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java.lang.Object net.sf.saxon.expr.Expression net.sf.saxon.expr.BinaryExpression net.sf.saxon.expr.GeneralComparison
public class GeneralComparison
GeneralComparison: a boolean expression that compares two expressions for equals, not-equals, greater-than or less-than. This implements the operators =, !=, <, >, etc. This implementation is not used when in backwards-compatible mode
Field Summary | |
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protected AtomicComparer |
comparer
|
protected int |
comparisonCardinality
|
static int |
MANY_TO_MANY
|
static int |
MANY_TO_ONE
|
protected boolean |
needsRuntimeCheck
|
static int |
ONE_TO_ONE
|
protected int |
singletonOperator
|
Fields inherited from class net.sf.saxon.expr.BinaryExpression |
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operand0, operand1, 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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GeneralComparison(Expression p0,
int op,
Expression p1)
Create a relational expression identifying the two operands and the operator |
Method Summary | |
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SequenceIterator |
call(SequenceIterator[] arguments,
XPathContext context)
Evaluate the expression |
static boolean |
compare(AtomicValue a0,
int operator,
AtomicValue a1,
AtomicComparer comparer,
boolean checkTypes,
XPathContext context)
Compare two atomic values |
int |
computeCardinality()
Determine the static cardinality. |
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)
Evaluate the expression in a boolean context |
Item |
evaluateItem(XPathContext context)
Evaluate the expression in a given context |
boolean |
evaluateManyToMany(SequenceIterator iter0,
SequenceIterator iter1,
XPathContext context)
Evaluate a (zero-or-one)-to-(zero-or-one) comparison |
protected void |
explainExtraAttributes(ExpressionPresenter out)
Add subclass-specific attributes to the expression tree explanation. |
AtomicComparer |
getAtomicComparer()
Get the AtomicComparer used to compare atomic values. |
int |
getComparisonCardinality()
Ask whether the comparison is known to be many-to-one, one-to-one, or many-to-many. |
static int |
getCorrespondingSingletonOperator(int op)
Return the singleton form of the comparison operator, e.g. |
String |
getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user. |
protected GeneralComparison |
getInverseComparison()
|
ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the expression |
int |
getSingletonOperator()
Get the primitive (singleton) operator used: one of Token.FEQ, Token.FNE, Token.FLT, Token.FGT, Token.FLE, Token.FGE |
boolean |
needsRuntimeCheck()
Ask whether a runtime check of the types of the operands is needed |
Expression |
optimize(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Optimize the expression |
void |
setAtomicComparer(AtomicComparer comparer)
Set the comparer to be used |
void |
setComparisonCardinality(int card)
Say whether the comparison is known to be many-to-one, one-to-one, or many-to-many. |
void |
setNeedsRuntimeCheck(boolean needsCheck)
Say whether a runtime check of the types of the operands is needed |
Expression |
simplify(ExpressionVisitor visitor)
Simplify an expression |
Expression |
typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Type-check the expression |
Methods inherited from class net.sf.saxon.expr.BinaryExpression |
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computeSpecialProperties, displayOperator, equals, explain, getArguments, getOperands, getOperator, hashCode, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, replaceSubExpression, setFlattened, toString |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Methods inherited from interface net.sf.saxon.expr.ComparisonExpression |
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getOperands |
Methods inherited from interface net.sf.saxon.expr.CallableExpression |
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getArguments |
Field Detail |
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public static final int ONE_TO_ONE
public static final int MANY_TO_ONE
public static final int MANY_TO_MANY
protected int singletonOperator
protected AtomicComparer comparer
protected boolean needsRuntimeCheck
protected int comparisonCardinality
Constructor Detail |
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public GeneralComparison(Expression p0, int op, Expression p1)
p0
- the left-hand operandop
- the operator, as a token returned by the Tokenizer (e.g. Token.LT)p1
- the right-hand operandMethod Detail |
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public boolean needsRuntimeCheck()
public void setNeedsRuntimeCheck(boolean needsCheck)
public int getComparisonCardinality()
public void setComparisonCardinality(int card)
public void setAtomicComparer(AtomicComparer comparer)
comparer
- the comparer to be usedpublic Expression simplify(ExpressionVisitor visitor) throws XPathException
BinaryExpression
simplify
in class BinaryExpression
visitor
- an expression visitor
XPathException
- if an error is discovered during expression
rewritingpublic String getExpressionName()
getExpressionName
in class Expression
public AtomicComparer getAtomicComparer()
getAtomicComparer
in interface ComparisonExpression
public int getSingletonOperator()
getSingletonOperator
in interface ComparisonExpression
public boolean convertsUntypedToOther()
convertsUntypedToOther
in interface ComparisonExpression
public int computeCardinality()
computeCardinality
in class BinaryExpression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
typeCheck
in class BinaryExpression
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
optimize
in class BinaryExpression
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 copy()
copy
in class Expression
public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in class Expression
context
- the given context for evaluation
XPathException
- if any dynamic error occurs evaluating the
expressionpublic SequenceIterator call(SequenceIterator[] arguments, XPathContext context) throws XPathException
call
in interface CallableExpression
arguments
- the values of the arguments, supplied as SequenceIteratorscontext
- the dynamic evaluation context
XPathException
- if a dynamic error occurs during the evaluation of the expressionpublic boolean effectiveBooleanValue(XPathContext context) throws XPathException
effectiveBooleanValue
in class Expression
context
- the given context for evaluation
XPathException
- if any dynamic error occurs evaluating the
expressionpublic boolean evaluateManyToMany(SequenceIterator iter0, SequenceIterator iter1, XPathContext context) throws XPathException
iter0
- iterator over the first valueiter1
- iterator the second valuecontext
- dynamic evaluation context
XPathException
- if a dynamic error occurspublic static boolean compare(AtomicValue a0, int operator, AtomicValue a1, AtomicComparer comparer, boolean checkTypes, XPathContext context) throws XPathException
a0
- the first valueoperator
- the operator, for example Token.EQUALS
a1
- the second valuecomparer
- the comparer to be used to perform the comparisoncheckTypes
- set to true if the operand types need to be checked for comparability at runtimecontext
- the XPath evaluation context @return true if the comparison succeeds
XPathException
public ItemType getItemType(TypeHierarchy th)
getItemType
in class Expression
th
- the type hierarchy cache
public static int getCorrespondingSingletonOperator(int op)
op
- the many-to-many form of the operator, for example Token.LE
Token.FLE
protected GeneralComparison getInverseComparison()
protected void explainExtraAttributes(ExpressionPresenter out)
BinaryExpression
explainExtraAttributes
in class BinaryExpression
out
- the output destination for the displayed expression tree
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