org.apache.xerces.validators.dtd
Class DFAContentModel

java.lang.Object
  |
  +--org.apache.xerces.validators.dtd.DFAContentModel

public class DFAContentModel

extends java.lang.Object

implements XMLContentModel

DFAContentModel is the derivative of ContentModel that does all of the non-trivial element content validation. This class does the conversion from the regular expression to the DFA that it then uses in its validation algorithm.

Note: Upstream work insures that this class will never see a content model with PCDATA in it. Any model with PCDATA is 'mixed' and is handled via the MixedContentModel class since mixed models are very constrained in form and easily handled via a special case. This also makes implementation of this class much easier.

Version:

Constructor Summary

DFAContentModel(StringPool stringPool, CMNode syntaxTree, int leafCount)
Constructs a DFA content model.

Method Summary

int	validateContent(int childCount, int[] children) Check that the specified content is valid according to this content model.
int	whatCanGoHere(boolean fullyValid, InsertableElementsInfo info) Returns information about which elements can be placed at a particular point in the passed element's content model.

Methods inherited from class java.lang.Object

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

Constructor Detail

DFAContentModel

public DFAContentModel(StringPool stringPool,
                       CMNode syntaxTree,
                       int leafCount)
                throws CMException

Constructs a DFA content model.

Parameters:

elementIndex - The element decl index.

stringPool - The string pool.

declPool - The element decl pool.

Throws:

CMException - Thrown if DMA can't be built.

Method Detail

validateContent

public int validateContent(int childCount,
                           int[] children)
                    throws CMException

Check that the specified content is valid according to this content model. This method can also be called to do 'what if' testing of content models just to see if they would be valid.

A value of -1 in the children array indicates a PCDATA node. All other indexes will be positive and represent child elements. The count can be zero, since some elements have the EMPTY content model and that must be confirmed.

Specified by:

validateContent in interface XMLContentModel

Parameters:

childCount - The number of entries in the children array.

children - The children of this element. Each integer is an index within the StringPool of the child element name. An index of -1 is used to indicate an occurrence of non-whitespace character data.

Returns:

The value -1 if fully valid, else the 0 based index of the child that first failed. If the value returned is equal to the number of children, then the specified children are valid but additional content is required to reach a valid ending state.

Throws:

CMException - Thrown on error.

whatCanGoHere

public int whatCanGoHere(boolean fullyValid,
                         InsertableElementsInfo info)
                  throws CMException

Returns information about which elements can be placed at a particular point in the passed element's content model.

Note that the incoming content model to test must be valid at least up to the insertion point. If not, then -1 will be returned and the info object will not have been filled in.

If, on return, the info.isValidEOC flag is set, then the 'insert after' element is a valid end of content. In other words, nothing needs to be inserted after it to make the parent element's content model valid.

Specified by:

whatCanGoHere in interface XMLContentModel

Parameters:

fullyValid - Only return elements that can be inserted and still maintain the validity of subsequent elements past the insertion point (if any). If the insertion point is at the end, and this is true, then only elements that can be legal final states will be returned.

info - An object that contains the required input data for the method, and which will contain the output information if successful.

Returns:

The value -1 if fully valid, else the 0 based index of the child that first failed before the insertion point. If the value returned is equal to the number of children, then the specified children are valid but additional content is required to reach a valid ending state.

See Also:

InsertableElementsInfo