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java.lang.Object net.sf.saxon.expr.Expression net.sf.saxon.expr.CompareToIntegerConstant
public class CompareToIntegerConstant
This class implements a comparison of a numeric value to an integer constant using one of the operators eq, ne, lt, gt, le, ge. The semantics are identical to ValueComparison, but this is a fast path for an important common case.
Field Summary 

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

EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD 
Constructor Summary  

CompareToIntegerConstant(Expression operand,
int operator,
long comparand)
Create the expression 
Method Summary  

protected int 
computeCardinality()
Compute the static cardinality of this expression 
int 
computeDependencies()
Compute the dependencies of an expression, as the union of the dependencies of its subexpressions. 
int 
computeSpecialProperties()
Compute the special properties of this expression. 
boolean 
convertsUntypedToOther()
Determine whether untyped atomic values should be converted to the type of the other operand 
Expression 
copy()
Copy an expression. 
boolean 
effectiveBooleanValue(XPathContext context)
Get the effective boolean value of the expression. 
Item 
evaluateItem(XPathContext context)
Evaluate an expression as a single item. 
void 
explain(ExpressionPresenter destination)
Diagnostic print of expression structure. 
AtomicComparer 
getAtomicComparer()
Get the AtomicComparer used to compare atomic values. 
long 
getComparand()
Get the integer value on the rhs of the expression 
int 
getComparisonOperator()
Get the comparison operator 
int 
getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). 
ItemType 
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible. 
Expression 
getOperand()
Get the expression on the lhs of the comparison 
Expression[] 
getOperands()
Get the two operands of the comparison 
int 
getSingletonOperator()
Get the primitive (singleton) operator used: one of Token.FEQ, Token.FNE, Token.FLT, Token.FGT, Token.FLE, Token.FGE 
Iterator<Expression> 
iterateSubExpressions()
Get the immediate subexpressions of this expression. 
Expression 
optimize(ExpressionVisitor visitor,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions. 
Expression 
promote(PromotionOffer offer,
Expression parent)
Offer promotion for this subexpression. 
boolean 
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression 
Expression 
simplify(ExpressionVisitor visitor)
Simplify an expression. 
Expression 
typeCheck(ExpressionVisitor visitor,
ItemType contextItemType)
Perform type checking of an expression and its subexpressions. 
Methods inherited from class java.lang.Object 

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait 
Constructor Detail 

public CompareToIntegerConstant(Expression operand, int operator, long comparand)
operand
 the operand to be compared with an integer constantoperator
 the comparison operator,
one of Token.FEQ
, Token.FNE
, Token.FGE
,
Token.FGT
, Token.FLE
, Token.FLT
comparand
 the integer constantMethod Detail 

public Expression getOperand()
public long getComparand()
public int getComparisonOperator()
Token.FEQ
, Token.FNE
, Token.FGE
,
Token.FGT
, Token.FLE
, Token.FLT
public int getImplementationMethod()
getImplementationMethod
in class Expression
Expression.EVALUATE_METHOD
public Expression simplify(ExpressionVisitor visitor) throws XPathException
simplify
in class Expression
visitor
 the expression visitor
XPathException
 if an error is discovered during expression
rewritingpublic 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

XPathException
 if any error is detectedpublic int computeSpecialProperties()
Expression
StaticProperty
. The "special" properties are properties
other than cardinality and dependencies, and most of them relate to properties of node sequences, for
example whether the nodes are in document order.
computeSpecialProperties
in class Expression
public int computeDependencies()
computeDependencies
in class Expression
public Expression copy()
copy
in class Expression
public Iterator<Expression> iterateSubExpressions()
iterateSubExpressions
in class Expression
public boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
in class Expression
original
 the original subexpressionreplacement
 the replacement subexpression
public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in interface EvaluableItem
evaluateItem
in class Expression
context
 The context in which the expression is to be evaluated
XPathException
 if any dynamic error occurs evaluating the
expressionpublic boolean effectiveBooleanValue(XPathContext context) throws XPathException
effectiveBooleanValue
in class Expression
context
 The context in which the expression is to be evaluated
XPathException
 if any dynamic error occurs evaluating the
expressionprotected int computeCardinality()
Expression
computeCardinality
in class Expression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
This checks statically that the operands of the expression have the correct type; if necessary it generates code to do runtime type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a runtime type error is inevitable. The call may return a modified form of the expression.
This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.
If the implementation returns a value other than "this", then it is required to ensure that the parent pointer and location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.
typeCheck
in class Expression
visitor
 the 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, 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.
optimize
in class Expression
visitor
 the 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 ItemType getItemType(TypeHierarchy th)
This method should always return a result, though it may be the best approximation that is available at the time.
getItemType
in class Expression
th
 the type hierarchy cache
public void explain(ExpressionPresenter destination)
explain
in class Expression
destination
 the expression presenter used to display the structurepublic AtomicComparer getAtomicComparer()
getAtomicComparer
in interface ComparisonExpression
public int getSingletonOperator()
getSingletonOperator
in interface ComparisonExpression
public Expression[] getOperands()
getOperands
in interface ComparisonExpression
public boolean convertsUntypedToOther()
convertsUntypedToOther
in interface ComparisonExpression


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