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An OSGi bundle for Saxon-HE
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2013 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.functions;
import net.sf.saxon.expr.*;
import net.sf.saxon.expr.parser.ExpressionVisitor;
import net.sf.saxon.om.GroundedValue;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.Int64Value;
import net.sf.saxon.value.IntegerValue;
import net.sf.saxon.value.StringValue;
/**
* Implement the XPath string-length() function
*/
public class StringLength extends SystemFunctionCall implements Callable {
boolean contextPossiblyUndefined = true;
/**
* Simplify and validate.
* This is a pure function so it can be simplified in advance if the arguments are known
* @param visitor an expression visitor
*/
/*@NotNull*/
public Expression simplify(ExpressionVisitor visitor) throws XPathException {
//useContextItemAsDefault();
return simplifyArguments(visitor);
}
/**
* For an expression that returns an integer or a sequence of integers, get
* a lower and upper bound on the values of the integers that may be returned, from
* static analysis. The default implementation returns null, meaning "unknown" or
* "not applicable". Other implementations return an array of two IntegerValue objects,
* representing the lower and upper bounds respectively. The values
* UNBOUNDED_LOWER and UNBOUNDED_UPPER are used by convention to indicate that
* the value may be arbitrarily large. The values MAX_STRING_LENGTH and MAX_SEQUENCE_LENGTH
* are used to indicate values limited by the size of a string or the size of a sequence.
*
* @return the lower and upper bounds of integer values in the result, or null to indicate
* unknown or not applicable.
*/
@Override
public IntegerValue[] getIntegerBounds() {
return new IntegerValue[]{Int64Value.ZERO, MAX_STRING_LENGTH};
}
/**
* Determine the intrinsic dependencies of an expression, that is, those which are not derived
* from the dependencies of its subexpressions. For example, position() has an intrinsic dependency
* on the context position, while (position()+1) does not. The default implementation
* of the method returns 0, indicating "no dependencies".
*
* @return a set of bit-significant flags identifying the "intrinsic"
* dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
*/
public int getIntrinsicDependencies() {
int d = super.getIntrinsicDependencies();
if (argument.length == 0) {
d |= StaticProperty.DEPENDS_ON_CONTEXT_ITEM;
}
return d;
}
/**
* Pre-evaluate a function at compile time. Functions that do not allow
* pre-evaluation, or that need access to context information, can override this method.
* @param visitor an expression visitor
* @return the expression, either unchanged, or pre-evaluated
*/
public Expression preEvaluate(ExpressionVisitor visitor) throws XPathException {
if (argument.length == 0) {
return this;
} else {
return Literal.makeLiteral(
(GroundedValue)evaluateItem(visitor.getStaticContext().makeEarlyEvaluationContext()));
}
}
/*@NotNull*/
public Expression typeCheck(ExpressionVisitor visitor, /*@Nullable*/ ExpressionVisitor.ContextItemType contextItemType) throws XPathException {
if (argument.length == 0 && contextItemType == null) {
XPathException err = new XPathException("The context item for string-length() is absent");
err.setErrorCode("XPDY0002");
err.setIsTypeError(true);
err.setLocator(this);
throw err;
} else if (contextItemType != null) {
contextPossiblyUndefined = contextItemType.contextMaybeUndefined;
}
return super.typeCheck(visitor, contextItemType);
}
/**
* Ask whether the context item may possibly be undefined
* @return true if it might be undefined
*/
public boolean isContextPossiblyUndefined() {
return contextPossiblyUndefined;
}
/**
* Evaluate in a general context
*/
public Int64Value evaluateItem(XPathContext c) throws XPathException {
AtomicValue sv;
if (argument.length == 0) {
final Item contextItem = c.getContextItem();
if (contextItem == null) {
dynamicError("The context item for string-length() is not set", "XPDY0002", c);
return null;
}
sv = StringValue.makeStringValue(contextItem.getStringValueCS());
} else {
sv = (AtomicValue)argument[0].evaluateItem(c);
}
if (sv==null) {
return Int64Value.ZERO;
}
if (sv instanceof StringValue) {
return Int64Value.makeIntegerValue(((StringValue)sv).getStringLength());
} else {
CharSequence s = sv.getStringValueCS();
return Int64Value.makeIntegerValue(StringValue.getStringLength(s));
}
}
/**
* Evaluate the expression
*
* @param context the dynamic evaluation context
* @param arguments the values of the arguments, supplied as Sequences
* @return the result of the evaluation, in the form of a Sequence
* @throws net.sf.saxon.trans.XPathException
* if a dynamic error occurs during the evaluation of the expression
*/
public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException {
AtomicValue sv;
if (argument.length == 0) {
final Item contextItem = context.getContextItem();
if (contextItem == null) {
dynamicError("The context item for string-length() is not set", "XPDY0002", context);
return null;
}
sv = StringValue.makeStringValue(contextItem.getStringValueCS());
} else {
sv = (AtomicValue)arguments[0].head();
}
if (sv==null) {
return Int64Value.ZERO;
}
if (sv instanceof StringValue) {
return Int64Value.makeIntegerValue(((StringValue)sv).getStringLength());
} else {
CharSequence s = sv.getStringValueCS();
return Int64Value.makeIntegerValue(StringValue.getStringLength(s));
}
}
}