Package net.sf.saxon.type.coercion

Class SequenceCoercer

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.UnaryExpression
net.sf.saxon.type.coercion.SequenceCoercer
All Implemented Interfaces:
ExportAgent, Locatable, IdentityComparable, Traceable
public class SequenceCoercer extends UnaryExpression
An SequenceCoercer is an expression that performs coercion on a sequence of items:

  • Field Details

  • Constructor Details

    • SequenceCoercer

      protected SequenceCoercer(Expression sequence, SequenceType requiredType, Supplier<RoleDiagnostic> role, boolean allow40)
      Constructor
      Parameters:
      sequence - this must be a sequence of function item values. This is not checked; a ClassCastException will occur if the precondition is not satisfied.
      requiredType - the function item type to which all items in the sequence should be converted,

  • Method Details

    • makeSequenceCoercer

      public static Expression makeSequenceCoercer(Expression sequence, SequenceType requiredType, Supplier<RoleDiagnostic> role, boolean allow40)

    • getOperandRole

      protected OperandRole getOperandRole()
      Description copied from class: UnaryExpression
      Get the usage (in terms of streamability analysis) of the single operand
      Specified by:
      getOperandRole in class UnaryExpression
      Returns:
      the operand usage

    • getRequiredType

      public SequenceType getRequiredType()

    • computeSpecialProperties

      protected int computeSpecialProperties()
      Description copied from class: UnaryExpression
      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 class UnaryExpression
      Returns:
      the special properties, as a bit-significant integer

    • simplify

      public Expression simplify() throws XPathException
      Simplify an expression
      Overrides:
      simplify in class Expression
      Returns:
      the simplified expression (or the original if unchanged, or if modified in-situ)
      Throws:
      XPathException - if an error is discovered during expression rewriting

    • typeCheck

      public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
      Type-check the expression
      Overrides:
      typeCheck in class UnaryExpression
      Parameters:
      visitor - an expression visitor
      contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.
      Returns:
      the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
      Throws:
      XPathException - if an error is discovered during this phase (typically a type error)

    • copy

      public Expression copy(RebindingMap rebindings)
      Copy an expression. This makes a deep copy.
      Specified by:
      copy in class Expression
      Parameters:
      rebindings - variables that need to be re-bound
      Returns:
      the copy of the original expression

    • toPattern

      public Pattern toPattern(Configuration config, boolean firstInPath) throws XPathException
      Description copied from class: Expression
      Convert this expression to an equivalent XSLT pattern
      Overrides:
      toPattern in class Expression
      Parameters:
      config - the Saxon configuration
      firstInPath - true if an axis step in this expression is to be treated as an initial step of the pattern
      Returns:
      the equivalent pattern
      Throws:
      XPathException - if conversion is not possible

    • getImplementationMethod

      public int getImplementationMethod()
      An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.
      Specified by:
      getImplementationMethod in class Expression
      Returns:
      the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

    • iterate

      public SequenceIterator iterate(XPathContext context) throws XPathException
      Evaluate the expression as a sequence iterator
      Overrides:
      iterate in class Expression
      Parameters:
      context - supplies the context for evaluation
      Returns:
      a SequenceIterator that can be used to iterate over the result of the expression
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression

    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      Evaluate the expression as an Item.
      Overrides:
      evaluateItem in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression

    • getItemType

      public ItemType getItemType()
      Determine the data type of the items returned by the expression
      Overrides:
      getItemType in class UnaryExpression
      Returns:
      a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known in advance)

    • computeCardinality

      protected int computeCardinality()
      Determine the static cardinality of the expression
      Overrides:
      computeCardinality in class UnaryExpression
      Returns:
      the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE. May also return StaticProperty.ALLOWS_ZERO if the result is known to be an empty sequence, or StaticProperty.ALLOWS_MANY if if is known to return a sequence of length two or more.

    • getRoleDiagnostic

      public RoleDiagnostic getRoleDiagnostic()
      Returns:
      the role locator

    • getRoleSupplier

      public Supplier<RoleDiagnostic> getRoleSupplier()

    • equals

      public boolean equals(Object other)
      Is this expression the same as another expression?
      Overrides:
      equals in class UnaryExpression
      Parameters:
      other - the other operand; the result is false if this is not an Expression
      Returns:
      true if the other operand is an expression and if it can be determined that the two expressions are equivalent, in the sense that they will always return the same result.

    • computeHashCode

      protected int computeHashCode()
      Description copied from class: UnaryExpression
      get HashCode for comparing two expressions. Note that this hashcode gives the same result for (A op B) and for (B op A), whether or not the operator is commutative.
      Overrides:
      computeHashCode in class UnaryExpression
      Returns:
      a computed hash code

    • getExpressionName

      public String getExpressionName()
      Description copied from class: Expression
      Get a name identifying the kind of expression, in terms meaningful to a user.
      Overrides:
      getExpressionName in class Expression
      Returns:
      a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in export() output displaying the expression.

    • export

      public void export(ExpressionPresenter destination) throws XPathException
      Export expression to SEF file. The abstract expression tree is written to the supplied output destination.
      Specified by:
      export in interface ExportAgent
      Overrides:
      export in class UnaryExpression
      Parameters:
      destination - the expression presenter used to display the structure
      Throws:
      XPathException - if the export fails, for example if an expression is found that won't work in the target environment.

    • getStreamerName

      public String getStreamerName()
      Description copied from class: Expression
      Get the (partial) name of a class that supports streaming of this kind of expression
      Overrides:
      getStreamerName in class Expression
      Returns:
      the partial name of a class that can be instantiated to provide streaming support in Saxon-EE, or null if there is no such class

    • getCoercionPlan

      public CoercionPlan getCoercionPlan()
      Construct a coercion plan

    • getElaborator

      public Elaborator getElaborator()
      Make an elaborator for this expression
      Overrides:
      getElaborator in class Expression
      Returns:
      an appropriate Elaborator