// $Id: ASTUtil.java 10000 2006-06-08 21:04:45Z steve.ebersole@jboss.com $
package org.hibernate.hql.ast.util;
import java.util.ArrayList;
import java.util.List;
import antlr.ASTFactory;
import antlr.collections.AST;
import antlr.collections.impl.ASTArray;
/**
* Provides utility methods for AST traversal and manipulation.
*
* @author Joshua Davis (pgmjsd@sourceforge.net)
*/
public final class ASTUtil {
/**
* Private empty constructor.
* (or else checkstyle says: 'warning: Utility classes should not have a public or default constructor.')
*
* @deprecated (tell clover to ignore this)
*/
private ASTUtil() {
}
/**
* Creates a single node AST.
*
* @param astFactory The factory.
* @param type The node type.
* @param text The node text.
* @return AST - A single node tree.
*/
public static AST create(ASTFactory astFactory, int type, String text) {
AST node = astFactory.create( type, text );
return node;
}
/**
* Creates a single node AST as a sibling.
*
* @param astFactory The factory.
* @param type The node type.
* @param text The node text.
* @param prevSibling The previous sibling.
* @return AST - A single node tree.
*/
public static AST createSibling(ASTFactory astFactory, int type, String text, AST prevSibling) {
AST node = astFactory.create( type, text );
node.setNextSibling( prevSibling.getNextSibling() );
prevSibling.setNextSibling( node );
return node;
}
public static AST insertSibling(AST node, AST prevSibling) {
node.setNextSibling( prevSibling.getNextSibling() );
prevSibling.setNextSibling( node );
return node;
}
/**
* Creates a 'binary operator' subtree, given the information about the
* parent and the two child nodex.
*
* @param factory The AST factory.
* @param parentType The type of the parent node.
* @param parentText The text of the parent node.
* @param child1 The first child.
* @param child2 The second child.
* @return AST - A new sub-tree of the form "(parent child1 child2)"
*/
public static AST createBinarySubtree(ASTFactory factory, int parentType, String parentText, AST child1, AST child2) {
ASTArray array = createAstArray( factory, 3, parentType, parentText, child1 );
array.add( child2 );
return factory.make( array );
}
/**
* Creates a single parent of the specified child (i.e. a 'unary operator'
* subtree).
*
* @param factory The AST factory.
* @param parentType The type of the parent node.
* @param parentText The text of the parent node.
* @param child The child.
* @return AST - A new sub-tree of the form "(parent child)"
*/
public static AST createParent(ASTFactory factory, int parentType, String parentText, AST child) {
ASTArray array = createAstArray( factory, 2, parentType, parentText, child );
return factory.make( array );
}
public static AST createTree(ASTFactory factory, AST[] nestedChildren) {
AST[] array = new AST[2];
int limit = nestedChildren.length - 1;
for ( int i = limit; i >= 0; i-- ) {
if ( i != limit ) {
array[1] = nestedChildren[i + 1];
array[0] = nestedChildren[i];
factory.make( array );
}
}
return array[0];
}
/**
* Finds the first node of the specified type in the chain of children.
*
* @param parent The parent
* @param type The type to find.
* @return The first node of the specified type, or null if not found.
*/
public static AST findTypeInChildren(AST parent, int type) {
AST n = parent.getFirstChild();
while ( n != null && n.getType() != type ) {
n = n.getNextSibling();
}
return n;
}
/**
* Returns the last direct child of 'n'.
*
* @param n The parent
* @return The last direct child of 'n'.
*/
public static AST getLastChild(AST n) {
return getLastSibling( n.getFirstChild() );
}
/**
* Returns the last sibling of 'a'.
*
* @param a The sibling.
* @return The last sibling of 'a'.
*/
private static AST getLastSibling(AST a) {
AST last = null;
while ( a != null ) {
last = a;
a = a.getNextSibling();
}
return last;
}
/**
* Returns the 'list' representation with some brackets around it for debugging.
*
* @param n The tree.
* @return The list representation of the tree.
*/
public static String getDebugString(AST n) {
StringBuffer buf = new StringBuffer();
buf.append( "[ " );
buf.append( ( n == null ) ? "{null}" : n.toStringTree() );
buf.append( " ]" );
return buf.toString();
}
/**
* Find the previous sibling in the parent for the given child.
*
* @param parent the parent node
* @param child the child to find the previous sibling of
* @return the previous sibling of the child
*/
public static AST findPreviousSibling(AST parent, AST child) {
AST prev = null;
AST n = parent.getFirstChild();
while ( n != null ) {
if ( n == child ) {
return prev;
}
prev = n;
n = n.getNextSibling();
}
throw new IllegalArgumentException( "Child not found in parent!" );
}
/**
* Determine if a given node (test) is a direct (throtle to one level down)
* child of another given node (fixture).
*
* @param fixture The node against which to testto be checked for children.
* @param test The node to be tested as being a child of the parent.
* @return True if test is contained in the fixtures's direct children;
* false otherwise.
*/
public static boolean isDirectChild(AST fixture, AST test) {
AST n = fixture.getFirstChild();
while ( n != null ) {
if ( n == test ) {
return true;
}
n = n.getNextSibling();
}
return false;
}
/**
* Determine if a given node (test) is contained anywhere in the subtree
* of another given node (fixture).
*
* @param fixture The node against which to testto be checked for children.
* @param test The node to be tested as being a subtree child of the parent.
* @return True if child is contained in the parent's collection of children.
*/
public static boolean isSubtreeChild(AST fixture, AST test) {
AST n = fixture.getFirstChild();
while ( n != null ) {
if ( n == test ) {
return true;
}
if ( n.getFirstChild() != null && isSubtreeChild( n, test ) ) {
return true;
}
n = n.getNextSibling();
}
return false;
}
/**
* Makes the child node a sibling of the parent, reconnecting all siblings.
*
* @param parent the parent
* @param child the child
*/
public static void makeSiblingOfParent(AST parent, AST child) {
AST prev = findPreviousSibling( parent, child );
if ( prev != null ) {
prev.setNextSibling( child.getNextSibling() );
}
else { // child == parent.getFirstChild()
parent.setFirstChild( child.getNextSibling() );
}
child.setNextSibling( parent.getNextSibling() );
parent.setNextSibling( child );
}
public static String getPathText(AST n) {
StringBuffer buf = new StringBuffer();
getPathText( buf, n );
return buf.toString();
}
private static void getPathText(StringBuffer buf, AST n) {
AST firstChild = n.getFirstChild();
// If the node has a first child, recurse into the first child.
if ( firstChild != null ) {
getPathText( buf, firstChild );
}
// Append the text of the current node.
buf.append( n.getText() );
// If there is a second child (RHS), recurse into that child.
if ( firstChild != null && firstChild.getNextSibling() != null ) {
getPathText( buf, firstChild.getNextSibling() );
}
}
public static boolean hasExactlyOneChild(AST n) {
return n != null && n.getFirstChild() != null && n.getFirstChild().getNextSibling() == null;
}
public static void appendSibling(AST n, AST s) {
while ( n.getNextSibling() != null ) {
n = n.getNextSibling();
}
n.setNextSibling( s );
}
/**
* Inserts the child as the first child of the parent, all other children are shifted over to the 'right'.
*
* @param parent the parent
* @param child the new first child
*/
public static void insertChild(AST parent, AST child) {
if ( parent.getFirstChild() == null ) {
parent.setFirstChild( child );
}
else {
AST n = parent.getFirstChild();
parent.setFirstChild( child );
child.setNextSibling( n );
}
}
/**
* Filters nodes out of a tree.
*/
public static interface FilterPredicate {
/**
* Returns true if the node should be filtered out.
*
* @param n The node.
* @return true if the node should be filtered out, false to keep the node.
*/
boolean exclude(AST n);
}
/**
* A predicate that uses inclusion, rather than exclusion semantics.
*/
public abstract static class IncludePredicate implements FilterPredicate {
public final boolean exclude(AST node) {
return !include( node );
}
public abstract boolean include(AST node);
}
private static ASTArray createAstArray(ASTFactory factory, int size, int parentType, String parentText, AST child1) {
ASTArray array = new ASTArray( size );
array.add( factory.create( parentType, parentText ) );
array.add( child1 );
return array;
}
public static List collectChildren(AST root, FilterPredicate predicate) {
// List children = new ArrayList();
// collectChildren( children, root, predicate );
// return children;
return new CollectingNodeVisitor( predicate ).collect( root );
}
private static class CollectingNodeVisitor implements NodeTraverser.VisitationStrategy {
private final FilterPredicate predicate;
private final List collectedNodes = new ArrayList();
public CollectingNodeVisitor(FilterPredicate predicate) {
this.predicate = predicate;
}
public void visit(AST node) {
if ( predicate == null || !predicate.exclude( node ) ) {
collectedNodes.add( node );
}
}
public List getCollectedNodes() {
return collectedNodes;
}
public List collect(AST root) {
NodeTraverser traverser = new NodeTraverser( this );
traverser.traverseDepthFirst( root );
return collectedNodes;
}
}
private static void collectChildren(List children, AST root, FilterPredicate predicate) {
for ( AST n = root.getFirstChild(); n != null; n = n.getNextSibling() ) {
if ( predicate == null || !predicate.exclude( n ) ) {
children.add( n );
}
collectChildren( children, n, predicate );
}
}
}
|
