net.sf.saxon.expr

Class CompareToStringConstant

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.UnaryExpression

net.sf.saxon.expr.CompareToConstant

net.sf.saxon.expr.CompareToStringConstant

All Implemented Interfaces:

ComparisonExpression, ExportAgent, Locatable, IdentityComparable, Traceable

public class CompareToStringConstant
extends CompareToConstant

This class implements a comparison of a computed value to a string constant using one of the operators eq, ne, lt, gt, le, ge. The semantics are identical to ValueComparison, with code-point collation, but this is a fast path for an important common case.

Field Summary

Fields inherited from class net.sf.saxon.expr.CompareToConstant

operator

Fields inherited from class net.sf.saxon.expr.Expression

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
CompareToStringConstant(Expression operand, int operator, UnicodeString comparand) Create the expression

Method Summary

Modifier and Type	Method and Description
protected int	computeCardinality() Determine the static cardinality.
protected int	computeHashCode() Hashcode supporting equals()
Expression	copy(RebindingMap rebindings) Copy an expression.
boolean	effectiveBooleanValue(XPathContext context) Get the effective boolean value of the expression.
boolean	equals(java.lang.Object other) Is this expression the same as another expression?
void	export(ExpressionPresenter destination) Diagnostic print of expression structure.
AtomicComparer	getAtomicComparer() Get the AtomicComparer used to compare atomic values.
UnicodeString	getComparand() Get the string value on the rhs of the expression
java.lang.String	getExpressionName() Get a name identifying the kind of expression, in terms meaningful to a user.
Expression	getRhsExpression() Get the effective right-hand-side expression (so that general logic for comparison expressions can be used)
java.lang.String	toShortString() Produce a short string identifying the expression for use in error messages
java.lang.String	toString() The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.

Methods inherited from class net.sf.saxon.expr.CompareToConstant

computeSpecialProperties, convertsUntypedToOther, evaluateItem, getComparisonOperator, getImplementationMethod, getItemType, getLhs, getLhsExpression, getOperandRole, getRhs, getSingletonOperator, optimize

Methods inherited from class net.sf.saxon.expr.UnaryExpression

displayOperator, emitExtraAttributes, getBaseExpression, getOperand, operands, setBaseExpression, typeCheck

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, getStreamerName, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface net.sf.saxon.trace.Traceable

gatherProperties

Constructor Detail

CompareToStringConstant

public CompareToStringConstant(Expression operand,
                               int operator,
                               UnicodeString comparand)

Create the expression

Parameters:

operand - the operand to be compared with an integer constant. This must have a static type of NUMERIC, and a cardinality of EXACTLY ONE

operator - the comparison operator, one of Token.FEQ, Token.FNE, Token.FGE, Token.FGT, Token.FLE, Token.FLT

comparand - the integer constant

Method Detail

getComparand

public UnicodeString getComparand()

Get the string value on the rhs of the expression

Returns:

the integer constant

getRhsExpression

public Expression getRhsExpression()

Get the effective right-hand-side expression (so that general logic for comparison expressions can be used)

Specified by:

getRhsExpression in interface ComparisonExpression

Specified by:

getRhsExpression in class CompareToConstant

Returns:

a Literal representing the RHS expression

copy

public Expression copy(RebindingMap rebindings)

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Parameters:

rebindings - variables that need to be re-bound

Returns:

the copy of the original expression

equals

public boolean equals(java.lang.Object other)

Is this expression the same as another expression?

Overrides:

equals in class UnaryExpression

Parameters:

other - the expression to be compared with this one

Returns:

true if the two expressions are statically equivalent

computeHashCode

protected int computeHashCode()

Hashcode supporting equals()

Overrides:

computeHashCode in class UnaryExpression

Returns:

a computed hash code

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
                              throws XPathException

Get the effective boolean value of the expression. This returns false if the value is the empty sequence, a zero-length string, a number equal to zero, or the boolean false. Otherwise it returns true.

Overrides:

effectiveBooleanValue in class Expression

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the effective boolean value

Throws:

XPathException - if any dynamic error occurs evaluating the expression

computeCardinality

protected int computeCardinality()

Description copied from class: UnaryExpression

Determine the static cardinality. Default implementation returns the cardinality of the operand

Overrides:

computeCardinality in class UnaryExpression

Returns:

the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE. May also return StaticProperty.ALLOWS_ZERO if the result is known to be an empty sequence, or StaticProperty.ALLOWS_MANY if if is known to return a sequence of length two or more.

getExpressionName

public java.lang.String getExpressionName()

Get a name identifying the kind of expression, in terms meaningful to a user.

Overrides:

getExpressionName in class Expression

Returns:

a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in export() output displaying the expression.

export

public void export(ExpressionPresenter destination)
            throws XPathException

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

export in interface ExportAgent

Overrides:

export in class UnaryExpression

Parameters:

destination - the expression presenter used to display the structure

Throws:

XPathException - if the export fails, for example if an expression is found that won't work in the target environment.

toString

public java.lang.String toString()

The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.

For subclasses of Expression that represent XPath expressions, the result should always be a string that parses as an XPath 3.0 expression

Overrides:

toString in class UnaryExpression

Returns:

a representation of the expression as a string

toShortString

public java.lang.String toShortString()

Produce a short string identifying the expression for use in error messages

Overrides:

toShortString in class UnaryExpression

Returns:

a short string, sufficient to identify the expression

getAtomicComparer

public AtomicComparer getAtomicComparer()

Get the AtomicComparer used to compare atomic values. This encapsulates any collation that is used

Returns:

the comparer