com.google.javascript.jscomp.TypedScope Maven / Gradle / Ivy
Show all versions of closure-compiler Show documentation
/*
* Copyright 2015 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.checkState;
import com.google.common.collect.Iterables;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.StaticScope;
import com.google.javascript.rhino.jstype.FunctionType;
import com.google.javascript.rhino.jstype.JSType;
import com.google.javascript.rhino.jstype.ObjectType;
import com.google.javascript.rhino.jstype.StaticTypedScope;
import com.google.javascript.rhino.jstype.StaticTypedSlot;
import java.util.HashSet;
import java.util.Set;
import javax.annotation.Nullable;
/**
* TypedScope contains information about variables and their types. Scopes can be nested; a scope
* points back to its parent scope.
*
* TypedScope is also used as a lattice element for flow-sensitive type inference. As a lattice
* element, a scope is viewed as a map from names to types. A name not in the map is considered to
* have the bottom type. The join of two maps m1 and m2 is the map of the union of names with {@link
* JSType#getLeastSupertype} to meet the m1 type and m2 type.
*
*
TypedScopes also have a concept of a set of 'reserved' names. These are names that will be
* declared as actual TypedVars later in the compilation. Looking up any of these reserved names
* will always return null, even if the name is available in a parent scope.
*
* @see NodeTraversal
* @see DataFlowAnalysis
*
Several methods in this class, such as {@code isBlockScope} throw an exception when
* called. The reason for this is that we want to shadow methods from the parent class, to avoid
* calling them accidentally.
*/
public class TypedScope extends AbstractScope implements StaticTypedScope {
private final TypedScope parent;
private final int depth;
/** Whether this is a bottom scope for the purposes of type inference. */
private final boolean isBottom;
private final Set reservedNames; // Not immutable; will shrink over time.
// Scope.java contains an arguments field.
// We haven't added it here because it's unused by the passes that need typed scopes.
TypedScope(TypedScope parent, Node rootNode) {
this(parent, rootNode, new HashSet<>());
}
/**
* Creates a new global or local TypedScope.
*
* @param parent The containing scope, unless this is the global scope.
* @param rootNode Can be any node that creates a scope.
* @param reservedNames set of simple names that will eventually be declared in this scope.
*/
TypedScope(TypedScope parent, Node rootNode, Set reservedNames) {
super(rootNode);
checkChildScope(parent);
this.parent = parent;
this.depth = parent.depth + 1;
this.isBottom = false;
this.reservedNames = reservedNames;
}
/**
* Creates a empty Scope (bottom of the lattice).
*
* @param rootNode Typically a FUNCTION node or the global ROOT.
* @param isBottom Whether this is the bottom of a lattice. Otherwise, it must be a global scope.
*/
private TypedScope(Node rootNode, boolean isBottom) {
super(rootNode);
checkRootScope();
this.parent = null;
this.depth = 0;
this.isBottom = isBottom;
this.reservedNames = new HashSet<>();
}
static TypedScope createGlobalScope(Node rootNode) {
return new TypedScope(rootNode, false);
}
static TypedScope createLatticeBottom(Node rootNode) {
return new TypedScope(rootNode, true);
}
@Override
public TypedScope typed() {
return this;
}
/** Asserts that all reserved names in the scope have been actually declared. */
void validateCompletelyBuilt() {
checkState(
reservedNames.isEmpty(),
"Expected %s to have no reserved names, found: %s",
this,
reservedNames);
}
/** Whether this is the bottom of the lattice. */
boolean isBottom() {
return isBottom;
}
@Override
public int getDepth() {
return depth;
}
@Override
public TypedScope getParent() {
return parent;
}
/**
* Gets the type of {@code this} in the current scope.
*/
@Override
public JSType getTypeOfThis() {
Node root = getRootNode();
if (isGlobal()) {
return ObjectType.cast(root.getJSType());
} else if (NodeUtil.isNonArrowFunction(root)) {
JSType nodeType = root.getJSType();
if (nodeType != null && nodeType.isFunctionType()) {
return nodeType.toMaybeFunctionType().getTypeOfThis();
} else {
// Executed when the current scope has not been typechecked.
return null;
}
} else {
return getParent().getTypeOfThis();
}
}
TypedVar declare(String name, Node nameNode,
JSType type, CompilerInput input, boolean inferred) {
checkState(name != null && !name.isEmpty());
reservedNames.remove(name);
TypedVar var = new TypedVar(inferred, name, nameNode, type, this, getVarCount(), input);
declareInternal(name, var);
return var;
}
@Override
TypedVar makeImplicitVar(ImplicitVar var) {
if (this.isGlobal()) {
// TODO(sdh): This is incorrect for 'global this', but since that's currently not handled
// by this code, it's okay to bail out now until we find the root cause. See b/74980936.
return null;
} else if (var.equals(ImplicitVar.EXPORTS)) {
// Instead of using the implicit 'exports' var, we want to pretend that the var is actually
// declared.
return null;
}
return new TypedVar(false, var.name, null, getImplicitVarType(var), this, -1, null);
}
@Override
protected boolean hasOwnImplicitSlot(@Nullable ImplicitVar name) {
return name != null && !name.equals(ImplicitVar.EXPORTS) && name.isMadeByScope(this);
}
private JSType getImplicitVarType(ImplicitVar var) {
switch (var) {
case ARGUMENTS:
// Look for an extern named "arguments" and use its type if available.
// TODO(sdh): consider looking for "Arguments" ctor rather than "arguments" var: this could
// allow deleting the variable, which doesn't really belong in externs in the first place.
TypedVar globalArgs = getGlobalScope().getVar(Var.ARGUMENTS);
return globalArgs != null && globalArgs.isExtern() ? globalArgs.getType() : null;
case THIS:
return getTypeOfThis();
case SUPER:
// Inside a constructor, `super` may have two different types. Calls to `super()` use the
// super-ctor type, while property accesses use the super-instance type. This logic always
// returns the latter case.
ObjectType receiverType = ObjectType.cast(getTypeOfThis());
if (receiverType == null) {
return null;
} else if (receiverType.isInstanceType()) {
FunctionType superclassCtor = receiverType.getSuperClassConstructor();
return superclassCtor == null ? null : superclassCtor.getInstanceType();
} else {
return receiverType.getImplicitPrototype();
}
case EXPORTS:
throw new AssertionError("TypedScopes should not contain an implicit 'exports'");
}
throw new AssertionError();
}
/**
* Returns the variables in this scope that have been declared with 'var' and not yet declared
* with a known type.
*
* These variables can safely be set to undefined (rather than unknown) at the start of type
* inference, and will be reset to the correct type when analyzing the first assignment to them.
* Parameters and externs are excluded because they are not initialized in the function body, and
* lexically-bound variables (let and const) are excluded because they are initialized when
* inferring the LET/CONST node, which is guaranteed to occur before any use, since they are not
* hoisted.
*/
public Iterable getDeclarativelyUnboundVarsWithoutTypes() {
return Iterables.filter(getVarIterable(), this::isDeclarativelyUnboundVarWithoutType);
}
private boolean isDeclarativelyUnboundVarWithoutType(TypedVar var) {
return var.getParentNode() != null
&& var.getType() == null
// TODO(bradfordcsmith): update this for destructuring
&& var.getParentNode().isVar() // NOTE: explicitly excludes let/const
&& !var.isExtern();
}
public JSType getNamespaceOrTypedefType(String typeName) {
StaticTypedSlot slot = getSlot(typeName);
return slot == null ? null : slot.getType();
}
public JSDocInfo getJsdocOfTypeDeclaration(String typeName) {
StaticTypedSlot slot = getSlot(typeName);
return slot == null ? null : slot.getJSDocInfo();
}
/**
* Returns the slot for {@code name}, considering shadowing of qualified names.
*
* The superclass method does not handle shadowing.
*
*
Lookup of qualified names (i.e. names with dots) executes against scopes in the following
* precedence:
*
*
* - This {@link Scope}.
*
- The first ancestor {@link Scope}, if any, that declares the root of the qualified name.
*
- The global {@link Scope}.
*
*
* An example of where this is necessary: say the global scope contains "a" and "a.b" and a
* function scope contains "a". When looking up "a.b" in the function scope, AbstractScope::getVar
* returns "a.b". This method returns null because the global "a" is shadowed.
*/
// Non-final for JSDev
@Override
public TypedVar getVar(String name) {
TypedVar ownSlot = getOwnSlot(name);
if (ownSlot != null) {
// Micro-optimization: variables declared directly in this scope cannot have been shadowed.
return ownSlot;
} else if (this.getParent() == null) {
return null;
}
// Find the root name and its slot.
int dot = name.indexOf('.');
String rootName = dot < 0 ? name : name.substring(0, dot);
TypedVar rootVar = super.getVar(rootName); // Use the superclass method to skip string checks.
if (dot < 0) {
return rootVar;
} else if (rootVar == null) {
// Default to the global scope because externs may have qualified names with undeclared roots.
return this.getParent().getGlobalScope().getOwnSlot(name);
} else {
// Qualified names 'a.b.c' are declared in the same scope as 'a', never a child scope, which
// is why calling `getOwnSlot` is sufficient.
return rootVar.getScope().getOwnSlot(name);
}
}
@Override
public StaticScope getTopmostScopeOfEventualDeclaration(String name) {
if (getOwnSlot(name) != null || reservedNames.contains(name)) {
return this;
} else if (this.getParent() == null) {
return null;
} else {
// Recurse on the parent because it, too, may be incomplete.
return this.getParent().getTopmostScopeOfEventualDeclaration(name);
}
}
}