var i = this.input();
   return i.mark == mark || i.stay || i.determinedBy == null;
 }
 BinaryConstraint.prototype.removeFromGraph = function () {
   if (this.v1 != null) this.v1.removeConstraint(this);
   if (this.v2 != null) this.v2.removeConstraint(this);
   this.direction = Direction.NONE;
 }
 /* --- *
  * S c a l e   C o n s t r a i n t
  * --- */
 /**
  * Relates two variables by the linear scaling relationship: "v2 =
  * (v1 * scale) + offset". Either v1 or v2 may be changed to maintain
  * this relationship but the scale factor and offset are considered
  * read-only.
  */
 function ScaleConstraint(src, scale, offset, dest, strength) {
   this.direction = Direction.NONE;
   this.scale = scale;
   this.offset = offset;
   ScaleConstraint.superConstructor.call(this, src, dest, strength);
 }
 ScaleConstraint.inheritsFrom(BinaryConstraint);
 /**
  * Adds this constraint to the constraint graph.
  */
 ScaleConstraint.prototype.addToGraph = function () {
   ScaleConstraint.superConstructor.prototype.addToGraph.call(this);
   this.scale.addConstraint(this);
   this.offset.addConstraint(this);
 }
 ScaleConstraint.prototype.removeFromGraph = function () {
   ScaleConstraint.superConstructor.prototype.removeFromGraph.call(this);
   if (this.scale != null) this.scale.removeConstraint(this);
   if (this.offset != null) this.offset.removeConstraint(this);
 }
 ScaleConstraint.prototype.markInputs = function (mark) {
   ScaleConstraint.superConstructor.prototype.markInputs.call(this, mark);
   this.scale.mark = this.offset.mark = mark;
 }
 /**
  * Enforce this constraint. Assume that it is satisfied.
  */
 ScaleConstraint.prototype.execute = function () {
   if (this.direction == Direction.FORWARD) {
     this.v2.value = this.v1.value * this.scale.value + this.offset.value;
   } else {
     this.v1.value = (this.v2.value - this.offset.value) / this.scale.value;
   }
 }
 /**
  * Calculate the walkabout strength, the stay flag, and, if it is
  * 'stay', the value for the current output of this constraint. Assume
  * this constraint is satisfied.
  */
 ScaleConstraint.prototype.recalculate = function () {
   var ihn = this.input(), out = this.output();
   out.walkStrength = Strength.weakestOf(this.strength, ihn.walkStrength);
   out.stay = ihn.stay && this.scale.stay && this.offset.stay;
   if (out.stay) this.execute();
 }
 /* --- *
  * E q u a l i t  y   C o n s t r a i n t
  * --- */
 /**
  * Constrains two variables to have the same value.
  */
 function EqualityConstraint(var1, var2, strength) {
   EqualityConstraint.superConstructor.call(this, var1, var2, strength);
 }
 EqualityConstraint.inheritsFrom(BinaryConstraint);
 /**
  * Enforce this constraint. Assume that it is satisfied.
  */
 EqualityConstraint.prototype.execute = function () {
   this.output().value = this.input().value;
 }
 /* --- *
  * V a r i a b l e
  * --- */
 /**
  * A constrained variable. In addition to its value, it maintain the
  * structure of the constraint graph, the current dataflow graph, and
  * various parameters of interest to the DeltaBlue incremental
  * constraint solver.
  **/
 function Variable(name, initialValue) {
   this.value = initialValue || 0;
   this.constraints = new OrderedCollection();
   this.determinedBy = null;
   this.mark = 0;
   this.walkStrength = Strength.WEAKEST;
   this.stay = true;
   this.name = name;
 }
 /**
  * Add the given constraint to the set of all constraints that refer
  * this variable.
  */
 Variable.prototype.addConstraint = function (c) {
   this.constraints.add(c);
 }
 /**
  * Removes all traces of c from this variable.
  */
 Variable.prototype.removeConstraint = function (c) {
   this.constraints.remove(c);
   if (this.determinedBy == c) this.determinedBy = null;
 }
 /* --- *
  * P l a n n e r
  * --- */
 /**
  * The DeltaBlue planner
  */
 function Planner() {
   this.currentMark = 0;
 }
 /**
  * Attempt to satisfy the given constraint and, if successful,
  * incrementally update the dataflow graph.  Details: If satifying
  * the constraint is successful, it may override a weaker constraint
  * on its output. The algorithm attempts to resatisfy that
  * constraint using some other method. This process is repeated
  * until either a) it reaches a variable that was not previously
  * determined by any constraint or b) it reaches a constraint that
  * is too weak to be satisfied using any of its methods. The
  * variables of constraints that have been processed are marked with
  * a unique mark value so that we know where we've been. This allows
  * the algorithm to avoid getting into an infinite loop even if the
  * constraint graph has an inadvertent cycle.
  */
 Planner.prototype.incrementalAdd = function (c) {
   var mark = this.newMark();
   var overridden = c.satisfy(mark);
   while (overridden != null)
     overridden = overridden.satisfy(mark);
 }
 /**
  * Entry point for retracting a constraint. Remove the given
  * constraint and incrementally update the dataflow graph.
  * Details: Retracting the given constraint may allow some currently
  * unsatisfiable downstream constraint to be satisfied. We therefore collect
  * a list of unsatisfied downstream constraints and attempt to
  * satisfy each one in turn. This list is traversed by constraint
  * strength, strongest first, as a heuristic for avoiding
  * unnecessarily adding and then overriding weak constraints.
  * Assume: c is satisfied.
  */
 Planner.prototype.incrementalRemove = function (c) {
   var out = c.output();
   c.markUnsatisfied();
   c.removeFromGraph();
   var unsatisfied = this.removePropagateFrom(out);
   var strength = Strength.REQUIRED;
   do {
     for (var i = 0; i < unsatisfied.size(); i++) {
       var u = unsatisfied.at(i);
       if (u.strength == strength)
         this.incrementalAdd(u);
     }
     strength = strength.nextWeaker();
   } while (strength != Strength.WEAKEST);
 }
 /**
  * Select a previously unused mark value.
  */
 Planner.prototype.newMark = function () {
   return ++this.currentMark;
 }
 /**
  * Extract a plan for resatisfaction starting from the given source
  * constraints, usually a set of input constraints. This method
  * assumes that stay optimization is desired; the plan will contain
  * only constraints whose output variables are not stay. Constraints
  * that do no computation, such as stay and edit constraints, are
  * not included in the plan.
  * Details: The outputs of a constraint are marked when it is added
  * to the plan under construction. A constraint may be appended to
  * the plan when all its input variables are known. A variable is
  * known if either a) the variable is marked (indicating that has
  * been computed by a constraint appearing earlier in the plan), b)
  * the variable is 'stay' (i.e. it is a constant at plan execution
  * time), or c) the variable is not determined by any
  * constraint. The last provision is for past states of history
  * variables, which are not stay but which are also not computed by
  * any constraint.
  * Assume: sources are all satisfied.
  */
 Planner.prototype.makePlan = function (sources) {
   var mark = this.newMark();
   var plan = new Plan();
   var todo = sources;
   while (todo.size() > 0) {
     var c = todo.removeFirst();
     if (c.output().mark != mark && c.inputsKnown(mark)) {
       plan.addConstraint(c);
       c.output().mark = mark;
       this.addConstraintsConsumingTo(c.output(), todo);
     }
   }
   return plan;
 }
 /**
  * Extract a plan for resatisfying starting from the output of the
  * given constraints, usually a set of input constraints.
  */
 Planner.prototype.extractPlanFromConstraints = function (constraints) {
   var sources = new OrderedCollection();
   for (var i = 0; i < constraints.size(); i++) {
     var c = constraints.at(i);
     if (c.isInput() && c.isSatisfied())
       // not in plan already and eligible for inclusion
       sources.add(c);
   }
   return this.makePlan(sources);
 }
 /**
  * Recompute the walkabout strengths and stay flags of all variables
  * downstream of the given constraint and recompute the actual
  * values of all variables whose stay flag is true. If a cycle is
  * detected, remove the given constraint and answer
  * false. Otherwise, answer true.
  * Details: Cycles are detected when a marked variable is
  * encountered downstream of the given constraint. The sender is
  * assumed to have marked the inputs of the given constraint with
  * the given mark. Thus, encountering a marked node downstream of
  * the output constraint means that there is a path from the
  * constraint's output to one of its inputs.
  */
 Planner.prototype.addPropagate = function (c, mark) {
   var todo = new OrderedCollection();
   todo.add(c);
   while (todo.size() > 0) {
     var d = todo.removeFirst();
     if (d.output().mark == mark) {
       this.incrementalRemove(c);
       return false;
     }
     d.recalculate();
     this.addConstraintsConsumingTo(d.output(), todo);
   }
   return true;
 }
 /**
  * Update the walkabout strengths and stay flags of all variables
  * downstream of the given constraint. Answer a collection of
  * unsatisfied constraints sorted in order of decreasing strength.
  */
 Planner.prototype.removePropagateFrom = function (out) {
   out.determinedBy = null;
   out.walkStrength = Strength.WEAKEST;
   out.stay = true;
   var unsatisfied = new OrderedCollection();
   var todo = new OrderedCollection();
   todo.add(out);
   while (todo.size() > 0) {
     var v = todo.removeFirst();
     for (var i = 0; i < v.constraints.size(); i++) {
       var c = v.constraints.at(i);
       if (!c.isSatisfied())
         unsatisfied.add(c);
     }
     var determining = v.determinedBy;
     for (var i = 0; i < v.constraints.size(); i++) {
       var next = v.constraints.at(i);
       if (next != determining && next.isSatisfied()) {
         next.recalculate();
         todo.add(next.output());
       }
     }
   }
   return unsatisfied;
 }
 Planner.prototype.addConstraintsConsumingTo = function (v, coll) {
   var determining = v.determinedBy;
   var cc = v.constraints;
   for (var i = 0; i < cc.size(); i++) {
     var c = cc.at(i);
     if (c != determining && c.isSatisfied())
       coll.add(c);
   }
 }
 /* --- *
  * P l a n
  * --- */
 /**
  * A Plan is an ordered list of constraints to be executed in sequence
  * to resatisfy all currently satisfiable constraints in the face of
  * one or more changing inputs.
  */
 function Plan() {
   this.v = new OrderedCollection();
 }
 Plan.prototype.addConstraint = function (c) {
   this.v.add(c);
 }
 Plan.prototype.size = function () {
   return this.v.size();
 }
 Plan.prototype.constraintAt = function (index) {
   return this.v.at(index);
 }
 Plan.prototype.execute = function () {
   for (var i = 0; i < this.size(); i++) {
     var c = this.constraintAt(i);
     c.execute();
   }
 }
 /* --- *
  * M a i n
  * --- */
 /**
  * This is the standard DeltaBlue benchmark. A long chain of equality
  * constraints is constructed with a stay constraint on one end. An
  * edit constraint is then added to the opposite end and the time is
  * measured for adding and removing this constraint, and extracting
  * and executing a constraint satisfaction plan. There are two cases.
  * In case 1, the added constraint is stronger than the stay
  * constraint and values must propagate down the entire length of the
  * chain. In case 2, the added constraint is weaker than the stay
  * constraint so it cannot be accomodated. The cost in this case is,
  * of course, very low. Typical situations lie somewhere between these
  * two extremes.
  */
 function chainTest(n) {
   planner = new Planner();
   var prev = null, first = null, last = null;
   // Build chain of n equality constraints
   for (var i = 0; i <= n; i++) {
     var name = "v" + i;
     var v = new Variable(name);
     if (prev != null)
       new EqualityConstraint(prev, v, Strength.REQUIRED);
     if (i == 0) first = v;
     if (i == n) last = v;
     prev = v;
   }
   new StayConstraint(last, Strength.STRONG_DEFAULT);
   var edit = new EditConstraint(first, Strength.PREFERRED);
   var edits = new OrderedCollection();
   edits.add(edit);
   var plan = planner.extractPlanFromConstraints(edits);
   for (var i = 0; i < 100; i++) {
     first.value = i;
     plan.execute();
     if (last.value != i)
       alert("Chain test failed.");
   }
 }
 /**
  * This test constructs a two sets of variables related to each
  * other by a simple linear transformation (scale and offset). The
  * time is measured to change a variable on either side of the
  * mapping and to change the scale and offset factors.
  */
 function projectionTest(n) {
   planner = new Planner();
   var scale = new Variable("scale", 10);
   var offset = new Variable("offset", 1000);
   var src = null, dst = null;
   var dests = new OrderedCollection();
   for (var i = 0; i < n; i++) {
     src = new Variable("src" + i, i);
     dst = new Variable("dst" + i, i);
     dests.add(dst);
     new StayConstraint(src, Strength.NORMAL);
     new ScaleConstraint(src, scale, offset, dst, Strength.REQUIRED);
   }
   change(src, 17);
   if (dst.value != 1170) alert("Projection 1 failed");
   change(dst, 1050);
   if (src.value != 5) alert("Projection 2 failed");
   change(scale, 5);
   for (var i = 0; i < n - 1; i++) {
     if (dests.at(i).value != i * 5 + 1000)
       alert("Projection 3 failed");
   }
   change(offset, 2000);
   for (var i = 0; i < n - 1; i++) {
     if (dests.at(i).value != i * 5 + 2000)
       alert("Projection 4 failed");
   }
 }
 function change(v, newValue) {
   var edit = new EditConstraint(v, Strength.PREFERRED);
   var edits = new OrderedCollection();
   edits.add(edit);
   var plan = planner.extractPlanFromConstraints(edits);
   for (var i = 0; i < 10; i++) {
     v.value = newValue;
     plan.execute();
   }
   edit.destroyConstraint();
 }
 // Global variable holding the current planner.
 var planner = null;
 function deltaBlue() {
   chainTest(100);
   projectionTest(100);
 }