com.saxonica.expr.compat

Class TypeChecker10

java.lang.Object

net.sf.saxon.expr.parser.TypeChecker

com.saxonica.expr.compat.TypeChecker10

public class TypeChecker10
extends TypeChecker

This class provides type checking capability with XPath 1.0 backwards compatibility enabled.

Constructor Summary

Constructors

Constructor and Description
TypeChecker10()

Method Summary

Modifier and Type	Method and Description
Expression	makeArithmeticExpression(Expression lhs, int operator, Expression rhs)
Expression	makeGeneralComparison(Expression lhs, int operator, Expression rhs)
Expression	processValueOf(Expression select, Configuration config)
Expression	staticTypeCheck(Expression supplied, SequenceType req, RoleDiagnostic role, ExpressionVisitor visitor) Check an expression against a required type, modifying it if necessary.

Methods inherited from class net.sf.saxon.expr.parser.TypeChecker

ebvError, strictTypeCheck, testConformance

Methods inherited from class java.lang.Object

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

Constructor Detail

TypeChecker10

public TypeChecker10()

Method Detail

staticTypeCheck

public Expression staticTypeCheck(Expression supplied,
                                  SequenceType req,
                                  RoleDiagnostic role,
                                  ExpressionVisitor visitor)
                           throws XPathException

Description copied from class: TypeChecker

Check an expression against a required type, modifying it if necessary.

This method takes the supplied expression and checks to see whether it is known statically to conform to the specified type. There are three possible outcomes. If the static type of the expression is a subtype of the required type, the method returns the expression unchanged. If the static type of the expression is incompatible with the required type (for example, if the supplied type is integer and the required type is string) the method throws an exception (this results in a compile-time type error being reported). If the static type is a supertype of the required type, then a new expression is constructed that evaluates the original expression and checks the dynamic type of the result; this new expression is returned as the result of the method.

The rules applied are those for function calling in XPath, that is, the rules that the argument of a function call must obey in relation to the signature of the function. Some contexts require slightly different rules (for example, operands of polymorphic operators such as "+"). In such cases this method cannot be used.

Note that this method does not do recursive type-checking of the sub-expressions.

Overrides:

staticTypeCheck in class TypeChecker

Parameters:

supplied - The expression to be type-checked

req - The required type for the context in which the expression is used

role - Information about the role of the subexpression within the containing expression, used to provide useful error messages

visitor - An expression visitor

Returns:

The original expression if it is type-safe, or the expression wrapped in a run-time type checking expression if not.

Throws:

XPathException - if the supplied type is statically inconsistent with the required type (that is, if they have no common subtype)

makeArithmeticExpression

public Expression makeArithmeticExpression(Expression lhs,
                                           int operator,
                                           Expression rhs)

Overrides:

makeArithmeticExpression in class TypeChecker

makeGeneralComparison

public Expression makeGeneralComparison(Expression lhs,
                                        int operator,
                                        Expression rhs)

Overrides:

makeGeneralComparison in class TypeChecker

processValueOf

public Expression processValueOf(Expression select,
                                 Configuration config)

Overrides:

processValueOf in class TypeChecker