107 lines
4.0 KiB
JavaScript
107 lines
4.0 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 TypeVariable extends Type {
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constructor(origin, name, protocol)
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{
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super();
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this._origin = origin;
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this._name = name;
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this._protocol = protocol;
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}
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get origin() { return this._origin; }
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get name() { return this._name; }
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get protocol() { return this._protocol; }
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get isPrimitive()
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{
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return this._protocol && this._protocol.isPrimitive;
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}
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get isUnifiable() { return true; }
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inherits(protocol)
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{
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if (!protocol)
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return {result: true};
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if (!this.protocol)
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return {result: false, reason: "Type variable " + this + " does not have a protocol"};
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return this.protocol.inherits(protocol);
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}
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typeVariableUnify(unificationContext, other)
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{
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if (!(other instanceof Type))
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return false;
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return this._typeVariableUnifyImpl(unificationContext, other);
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}
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unifyImpl(unificationContext, other)
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{
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return this.typeVariableUnify(unificationContext, other);
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}
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verifyAsArgument(unificationContext)
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{
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let realThis = unificationContext.find(this);
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// The thing we get unified with must be a type variable that accepts a broader set of
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// things than we do.
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if (!(realThis instanceof TypeVariable))
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return {result: false, reason: "Type variable argument " + this + " cannot be passed to non-type-variable parameter type " + realThis};
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if (!this.protocol) {
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if (realThis.protocol)
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return {result: false, reason: "Type variable without protocol " + this + " cannot be passed to parameter type variable with protocol " + realThis.protocol};
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return {result: true};
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}
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let result = this.protocol.inherits(realThis.protocol);
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if (!result.result)
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return {result: false, reason: "Protocol " + this.protocol + " does not subsume protocol " + realThis.protocol + " (passing type " + this + " to type " + realThis + "): " + result.reason};
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return {result: true};
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}
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verifyAsParameter(unificationContext)
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{
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if (!this.protocol)
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return {result: true};
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let realThis = unificationContext.find(this);
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let result = realThis.inherits(this.protocol);
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if (!result.result)
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return {result: false, reason: "Type " + realThis + " does not inherit protocol " + this.protocol + " (passing type " + realThis + " to type " + this + "): " + result.reason};
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return {result: true};
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}
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toString()
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{
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return this.name + (this.protocol ? ":" + this.protocol.name : "");
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}
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}
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