package org.relaxng.datatype;
/**
* Datatype object.
*
* This object has the following functionality:
*
* <ol>
* <li> functionality to identify a class of character sequences. This is
* done through the isValid method.
*
* <li> functionality to produce a "value object" from a character sequence and
* context information.
*
* <li> functionality to test the equality of two value objects.
* </ol>
*
* This interface also defines the createStreamingValidator method,
* which is intended to efficiently support the validation of
* large character sequences.
*
* @author <a href="mailto:jjc@jclark.com">James Clark</a>
* @author <a href="mailto:kohsuke.kawaguchi@sun.com">Kohsuke KAWAGUCHI</a>
*/
public interface Datatype {
/**
* Checks if the specified 'literal' matches this Datatype
* with respect to the current context.
*
* @param literal
* the lexical representation to be checked.
* @param context
* If this datatype is context-dependent
* (i.e. the {@link #isContextDependent} method returns true),
* then the caller must provide a non-null valid context object.
* Otherwise, the caller can pass null.
*
* @return
* true if the 'literal' is a member of this Datatype;
* false if it's not a member of this Datatype.
*/
boolean isValid( String literal, ValidationContext context );
/**
* Similar to the isValid method but throws an exception with diagnosis
* in case of errors.
*
* <p>
* If the specified 'literal' is a valid lexical representation for this
* datatype, then this method must return without throwing any exception.
* If not, the callee must throw an exception (with diagnosis message,
* if possible.)
*
* <p>
* The application can use this method to provide detailed error message
* to users. This method is kept separate from the isValid method to
* achieve higher performance during normal validation.
*
* @exception DatatypeException
* If the given literal is invalid, then this exception is thrown.
* If the callee supports error diagnosis, then the exception should
* contain a diagnosis message.
*/
void checkValid( String literal, ValidationContext context )
throws DatatypeException;
/**
* Creates an instance of a streaming validator for this type.
*
* <p>
* By using streaming validators instead of the isValid method,
* the caller can avoid keeping the entire string, which is
* sometimes quite big, in memory.
*
* @param context
* If this datatype is context-dependent
* (i.e. the {@link #isContextDependent} method returns true),
* then the caller must provide a non-null valid context object.
* Otherwise, the caller can pass null.
* The callee may keep a reference to this context object
* only while the returned streaming validator is being used.
*/
DatatypeStreamingValidator createStreamingValidator( ValidationContext context );
/**
* Converts lexcial value and the current context to the corresponding
* value object.
*
* <p>
* The caller cannot generally assume that the value object is
* a meaningful Java object. For example, the caller cannot expect
* this method to return <code>java.lang.Number</code> type for
* the "integer" type of XML Schema Part 2.
*
* <p>
* Also, the caller cannot assume that the equals method and
* the hashCode method of the value object are consistent with
* the semantics of the datatype. For that purpose, the sameValue
* method and the valueHashCode method have to be used. Note that
* this means you cannot use classes like
* <code>java.util.Hashtable</code> to store the value objects.
*
* <p>
* The returned value object should be used solely for the sameValue
* and valueHashCode methods.
*
* @param context
* If this datatype is context-dependent
* (when the {@link #isContextDependent} method returns true),
* then the caller must provide a non-null valid context object.
* Otherwise, the caller can pass null.
*
* @return null
* when the given lexical value is not a valid lexical
* value for this type.
*/
Object createValue( String literal, ValidationContext context );
/**
* Tests the equality of two value objects which were originally
* created by the createValue method of this object.
*
* The behavior is undefined if objects not created by this type
* are passed. It is the caller's responsibility to ensure that
* value objects belong to this type.
*
* @return
* true if two value objects are considered equal according to
* the definition of this datatype; false if otherwise.
*/
boolean sameValue( Object value1, Object value2 );
/**
* Computes the hash code for a value object,
* which is consistent with the sameValue method.
*
* @return
* hash code for the specified value object.
*/
int valueHashCode( Object value );
/**
* Indicates that the datatype doesn't have ID/IDREF semantics.
*
* This value is one of the possible return values of the
* {@link #getIdType} method.
*/
public static final int ID_TYPE_NULL = 0;
/**
* Indicates that RELAX NG compatibility processors should
* treat this datatype as having ID semantics.
*
* This value is one of the possible return values of the
* {@link #getIdType} method.
*/
public static final int ID_TYPE_ID = 1;
/**
* Indicates that RELAX NG compatibility processors should
* treat this datatype as having IDREF semantics.
*
* This value is one of the possible return values of the
* {@link #getIdType} method.
*/
public static final int ID_TYPE_IDREF = 2;
/**
* Indicates that RELAX NG compatibility processors should
* treat this datatype as having IDREFS semantics.
*
* This value is one of the possible return values of the
* {@link #getIdType} method.
*/
public static final int ID_TYPE_IDREFS = 3;
/**
* Checks if the ID/IDREF semantics is associated with this
* datatype.
*
* <p>
* This method is introduced to support the RELAX NG DTD
* compatibility spec. (Of course it's always free to use
* this method for other purposes.)
*
* <p>
* If you are implementing a datatype library and have no idea about
* the "RELAX NG DTD compatibility" thing, just return
* <code>ID_TYPE_NULL</code> is fine.
*
* @return
* If this datatype doesn't have any ID/IDREF semantics,
* it returns {@link #ID_TYPE_NULL}. If it has such a semantics
* (for example, XSD:ID, XSD:IDREF and comp:ID type), then
* it returns {@link #ID_TYPE_ID}, {@link #ID_TYPE_IDREF} or
* {@link #ID_TYPE_IDREFS}.
*/
public int getIdType();
/**
* Checks if this datatype may need a context object for
* the validation.
*
* <p>
* The callee must return true even when the context
* is not always necessary. (For example, the "QName" type
* doesn't need a context object when validating unprefixed
* string. But nonetheless QName must return true.)
*
* <p>
* XSD's <code>string</code> and <code>short</code> types
* are examples of context-independent datatypes.
* Its <code>QName</code> and <code>ENTITY</code> types
* are examples of context-dependent datatypes.
*
* <p>
* When a datatype is context-independent, then
* the {@link #isValid} method, the {@link #checkValid} method,
* the {@link #createStreamingValidator} method and
* the {@link #createValue} method can be called without
* providing a context object.
*
* @return
* <b>true</b> if this datatype is context-dependent
* (it needs a context object sometimes);
*
* <b>false</b> if this datatype is context-<b>in</b>dependent
* (it never needs a context object).
*/
public boolean isContextDependent();
}
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