/**
* Flatten an expression with respect to an associative operator: for example the expression (a+b)
* + (c+d) becomes list(a,b,c,d), with the list in canonical order (sorted by hashCode)
*
* @param list a list provided by the caller to contain the result
* @return the list of expressions
*/
private List flattenExpression(List list) {
if (operand0 instanceof BinaryExpression
&& ((BinaryExpression) operand0).operator == operator) {
((BinaryExpression) operand0).flattenExpression(list);
} else {
int h = operand0.hashCode();
list.add(operand0);
int i = list.size() - 1;
while (i > 0 && h > list.get(i - 1).hashCode()) {
list.set(i, list.get(i - 1));
list.set(i - 1, operand0);
i--;
}
}
if (operand1 instanceof BinaryExpression
&& ((BinaryExpression) operand1).operator == operator) {
((BinaryExpression) operand1).flattenExpression(list);
} else {
int h = operand1.hashCode();
list.add(operand1);
int i = list.size() - 1;
while (i > 0 && h > list.get(i - 1).hashCode()) {
list.set(i, list.get(i - 1));
list.set(i - 1, operand1);
i--;
}
}
return list;
}
/** Is this expression the same as another expression? */
public boolean equals(Object other) {
if (other instanceof BinaryExpression) {
BinaryExpression b = (BinaryExpression) other;
if (operator == b.operator) {
if (operand0.equals(b.operand0) && operand1.equals(b.operand1)) {
return true;
}
if (isCommutative(operator) && operand0.equals(b.operand1) && operand1.equals(b.operand0)) {
return true;
}
if (isAssociative(operator)
&& pairwiseEqual(
flattenExpression(new ArrayList(4)), b.flattenExpression(new ArrayList(4)))) {
return true;
}
}
if (isInverse(operator, b.operator)
&& operand0.equals(b.operand1)
&& operand1.equals(b.operand0)) {
return true;
}
}
return false;
}
/**
* @param result
* @param expr
*/
private static void serialize(
FastStringBuffer result, Expression expr, Map reversePrefixMapping) {
if (expr instanceof Assignation) {
// XXX not yet supported
} else if (expr instanceof AxisExpression) {
AxisExpression axisExpression = (AxisExpression) expr;
result.append(Axis.axisName[axisExpression.getAxis()]);
result.append("::");
final NodeTest nodeTest = axisExpression.getNodeTest();
if (nodeTest == null) {
result.append("node()");
} else {
result.append(fixPreFixes(nodeTest.toString(), reversePrefixMapping));
}
} else if (expr instanceof BinaryExpression) {
BinaryExpression binaryExpression = (BinaryExpression) expr;
result.append('(');
serialize(result, binaryExpression.getOperands()[0], reversePrefixMapping);
result.append(Token.tokens[binaryExpression.getOperator()]);
serialize(result, binaryExpression.getOperands()[1], reversePrefixMapping);
result.append(')');
} else if (expr instanceof CompareToIntegerConstant) {
CompareToIntegerConstant compareToIntegerConstant = (CompareToIntegerConstant) expr;
result.append('(');
serialize(result, compareToIntegerConstant.getOperand(), reversePrefixMapping);
result.append(Token.tokens[compareToIntegerConstant.getComparisonOperator()]);
result.append(Long.toString(compareToIntegerConstant.getComparand()));
result.append(')');
} else if (expr instanceof ConditionalSorter) {
// XXX not yet supported
} else if (expr instanceof ContextItemExpression) {
result.append('.');
} else if (expr instanceof ErrorExpression) {
// Error do nothing
} else if (expr instanceof FilterExpression) {
FilterExpression filterExpression = (FilterExpression) expr;
result.append('(');
serialize(result, filterExpression.getControllingExpression(), reversePrefixMapping);
result.append('[');
serialize(result, filterExpression.getFilter(), reversePrefixMapping);
result.append("])");
} else if (expr instanceof FunctionCall) {
FunctionCall functionCall = (FunctionCall) expr;
StructuredQName name = functionCall.getFunctionName();
if (name.getPrefix() != null && name.getPrefix().length() > 0) {
result.append(name.getPrefix());
result.append(":");
}
result.append(name.getLocalName());
result.append("(");
Iterator iter = functionCall.iterateSubExpressions();
boolean first = true;
while (iter.hasNext()) {
result.append(first ? "" : ", ");
SaxonXPathExpressionSerializer.serialize(
result, (Expression) iter.next(), reversePrefixMapping);
first = false;
}
result.append(")");
} else if (expr instanceof Instruction) {
// This is not an XPath expression
} else if (expr instanceof IntegerRangeTest) {
// XXX not yet supported
} else if (expr instanceof IsLastExpression) {
result.append("position() eq last()");
} else if (expr instanceof Literal) {
Literal literal = (Literal) expr;
result.append(literal.getValue().toString());
} else if (expr instanceof NumberInstruction) {
// This is not an XPath expression
} else if (expr instanceof PathExpression) {
PathExpression pathExpression = (PathExpression) expr;
result.append('(');
serialize(result, pathExpression.getControllingExpression(), reversePrefixMapping);
result.append('/');
serialize(result, pathExpression.getControlledExpression(), reversePrefixMapping);
result.append(')');
} else if (expr instanceof PatternMatchExpression) {
// XXX not yet supported
} else if (expr instanceof PatternSponsor) {
// XXX not yet supported
} else if (expr instanceof SimpleContentConstructor) {
// This is not an XPath expression
} else if (expr instanceof SimpleExpression) {
// This is not an XPath expression
}
/*
else if (expr instanceof SimpleMappingExpression) {
// XXX not yet supported
}
*/
else if (expr instanceof ParentNodeExpression) {
result.append("..");
} else if (expr instanceof RootExpression) {
// do nothing
} else if (expr instanceof SortExpression) {
// XXX not yet supported
} else if (expr instanceof TailExpression) {
// XXX not yet supported
} else if (expr instanceof TupleExpression) {
// This is not an XPath expression
} else if (expr instanceof TupleSorter) {
// This is not an XPath expression
} else if (expr instanceof UnaryExpression) {
UnaryExpression unaryExpression = (UnaryExpression) expr;
serialize(
result,
unaryExpression.getBaseExpression(),
reversePrefixMapping); // Not sure if this is correct in all cases
} else if (expr instanceof VariableReference) {
VariableReference variableReference = (VariableReference) expr;
String d = variableReference.getDisplayName();
result.append("$");
result.append(d == null ? "$" : d);
}
}
