134 lines
4.4 KiB
JavaScript
134 lines
4.4 KiB
JavaScript
/*
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* Copyright (C) 2017 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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"use strict";
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class Node {
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visit(visitor)
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{
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let visitFunc = visitor["visit" + this.constructor.name];
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if (!visitFunc)
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throw new Error("No visit function for " + this.constructor.name + " in " + visitor.constructor.name);
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let returnValue = visitFunc.call(visitor, this);
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if ("returnValue" in visitor)
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returnValue = visitor.returnValue;
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return returnValue;
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}
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static visit(node, visitor)
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{
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if (node instanceof Node)
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return node.visit(visitor);
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return node;
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}
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unify(unificationContext, other)
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{
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if (!other)
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throw new Error("Null other");
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let unifyThis = this.unifyNode;
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let unifyOther = other.unifyNode;
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if (unifyThis == unifyOther)
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return true;
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if (unifyOther.typeVariableUnify(unificationContext, unifyThis))
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return true;
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return unifyThis.unifyImpl(unificationContext, unifyOther);
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}
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unifyImpl(unificationContext, other)
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{
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if (other.typeVariableUnify(unificationContext, this))
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return true;
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return this == other;
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}
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typeVariableUnify(unificationContext, other)
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{
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return false;
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}
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_typeVariableUnifyImpl(unificationContext, other)
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{
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let realThis = unificationContext.find(this);
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if (realThis != this)
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return realThis.unify(unificationContext, other);
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unificationContext.union(this, other);
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return true;
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}
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// Most type variables don't care about this.
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prepareToVerify(unificationContext) { }
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commitUnification(unificationContext) { }
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get unifyNode() { return this; }
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get isUnifiable() { return false; }
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get isLiteral() { return false; }
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get isNative() { return false; }
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conversionCost(unificationContext) { return 0; }
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equals(other)
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{
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let unificationContext = new UnificationContext();
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if (this.unify(unificationContext, other) && unificationContext.verify().result)
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return unificationContext;
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return false;
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}
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equalsWithCommit(other)
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{
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let unificationContext = this.equals(other);
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if (!unificationContext)
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return false;
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unificationContext.commit();
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return unificationContext;
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}
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commit()
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{
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let unificationContext = new UnificationContext();
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unificationContext.addExtraNode(this);
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let result = unificationContext.verify();
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if (!result.result)
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throw new WError(node.origin.originString, "Could not infer type: " + result.reason);
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unificationContext.commit();
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return unificationContext.find(this);
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}
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substitute(parameters, argumentList)
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{
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return this.visit(new Substitution(parameters, argumentList));
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}
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substituteToUnification(parameters, unificationContext)
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{
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return this.substitute(
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parameters,
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parameters.map(type => unificationContext.find(type)));
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}
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}
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