net.sf.saxon.expr

Class ArithmeticExpression

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.BinaryExpression

net.sf.saxon.expr.ArithmeticExpression

All Implemented Interfaces:

IdentityComparable

public class ArithmeticExpression
extends BinaryExpression

Arithmetic Expression: an expression using one of the operators plus, minus, multiply, div, idiv, mod. Note that this code does not handle backwards compatibility mode: see ArithmeticExpression10

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	simplified

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

operator

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

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

Constructor Summary

Constructors

Constructor and Description
ArithmeticExpression(Expression p0, int operator, Expression p1) Create an arithmetic expression

Method Summary

Methods

Modifier and Type	Method and Description
static AtomicValue	compute(AtomicValue value0, int operator, AtomicValue value1, XPathContext context) Static method to apply arithmetic to two values
Expression	copy() Copy an expression.
AtomicValue	evaluateItem(XPathContext context) Evaluate the expression.
protected void	explainExtraAttributes(ExpressionPresenter out) Add subclass-specific attributes to the expression tree explanation.
Calculator	getCalculator() Get the calculator allocated to evaluate this expression
ExpressionCompiler	getExpressionCompiler() Return the compiler of the Arithmetic expression
String	getExpressionName() Get a name identifying the kind of expression, in terms meaningful to a user.
IntegerValue[]	getIntegerBounds() 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.
PlainType	getItemType() Determine the data type of the expression, insofar as this is known statically
static int	mapOpCode(int op) Map operator codes from those in the Token class to those in the Calculator class
void	resetLocalStaticProperties() Reset the static properties of the expression to -1, so that they have to be recomputed next time they are used.
void	setCalculator(Calculator calculator) Set the calculator allocated to evaluate this expression
Expression	simplify() Simplify an expression.
protected String	tag() Get the element name used to identify this expression in exported expression format
Expression	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Type-check the expression statically.

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

computeCardinality, computeSpecialProperties, displayOperator, equals, export, getImplementationMethod, getLhs, getLhsExpression, getOperandRole, getOperator, getRhs, getRhsExpression, hashCode, isAssociative, isCommutative, isInverse, operands, optimize, setFlattened, setLhsExpression, setRhsExpression, toShortString, toString

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

addToPathMap, adoptChildExpression, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getHostLanguage, getIntrinsicDependencies, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getPosture, getPostureAndSweepIfKnown, getProperties, getProperty, getRetainedStaticContext, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStreamability, getStreamingAdjunct, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isCallOnSystemFunction, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, makeStreamingAdjunct, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, optimizeForType, process, promote, promoteChildren, restoreParentPointers, setEvaluationMethod, setFiltered, setLocation, setParentExpression, setPostureAndSweep, setRetainedStaticContext, setRetainedStaticContextLocally, setStaticProperty, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeCheckChildren, typeError, unordered

Methods inherited from class java.lang.Object

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

Field Detail

simplified

protected boolean simplified

Constructor Detail

ArithmeticExpression

public ArithmeticExpression(Expression p0,
                    int operator,
                    Expression p1)

Create an arithmetic expression

Parameters:

p0 - the first operand

operator - the operator, for example Token.PLUS

p1 - the second operand

Method Detail

getExpressionName

public 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 explain() output displaying the expression.

simplify

public Expression simplify()
                    throws XPathException

Description copied from class: Expression

Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation simplifies its operands.

Overrides:

simplify in class Expression

Returns:

the simplified expression (or the original if unchanged, or if modified in-situ)

Throws:

XPathException - if an error is discovered during expression rewriting

setCalculator

public void setCalculator(Calculator calculator)

Set the calculator allocated to evaluate this expression

Parameters:

calculator - the calculator to be used

getCalculator

public Calculator getCalculator()

Get the calculator allocated to evaluate this expression

Returns:

the calculator, a helper object that does the actual calculation

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                   ContextItemStaticInfo contextInfo)
                     throws XPathException

Type-check the expression statically. We try to work out which particular arithmetic function to use if the types of operands are known an compile time.

Overrides:

typeCheck in class BinaryExpression

Parameters:

visitor - an expression visitor

contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

getIntegerBounds

public IntegerValue[] getIntegerBounds()

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.

Overrides:

getIntegerBounds in class Expression

Returns:

the lower and upper bounds of integer values in the result, or null to indicate unknown or not applicable.

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

compute

public static AtomicValue compute(AtomicValue value0,
                  int operator,
                  AtomicValue value1,
                  XPathContext context)
                           throws XPathException

Static method to apply arithmetic to two values

Parameters:

value0 - the first value

operator - the operator as denoted in the Calculator class, for example Calculator.PLUS

value1 - the second value

context - the XPath dynamic evaluation context

Returns:

the result of the arithmetic operation

Throws:

XPathException - if a dynamic error occurs during evaluation

mapOpCode

public static int mapOpCode(int op)

Map operator codes from those in the Token class to those in the Calculator class

Parameters:

op - an operator denoted by a constant in the Token class, for example Token.PLUS

Returns:

an operator denoted by a constant defined in the Calculator class, for example Calculator.PLUS

getItemType

public PlainType getItemType()

Determine the data type of the expression, insofar as this is known statically

Specified by:

getItemType in class Expression

Returns:

the atomic type of the result of this arithmetic expression

resetLocalStaticProperties

public void resetLocalStaticProperties()

Reset the static properties of the expression to -1, so that they have to be recomputed next time they are used.

Overrides:

resetLocalStaticProperties in class Expression

evaluateItem

public AtomicValue evaluateItem(XPathContext context)
                         throws XPathException

Evaluate the expression.

Overrides:

evaluateItem in class Expression

Parameters:

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

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression

tag

protected String tag()

Description copied from class: BinaryExpression

Get the element name used to identify this expression in exported expression format

Overrides:

tag in class BinaryExpression

Returns:

the element name used to identify this expression

explainExtraAttributes

protected void explainExtraAttributes(ExpressionPresenter out)

Description copied from class: BinaryExpression

Add subclass-specific attributes to the expression tree explanation. Default implementation does nothing; this is provided for subclasses to override.

Overrides:

explainExtraAttributes in class BinaryExpression

Parameters:

out - the output destination for the displayed expression tree

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the Arithmetic expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler