/*
* Copyright 2009 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 com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableSet;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
/**
* Models an assignment that defines a variable and the removal of it.
*
*/
class DefinitionsRemover {
/**
* This logic must match {@link isDefinitionNode}.
*
* @return an {@link Definition} object if the node contains a definition or {@code null}
* otherwise.
*/
static Definition getDefinition(Node n, boolean isExtern) {
Node parent = n.getParent();
if (parent == null) {
return null;
}
if (NodeUtil.isVarDeclaration(n) && (isExtern || n.hasChildren())) {
return new VarDefinition(n, isExtern);
} else if (parent.isFunction() && parent.getFirstChild() == n) {
if (!NodeUtil.isFunctionExpression(parent)) {
return new NamedFunctionDefinition(parent, isExtern);
} else if (!n.getString().isEmpty()) {
return new FunctionExpressionDefinition(parent, isExtern);
}
} else if (parent.isAssign() && parent.getFirstChild() == n) {
return new AssignmentDefinition(parent, isExtern);
} else if (NodeUtil.isObjectLitKey(n)) {
return new ObjectLiteralPropertyDefinition(parent, n, n.getFirstChild(), isExtern);
} else if (parent.isParamList()) {
Node function = parent.getParent();
return new FunctionArgumentDefinition(function, n, isExtern);
} else if (parent.getToken() == Token.COLON && parent.getFirstChild() == n && isExtern) {
Node grandparent = parent.getParent();
Preconditions.checkState(grandparent.getToken() == Token.LB);
Preconditions.checkState(grandparent.getParent().getToken() == Token.LC);
return new RecordTypePropertyDefinition(n);
} else if (isExtern && n.isGetProp() && parent.isExprResult() && n.isQualifiedName()) {
return new ExternalNameOnlyDefinition(n);
}
return null;
}
/**
* This logic must match {@link getDefinition}.
*
* @return Whether a definition object can be created.
*/
static boolean isDefinitionNode(Node n) {
Node parent = n.getParent();
if (parent == null) {
return false;
}
if (NodeUtil.isVarDeclaration(n) && (n.isFromExterns() || n.hasChildren())) {
return true;
} else if (parent.isFunction() && parent.getFirstChild() == n) {
if (!NodeUtil.isFunctionExpression(parent)) {
return true;
} else if (!n.getString().isEmpty()) {
return true;
}
} else if (parent.isAssign() && parent.getFirstChild() == n) {
return true;
} else if (NodeUtil.isObjectLitKey(n)) {
return true;
} else if (parent.isParamList()) {
return true;
} else if (parent.getToken() == Token.COLON
&& parent.getFirstChild() == n
&& n.isFromExterns()) {
Node grandparent = parent.getParent();
Preconditions.checkState(grandparent.getToken() == Token.LB);
Preconditions.checkState(grandparent.getParent().getToken() == Token.LC);
return true;
} else if (n.isFromExterns() && parent.isExprResult() && n.isGetProp() && n.isQualifiedName()) {
return true;
}
return false;
}
abstract static class Definition {
private final boolean isExtern;
Definition(boolean isExtern) {
this.isExtern = isExtern;
}
/**
* Removes this definition from the AST if it is not an extern.
*
* This method should not be called on a definition for which isExtern()
* is true.
*/
public void remove(AbstractCompiler compiler) {
if (!isExtern) {
performRemove(compiler);
} else {
throw new IllegalStateException("Attempt to remove() an extern definition.");
}
}
/**
* Subclasses should override to remove the definition from the AST.
*/
protected abstract void performRemove(AbstractCompiler compiler);
/**
* Variable or property name represented by this definition.
* For example, in the case of assignments this method would
* return the NAME, GETPROP or GETELEM expression that acts as the
* assignment left hand side.
*
* @return the L-Value associated with this definition.
* The node's type is always NAME, GETPROP or GETELEM.
*/
public abstract Node getLValue();
/**
* Value expression that acts as the right hand side of the
* definition statement.
*/
public abstract Node getRValue();
/**
* Returns true if the definition is an extern.
*/
public boolean isExtern() {
return isExtern;
}
@Override
public String toString() {
return getLValue().getQualifiedName() + " = " + getRValue();
}
}
/**
* Represents an name-only external definition. The definition's
* RHS is missing.
*/
abstract static class IncompleteDefinition extends Definition {
private static final ImmutableSet<Token> ALLOWED_TYPES =
ImmutableSet.of(Token.NAME, Token.GETPROP, Token.GETELEM);
private final Node lValue;
IncompleteDefinition(Node lValue, boolean inExterns) {
super(inExterns);
Preconditions.checkNotNull(lValue);
Preconditions.checkArgument(
ALLOWED_TYPES.contains(lValue.getToken()),
"Unexpected lValue type %s",
lValue.getToken());
this.lValue = lValue;
}
@Override
public Node getLValue() {
return lValue;
}
@Override
public Node getRValue() {
return null;
}
}
/**
* Represents an unknown definition.
*/
static final class UnknownDefinition extends IncompleteDefinition {
UnknownDefinition(Node lValue, boolean inExterns) {
super(lValue, inExterns);
}
@Override
public void performRemove(AbstractCompiler compiler) {
throw new IllegalArgumentException("Can't remove an UnknownDefinition");
}
}
/**
* Represents an name-only external definition. The definition's
* RHS is missing.
*/
static final class ExternalNameOnlyDefinition extends IncompleteDefinition {
ExternalNameOnlyDefinition(Node lValue) {
super(lValue, true);
}
@Override
public void performRemove(AbstractCompiler compiler) {
throw new IllegalArgumentException(
"Can't remove external name-only definition");
}
}
/**
* Represents a function formal parameter. The definition's RHS is missing.
*/
static final class FunctionArgumentDefinition extends IncompleteDefinition {
FunctionArgumentDefinition(Node function,
Node argumentName,
boolean inExterns) {
super(argumentName, inExterns);
Preconditions.checkArgument(function.isFunction());
Preconditions.checkArgument(argumentName.isName());
}
@Override
public void performRemove(AbstractCompiler compiler) {
throw new IllegalArgumentException(
"Can't remove a FunctionArgumentDefinition");
}
}
/**
* Represents a function declaration or function expression.
*/
abstract static class FunctionDefinition extends Definition {
protected final Node function;
FunctionDefinition(Node node, boolean inExterns) {
super(inExterns);
Preconditions.checkArgument(node.isFunction());
function = node;
}
@Override
public Node getLValue() {
return function.getFirstChild();
}
@Override
public Node getRValue() {
return function;
}
}
/**
* Represents a function declaration without assignment node such as
* {@code function foo()}.
*/
static final class NamedFunctionDefinition extends FunctionDefinition {
NamedFunctionDefinition(Node node, boolean inExterns) {
super(node, inExterns);
}
@Override
public void performRemove(AbstractCompiler compiler) {
compiler.reportChangeToEnclosingScope(function);
function.detach();
}
}
/**
* Represents a function expression that acts as a RHS. The defined
* name is only reachable from within the function.
*/
static final class FunctionExpressionDefinition extends FunctionDefinition {
FunctionExpressionDefinition(Node node, boolean inExterns) {
super(node, inExterns);
Preconditions.checkArgument(
NodeUtil.isFunctionExpression(node));
}
@Override
public void performRemove(AbstractCompiler compiler) {
// replace internal name with ""
function.replaceChild(function.getFirstChild(), IR.name(""));
compiler.reportChangeToEnclosingScope(function.getFirstChild());
}
}
/**
* Represents a declaration within an assignment.
*/
static final class AssignmentDefinition extends Definition {
private final Node assignment;
AssignmentDefinition(Node node, boolean inExterns) {
super(inExterns);
Preconditions.checkArgument(node.isAssign());
assignment = node;
}
@Override
public void performRemove(AbstractCompiler compiler) {
// A simple assignment. foo = bar() -> bar();
Node parent = assignment.getParent();
Node last = assignment.getLastChild();
assignment.removeChild(last);
parent.replaceChild(assignment, last);
compiler.reportChangeToEnclosingScope(parent);
}
@Override
public Node getLValue() {
return assignment.getFirstChild();
}
@Override
public Node getRValue() {
return assignment.getLastChild();
}
}
/**
* Represents member declarations using a record type from externs.
* Example: /** @typedef {{prop: number}} *\/ var typdef;
*/
static final class RecordTypePropertyDefinition extends IncompleteDefinition {
RecordTypePropertyDefinition(Node name) {
super(IR.getprop(IR.objectlit(), name.cloneNode()),
/** isExtern */ true);
Preconditions.checkArgument(name.isString());
}
@Override
public void performRemove(AbstractCompiler compiler) {
throw new UnsupportedOperationException("Can't remove RecordType def");
}
}
/**
* Represents member declarations using a object literal.
* Example: var x = { e : function() { } };
*/
static final class ObjectLiteralPropertyDefinition extends Definition {
private final Node literal;
private final Node name;
private final Node value;
ObjectLiteralPropertyDefinition(Node lit, Node name, Node value,
boolean isExtern) {
super(isExtern);
this.literal = lit;
this.name = name;
this.value = value;
}
@Override
public void performRemove(AbstractCompiler compiler) {
literal.removeChild(name);
compiler.reportChangeToEnclosingScope(literal);
}
@Override
public Node getLValue() {
// TODO(user) revisit: object literal definitions are an example
// of definitions whose LHS doesn't correspond to a node that
// exists in the AST. We will have to change the return type of
// getLValue sooner or later in order to provide this added
// flexibility.
switch (name.getToken()) {
case SETTER_DEF:
case GETTER_DEF:
case STRING_KEY:
// TODO(johnlenz): return a GETELEM for quoted strings.
return IR.getprop(
IR.objectlit(),
IR.string(name.getString()));
default:
throw new IllegalStateException("unexpected");
}
}
@Override
public Node getRValue() {
return value;
}
}
/**
* Represents a VAR declaration with an assignment.
*/
static final class VarDefinition extends Definition {
private final Node name;
VarDefinition(Node node, boolean inExterns) {
super(inExterns);
Preconditions.checkArgument(NodeUtil.isVarDeclaration(node));
Preconditions.checkArgument(inExterns || node.hasChildren(),
"VAR Declaration of %s must be assigned a value.", node.getString());
name = node;
}
@Override
public void performRemove(AbstractCompiler compiler) {
Node var = name.getParent();
Preconditions.checkState(var.getFirstChild() == var.getLastChild(),
"AST should be normalized first");
Node parent = var.getParent();
Node rValue = name.removeFirstChild();
Preconditions.checkState(!NodeUtil.isLoopStructure(parent));
parent.replaceChild(var, NodeUtil.newExpr(rValue));
compiler.reportChangeToEnclosingScope(parent);
}
@Override
public Node getLValue() {
return name;
}
@Override
public Node getRValue() {
return name.getFirstChild();
}
}
}