org.apache.xalan.xsltc.compiler
Class Predicate

java.lang.Object
  org.apache.xalan.xsltc.compiler.SyntaxTreeNode
      org.apache.xalan.xsltc.compiler.Expression
          org.apache.xalan.xsltc.compiler.Predicate

All Implemented Interfaces:

Closure, Constants

final class Predicate
extends Expression
implements Closure

Field Summary

private boolean	_canOptimize This flag indicates if optimizations are turned on.
private java.lang.String	_className Name of the inner class.
private java.util.ArrayList	_closureVars List of variables in closure.
private Expression	_exp The predicate's expression.
private boolean	_nthDescendant Flag indicatig if the nth position descendant is on.
private boolean	_nthPositionFilter Flag indicatig if the nth position optimization is on.
private Closure	_parentClosure Reference to parent closure.
(package private) int	_ptype Cached node type of the expression that owns this predicate.
private Step	_step Cached value of method getCompareValue().
private Expression	_value Cached value of method getCompareValue().

Fields inherited from class org.apache.xalan.xsltc.compiler.Expression

_falseList, _trueList, _type

Fields inherited from class org.apache.xalan.xsltc.compiler.SyntaxTreeNode

_attributes, _parent, _qname, Dummy, IndentIncrement, UNKNOWN_STYLESHEET_NODE_ID

Fields inherited from interface org.apache.xalan.xsltc.compiler.Constants

ABSOLUTE_ITERATOR, ACC_FINAL, ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC, ACC_STATIC, ACC_SUPER, ADD_ATTRIBUTE, ADD_ATTRIBUTE_SIG, ADD_ITERATOR, ADD_ITERATOR_SIG, ADD_PARAMETER, ADD_PARAMETER_SIG, APPLY_TEMPLATES, ATTR_SET_SIG, ATTRIBUTE_LIST_FIELD, ATTRIBUTE_LIST_IMPL_CLASS, ATTRIBUTE_LIST_IMPL_SIG, ATTRIBUTES_SIG, BASIS_LIBRARY_CLASS, BOOLEAN_CLASS, BOOLEAN_VALUE, BOOLEAN_VALUE_SIG, CACHED_NODE_LIST_ITERATOR_CLASS, CHARACTERS, CHARACTERS_SIG, CHARACTERSW, CHARACTERSW_SIG, CLEAR_ATTRIBUTES, CLEAR_ATTRIBUTES_SIG, COLLATOR_CLASS, COLLATOR_SIG, COMPILER_PACKAGE, CURRENT_NODE_LIST_FILTER, CURRENT_NODE_LIST_FILTER_SIG, CURRENT_NODE_LIST_ITERATOR, CURRENT_NODE_LIST_ITERATOR_SIG, DEFAULT_NODE_COUNTER, DEFAULT_NODE_COUNTER_SIG, DOCUMENT_PNAME, DOM_ADAPTER_CLASS, DOM_ADAPTER_SIG, DOM_FIELD, DOM_IMPL, DOM_IMPL_CLASS, DOM_IMPL_SIG, DOM_INTF, DOM_INTF_SIG, DOM_PNAME, DOUBLE_CLASS, DOUBLE_SIG, DOUBLE_VALUE, DOUBLE_VALUE_SIG, DUP_FILTERED_ITERATOR, EMPTYATTR_FIELD, EMPTYSTRING, ERROR, EXPAND_STYLESHEET_QNAME_REF, EXPAND_STYLESHEET_QNAME_SIG, FALLBACK_CLASS, FATAL, FILTER_INTERFACE, FILTER_INTERFACE_SIG, FILTER_ITERATOR, FILTER_STEP_ITERATOR, FORMAT_SYMBOLS_FIELD, GET_ATTRIBUTE_VALUE, GET_ATTRIBUTE_VALUE_SIG, GET_CHILDREN, GET_CHILDREN_SIG, GET_ELEMENT_VALUE, GET_ELEMENT_VALUE_SIG, GET_ITERATOR_SIG, GET_NODE_NAME, GET_NODE_NAME_SIG, GET_NODE_TYPE, GET_NODE_TYPE_SIG, GET_NODE_VALUE, GET_NODE_VALUE_ITERATOR, GET_NODE_VALUE_ITERATOR_SIG, GET_NODE_VALUE_SIG, GET_PARAMETER, GET_PARAMETER_SIG, GET_PARENT, GET_PARENT_SIG, GET_TYPED_CHILDREN, GET_TYPED_CHILDREN_SIG, GET_UNPARSED_ENTITY_URI, GET_UNPARSED_ENTITY_URI_SIG, HAS_ATTRIBUTE, HAS_ATTRIBUTE_SIG, HASIDCALL_INDEX, HASIDCALL_INDEX_SIG, INT_VALUE, INT_VALUE_SIG, INTEGER_CLASS, INTEGER_SIG, INTERNAL, INVOKE_METHOD, ITERATOR_FIELD_SIG, ITERATOR_PNAME, KEY_INDEX_CLASS, KEY_INDEX_ITERATOR_SIG, KEY_INDEX_SIG, LAST_INDEX, LOAD_DOCUMENT_CLASS, LOCALE_CLASS, LOCALE_SIG, LOOKUP_STYLESHEET_QNAME_NS_REF, LOOKUP_STYLESHEET_QNAME_NS_SIG, MAKE_NODE, MAKE_NODE_LIST, MAKE_NODE_LIST_SIG, MAKE_NODE_LIST_SIG2, MAKE_NODE_SIG, MAKE_NODE_SIG2, MATCHING_ITERATOR, MATH_CLASS, MULTI_DOM_CLASS, MULTI_DOM_SIG, NAMES_INDEX, NAMES_INDEX_SIG, NAMESPACE_FEATURE, NAMESPACE_INDEX, NAMESPACE_INDEX_SIG, NEXT, NEXT_SIG, NEXTID, NODE, NODE_COUNTER, NODE_COUNTER_SIG, NODE_FIELD, NODE_FIELD_SIG, NODE_ITERATOR, NODE_ITERATOR_BASE, NODE_ITERATOR_SIG, NODE_PNAME, NODE_SIG, NODE_SORT_FACTORY, NODE_SORT_FACTORY_SIG, NODE_SORT_RECORD, NODE_SORT_RECORD_SIG, NS_ANCESTORS_INDEX_SIG, NTH_ITERATOR_CLASS, OBJECT_CLASS, OBJECT_SIG, ORDER_ITERATOR, ORDER_ITERATOR_SIG, OUTPUT_BASE, OUTPUT_HANDLER, OUTPUT_HANDLER_SIG, POP_PARAM_FRAME, POP_PARAM_FRAME_SIG, POSITION_INDEX, PREFIX_URIS_ARRAY_SIG, PREFIX_URIS_IDX_SIG, PUSH_PARAM_FRAME, PUSH_PARAM_FRAME_SIG, REDIRECT_URI, RESET, RESET_SIG, RTF_INITIAL_SIZE, RUNTIME_NODE_CLASS, RUNTIME_PACKAGE, SAX_IMPL, SAX_IMPL_CLASS, SAX_IMPL_SIG, SET_START_NODE, SET_START_NODE_SIG, SINGLETON_ITERATOR, SORT_ITERATOR, SORT_ITERATOR_SIG, STATIC_CHAR_DATA_FIELD, STATIC_CHAR_DATA_FIELD_SIG, STATIC_NAMES_ARRAY_FIELD, STATIC_NAMESPACE_ARRAY_FIELD, STATIC_NS_ANCESTORS_ARRAY_FIELD, STATIC_PREFIX_URIS_ARRAY_FIELD, STATIC_PREFIX_URIS_IDX_ARRAY_FIELD, STATIC_TYPES_ARRAY_FIELD, STATIC_URIS_ARRAY_FIELD, STEP_ITERATOR_CLASS, STREAM_XML_OUTPUT, STRING, STRING_BUFFER_CLASS, STRING_BUFFER_SIG, STRING_CLASS, STRING_SIG, STRING_TO_INT, STRING_TO_INT_SIG, STRING_TO_REAL, STRING_TO_REAL_SIG, STRING_VALUE_HANDLER, STRING_VALUE_HANDLER_SIG, STRING_WRITER, STRIP_SPACE, STRIP_SPACE_INTF, STRIP_SPACE_PARAMS, STRIP_SPACE_SIG, TRANSLET_CLASS, TRANSLET_FIELD, TRANSLET_FIELD_SIG, TRANSLET_INTF, TRANSLET_INTF_SIG, TRANSLET_OUTPUT_BASE, TRANSLET_OUTPUT_INTERFACE, TRANSLET_OUTPUT_PNAME, TRANSLET_OUTPUT_SIG, TRANSLET_PNAME, TRANSLET_SIG, TRANSLET_URI, TRANSLET_VERSION_INDEX, TRANSLET_VERSION_INDEX_SIG, TYPES_INDEX, TYPES_INDEX_SIG, UNION_ITERATOR_CLASS, UNION_ITERATOR_SIG, UNSUPPORTED, URIS_INDEX, URIS_INDEX_SIG, WARNING, WRITER_SIG, XHTML_URI, XMLNS_PREFIX, XMLNS_STRING, XMLNS_URI, XSLT_PACKAGE, XSLT_URI

Constructor Summary

Predicate(Expression exp)
Initializes a predicate.

Method Summary

void	addVariable(VariableRefBase variableRef) Add new variable to the closure.
private void	compileFilter(ClassGenerator classGen, MethodGenerator methodGen) Create a new "Filter" class implementing CurrentNodeListFilter.
void	dontOptimize() Turns off all optimizations for this predicate.
Expression	getCompareValue() Returns the value in an expression of the form 'step = value'.
Expression	getExpr()
java.lang.String	getInnerClassName() Returns the name of the auxiliary class or null if this predicate is compiled inside the Translet.
Closure	getParentClosure() Returns a reference to its parent closure or null if outermost.
int	getPosType() Returns the node type of the expression owning this predicate.
Step	getStep() Returns the step in an expression of the form 'step = value'.
boolean	hasLastCall() Returns true if the expression in this predicate contains a call to last().
boolean	hasPositionCall() Returns true if the expression in this predicate contains a call to position().
boolean	inInnerClass() Returns true if this closure is compiled in an inner class (i.e.
boolean	isBooleanTest() Returns true if the predicate is a test for the existance of an element or attribute.
boolean	isNodeValueTest() Method to see if we can optimise the predicate by using a specialised iterator for expressions like '/foo/bar[@attr = $var]', which are very common in many stylesheets
boolean	isNthDescendant() Returns a boolean value indicating if the nth descendant optimization is on.
boolean	isNthPositionFilter() Returns a boolean value indicating if the nth position optimization is on.
boolean	parentIsPattern()
void	setParser(Parser parser) Set the parser for this expression.
java.lang.String	toString()
void	translate(ClassGenerator classGen, MethodGenerator methodGen) Translate a predicate expression.
void	translateFilter(ClassGenerator classGen, MethodGenerator methodGen) Translate a predicate expression.
Type	typeCheck(SymbolTable stable) Type check a predicate expression.

Methods inherited from class org.apache.xalan.xsltc.compiler.Expression

backPatchFalseList, backPatchTrueList, compile, desynthesize, evaluateAtCompileTime, getFalseList, getTrueList, getType, lookupPrimop, startIterator, synthesize, translateDesynthesized

Methods inherited from class org.apache.xalan.xsltc.compiler.SyntaxTreeNode

addAttribute, addElement, addPrefixMapping, compileResultTree, contextDependent, dependentContents, display, displayContents, elementAt, elementCount, elements, getAttribute, getAttribute, getAttributes, getContents, getImportPrecedence, getLineNumber, getNodeIDForStylesheetNSLookup, getParent, getParser, getPrefixMapping, getQName, getStylesheet, getSymbolTable, getTemplate, getXSLTC, hasAttribute, hasContents, indent, isDummy, lastChild, lookupNamespace, lookupPrefix, parseChildren, parseContents, removeElement, reportError, reportWarning, setAttributes, setFirstElement, setLineNumber, setParent, setPrefixMapping, setQName, setQName, translateContents, typeCheckContents, updateScope

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

_exp

private Expression _exp

The predicate's expression.

_canOptimize

private boolean _canOptimize

This flag indicates if optimizations are turned on. The method dontOptimize() can be called to turn optimizations off.

_nthPositionFilter

private boolean _nthPositionFilter

Flag indicatig if the nth position optimization is on. It is set in typeCheck().

_nthDescendant

private boolean _nthDescendant

Flag indicatig if the nth position descendant is on. It is set in typeCheck().

_ptype

int _ptype

Cached node type of the expression that owns this predicate.

_className

private java.lang.String _className

Name of the inner class.

_closureVars

private java.util.ArrayList _closureVars

List of variables in closure.

_parentClosure

private Closure _parentClosure

Reference to parent closure.

_value

private Expression _value

Cached value of method getCompareValue().

_step

private Step _step

Cached value of method getCompareValue().

Constructor Detail

Predicate

public Predicate(Expression exp)

Initializes a predicate.

Method Detail

setParser

public void setParser(Parser parser)

Set the parser for this expression.

Overrides:

setParser in class SyntaxTreeNode

Parameters:

parser - The XSLT parser.

isNthPositionFilter

public boolean isNthPositionFilter()

Returns a boolean value indicating if the nth position optimization is on. Must be call after type checking!

isNthDescendant

public boolean isNthDescendant()

Returns a boolean value indicating if the nth descendant optimization is on. Must be call after type checking!

dontOptimize

public void dontOptimize()

Turns off all optimizations for this predicate.

hasPositionCall

public boolean hasPositionCall()

Returns true if the expression in this predicate contains a call to position().

Overrides:

hasPositionCall in class Expression

hasLastCall

public boolean hasLastCall()

Returns true if the expression in this predicate contains a call to last().

Overrides:

hasLastCall in class Expression

inInnerClass

public boolean inInnerClass()

Returns true if this closure is compiled in an inner class (i.e. if this is a real closure).

Specified by:

inInnerClass in interface Closure

getParentClosure

public Closure getParentClosure()

Returns a reference to its parent closure or null if outermost.

Specified by:

getParentClosure in interface Closure

getInnerClassName

public java.lang.String getInnerClassName()

Returns the name of the auxiliary class or null if this predicate is compiled inside the Translet.

Specified by:

getInnerClassName in interface Closure

addVariable

public void addVariable(VariableRefBase variableRef)

Add new variable to the closure.

Specified by:

addVariable in interface Closure

getPosType

public int getPosType()

Returns the node type of the expression owning this predicate. The return value is cached in _ptype.

parentIsPattern

public boolean parentIsPattern()

getExpr

public Expression getExpr()

toString

public java.lang.String toString()

Specified by:

toString in class Expression

typeCheck

public Type typeCheck(SymbolTable stable)
               throws TypeCheckError

Type check a predicate expression. If the type of the expression is number convert it to boolean by adding a comparison with position(). Note that if the expression is a parameter, we cannot distinguish at compile time if its type is number or not. Hence, expressions of reference type are always converted to booleans. This method may be called twice, before and after calling dontOptimize(). If so, the second time it should honor the new value of _canOptimize.

Overrides:

typeCheck in class Expression

Parameters:

stable - The compiler/parser's symbol table

Throws:

TypeCheckError

compileFilter

private void compileFilter(ClassGenerator classGen,
                           MethodGenerator methodGen)

Create a new "Filter" class implementing CurrentNodeListFilter. Allocate registers for local variables and local parameters passed in the closure to test(). Notice that local variables need to be "unboxed".

isBooleanTest

public boolean isBooleanTest()

Returns true if the predicate is a test for the existance of an element or attribute. All we have to do is to get the first node from the step, check if it is there, and then return true/false.

isNodeValueTest

public boolean isNodeValueTest()

Method to see if we can optimise the predicate by using a specialised iterator for expressions like '/foo/bar[@attr = $var]', which are very common in many stylesheets

getStep

public Step getStep()

Returns the step in an expression of the form 'step = value'. Null is returned if the expression is not of the right form. Optimization if off if null is returned.

getCompareValue

public Expression getCompareValue()

Returns the value in an expression of the form 'step = value'. A value may be either a literal string or a variable whose type is string. Optimization if off if null is returned.

translateFilter

public void translateFilter(ClassGenerator classGen,
                            MethodGenerator methodGen)

Translate a predicate expression. This translation pushes two references on the stack: a reference to a newly created filter object and a reference to the predicate's closure.

translate

public void translate(ClassGenerator classGen,
                      MethodGenerator methodGen)

Translate a predicate expression. If non of the optimizations apply then this translation pushes two references on the stack: a reference to a newly created filter object and a reference to the predicate's closure. See class Step for further details.

Overrides:

translate in class Expression

Parameters:

classGen - BCEL Java class generator

methodGen - BCEL Java method generator