Package org.apache.xpath.compiler
Class Compiler
java.lang.Object
org.apache.xpath.compiler.OpMap
org.apache.xpath.compiler.Compiler
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
Fields inherited from class org.apache.xpath.compiler.OpMap
MAPINDEX_LENGTH
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Constructor Summary
ConstructorsConstructorDescriptionCompiler()
Construct a Compiler instance that has a null error listener and a null source locator.Compiler
(ErrorListener errorHandler, SourceLocator locator, FunctionTable fTable) Construct a Compiler object with a specific ErrorListener and SourceLocator where the expression is located. -
Method Summary
Modifier and TypeMethodDescriptionvoid
Tell the user of an assertion error, and probably throw an exception.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
Tell the user of an error, and probably throw an exception.getCompiledPredicates
(int opPos) Compile a zero or more predicates for a given match pattern.int
Get the level of the location path or union being constructed.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.locationPath
(int opPos) Compile a location path.locationPathPattern
(int opPos) Compile a location match pattern unit expression.predicate
(int opPos) Compile a location step predicate expression.void
Set the current namespace context for the xpath.void
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 Details
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Compiler
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 Details
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compile
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:
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
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:
TransformerException
- if a error occurs creating the Expression.
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predicate
Compile a location step predicate expression.- Parameters:
opPos
- The current position in the m_opMap array.- Returns:
- the contained predicate expression.
- Throws:
TransformerException
- if a error occurs creating the Expression.
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locationPathPattern
Compile a location match pattern unit expression.- Parameters:
opPos
- The current position in the m_opMap array.- Returns:
- reference to
StepPattern
instance. - Throws:
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
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:
TransformerException
- if a error occurs creating the Expression.
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countPredicates
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:
TransformerException
- if a error occurs creating the Expression.
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warn
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:
TransformerException
- if the current ErrorListoner determines to throw an exception.
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assertion
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:
RuntimeException
- if the b argument is false.
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error
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:
TransformerException
- if the current ErrorListoner determines to throw an exception.
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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
Set the current namespace context for the xpath.- Parameters:
pr
- The resolver for prefixes in the XPath expression.
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