Class Value

java.lang.Object
com.icl.saxon.expr.Expression
com.icl.saxon.expr.Value
Direct Known Subclasses:
BooleanValue, NodeSetValue, NumericValue, ObjectValue, StringValue
public abstract class Value extends Expression
A value is the result of an expression but it is also an expression in its own right

  • Field Details

  • Constructor Details

    • Value

      public Value()

  • Method Details

    • stringToNumber

      public static double stringToNumber(String s)
      Static method to convert strings to numbers. Might as well go here as anywhere else.
      Parameters:
      s - the String to be converted
      Returns:
      a double representing the value of the String; if it cannot be converted, return NaN (as required by the XSL specification)

    • evaluate

      public Value evaluate(Context context) throws XPathException
      Evaluate the Value. Null operation, because it has already been evaluated
      Specified by:
      evaluate in class Expression
      Parameters:
      context - The context (not used)
      Returns:
      the value, unchanged
      Throws:
      XPathException

    • simplify

      public Expression simplify()
      Simplify an expression
      Overrides:
      simplify in class Expression
      Returns:
      the simplified expression

    • getDependencies

      public int getDependencies()
      Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE
      Specified by:
      getDependencies in class Expression

    • asString

      public abstract String asString() throws XPathException
      Convert the value to a String value
      Returns:
      the value converted to a String
      Throws:
      XPathException

    • asNumber

      public abstract double asNumber() throws XPathException
      Convert the value to a Number
      Returns:
      the value converted to a String
      Throws:
      XPathException

    • asBoolean

      public abstract boolean asBoolean() throws XPathException
      Convert the value to a Boolean
      Returns:
      the value converted to a Boolean
      Throws:
      XPathException

    • equals

      public boolean equals(Value other) throws XPathException
      Test whether two values are equal. See the XSL specification: if either operand is a nodeset, they are compared as nodesets; else if either is a boolean, they are compared as booleans; else if either operand is a number, they are compared as numbers; else they are compared as strings.
      Returns:
      a boolean giving the value of the expression, evaluated in the current context
      Throws:
      XPathException

    • notEquals

      public boolean notEquals(Value other) throws XPathException
      Test whether two values are not-equal. Note that a!=b means the same as !(a=b) except where either a or b is a nodeset.
      Returns:
      a boolean giving the value of the expression, evaluated in the current context
      Throws:
      XPathException

    • compare

      public boolean compare(int operator, Value other) throws XPathException
      Test how a Value compares to another Value under a relational comparison. Note that the method is overridden for NodeSetValue
      Parameters:
      operator - The comparison operator, one of Tokenizer.LE, Tokenizer.LT, Tokenizer.GE, Tokenizer.GT, Tokenizer.EQUALS, Tokenizer.NE.
      Throws:
      XPathException

    • inverse

      protected static final int inverse(int operator)
      Return the inverse of a relational operator, so that "a op b" can be rewritten as "b inverse(op) a"

    • numericCompare

      protected final boolean numericCompare(int operator, double x, double y)

    • reduce

      public Expression reduce(int dependencies, Context context)
      Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
      Specified by:
      reduce in class Expression
      Parameters:
      dependencies - The dependencies to be removed
      context - The context to be used for the partial evaluation
      Returns:
      a new expression that does not have any of the specified dependencies

    • convertToJava

      public abstract Object convertToJava(Class target) throws XPathException
      Convert to Java object (for passing to external functions)
      Parameters:
      target - The class required by the external function
      Returns:
      an object of the target class
      Throws:
      XPathException

    • conversionPreference

      public abstract int conversionPreference(Class required)
      Get conversion preference for this value to a Java class. A low result indicates higher preference.