net.sf.saxon.expr

Class GeneralComparison

public class GeneralComparison extends BinaryExpression

GeneralComparison: a boolean expression that compares two expressions for equals, not-equals, greater-than or less-than. This implements the operators =, !=, <, >, etc. This implementation is not used when in backwards-compatible mode

Field Summary
protected AtomicComparer	comparer
protected int	singletonOperator

Constructor Summary
	GeneralComparison(Expression p0, int op, Expression p1) Create a relational expression identifying the two operands and the operator

Method Summary
protected static boolean	compare(AtomicValue a1, int operator, AtomicValue a2, AtomicComparer comparer, XPathContext context) Compare two atomic values
int	computeCardinality() Determine the static cardinality.
protected String	displayOperator()
boolean	effectiveBooleanValue(XPathContext context) Evaluate the expression in a boolean context
Item	evaluateItem(XPathContext context) Evaluate the expression in a given context
protected GeneralComparison	getInverseComparison()
ItemType	getItemType(TypeHierarchy th) Determine the data type of the expression
Expression	optimize(Optimizer opt, StaticContext env, ItemType contextItemType) Optimize the expression
Expression	typeCheck(StaticContext env, ItemType contextItemType) Type-check the expression

Field Detail

comparer

protected AtomicComparer comparer

singletonOperator

protected int singletonOperator

Constructor Detail

GeneralComparison

public GeneralComparison(Expression p0, int op, Expression p1)

Create a relational expression identifying the two operands and the operator

Parameters: p0 the left-hand operand op the operator, as a token returned by the Tokenizer (e.g. Token.LT) p1 the right-hand operand

Method Detail

compare

protected static boolean compare(AtomicValue a1, int operator, AtomicValue a2, AtomicComparer comparer, XPathContext context)

Compare two atomic values

computeCardinality

public int computeCardinality()

Determine the static cardinality. Returns [1..1]

displayOperator

protected String displayOperator()

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)

Evaluate the expression in a boolean context

Parameters: context the given context for evaluation

Returns: a boolean representing the result of the numeric comparison of the two operands

evaluateItem

public Item evaluateItem(XPathContext context)

Evaluate the expression in a given context

Parameters: context the given context for evaluation

Returns: a BooleanValue representing the result of the numeric comparison of the two operands

getInverseComparison

protected GeneralComparison getInverseComparison()

getItemType

public ItemType getItemType(TypeHierarchy th)

Determine the data type of the expression

Parameters: th

Returns: Type.BOOLEAN

optimize

public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType)

Optimize the expression

Returns: the checked expression

typeCheck

public Expression typeCheck(StaticContext env, ItemType contextItemType)

Type-check the expression

Returns: the checked expression