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java.lang.Object net.sf.saxon.expr.Expression net.sf.saxon.expr.BinaryExpression
public abstract class BinaryExpression
Binary Expression: a numeric or boolean expression consisting of the two operands and an operator
Field Summary | |
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protected Expression |
operand0
|
protected Expression |
operand1
|
protected int |
operator
|
Fields inherited from class net.sf.saxon.expr.Expression |
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EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD |
Constructor Summary | |
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BinaryExpression(Expression p0,
int op,
Expression p1)
Create a binary expression identifying the two operands and the operator |
Method Summary | |
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int |
computeCardinality()
Determine the static cardinality. |
int |
computeSpecialProperties()
Determine the special properties of this expression |
protected String |
displayOperator()
Display the operator used by this binary expression |
boolean |
equals(Object other)
Is this expression the same as another expression? |
void |
explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
protected void |
explainExtraAttributes(ExpressionPresenter out)
Add subclass-specific attributes to the expression tree explanation. |
Expression[] |
getArguments()
Get the subexpressions (arguments to this 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. |
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<Expression> |
iterateSubExpressions()
Get the immediate subexpressions of this expression |
Expression |
optimize(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Perform optimisation of an expression and its subexpressions. |
Expression |
promote(PromotionOffer offer,
Expression parent)
Promote this expression if possible |
boolean |
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression |
void |
setFlattened(boolean flattened)
Mark an expression as being "flattened". |
Expression |
simplify(ExpressionVisitor visitor)
Simplify an expression |
String |
toString()
The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath. |
Expression |
typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Type-check the expression. |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Field Detail |
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protected Expression operand0
protected Expression operand1
protected int operator
Constructor Detail |
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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 operandMethod Detail |
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public Expression simplify(ExpressionVisitor visitor) throws XPathException
simplify
in class Expression
visitor
- an expression visitor
XPathException
- if an error is discovered during expression
rewritingpublic Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
typeCheck
in class Expression
visitor
- an expression visitorcontextItemType
- 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
XPathException
- if an error is discovered during this phase
(typically a type error)public Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType 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.
optimize
in class Expression
visitor
- an expression visitorcontextItemType
- 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
XPathException
- if an error is discovered during this phase
(typically a type error)public void setFlattened(boolean flattened)
setFlattened
in class Expression
flattened
- set to true if the result of the expression is atomized or otherwise turned into
an atomic valuepublic Expression promote(PromotionOffer offer, Expression parent) throws XPathException
promote
in class Expression
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 expressionparent
- the containing expression in the expression tree
XPathException
- if any error is detectedpublic Iterator<Expression> iterateSubExpressions()
iterateSubExpressions
in class Expression
public Expression[] getArguments()
public boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
in class Expression
original
- the original subexpressionreplacement
- the replacement subexpression
public int getOperator()
Token.PLUS
public Expression[] getOperands()
public int computeCardinality()
computeCardinality
in class Expression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public int computeSpecialProperties()
computeSpecialProperties
in class Expression
StaticProperty.NON_CREATIVE
. This is overridden
for some subclasses.protected static boolean isCommutative(int operator)
operator
- the operator, for example Token.PLUS
protected static boolean isAssociative(int operator)
operator
- the operator, for example Token.PLUS
protected static boolean isInverse(int op1, int op2)
op1
- the first operatorop2
- the second operator
public boolean equals(Object other)
equals
in class Object
public int hashCode()
hashCode
in class Object
public String toString()
toString
in class Expression
public void explain(ExpressionPresenter out)
explain
in class Expression
out
- the output destination for the displayed expression treeprotected void explainExtraAttributes(ExpressionPresenter out)
out
- the output destination for the displayed expression treeprotected String displayOperator()
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