Class node

public boolean _closed

True for the node that cannot be visited again.

public char binary

The binary operation for this node.

public node previous

The previous node in content model (used for closing nodes).

public Object token

The token to match (can be instance of list).

public char unary

The unary opeation for this node.

public int visits

The number of times the node already was visited.

public node(char binary_operator,
            char unary_operator,
            Object a_token)

Creates a new node.

Parameters:

binary_operator - The operator, connecting all nodes in the list. The nodes, connected by the different operators, must be arranged into the different lists.

unary_operator - The unary operator for this node or zero if no such was specified.

protected void close()

Closes this node and, if closePrevious() returs true, calls close() for the previous node.

public boolean closePrevious()

Check if closing this node means closing the previous node.

protected boolean compare(Object a_token)

Compare the provided token object with the token object of this node.

public Object findFreeNode()

Return the token object if it could match as a next token in a token list of null if it could not.

Returns:

public boolean isClosed()

Checks if this node is in the closed state.

Returns:

True if the node is closed.

protected void matches()

Fire the changes that must happen then the token matches this node.

public boolean mustClose()

Check if the current situation is such that the node must be closed now.

public boolean performMatch(Object a_token)

Do the match operation with the given token. This sets various flags.

Parameters:

a_token - The token to match.

Returns:

true if the the token matches node, false if it does not match or if the node is closed.

public void reset()

Prepares the node for matching against a new list of tokens.

public Object show(Object x)

Check if the provided token can match this node. In the case of match, the node state changes, moving current position after the matched token. However if this method returns a suggested new token to insert before the provided one, the state of the list does not change.

Returns:

Boolean.TRUE if the match is found, Boolean.FALSE if the match is not possible and no token can be inserted to make the match valid. Otherwise, returns the token object that can be inserted before the last token in the list, probably (not for sure) making the match valid.

public boolean silenceAllowed()

Check if it would be a valid case if this node is visited zero times. Nodes with unary operator * or ? need not be matched to make a model valid.

public String toString()

Returns a string representation of the list.

Overrides:

toString in interface Object

Returns:

String representation, similar to BNF expression.

public boolean valid()

Check if the node state is valid.

public boolean validPreliminary()