org.exist.xquery
Class GeneralComparison

java.lang.Object
  extended byorg.exist.xquery.AbstractExpression
      extended byorg.exist.xquery.PathExpr
          extended byorg.exist.xquery.BinaryOp
              extended byorg.exist.xquery.GeneralComparison
All Implemented Interfaces:
CompiledExpression, CompiledXQuery, Expression
Direct Known Subclasses:
ValueComparison

public class GeneralComparison
extends BinaryOp

A general XQuery/XPath2 comparison expression.

Author:
wolf

Field Summary
 
Fields inherited from interface org.exist.xquery.Expression
DOT_TEST, EXPRESSION_ID_INVALID, IGNORE_CONTEXT, IN_PREDICATE, IN_UPDATE, IN_WHERE_CLAUSE, NO_CONTEXT_ID, SINGLE_STEP_EXECUTION
 
Constructor Summary
GeneralComparison(XQueryContext context, Expression left, Expression right, int relation)
           
GeneralComparison(XQueryContext context, Expression left, Expression right, int relation, int truncation)
           
GeneralComparison(XQueryContext context, int relation)
           
GeneralComparison(XQueryContext context, int relation, int truncation)
           
 
Method Summary
 void analyze(AnalyzeContextInfo contextInfo)
          Statically analyze the expression and its subexpressions.
static boolean compareAtomic(java.text.Collator collator, AtomicValue lv, AtomicValue rv, boolean backwardsCompatible, int truncation, int relation)
           
 void dump(ExpressionDumper dumper)
          Write a diagnostic dump of the expression to the passed ExpressionDumper.
 Sequence eval(Sequence contextSequence, Item contextItem)
          Evaluate the expression represented by this object.
 int getDependencies()
          Returns Dependency.DEFAULT_DEPENDENCIES.
 void resetState()
          Called to inform an expression that it should reset to its initial state.
 int returnsType()
          The static return type of the expression.
 void setCollation(Expression collationArg)
           
 java.lang.String toString()
           
 
Methods inherited from class org.exist.xquery.BinaryOp
getLeft, getRight, setContextDocSet, setLeft, setRight
 
Methods inherited from class org.exist.xquery.PathExpr
accept, add, add, addPath, addPredicate, dump, getASTNode, getCardinality, getContext, getDocumentSet, getExpression, getLastExpression, getLength, getLiteralValue, getSource, isValid, replaceLastExpression, reset, setContext, setPrimaryAxis, setSource
 
Methods inherited from class org.exist.xquery.AbstractExpression
eval, getContextDocSet, getContextId, getExpressionId, setASTNode
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface org.exist.xquery.CompiledXQuery
eval
 

Constructor Detail

GeneralComparison

public GeneralComparison(XQueryContext context,
                         int relation)

GeneralComparison

public GeneralComparison(XQueryContext context,
                         int relation,
                         int truncation)

GeneralComparison

public GeneralComparison(XQueryContext context,
                         Expression left,
                         Expression right,
                         int relation)

GeneralComparison

public GeneralComparison(XQueryContext context,
                         Expression left,
                         Expression right,
                         int relation,
                         int truncation)
Method Detail

analyze

public void analyze(AnalyzeContextInfo contextInfo)
             throws XPathException
Description copied from interface: Expression
Statically analyze the expression and its subexpressions. During the static analysis phase, the query engine can detect unknown variables and some type errors.

Specified by:
analyze in interface Expression
Overrides:
analyze in class BinaryOp
Throws:
XPathException

returnsType

public int returnsType()
Description copied from interface: Expression
The static return type of the expression. This method should return one of the type constants defined in class Type. If the return type cannot be determined statically, return Type.ITEM.

Specified by:
returnsType in interface Expression
Overrides:
returnsType in class BinaryOp

getDependencies

public int getDependencies()
Description copied from class: AbstractExpression
Returns Dependency.DEFAULT_DEPENDENCIES.

Specified by:
getDependencies in interface Expression
Overrides:
getDependencies in class PathExpr

eval

public Sequence eval(Sequence contextSequence,
                     Item contextItem)
              throws XPathException
Description copied from interface: Expression
Evaluate the expression represented by this object. Depending on the context in which this expression is executed, either the context sequence, the context item or both of them may be set. An implementing class should know how to handle this. The general contract is as follows: if the Dependency.CONTEXT_ITEM bit is set in the bit field returned by Expression.getDependencies(), the eval method will be called once for every item in the context sequence. The contextItem parameter will be set to the current item. Otherwise, the eval method will only be called once for the whole context sequence and contextItem will be null. eXist tries to process the entire context set in one, single step whenever possible. Thus, most classes only expect context to contain a list of nodes which represents the current context of the expression. The position() function in XPath is an example for an expression, which requires both, context sequence and context item to be set. The context sequence might be a node set, a sequence of atomic values or a single node or atomic value.

Specified by:
eval in interface Expression
Specified by:
eval in class BinaryOp
Throws:
XPathException

compareAtomic

public static boolean compareAtomic(java.text.Collator collator,
                                    AtomicValue lv,
                                    AtomicValue rv,
                                    boolean backwardsCompatible,
                                    int truncation,
                                    int relation)
                             throws XPathException
Throws:
XPathException

dump

public void dump(ExpressionDumper dumper)
Description copied from interface: Expression
Write a diagnostic dump of the expression to the passed ExpressionDumper.

Specified by:
dump in interface Expression
Overrides:
dump in class PathExpr

toString

public java.lang.String toString()
Overrides:
toString in class PathExpr

setCollation

public void setCollation(Expression collationArg)

resetState

public void resetState()
Description copied from interface: Expression
Called to inform an expression that it should reset to its initial state. All cached data in the expression object should be dropped. For example, the document() function calls this method whenever the input document set has changed.

Specified by:
resetState in interface Expression
Overrides:
resetState in class PathExpr


Copyright (C) Wolfgang Meier. All rights reserved.