Package org.apache.xpath.compiler
Class Compiler
- java.lang.Object
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- org.apache.xpath.compiler.OpMap
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- org.apache.xpath.compiler.Compiler
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public class Compiler extends OpMap
An instance of this class compiles an XPath string expression into a Expression object. This class compiles the string into a sequence of operation codes (op map) and then builds from that into an Expression tree.
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Field Summary
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Fields inherited from class org.apache.xpath.compiler.OpMap
MAPINDEX_LENGTH
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Constructor Summary
Constructors Constructor Description Compiler()
Construct a Compiler instance that has a null error listener and a null source locator.Compiler(javax.xml.transform.ErrorListener errorHandler, javax.xml.transform.SourceLocator locator, FunctionTable fTable)
Construct a Compiler object with a specific ErrorListener and SourceLocator where the expression is located.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
assertion(boolean b, java.lang.String msg)
Tell the user of an assertion error, and probably throw an exception.Expression
compile(int opPos)
Execute the XPath object from a given opcode position.int
countPredicates(int opPos)
Count the number of predicates in the step.void
error(java.lang.String msg, java.lang.Object[] args)
Tell the user of an error, and probably throw an exception.Expression[]
getCompiledPredicates(int opPos)
Compile a zero or more predicates for a given match pattern.int
getLocationPathDepth()
Get the level of the location path or union being constructed.PrefixResolver
getNamespaceContext()
Get the current namespace context for the xpath.int
getWhatToShow(int opPos)
Get aNodeFilter
bit set that tells what to show for a given node test.Expression
locationPath(int opPos)
Compile a location path.Expression
locationPathPattern(int opPos)
Compile a location match pattern unit expression.Expression
predicate(int opPos)
Compile a location step predicate expression.void
setNamespaceContext(PrefixResolver pr)
Set the current namespace context for the xpath.void
warn(java.lang.String msg, java.lang.Object[] args)
Warn the user of an problem.-
Methods inherited from class org.apache.xpath.compiler.OpMap
getArgLength, getArgLengthOfStep, getFirstChildPos, getFirstChildPosOfStep, getFirstPredicateOpPos, getNextOpPos, getNextOpPos, getNextStepPos, getOp, getOpMap, getPatternString, getStepLocalName, getStepNS, getStepTestType, getToken, getTokenQueue, getTokenQueueSize, setOp, toString
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Constructor Detail
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Compiler
public Compiler(javax.xml.transform.ErrorListener errorHandler, javax.xml.transform.SourceLocator locator, FunctionTable fTable)
Construct a Compiler object with a specific ErrorListener and SourceLocator where the expression is located.- Parameters:
errorHandler
- Error listener where messages will be sent, or null if messages should be sent to System err.locator
- The location object where the expression lives, which may be null, but which, if not null, must be valid over the long haul, in other words, it will not be cloned.fTable
- The FunctionTable object where the xpath build-in functions are stored.
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Compiler
public Compiler()
Construct a Compiler instance that has a null error listener and a null source locator.
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Method Detail
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compile
public Expression compile(int opPos) throws javax.xml.transform.TransformerException
Execute the XPath object from a given opcode position.- Parameters:
opPos
- The current position in the xpath.m_opMap array.- Returns:
- The result of the XPath.
- Throws:
javax.xml.transform.TransformerException
- if there is a syntax or other error.
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getLocationPathDepth
public int getLocationPathDepth()
Get the level of the location path or union being constructed.- Returns:
- 0 if it is a top-level path.
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locationPath
public Expression locationPath(int opPos) throws javax.xml.transform.TransformerException
Compile a location path. The LocPathIterator itself may createAxesWalker
children.- Parameters:
opPos
- The current position in the m_opMap array.- Returns:
- reference to
LocPathIterator
instance. - Throws:
javax.xml.transform.TransformerException
- if a error occurs creating the Expression.
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predicate
public Expression predicate(int opPos) throws javax.xml.transform.TransformerException
Compile a location step predicate expression.- Parameters:
opPos
- The current position in the m_opMap array.- Returns:
- the contained predicate expression.
- Throws:
javax.xml.transform.TransformerException
- if a error occurs creating the Expression.
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locationPathPattern
public Expression locationPathPattern(int opPos) throws javax.xml.transform.TransformerException
Compile a location match pattern unit expression.- Parameters:
opPos
- The current position in the m_opMap array.- Returns:
- reference to
StepPattern
instance. - Throws:
javax.xml.transform.TransformerException
- if a error occurs creating the Expression.
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getWhatToShow
public int getWhatToShow(int opPos)
Get aNodeFilter
bit set that tells what to show for a given node test.- Parameters:
opPos
- the op map position for the location step.- Returns:
NodeFilter
bit set that tells what to show for a given node test.
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getCompiledPredicates
public Expression[] getCompiledPredicates(int opPos) throws javax.xml.transform.TransformerException
Compile a zero or more predicates for a given match pattern.- Parameters:
opPos
- The position of the first predicate the m_opMap array.- Returns:
- reference to array of
Expression
instances. - Throws:
javax.xml.transform.TransformerException
- if a error occurs creating the Expression.
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countPredicates
public int countPredicates(int opPos) throws javax.xml.transform.TransformerException
Count the number of predicates in the step.- Parameters:
opPos
- The position of the first predicate the m_opMap array.- Returns:
- The number of predicates for this step.
- Throws:
javax.xml.transform.TransformerException
- if a error occurs creating the Expression.
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warn
public void warn(java.lang.String msg, java.lang.Object[] args) throws javax.xml.transform.TransformerException
Warn the user of an problem.- Parameters:
msg
- An error msgkey that corresponds to one of the constants found inXPATHErrorResources
, which is a key for a format string.args
- An array of arguments represented in the format string, which may be null.- Throws:
javax.xml.transform.TransformerException
- if the current ErrorListoner determines to throw an exception.
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assertion
public void assertion(boolean b, java.lang.String msg)
Tell the user of an assertion error, and probably throw an exception.- Parameters:
b
- If false, a runtime exception will be thrown.msg
- The assertion message, which should be informative.- Throws:
java.lang.RuntimeException
- if the b argument is false.
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error
public void error(java.lang.String msg, java.lang.Object[] args) throws javax.xml.transform.TransformerException
Tell the user of an error, and probably throw an exception.- Overrides:
error
in classOpMap
- Parameters:
msg
- An error msgkey that corresponds to one of the constants found inXPATHErrorResources
, which is a key for a format string.args
- An array of arguments represented in the format string, which may be null.- Throws:
javax.xml.transform.TransformerException
- if the current ErrorListoner determines to throw an exception.
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getNamespaceContext
public PrefixResolver getNamespaceContext()
Get the current namespace context for the xpath.- Returns:
- The current prefix resolver, *may* be null, though hopefully not.
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setNamespaceContext
public void setNamespaceContext(PrefixResolver pr)
Set the current namespace context for the xpath.- Parameters:
pr
- The resolver for prefixes in the XPath expression.
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