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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;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.base.Supplier;
import com.google.common.collect.ImmutableList;
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.
*
* 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.
*/
public 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.
*/
@Nullable 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}`
*
*
This is only called by {@inferType}, not when calling {@code createTarget}.
*/
private final Supplier patternTypeSupplier;
/** The default value of this target, or null if none. e.g. for `[a = 3] = rhs`, this is `3`. */
@Nullable private final Node defaultValue;
/** Whether this is a rest key */
private final boolean isRest;
/** The destructuring pattern containing this target */
private final Node pattern;
private DestructuredTarget(
Node pattern,
Node node,
@Nullable Node defaultValue,
@Nullable Node objectPatternKey,
JSTypeRegistry registry,
Supplier patternTypeSupplier,
boolean isRest) {
this.pattern = pattern;
this.node = node;
this.objectPatternKey = objectPatternKey;
this.registry = registry;
this.patternTypeSupplier = patternTypeSupplier;
this.isRest = isRest;
this.defaultValue = defaultValue;
}
/** Returns a COMPUTED_PROP node or null */
@Nullable
public Node getComputedProperty() {
return hasComputedProperty() ? objectPatternKey : null;
}
public boolean hasComputedProperty() {
return objectPatternKey != null && objectPatternKey.isComputedProp();
}
public boolean hasStringKey() {
return objectPatternKey != null && objectPatternKey.isStringKey();
}
/** Returns a STRING_KEY node or null */
@Nullable
public Node getStringKey() {
return hasStringKey() ? objectPatternKey : null;
}
@Nullable
public Node getDefaultValue() {
return defaultValue;
}
public boolean hasDefaultValue() {
return defaultValue != null;
}
public Node getNode() {
return node;
}
private static class Builder {
private final JSTypeRegistry registry;
private final Supplier patternTypeSupplier;
private final Node pattern;
private Node node;
@Nullable private Node defaultValue = null;
@Nullable private Node objectPatternKey = null;
private boolean isRest = false;
Builder(JSTypeRegistry registry, Node pattern, Supplier patternTypeSupplier) {
this.registry = registry;
this.patternTypeSupplier = patternTypeSupplier;
this.pattern = pattern;
}
Builder setNode(Node node) {
this.node = node;
return this;
}
Builder setDefaultValue(Node defaultValue) {
this.defaultValue = defaultValue;
return this;
}
Builder setObjectPatternKey(Node objectPatternKey) {
this.objectPatternKey = objectPatternKey;
return this;
}
Builder setIsRest(boolean isRest) {
this.isRest = isRest;
return this;
}
DestructuredTarget build() {
checkNotNull(this.node, "Must set a node");
return new DestructuredTarget(
pattern, node, defaultValue, objectPatternKey, registry, patternTypeSupplier, isRest);
}
}
static DestructuredTarget createTarget(
JSTypeRegistry registry, JSType destructuringPatternType, Node destructuringChild) {
return createTarget(registry, () -> destructuringPatternType, destructuringChild);
}
/**
* Converts a given child of a destructuring pattern (in the AST) to an instance of this class.
*
* NOTE: does not accept EMPTY nodes
*/
static DestructuredTarget createTarget(
JSTypeRegistry registry, Supplier destructuringPatternType, Node destructuringChild) {
checkArgument(destructuringChild.getParent().isDestructuringPattern(), destructuringChild);
Builder builder =
new Builder(registry, destructuringChild.getParent(), destructuringPatternType);
switch (destructuringChild.getToken()) {
case STRING_KEY:
// const {objectLiteralKey: x} = ...
builder.setObjectPatternKey(destructuringChild);
Node value = destructuringChild.getFirstChild();
if (value.isDefaultValue()) {
builder.setNode(value.getFirstChild());
builder.setDefaultValue(value.getSecondChild());
} else {
builder.setNode(value);
}
break;
case COMPUTED_PROP:
// const {['objectLiteralKey']: x} = ...
builder.setObjectPatternKey(destructuringChild);
value = destructuringChild.getSecondChild();
if (value.isDefaultValue()) {
builder.setNode(value.getFirstChild());
builder.setDefaultValue(value.getSecondChild());
} else {
builder.setNode(value);
}
break;
case OBJECT_PATTERN: // const [{x}] = ...
case ARRAY_PATTERN: // const [[x]] = ...
case NAME: // const [x] = ...
case GETELEM: // [obj[3]] = ...
case GETPROP: // [this.x] = ...
builder.setNode(destructuringChild);
break;
case DEFAULT_VALUE: // const [x = 3] = ...
builder.setNode(destructuringChild.getFirstChild());
builder.setDefaultValue(destructuringChild.getSecondChild());
break;
case ITER_REST:
case OBJECT_REST:
// const [...x] = ...
// const {...x} = ...
builder.setNode(destructuringChild.getFirstChild());
builder.setIsRest(true);
break;
default:
throw new IllegalArgumentException(
"Unexpected child of destructuring pattern " + destructuringChild);
}
return builder.build();
}
/**
* Returns all the targets directly in the given pattern, except for EMPTY nodes
*
* EMPTY nodes occur in array patterns with elisions, e.g. `[, , a] = []`
*/
public static ImmutableList createAllNonEmptyTargetsInPattern(
JSTypeRegistry registry, JSType patternType, Node pattern) {
return createAllNonEmptyTargetsInPattern(registry, () -> patternType, pattern);
}
/**
* Returns all the targets directly in the given pattern, except for EMPTY nodes
*
* EMPTY nodes occur in array patterns with elisions, e.g. `[, , a] = []`
*/
public static ImmutableList createAllNonEmptyTargetsInPattern(
JSTypeRegistry registry, Supplier patternType, Node pattern) {
checkArgument(pattern.isDestructuringPattern(), pattern);
ImmutableList.Builder builder = ImmutableList.builder();
for (Node child = pattern.getFirstChild(); child != null; child = child.getNext()) {
if (child.isEmpty()) {
continue;
}
builder.add(createTarget(registry, patternType, child));
}
return builder.build();
}
/**
* Infers the type of this target before the default value (if any) is applied.
*
* e.g. given `a` in const {a = 3} = {}; returns `undefined`
*/
JSType inferTypeWithoutUsingDefaultValue() {
if (pattern.isObjectPattern()) {
return inferObjectPatternKeyType();
} else {
return inferArrayPatternTargetType();
}
}
/**
* Infers the type of this target
*
*
e.g. given `a` in const {a = 3} = {}; returns `number`
*/
JSType inferType() {
JSType inferredType = inferTypeWithoutUsingDefaultValue();
if (!inferredType.isUnknownType() && hasDefaultValue()) {
JSType defaultValueType = getDefaultValue().getJSType();
if (defaultValueType == null) {
defaultValueType = registry.getNativeType(JSTypeNative.UNKNOWN_TYPE);
}
// We effectively replace '|undefined" with '|typeOfDefaultValue'
return registry.createUnionType(inferredType.restrictByNotUndefined(), defaultValueType);
} else {
return inferredType;
}
}
private JSType inferObjectPatternKeyType() {
JSType patternType = patternTypeSupplier.get();
if (isRest) {
// TODO(b/128355893): Do smarter inferrence. There are a lot of potential issues with
// inference on object-rest, so for now we just give up and say `Object`.
return registry.getNativeType(JSTypeNative.OBJECT_TYPE);
}
if (patternType == null || patternType.isUnknownType()) {
return registry.getNativeType(JSTypeNative.UNKNOWN_TYPE);
}
switch (objectPatternKey.getToken()) {
case STRING_KEY:
JSType propertyType = patternType.findPropertyType(objectPatternKey.getString());
return propertyType != null
? propertyType
: registry.getNativeType(JSTypeNative.UNKNOWN_TYPE);
case COMPUTED_PROP:
return patternType != null
? patternType
.getTemplateTypeMap()
.getResolvedTemplateType(registry.getObjectElementKey())
: registry.getNativeType(JSTypeNative.UNKNOWN_TYPE);
default:
throw new IllegalStateException("Unexpected key " + objectPatternKey);
}
}
private JSType inferArrayPatternTargetType() {
JSType patternType = patternTypeSupplier.get();
// e.g. get `number` from `!Iterable`
JSType templateTypeOfIterable =
patternType.getTemplateTypeMap().getResolvedTemplateType(registry.getIterableTemplate());
if (isRest) {
// return `!Array`
return registry.createTemplatizedType(
registry.getNativeObjectType(JSTypeNative.ARRAY_TYPE), templateTypeOfIterable);
} else {
return templateTypeOfIterable;
}
}
}