public abstract class BinaryExpression extends ComputedExpression
Modifier and Type | Field and Description |
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protected Expression |
operand0 |
protected Expression |
operand1 |
protected int |
operator |
locationId, staticProperties
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
Constructor and Description |
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BinaryExpression(Expression p0,
int op,
Expression p1)
Create a binary expression identifying the two operands and the operator
|
Modifier and Type | Method and Description |
---|---|
int |
computeCardinality()
Determine the static cardinality.
|
int |
computeSpecialProperties()
Determine the special properties of this expression
|
void |
display(int level,
NamePool pool,
PrintStream out)
Diagnostic print of expression structure
|
protected String |
displayOperator() |
boolean |
equals(Object other)
Is this expression the same as another expression?
|
Expression[] |
getOperands()
Get the operands
|
int |
getOperator()
Get the operator
|
int |
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.
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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).
|
Iterator |
iterateSubExpressions()
Get the immediate subexpressions of this expression
|
Expression |
optimize(Optimizer opt,
StaticContext env,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
|
Expression |
promote(PromotionOffer offer)
Promote this expression if possible
|
Expression |
simplify(StaticContext env)
Simplify an expression
|
Expression |
typeCheck(StaticContext env,
ItemType contextItemType)
Type-check the expression.
|
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, 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, suppressValidation, typeError, typeError
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
getItemType
protected Expression operand0
protected Expression operand1
protected int operator
public BinaryExpression(Expression p0, int op, Expression p1)
p0
- the left-hand operandop
- the operator, as a token returned by the Tokenizer (e.g. Token.AND)p1
- the right-hand operandpublic Expression simplify(StaticContext env) throws XPathException
simplify
in interface Expression
simplify
in class ComputedExpression
XPathException
- if an error is discovered during expression
rewritingpublic Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
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 to
Type.ITEM_TYPE
StaticError
- if an error is discovered during this phase
(typically a type error)XPathException
public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException
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.
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 to
Type.ITEM_TYPE
StaticError
- if an error is discovered during this phase
(typically a type error)XPathException
public Expression promote(PromotionOffer offer) throws XPathException
promote
in interface Expression
promote
in class ComputedExpression
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 expressionXPathException
- if any error is detectedpublic Iterator iterateSubExpressions()
iterateSubExpressions
in interface Expression
iterateSubExpressions
in class ComputedExpression
public int getOperator()
public Expression[] getOperands()
public int computeCardinality()
computeCardinality
in class ComputedExpression
public int computeSpecialProperties()
computeSpecialProperties
in class ComputedExpression
StaticProperty.NON_CREATIVE
. This is overridden
for some subclasses.protected static boolean isCommutative(int operator)
operator
- protected static boolean isAssociative(int operator)
protected static boolean isInverse(int op1, int op2)
op1
- the first operatorop2
- the second operatorpublic boolean equals(Object other)
public int hashCode()
public void display(int level, NamePool pool, PrintStream out)
level
- indentation level for this expressionpool
- NamePool used to expand any names appearing in the expressionout
- Output destinationprotected String displayOperator()