net.sf.saxon.functions

Class Matches

public class Matches extends SystemFunction

This class implements the matches() function for regular expression matching
Method Summary
ItemevaluateItem(XPathContext c)
Evaluate the matches() function to give a Boolean value.
RegularExpressiongetCompiledRegularExpression()
Get the compiled regular expression, returning null if the regex has not been compiled
Expressionoptimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
Expressionsimplify(ExpressionVisitor visitor)
Simplify and validate.
static RegularExpressiontryToCompile(Expression[] args, int patternArg, int flagsArg, StaticContext env)
Try to precompile the arguments to the function.

Method Detail

evaluateItem

public Item evaluateItem(XPathContext c)
Evaluate the matches() function to give a Boolean value.

Parameters: c The dynamic evaluation context

Returns: the result as a BooleanValue, or null to indicate the empty sequence

Throws: XPathException on an error

getCompiledRegularExpression

public RegularExpression getCompiledRegularExpression()
Get the compiled regular expression, returning null if the regex has not been compiled

Returns: the compiled regular expression, or null

optimize

public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

Parameters: visitor an expression visitor contextItemType the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to ITEM_TYPE

Returns: the original expression, rewritten if appropriate to optimize execution

Throws: net.sf.saxon.trans.XPathException if an error is discovered during this phase (typically a type error)

simplify

public Expression simplify(ExpressionVisitor visitor)
Simplify and validate. This is a pure function so it can be simplified in advance if the arguments are known

Parameters: visitor an expression visitor

Returns: the simplified expression

Throws: XPathException if any error is found (e.g. invalid regular expression)

tryToCompile

public static RegularExpression tryToCompile(Expression[] args, int patternArg, int flagsArg, StaticContext env)
Try to precompile the arguments to the function. This method is shared by the implementations of the three XPath functions matches(), replace(), and tokenize().

Parameters: args the supplied arguments to the function, as an array patternArg the position of the argument containing the regular expression flagsArg the position of the argument containing the flags env the static context

Returns: the compiled regular expression, or null indicating that the information is not available statically so it cannot be precompiled

Throws: XPathException if any failure occurs, in particular, if the regular expression is invalid