Package net.sf.saxon.sort
Class TextComparer
- java.lang.Object
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- net.sf.saxon.sort.TextComparer
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- All Implemented Interfaces:
java.io.Serializable
,AtomicComparer
public class TextComparer extends java.lang.Object implements AtomicComparer, java.io.Serializable
A Comparer used for comparing sort keys when data-type="text". The items to be compared are converted to strings, and the strings are then compared using an underlying collator- Author:
- Michael H. Kay
- See Also:
- Serialized Form
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Constructor Summary
Constructors Constructor Description TextComparer(AtomicComparer baseComparer)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
compareAtomicValues(AtomicValue a, AtomicValue b)
Compare two Items by converting them to strings and comparing the string values.boolean
comparesEqual(AtomicValue a, AtomicValue b)
Compare two AtomicValue objects for equality according to the rules for their data type.AtomicComparer
getBaseComparer()
Get the underlying comparer (which doesn't do conversion to string)ComparisonKey
getComparisonKey(AtomicValue a)
Get a comparison key for an object.AtomicComparer
provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison
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Constructor Detail
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TextComparer
public TextComparer(AtomicComparer baseComparer)
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Method Detail
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getBaseComparer
public AtomicComparer getBaseComparer()
Get the underlying comparer (which doesn't do conversion to string)
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provideContext
public AtomicComparer provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison- Specified by:
provideContext
in interfaceAtomicComparer
- Parameters:
context
- the dynamic evaluation context- Returns:
- either the original AtomicComparer, or a new AtomicComparer in which the context is known. The original AtomicComparer is not modified
- Throws:
NoDynamicContextException
- if the context is an "early evaluation" (compile-time) context
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compareAtomicValues
public int compareAtomicValues(AtomicValue a, AtomicValue b) throws java.lang.ClassCastException, NoDynamicContextException
Compare two Items by converting them to strings and comparing the string values.- Specified by:
compareAtomicValues
in interfaceAtomicComparer
- Parameters:
a
- the first Item to be compared.b
- the second Item to be compared.- Returns:
- <0 if a0 if a>b
- Throws:
java.lang.ClassCastException
- if the objects are not Items, or are items that cannot be convered to strings (e.g. QNames)NoDynamicContextException
- if this comparer required access to dynamic context information, notably the implicit timezone, and this information is not available. In general this happens if a context-dependent comparison is attempted at compile-time, and it signals the compiler to generate code that tries again at run-time.
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comparesEqual
public boolean comparesEqual(AtomicValue a, AtomicValue b) throws NoDynamicContextException
Compare two AtomicValue objects for equality according to the rules for their data type. UntypedAtomic values are compared by converting to the type of the other operand.- Specified by:
comparesEqual
in interfaceAtomicComparer
- Parameters:
a
- the first object to be compared.b
- the second object to be compared.- Returns:
- true if the values are equal, false if not
- Throws:
java.lang.ClassCastException
- if the objects are not comparableNoDynamicContextException
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getComparisonKey
public ComparisonKey getComparisonKey(AtomicValue a) throws NoDynamicContextException
Get a comparison key for an object. This must satisfy the rule that if two objects are equal according to the XPath eq operator, then their comparison keys are equal according to the Java equals() method, and vice versa. There is no requirement that the comparison keys should reflect the ordering of the underlying objects.- Specified by:
getComparisonKey
in interfaceAtomicComparer
- Throws:
NoDynamicContextException
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