- package org.apache.xpath.axes;
-
- import org.apache.xpath.Expression;
- import org.apache.xpath.ExpressionOwner;
- import org.apache.xpath.XPathVisitor;
- import org.apache.xpath.functions.FuncLast;
- import org.apache.xpath.functions.FuncPosition;
- import org.apache.xpath.functions.Function;
- import org.apache.xpath.objects.XNumber;
- import org.apache.xpath.operations.Div;
- import org.apache.xpath.operations.Minus;
- import org.apache.xpath.operations.Mod;
- import org.apache.xpath.operations.Mult;
- import org.apache.xpath.operations.Plus;
- import org.apache.xpath.operations.Quo;
- import org.apache.xpath.operations.Variable;
-
- public class HasPositionalPredChecker extends XPathVisitor
- {
- private boolean m_hasPositionalPred = false;
- private int m_predDepth = 0;
-
- /**
- * Process the LocPathIterator to see if it contains variables
- * or functions that may make it context dependent.
- * @param path LocPathIterator that is assumed to be absolute, but needs checking.
- * @return true if the path is confirmed to be absolute, false if it
- * may contain context dependencies.
- */
- public static boolean check(LocPathIterator path)
- {
- HasPositionalPredChecker hppc = new HasPositionalPredChecker();
- path.callVisitors(null, hppc);
- return hppc.m_hasPositionalPred;
- }
-
- /**
- * Visit a function.
- * @param owner The owner of the expression, to which the expression can
- * be reset if rewriting takes place.
- * @param func The function reference object.
- * @return true if the sub expressions should be traversed.
- */
- public boolean visitFunction(ExpressionOwner owner, Function func)
- {
- if((func instanceof FuncPosition) ||
- (func instanceof FuncLast))
- m_hasPositionalPred = true;
- return true;
- }
-
- // /**
- // * Visit a variable reference.
- // * @param owner The owner of the expression, to which the expression can
- // * be reset if rewriting takes place.
- // * @param var The variable reference object.
- // * @return true if the sub expressions should be traversed.
- // */
- // public boolean visitVariableRef(ExpressionOwner owner, Variable var)
- // {
- // m_hasPositionalPred = true;
- // return true;
- // }
-
- /**
- * Visit a predicate within a location path. Note that there isn't a
- * proper unique component for predicates, and that the expression will
- * be called also for whatever type Expression is.
- *
- * @param owner The owner of the expression, to which the expression can
- * be reset if rewriting takes place.
- * @param pred The predicate object.
- * @return true if the sub expressions should be traversed.
- */
- public boolean visitPredicate(ExpressionOwner owner, Expression pred)
- {
- m_predDepth++;
-
- if(m_predDepth == 1)
- {
- if((pred instanceof Variable) ||
- (pred instanceof XNumber) ||
- (pred instanceof Div) ||
- (pred instanceof Plus) ||
- (pred instanceof Minus) ||
- (pred instanceof Mod) ||
- (pred instanceof Quo) ||
- (pred instanceof Mult) ||
- (pred instanceof org.apache.xpath.operations.Number) ||
- (pred instanceof Function))
- m_hasPositionalPred = true;
- else
- pred.callVisitors(owner, this);
- }
-
- m_predDepth--;
-
- // Don't go have the caller go any further down the subtree.
- return false;
- }
-
-
- }
-