Package net.sf.saxon.expr
Class BinaryExpression
- java.lang.Object
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- net.sf.saxon.expr.ComputedExpression
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- net.sf.saxon.expr.BinaryExpression
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,Container
,Expression
,InstructionInfoProvider
- Direct Known Subclasses:
ArithmeticExpression
,BooleanExpression
,GeneralComparison
,GeneralComparison10
,IdentityComparison
,RangeExpression
,SingletonComparison
,ValueComparison
,VennExpression
public abstract class BinaryExpression extends ComputedExpression
Binary Expression: a numeric or boolean expression consisting of the two operands and an operator- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description protected Expression
operand0
protected Expression
operand1
protected int
operator
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Fields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
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Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
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Constructor Summary
Constructors Constructor Description BinaryExpression(Expression p0, int op, Expression p1)
Create a binary expression identifying the two operands and the operator
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description int
computeCardinality()
Determine the static cardinality.int
computeSpecialProperties()
Determine the special properties of this expressionvoid
display(int level, java.io.PrintStream out, Configuration config)
Diagnostic print of expression structureprotected java.lang.String
displayOperator()
boolean
equals(java.lang.Object other)
Is this expression the same as another expression?Expression[]
getOperands()
Get the operandsint
getOperator()
Get the operatorint
hashCode()
Get a hashCode for comparing two expressions.protected static boolean
isAssociative(int operator)
Determine whether an operator is associative, that is, ((a^b)^c) = (a^(b^c))protected static boolean
isCommutative(int operator)
Determine whether a binary operator is commutative, that is, A op B = B op A.protected static boolean
isInverse(int op1, int op2)
Test if one operator is the inverse of another, so that (A op1 B) is equivalent to (B op2 A).java.util.Iterator
iterateSubExpressions()
Get the immediate subexpressions of this expressionExpression
optimize(Optimizer opt, StaticContext env, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.Expression
promote(PromotionOffer offer)
Promote this expression if possibleboolean
replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpressionExpression
simplify(StaticContext env)
Simplify an expressionExpression
typeCheck(StaticContext env, ItemType contextItemType)
Type-check the expression.-
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface net.sf.saxon.expr.Expression
getItemType
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Field Detail
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operand0
protected Expression operand0
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operand1
protected Expression operand1
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operator
protected int operator
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Constructor Detail
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BinaryExpression
public BinaryExpression(Expression p0, int op, Expression p1)
Create a binary expression identifying the two operands and the operator- Parameters:
p0
- the left-hand operandop
- the operator, as a token returned by the Tokenizer (e.g. Token.AND)p1
- the right-hand operand
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Method Detail
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simplify
public Expression simplify(StaticContext env) throws XPathException
Simplify an expression- Specified by:
simplify
in interfaceExpression
- Overrides:
simplify
in classComputedExpression
- Parameters:
env
- the static context- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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typeCheck
public Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
Type-check the expression. Default implementation for binary operators that accept any kind of operand- Parameters:
env
- the static context of the expressioncontextItemType
- 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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
- Throws:
StaticError
- if an error is discovered during this phase (typically a type error)XPathException
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optimize
public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException
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:
opt
- the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.env
- the static context of the expressioncontextItemType
- 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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten if appropriate to optimize execution
- Throws:
StaticError
- if an error is discovered during this phase (typically a type error)XPathException
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promote
public Expression promote(PromotionOffer offer) throws XPathException
Promote this expression if possible- Specified by:
promote
in interfaceExpression
- Overrides:
promote
in classComputedExpression
- Parameters:
offer
- details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression- Returns:
- if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
- Throws:
XPathException
- if any error is detected
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iterateSubExpressions
public java.util.Iterator iterateSubExpressions()
Get the immediate subexpressions of this expression- Specified by:
iterateSubExpressions
in interfaceExpression
- Overrides:
iterateSubExpressions
in classComputedExpression
- Returns:
- an iterator containing the sub-expressions of this expression
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replaceSubExpression
public boolean replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression- Specified by:
replaceSubExpression
in interfaceContainer
- Overrides:
replaceSubExpression
in classComputedExpression
- Parameters:
original
- the original subexpressionreplacement
- the replacement subexpression- Returns:
- true if the original subexpression is found
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getOperator
public int getOperator()
Get the operator
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getOperands
public Expression[] getOperands()
Get the operands
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computeCardinality
public int computeCardinality()
Determine the static cardinality. Default implementation returns [0..1] if either operand can be empty, or [1..1] otherwise.- Specified by:
computeCardinality
in classComputedExpression
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computeSpecialProperties
public int computeSpecialProperties()
Determine the special properties of this expression- Overrides:
computeSpecialProperties
in classComputedExpression
- Returns:
StaticProperty.NON_CREATIVE
. This is overridden for some subclasses.
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isCommutative
protected static boolean isCommutative(int operator)
Determine whether a binary operator is commutative, that is, A op B = B op A.- Parameters:
operator
-- Returns:
- true if the operator is commutative
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isAssociative
protected static boolean isAssociative(int operator)
Determine whether an operator is associative, that is, ((a^b)^c) = (a^(b^c))
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isInverse
protected static boolean isInverse(int op1, int op2)
Test if one operator is the inverse of another, so that (A op1 B) is equivalent to (B op2 A). Commutative operators are the inverse of themselves and are therefore not listed here.- Parameters:
op1
- the first operatorop2
- the second operator- Returns:
- true if the operators are the inverse of each other
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equals
public boolean equals(java.lang.Object other)
Is this expression the same as another expression?- Overrides:
equals
in classjava.lang.Object
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hashCode
public int hashCode()
Get a hashCode for comparing two expressions. Note that this hashcode gives the same result for (A op B) and for (B op A), whether or not the operator is commutative.- Overrides:
hashCode
in classjava.lang.Object
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display
public void display(int level, java.io.PrintStream out, Configuration config)
Diagnostic print of expression structure- Parameters:
level
- indentation level for this expressionout
- Output destination
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displayOperator
protected java.lang.String displayOperator()
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