* Validator instances are created from and by non-stateful * {@link XMLValidationSchema} instances. A new validator instance has to * be created for each document read or written, ie. can not be shared * or reused, unlike schema instances which can be. */ public abstract class XMLValidator { // // // Shared constants /* First, constants used by validators to indicate kind of pre-validation * (with respect to text, and in some cases, other non-element events) * caller needs to take, before calling the validator. The idea is to * allow stream readers and writers to do parts of validity checks they * are in best position to do, while leaving the real structural and * content-based validation to validators. */ /** * This value indicates that no content whatsoever * is legal within current context, that is, where the only legal content * to follow is the closing end tag -- not even comments or processing * instructions are allowed. This is the case for example for * elements that DTD defines to have EMPTY content model. *
*/ public final static int CONTENT_ALLOW_NONE = 0; /** * This value indicates that only white space text content is allowed, * not other kinds of text. Other non-text events may be allowed; * validator will deal with element validation. * Value also indicates that if non-white space text content is * encountered, a validation problem is reported */ public final static int CONTENT_ALLOW_WS = 1; /** * This value is similar to {@link #CONTENT_ALLOW_WS_NONSTRICT}, * but only used for content typing purposes, not for validation. * This means that if non-white space text content is encountered, * no problem is reported. *
* This value is currently only used with DTD processors, when in
* typing (non-validating) mode.
*
* @since 3.0
*/
public final static int CONTENT_ALLOW_WS_NONSTRICT = 2;
/**
* This value indicates that textual content is allowed, but that
* the validator needs to be called to let it do actual content-based
* validation. Other event types are ok, and elements will need to be
* validated by the validator as well.
*/
public final static int CONTENT_ALLOW_VALIDATABLE_TEXT = 3;
/**
* This value indicates that any textual content (plain PCTEXT) is
* allowed, and that validator is not going to do any validation
* for it. It will, however, need to be called with respect
* to element events.
*/
public final static int CONTENT_ALLOW_ANY_TEXT = 4;
/**
* This value is a placeholder that should never be returned by
* validators, but that can be used internally as an uninitialized
* value.
*/
public final static int CONTENT_ALLOW_UNDEFINED = 5;
/*
///////////////////////////////////////////////////
// Life-cycle
///////////////////////////////////////////////////
*/
protected XMLValidator() { }
/*
///////////////////////////////////////////////////
// Configuration, properties
///////////////////////////////////////////////////
*/
/**
* Returns type of schema that was used to construct this
* validator instance.
*
* @return One of external schema identifier values (such as
* {@link XMLValidationSchema#SCHEMA_ID_DTD}).
*/
public String getSchemaType() {
XMLValidationSchema sch = getSchema();
return (sch == null) ? null : sch.getSchemaType();
}
/**
* Returns the schema instance that created this validator
* object, if known (and applicable). May return null for
* some instances: specifically, {@link ValidatorPair}
* will return null since it 'contains' multiple validators
* and generally does not have just one parent or owner schema.
*/
public abstract XMLValidationSchema getSchema();
/*
///////////////////////////////////////////////////
// Actual validation interface
///////////////////////////////////////////////////
*/
public abstract void validateElementStart(String localName, String uri,
String prefix)
throws XMLStreamException;
/**
* Callback method called on validator to give it a chance to validate
* the value of an attribute, as well as to normalize its value if
* appropriate (remove leading/trailing/intervening white space for
* certain token types etc.).
*
* @return Null, if the passed value is fine as is; or a String, if
* it needs to be replaced. In latter case, caller will replace the
* value before passing it to other validators. Also, if the attribute
* value is accessible via caller (as is the case for stream readers),
* caller should return this value, instead of the original one.
*/
public abstract String validateAttribute(String localName, String uri,
String prefix, String value)
throws XMLStreamException;
/**
* Callback method called on validator to give it a chance to validate
* the value of an attribute, as well as to normalize its value if
* appropriate (remove leading/trailing/intervening white space for
* certain token types etc.).
*
* @param valueChars Character array that contains value (possibly
* along with some other text)
* @param valueStart Index of the first character of the value in
* in valueChars array
* @param valueEnd Index of the character AFTER the last character;
* so that the length of the value String is
* valueEnd - valueStart
*
* @return Null, if the passed value is fine as is; or a String, if
* it needs to be replaced. In latter case, caller will replace the
* value before passing it to other validators. Also, if the attribute
* value is accessible via caller (as is the case for stream readers),
* caller should return this value, instead of the original one.
*/
public abstract String validateAttribute(String localName, String uri,
String prefix,
char[] valueChars, int valueStart,
int valueEnd)
throws XMLStreamException;
/**
* Method called after calling {@link #validateAttribute} on all
* attributes (if any), but before starting to handle element
* content.
*
* @return One of CONTENT_ALLOW_ constants, to indicate
* what kind of textual content is allowed at the scope returned
* to after the element has closed.
*/
public abstract int validateElementAndAttributes()
throws XMLStreamException;
/**
* Method called right after encountering an element close tag.
*
* @return One of CONTENT_ALLOW_ constants, to indicate
* what kind of textual content is allowed at the scope returned
* to after the element has closed.
*/
public abstract int validateElementEnd(String localName, String uri,
String prefix)
throws XMLStreamException;
/**
* Method called to validate textual content.
*
* Note: this method is only guaranteed to be called when * {@link #validateElementAndAttributes()} for the currently open * element returned {@link #CONTENT_ALLOW_VALIDATABLE_TEXT} (or, * in case of mixed content, {@link #validateElementEnd}, for the * last enclosed element). Otherwise, validator context may choose * not to call the method as an optimization. * * @param text Text content to validate * @param lastTextSegment Whether this text content is the last text * segment before a close element; true if it is, false if it is not, * or no determination can be made. Can be used for optimizing * validation -- if this is true, no text needs to be buffered since * no more will be sent before the current element closes. */ public abstract void validateText(String text, boolean lastTextSegment) throws XMLStreamException; /** * Method called to validate textual content. *
* Note: this method is only guaranteed to be called when
* {@link #validateElementAndAttributes()} for the currently open
* element returned {@link #CONTENT_ALLOW_VALIDATABLE_TEXT} (or,
* in case of mixed content, {@link #validateElementEnd}, for the
* last enclosed element). Otherwise, validator context may choose
* not to call the method as an optimization.
*
* @param cbuf Character array that contains text content to validate
* @param textStart Index of the first character of the content to
* validate
* @param textEnd Character following the last character of the
* content to validate (that is, length of content to validate is
* textEnd - textStart).
* @param lastTextSegment Whether this text content is the last text
* segment before a close element; true if it is, false if it is not,
* or no determination can be made. Can be used for optimizing
* validation -- if this is true, no text needs to be buffered since
* no more will be sent before the current element closes.
*/
public abstract void validateText(char[] cbuf, int textStart, int textEnd,
boolean lastTextSegment)
throws XMLStreamException;
/**
* Method called when the validation is completed; either due to the
* input stream ending, or due to an explicit 'stop validation' request
* by the application (via context object).
*
* @param eod Flag that indicates whether this method was called by the
* context due to the end of the stream (true); or by an application
* requesting end of validation (false).
*/
public abstract void validationCompleted(boolean eod)
throws XMLStreamException;
/*
///////////////////////////////////////////////////
// Access to post-validation data (type info)
///////////////////////////////////////////////////
*/
/**
* Method for getting schema-specified type of an attribute, if
* information is available. If not, validators can return
* null to explicitly indicate no information was available.
*/
public abstract String getAttributeType(int index);
/**
* Method for finding out the index of the attribute that
* is of type ID; derived from DTD, W4C Schema, or some other validation
* source. Usually schemas explicitly specifies that at most one
* attribute can have this type for any element.
*
* @return Index of the attribute with type ID, in the current
* element, if one exists: -1 otherwise
*/
public abstract int getIdAttrIndex();
/**
* Method for finding out the index of the attribute (collected using
* the attribute collector; having DTD/Schema-derived info in same order)
* that is of type NOTATION. DTD explicitly specifies that at most one
* attribute can have this type for any element.
*
* @return Index of the attribute with type NOTATION, in the current
* element, if one exists: -1 otherwise
*/
public abstract int getNotationAttrIndex();
}