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java.lang.Objectnet.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 | |
|---|---|
protected Expression |
operand0
|
protected Expression |
operand1
|
protected int |
operator
|
| Fields inherited from class net.sf.saxon.expr.Expression |
|---|
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 | |
|---|---|
BinaryExpression(Expression p0,
int op,
Expression p1)
Create a binary expression identifying the two operands and the operator |
|
| Method Summary | |
|---|---|
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 |
|---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
| Field Detail |
|---|
protected Expression operand0
protected Expression operand1
protected int operator
| Constructor Detail |
|---|
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 operand| Method Detail |
|---|
public Expression simplify(ExpressionVisitor visitor)
throws XPathException
simplify in class Expressionvisitor - an expression visitor
XPathException - if an error is discovered during expression
rewriting
public Expression typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
throws XPathException
typeCheck in class Expressionvisitor - 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 Expressionvisitor - 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 Expressionflattened - set to true if the result of the expression is atomized or otherwise turned into
an atomic value
public Expression promote(PromotionOffer offer,
Expression parent)
throws XPathException
promote in class Expressionoffer - 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 Expressionpublic Expression[] getArguments()
public boolean replaceSubExpression(Expression original,
Expression replacement)
replaceSubExpression in class Expressionoriginal - the original subexpressionreplacement - the replacement subexpression
public int getOperator()
Token.PLUSpublic Expression[] getOperands()
public int computeCardinality()
computeCardinality in class ExpressionStaticProperty.ALLOWS_ZERO_OR_ONE,
StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE,
StaticProperty.ALLOWS_ZERO_OR_MOREpublic int computeSpecialProperties()
computeSpecialProperties in class ExpressionStaticProperty.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 Objectpublic int hashCode()
hashCode in class Objectpublic String toString()
toString in class Expressionpublic void explain(ExpressionPresenter out)
explain in class Expressionout - 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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