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Do some basic inference for const object destructuring declarations i…
…n TypedScopeCreator ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=206943596
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src/com/google/javascript/jscomp/DestructuredTarget.java
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| /* | ||
| * Copyright 2018 The Closure Compiler Authors. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package com.google.javascript.jscomp; | ||
|
|
||
| import static com.google.common.base.Preconditions.checkArgument; | ||
|
|
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| import com.google.common.base.Supplier; | ||
| import com.google.javascript.rhino.Node; | ||
| import com.google.javascript.rhino.jstype.JSType; | ||
| import com.google.javascript.rhino.jstype.JSTypeNative; | ||
| import com.google.javascript.rhino.jstype.JSTypeRegistry; | ||
| import javax.annotation.Nullable; | ||
|
|
||
| /** | ||
| * Represents a single target inside a destructuring pattern, whether another pattern or a lhs | ||
| * expression. | ||
| * | ||
| * <p>Call {@code inferType} to do type inference on the target lazily. This class is designed so | ||
| * that a caller can get information about a target, use that information to do additional type | ||
| * inference, and finally call {@code inferType} if desired. | ||
| */ | ||
| final class DestructuredTarget { | ||
| private final JSTypeRegistry registry; | ||
| /** | ||
| * Holds the STRING_KEY or COMPUTED_PROPERTY for a target in an object pattern. Null for targets | ||
| * in array patterns. | ||
| */ | ||
| @Nullable private final Node objectPatternKey; | ||
| /** | ||
| * The target being assigned to. Can be a destructuring pattern or name, if from a declaration, or | ||
| * an arbitrary lhs expression in an assign. | ||
| */ | ||
| private final Node node; | ||
| /** | ||
| * A supplier to get the type of the pattern containing this target. e.g. for `a` in `const {a} = | ||
| * {a: 3}`, the supplier provides the record type `{a: number}` | ||
| * | ||
| * <p>This is only called by {@inferType}, not when calling {@code createTarget}. | ||
| */ | ||
| private final Supplier<JSType> patternTypeSupplier; | ||
|
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| private DestructuredTarget( | ||
| Node node, | ||
| @Nullable Node objectPatternKey, | ||
| JSTypeRegistry registry, | ||
| Supplier<JSType> patternTypeSupplier) { | ||
| this.node = node; | ||
| this.objectPatternKey = objectPatternKey; | ||
| this.registry = registry; | ||
| this.patternTypeSupplier = patternTypeSupplier; | ||
| } | ||
|
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| public Node getNode() { | ||
| return node; | ||
| } | ||
|
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| static DestructuredTarget createTarget( | ||
| JSTypeRegistry registry, Supplier<JSType> destructuringPatternType, Node destructuringChild) { | ||
| checkArgument(destructuringChild.getParent().isDestructuringPattern(), destructuringChild); | ||
| final Node node; | ||
| Node objectLiteralKey = null; | ||
| switch (destructuringChild.getToken()) { | ||
| case STRING_KEY: | ||
| // const {objectLiteralKey: x} = ... | ||
| objectLiteralKey = destructuringChild; | ||
| Node value = destructuringChild.getFirstChild(); | ||
| node = value.isDefaultValue() ? value.getFirstChild() : value; | ||
| break; | ||
|
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| case COMPUTED_PROP: | ||
| // const {['objectLiteralKey']: x} = ... | ||
| objectLiteralKey = destructuringChild; | ||
| value = destructuringChild.getSecondChild(); | ||
| node = value.isDefaultValue() ? value.getFirstChild() : value; | ||
| break; | ||
|
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| case OBJECT_PATTERN: // const [{x}] = ... | ||
| case ARRAY_PATTERN: // const [[x]] = ... | ||
| case NAME: // const [x] = ... | ||
| node = destructuringChild; | ||
| break; | ||
|
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| case DEFAULT_VALUE: // const [x = 3] = ... | ||
| case REST: // const [...x] = ... | ||
| node = destructuringChild.getFirstChild(); | ||
| break; | ||
|
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||
| default: | ||
| throw new IllegalStateException("Unexpected parameter node " + destructuringChild); | ||
| } | ||
| return new DestructuredTarget(node, objectLiteralKey, registry, destructuringPatternType); | ||
| } | ||
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| Supplier<JSType> getInferredTypeSupplier() { | ||
| return () -> inferType(); | ||
| } | ||
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| JSType inferType() { | ||
| // TODO(b/203401365): handle array patterns | ||
| return objectPatternKey != null ? inferObjectPatternKeyType() : null; | ||
| } | ||
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| private JSType inferObjectPatternKeyType() { | ||
| JSType patternType = patternTypeSupplier.get(); | ||
| switch (objectPatternKey.getToken()) { | ||
| case STRING_KEY: | ||
| JSType propertyType = patternType.findPropertyType(objectPatternKey.getString()); | ||
| return propertyType != null | ||
| ? propertyType | ||
| : registry.getNativeType(JSTypeNative.UNKNOWN_TYPE); | ||
|
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| case COMPUTED_PROP: | ||
| return patternType != null | ||
| ? patternType | ||
| .getTemplateTypeMap() | ||
| .getResolvedTemplateType(registry.getObjectElementKey()) | ||
| : registry.getNativeType(JSTypeNative.UNKNOWN_TYPE); | ||
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| default: | ||
| // TODO(b/203401365): handle object rest | ||
| throw new IllegalStateException("Unexpected key " + objectPatternKey); | ||
| } | ||
|
|
||
| // TODO(b/77597706): handle default values | ||
| } | ||
| } |
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