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java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.PathExpression
Field Summary |
Fields inherited from class net.sf.saxon.expr.Expression | |
EVALUATE_METHOD , ITERATE_METHOD , PROCESS_METHOD , locationId , staticProperties |
Constructor Summary | |
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Method Summary | |
PathMap.PathMapNodeSet |
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int |
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int |
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int |
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Expression |
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boolean |
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void |
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Expression |
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ItemType |
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Expression |
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Expression |
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Expression |
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Expression |
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Expression |
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boolean |
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int |
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boolean |
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SequenceIterator |
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Iterator |
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SequenceIterator |
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Expression |
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Expression |
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boolean |
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Expression |
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String |
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PathExpression |
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Expression |
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public PathExpression(Expression start, Expression step)
Constructor
- Parameters:
start
- A node-set expression denoting the absolute or relative set of nodes from which the navigation path should start.step
- The step to be followed from each node in the start expression to yield a new node-set
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.
- Overrides:
- addToPathMap in interface Expression
- Parameters:
pathMap
- the PathMap to which the expression should be addedpathMapNodeSet
-
- Returns:
- the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression
public int computeCardinality()
Determine the static cardinality of the expression
- Overrides:
- computeCardinality in interface Expression
public int computeDependencies()
Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as XPathContext.VARIABLES and XPathContext.CURRENT_NODE
- Overrides:
- computeDependencies in interface Expression
public int computeSpecialProperties()
Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.
- Overrides:
- computeSpecialProperties in interface Expression
public Expression copy()
Copy an expression. This makes a deep copy.
- Overrides:
- copy in interface Expression
- Returns:
- the copy of the original expression
public boolean equals(Object other)
Is this expression the same as another expression?
public void explain(ExpressionPresenter destination)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
- Overrides:
- explain in interface Expression
public Expression getFirstStep()
Get the first step in this expression. A path expression A/B/C is represented as (A/B)/C, but the first step is A
- Returns:
- the first step in the expression, after expanding any nested path expressions
public final ItemType getItemType(TypeHierarchy th)
Determine the data type of the items returned by this exprssion
- Overrides:
- getItemType in interface Expression
- Parameters:
th
- the type hierarchy cache
- Returns:
- the type of the step
public Expression getLastStep()
Get the last step of the path expression
- Returns:
- the last step in the expression, after expanding any nested path expressions
public Expression getLeadingSteps()
Get a path expression consisting of all steps except the last
- Returns:
- a path expression containing all steps in this path expression other than the last, after expanding any nested path expressions
public Expression getRemainingSteps()
Get all steps after the first. This is complicated by the fact that A/B/C is represented as ((A/B)/C; we are required to return B/C
- Returns:
- a path expression containing all steps in this path expression other than the first, after expanding any nested path expressions
public Expression getStartExpression()
Get the start expression (the left-hand operand)
- Returns:
- the left-hand operand
public Expression getStepExpression()
Get the step expression (the right-hand operand)
- Returns:
- the right-hand operand
public boolean hasLoopingSubexpression(Expression child)
Given an expression that is an immediate child of this expression, test whether the evaluation of the parent expression causes the child expression to be evaluated repeatedly
- Overrides:
- hasLoopingSubexpression in interface Expression
- Parameters:
child
- the immediate subexpression
- Returns:
- true if the child expression is evaluated repeatedly
public int hashCode()
get HashCode for comparing two expressions
public boolean isAbsolute(TypeHierarchy th)
Test whether a path expression is an absolute path - that is, a path whose first step selects a document node
- Parameters:
th
- the type hierarchy cache
- Returns:
- true if the first step in this path expression selects a document node
public SequenceIterator iterate(XPathContext context) throws XPathException
Iterate the path-expression in a given context
- Specified by:
- iterate in interface SequenceIterable
- Overrides:
- iterate in interface Expression
- Parameters:
context
- the evaluation context
public Iterator iterateSubExpressions()
Get the immediate subexpressions of this expression
- Overrides:
- iterateSubExpressions in interface Expression
public SequenceIterator map(XPathContext context) throws XPathException
Mapping function, from a node returned by the start iteration, to a sequence returned by the child.
- Specified by:
- map in interface ContextMappingFunction
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Optimize the expression and perform type analysis
- Overrides:
- optimize in interface Expression
public Expression promote(PromotionOffer offer) throws XPathException
Promote this expression if possible
- Overrides:
- promote in interface Expression
public boolean replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression
- Overrides:
- replaceSubExpression in interface Expression
- Parameters:
original
- the original subexpressionreplacement
- the replacement subexpression
- Returns:
- true if the original subexpression is found
public Expression simplify(ExpressionVisitor visitor) throws XPathException
Simplify an expression
- Overrides:
- simplify in interface Expression
- Parameters:
visitor
- the expression visitor
- Returns:
- the simplified expression
public String toString()
The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath. In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax
- Overrides:
- toString in interface Expression
public PathExpression tryToMakeAbsolute(TypeHierarchy th)
Test whether a path expression is an absolute path - that is, a path whose first step selects a document node; if not, see if it can be converted to an absolute path. This is possible in cases where the path expression has the form a/b/c and it is known that the context item is a document node; in this case it is safe to change the path expression to /a/b/c
- Parameters:
th
- the type hierarchy cache
- Returns:
- the path expression if it is absolute; the converted path expression if it can be made absolute; or null if neither condition applies.
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Perform type analysis
- Overrides:
- typeCheck in interface Expression