// Copyright (C) 2005-2006 Google Inc.
//
// 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.caja.parser;
import com.google.caja.SomethingWidgyHappenedError;
import com.google.caja.lexer.FilePosition;
import com.google.caja.lexer.Token;
import com.google.caja.reporting.MessageContext;
import com.google.caja.reporting.MessagePart;
import com.google.caja.util.Join;
import com.google.caja.util.Lists;
import com.google.caja.util.SyntheticAttributeKey;
import com.google.caja.util.SyntheticAttributes;
import java.io.IOException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
/**
* An abstract base class for a mutable parse tree node implementations.
*
* @author mikesamuel@gmail.com
*/
public abstract class AbstractParseTreeNode implements MutableParseTreeNode,
Serializable {
private static final long serialVersionUID = 871767772158380954L;
private FilePosition pos;
private List<Token<?>> comments = Collections.<Token<?>>emptyList();
private SyntheticAttributes attributes;
private boolean immutable = false;
private boolean synthetic = false;
@Override
public boolean makeImmutable() {
if (immutable) { return true; }
if (!children.makeImmutable()) { return false; }
getAttributes().makeImmutable();
this.immutable = true;
return true;
}
@Override
public boolean isImmutable() { return immutable; }
public boolean isSynthetic() { return synthetic; }
public void setSynthetic(boolean value) {
if (immutable) {
throw new UnsupportedOperationException();
}
synthetic = value;
}
/**
* The list of children. This can be appended to for efficient initialization
* but any operations that remove or insert except at the end require
* copy-on-write to provide for efficient visitors.
*/
private ChildNodes<ParseTreeNode> children;
protected <T extends ParseTreeNode>
List<? extends T> childrenAs(Class<T> clazz) {
return children.as(clazz).getImmutableFacet();
}
protected AbstractParseTreeNode(FilePosition pos) {
this(pos, ParseTreeNode.class);
}
protected AbstractParseTreeNode(
FilePosition pos, Class<? extends ParseTreeNode> childClass) {
assert pos != null && childClass != null;
// populated via mutators
this.children = new ChildNodes<ParseTreeNode>(childClass);
this.pos = pos;
}
public FilePosition getFilePosition() { return pos; }
public void setFilePosition(FilePosition pos) {
if (immutable) {
throw new UnsupportedOperationException();
}
assert pos != null; this.pos = pos;
}
public List<Token<?>> getComments() {
return Collections.unmodifiableList(comments);
}
public List<? extends ParseTreeNode> children() {
return children.getImmutableFacet();
}
@SuppressWarnings("unchecked")
protected <T2> List<T2> childrenPart(
int start, int end, Class<T2> cl) {
List<ParseTreeNode> sub = Lists.newArrayList(
children.getImmutableFacet().subList(start, end));
for (ParseTreeNode el : sub) {
if (!cl.isInstance(el)) {
throw new ClassCastException(
"element not an instance of " + cl + " : "
+ (null != el ? el.getClass() : "<null>"));
}
}
return Collections.unmodifiableList((List<T2>) sub);
}
public abstract Object getValue();
public SyntheticAttributes getAttributes() {
if (null == this.attributes) {
this.attributes = new SyntheticAttributes();
}
return this.attributes;
}
@SuppressWarnings("unchecked")
public void setComments(List<? extends Token<?>> comments) {
if (immutable) {
throw new UnsupportedOperationException();
}
List<Token<?>> tokens = (List<Token<?>>) comments;
this.comments = !comments.isEmpty()
? Collections.unmodifiableList(new ArrayList<Token<?>>(tokens))
: Collections.<Token<?>>emptyList();
}
public void replaceChild(ParseTreeNode replacement, ParseTreeNode child) {
createMutation().replaceChild(replacement, child).execute();
}
public void insertBefore(ParseTreeNode toAdd, ParseTreeNode before) {
createMutation().insertBefore(toAdd, before).execute();
}
public void appendChild(ParseTreeNode toAppend) {
insertBefore(toAppend, null);
}
public void removeChild(ParseTreeNode toRemove) {
createMutation().removeChild(toRemove).execute();
}
// Fast appendChild that's only safe to run in constructors.
protected void ctorAppendChild(ParseTreeNode child) {
children.getMutableFacet().add(child);
childrenChanged();
}
protected void ctorAppendChildren(List<? extends ParseTreeNode> children) {
this.children.getMutableFacet().addAll(children);
childrenChanged();
}
public Mutation createMutation() { return new MutationImpl(); }
private void setChild(int i, ParseTreeNode child) {
if (immutable) {
throw new UnsupportedOperationException();
}
children.getMutableFacet().set(i, child);
}
private void addChild(int i, ParseTreeNode child) {
children.getMutableFacet().add(i, child);
}
private void copyOnWrite() {
children = new ChildNodes<ParseTreeNode>(children);
}
private int indexOf(ParseTreeNode child) {
return children.getImmutableFacet().indexOf(child);
}
/**
* Called to perform consistency checks on the child list after changes have
* been made. This can be overridden to do additional checks by subclasses,
* and to update derived state, but all subclasses must chain to super after
* performing their own checks.
*
* <p>This method may throw any RuntimeException on an invalid child.
*/
protected void childrenChanged() {
if (children.getImmutableFacet().contains(null)) {
throw new NullPointerException();
}
}
protected void formatSelf(MessageContext context, int depth, Appendable out)
throws IOException {
out.append(this.getClass().getSimpleName());
Object value = getValue();
if (null != value) {
out.append(" : ");
if (value instanceof MessagePart) {
((MessagePart) value).format(context, out);
} else {
out.append(value.toString());
}
}
if (!context.relevantKeys.isEmpty() && null != attributes) {
for (SyntheticAttributeKey<?> k : context.relevantKeys) {
if (attributes.containsKey(k)) {
out.append(" ; ").append(k.getName()).append('=');
Object attribValue = attributes.get(k);
if (attribValue instanceof MessagePart) {
StringBuilder sb = new StringBuilder();
((MessagePart) attribValue).format(context, sb);
String[] lines = sb.toString().split("\n");
String keyValue;
if (lines.length == 1) {
keyValue = lines[0];
} else {
sb.setLength(0);
sb.append("\n ");
for (int i = depth; --i >= 0;) { sb.append(" "); }
String prefix = sb.toString();
sb.setLength(0);
sb.append('(');
sb.append(Join.join(prefix, lines));
sb.append(')');
keyValue = sb.toString();
}
out.append(keyValue);
} else {
out.append(String.valueOf(attribValue));
}
}
}
}
}
public void format(MessageContext context, Appendable out)
throws IOException {
formatTree(context, out);
}
public final void formatTree(MessageContext context, Appendable out)
throws IOException {
formatTree(context, 0, out);
}
public final void formatTree(
MessageContext context, int depth, Appendable out)
throws IOException {
for (int d = depth; --d >= 0;) { out.append(" "); }
formatSelf(context, depth, out);
for (ParseTreeNode child : children()) {
out.append("\n");
child.formatTree(context, depth + 1, out);
}
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
try {
formatSelf(new MessageContext(), 0, sb);
} catch (IOException ex) {
throw new SomethingWidgyHappenedError(
"StringBuilders shouldn't throw IOExceptions");
}
return sb.toString();
}
public String toStringDeep() { return toStringDeep(0); }
public String toStringDeep(int d) {
StringBuilder sb = new StringBuilder();
try {
formatTree(new MessageContext(), d, sb);
} catch (IOException ex) {
throw new SomethingWidgyHappenedError(
"StringBuilders shouldn't throw IOExceptions");
}
return sb.toString();
}
private enum TraversalType { PREORDER, POSTORDER; }
private boolean visitChildren(
Visitor v, AncestorChain<?> ancestors, TraversalType traversalType) {
if (this.children.getImmutableFacet().isEmpty()) { return true; }
boolean result = true;
// This loop is complicated because it needs to survive mutations to the
// child list.
ChildNodes<ParseTreeNode> childrenCache = this.children;
ParseTreeNode next = childrenCache.getImmutableFacet().get(0);
childLoop:
for (int i = 0; i < childrenCache.getImmutableFacet().size(); ++i) {
if (childrenCache != this.children) {
// Used lastIndexOf so we make progress in case a child is on the
// children list multiple times.
int j = this.children.getImmutableFacet().lastIndexOf(next);
if (j < 0) {
// Try to find the next one to use by looking at children we've
// already visited.
for (int k = i; --k >= 0;) {
j = this.children.getImmutableFacet().lastIndexOf(
childrenCache.getImmutableFacet().get(k));
if (j >= 0) { break; }
}
if (j >= 0 && j + 1 < this.children.getImmutableFacet().size()) {
++j; // Add one since we don't want to reprocess childrenCache[k].
} else {
// Check if children from the cached list that we haven't
// processed yet are still in the new list.
for (int k = i + 1; k < childrenCache.getImmutableFacet().size();
++k) {
j = this.children.getImmutableFacet().lastIndexOf(
childrenCache.getImmutableFacet().get(k));
if (j >= 0) { break; }
}
// No children left to process.
if (j < 0) { break childLoop; }
}
}
i = j;
childrenCache = this.children;
next = childrenCache.getImmutableFacet().get(i);
}
ParseTreeNode child = next;
next = (i + 1 < childrenCache.getImmutableFacet().size() ?
childrenCache.getImmutableFacet().get(i + 1) : null);
switch (traversalType) {
case PREORDER:
child.acceptPreOrder(v, ancestors);
break;
case POSTORDER:
if (!child.acceptPostOrder(v, ancestors)) {
result = false;
break childLoop;
}
break;
}
}
return result;
}
// This contains() check makes traversal O(n**2) where n is the
// maximal number of children of any node in the tree.
private boolean stillInParent(AncestorChain<?> ancestors) {
// If ancestors is empty, then it can't have been removed from its parent
// by the Visitor unless the visitor has some handle to the parent through
// another mechanism.
return ancestors == null || ancestors.node.children().contains(this);
}
public final boolean acceptPreOrder(Visitor v, AncestorChain<?> ancestors) {
ancestors = AncestorChain.instance(ancestors, this);
if (!v.visit(ancestors)) { return false; }
// Handle the case where v.visit() replaces this with another, inserts
// another following, or deletes the node or a following node.
if (!stillInParent(ancestors.parent)) { return true; }
// Not removed or replaced, so recurse to children.
visitChildren(v, ancestors, TraversalType.PREORDER);
return true;
}
public final boolean acceptPostOrder(Visitor v, AncestorChain<?> ancestors) {
ancestors = AncestorChain.instance(ancestors, this);
// Descend into this node's children.
if (!visitChildren(v, ancestors, TraversalType.POSTORDER)) {
return false;
}
// If this node has been orphaned, don't visit it...
if (stillInParent(ancestors.parent)) {
return v.visit(ancestors);
}
return true;
}
public final boolean visitPreOrder(ParseTreeNodeVisitor v) {
if (!v.visit(this)) { return false; }
for (ParseTreeNode child : children.getImmutableFacet()) {
child.visitPreOrder(v);
}
return true;
}
/** Uses identity hash code since this is mutable. */
@Override
public final int hashCode() { return super.hashCode(); }
/** Uses identity hash code since this is mutable. */
@Override
public final boolean equals(Object o) { return this == o; }
@Override
public ParseTreeNode clone() {
if (immutable) { return this; }
List<ParseTreeNode> clonedChildren
= new ArrayList<ParseTreeNode>(children.getImmutableFacet().size());
for (ParseTreeNode child : children.getImmutableFacet()) {
clonedChildren.add(child.clone());
}
AbstractParseTreeNode cloned = ParseTreeNodes.newNodeInstance(
getClass(), getFilePosition(), getValue(), clonedChildren);
if (attributes != null) {
cloned.attributes = new SyntheticAttributes(attributes);
}
cloned.synthetic = synthetic;
return cloned;
}
private final class MutationImpl implements MutableParseTreeNode.Mutation {
private final List<Change> changes = new ArrayList<Change>();
public Mutation replaceChild(ParseTreeNode replacement, ParseTreeNode child) {
changes.add(new Replacement(replacement, child));
return this;
}
public Mutation insertBefore(ParseTreeNode toAdd, ParseTreeNode before) {
changes.add(new Insertion(toAdd, before));
return this;
}
public Mutation appendChild(ParseTreeNode toAppend) {
return insertBefore(toAppend, null);
}
public Mutation appendChildren(Iterable<? extends ParseTreeNode> nodes) {
Iterator<? extends ParseTreeNode> it = nodes.iterator();
while (it.hasNext()) { insertBefore(it.next(), null); }
return this;
}
public Mutation removeChild(ParseTreeNode toRemove) {
changes.add(new Removal(toRemove));
return this;
}
@SuppressWarnings("finally")
public void execute() {
boolean copied = false;
for (Change change : changes) {
copied = change.apply(copied);
}
try {
childrenChanged();
} catch (RuntimeException ex) {
for (int i = changes.size(); --i >= 0;) { changes.get(i).rollback(); }
try {
childrenChanged();
} finally {
throw ex;
}
}
}
}
private abstract class Change {
/**
* Index of modified child in original set by apply, so that we can
* rollback.
*/
int backupIndex = -1;
/**
* Change the parse tree and store enough information so that rollback can
* reverse it.
* @param copied true if the children list has already been copied by an
* operation that requires copy on write.
* @return true if the children list has been copied by an operation
* that requires copy on write.
*/
abstract boolean apply(boolean copied);
/**
* Rolls back the change effected by apply, and can assume that apply
* was the most recent change to this node, and that it will be called
* at most once after a given apply.
*/
abstract void rollback();
}
private final class Replacement extends Change {
private final ParseTreeNode replacement;
private final ParseTreeNode replaced;
Replacement(ParseTreeNode replacement, ParseTreeNode replaced) {
this.replacement = replacement;
this.replaced = replaced;
}
@Override
boolean apply(boolean copied) {
if (!copied) { copyOnWrite(); }
// Find where to insert
int childIndex = indexOf(replaced);
if (childIndex < 0) {
throw new NoSuchElementException(
"Node to replace is not a child of this node.");
}
if (indexOf(replacement) >= 0) {
throw new NoSuchElementException(
"Node to add is already a child of this node.");
}
// Update the child list
backupIndex = childIndex;
setChild(childIndex, replacement);
return true;
}
@Override
void rollback() {
int childIndex = backupIndex;
// This check corresponds to the replacement.parent == null check in apply
// which has the effect of asserting that replacement is not rooted.
if (children.getImmutableFacet().contains(replaced)) { return; }
setChild(childIndex, replaced); // roll back
}
}
private final class Removal extends Change {
private final ParseTreeNode toRemove;
Removal(ParseTreeNode toRemove) {
this.toRemove = toRemove;
}
@Override
boolean apply(boolean copied) {
if (!copied) { copyOnWrite(); }
// Find which to remove
int childIndex = indexOf(toRemove);
if (childIndex < 0) {
throw new NoSuchElementException("child not in parent");
}
// Update the child list
backupIndex = childIndex;
children.getMutableFacet().remove(childIndex);
return true;
}
@Override
void rollback() {
if (children.getImmutableFacet().contains(toRemove)) { return; }
addChild(backupIndex, toRemove);
}
}
private final class Insertion extends Change {
private final ParseTreeNode toAdd;
private final ParseTreeNode before;
Insertion(ParseTreeNode toAdd, ParseTreeNode before) {
this.toAdd = toAdd;
this.before = before;
}
@Override
boolean apply(boolean copied) {
// Find where to insert
int childIndex;
if (null == before) {
childIndex = children.getImmutableFacet().size();
} else {
childIndex = indexOf(before);
if (childIndex < 0) {
throw new NoSuchElementException("Child not in parent");
}
if (!copied) {
copyOnWrite();
copied = true;
}
}
// Update the child list
backupIndex = childIndex;
addChild(childIndex, toAdd);
return copied;
}
@Override
void rollback() {
int childIndex = backupIndex;
ParseTreeNode removed = children.getMutableFacet().remove(childIndex);
if (removed != toAdd) {
setChild(childIndex, removed);
throw new IllegalStateException();
}
}
}
}