net.percederberg.grammatica.parser

Class Analyzer

java.lang.Object

net.percederberg.grammatica.parser.Analyzer

public class Analyzer
extends java.lang.Object

A parse tree analyzer. This class provides callback methods that may be used either during parsing, or for a parse tree traversal. This class should be subclassed to provide adequate handling of the parse tree nodes. The general contract for the analyzer class does not guarantee a strict call order for the callback methods. Depending on the type of parser, the enter() and exit() methods for production nodes can be called either in a top-down or a bottom-up fashion. The only guarantee provided by this API, is that the calls for any given node will always be in the order enter(), child(), and exit(). If various child() calls are made, they will be made from left to right as child nodes are added (to the right).

Constructor Summary

Constructors

Constructor and Description
Analyzer()

Method Summary

Modifier and Type	Method and Description
Node	analyze(Node node) Analyzes a parse tree node by traversing all it's child nodes.
protected void	child(Production node, Node child) Called when adding a child to a parse tree node.
protected void	enter(Node node) Called when entering a parse tree node.
protected Node	exit(Node node) Called when exiting a parse tree node.
protected Node	getChildAt(Node node, int pos) Returns a child at the specified position.
protected java.util.ArrayList	getChildValues(Node node) Returns all the node values for all child nodes.
protected Node	getChildWithId(Node node, int id) Returns the first child with the specified id.
protected int	getIntValue(Node node, int pos) Returns the node integer value at the specified position.
protected java.lang.String	getStringValue(Node node, int pos) Returns the node string value at the specified position.
protected java.lang.Object	getValue(Node node, int pos) Returns the node value at the specified position.
protected Production	newProduction(ProductionPattern pattern) Factory method to create a new production node.
void	reset() Resets this analyzer when the parser is reset for another input stream.

Methods inherited from class java.lang.Object

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

Constructor Detail

Analyzer

public Analyzer()

Method Detail

reset

public void reset()

Resets this analyzer when the parser is reset for another input stream. The default implementation of this method does nothing.

Since:

1.5

analyze

public Node analyze(Node node)
             throws ParserLogException

Analyzes a parse tree node by traversing all it's child nodes. The tree traversal is depth-first, and the appropriate callback methods will be called. If the node is a production node, a new production node will be created and children will be added by recursively processing the children of the specified production node. This method is used to process a parse tree after creation.

Parameters:

node - the parse tree node to process

Returns:

the resulting parse tree node

Throws:

ParserLogException - if the node analysis discovered errors

newProduction

protected Production newProduction(ProductionPattern pattern)

Factory method to create a new production node. This method can be overridden to provide other production implementations than the default one.

Parameters:

pattern - the production pattern

Returns:

the new production node

Since:

1.5

enter

protected void enter(Node node)
              throws ParseException

Called when entering a parse tree node. By default this method does nothing. A subclass can override this method to handle each node separately.

Parameters:

node - the node being entered

Throws:

ParseException - if the node analysis discovered errors

exit

protected Node exit(Node node)
             throws ParseException

Called when exiting a parse tree node. By default this method returns the node. A subclass can override this method to handle each node separately. If no parse tree should be created, this method should return null.

Parameters:

node - the node being exited

Returns:

the node to add to the parse tree, or null if no parse tree should be created

Throws:

ParseException - if the node analysis discovered errors

child

protected void child(Production node,
                     Node child)
              throws ParseException

Called when adding a child to a parse tree node. By default this method adds the child to the production node. A subclass can override this method to handle each node separately. Note that the child node may be null if the corresponding exit() method returned null.

Parameters:

node - the parent node

child - the child node, or null

Throws:

ParseException - if the node analysis discovered errors

getChildAt

protected Node getChildAt(Node node,
                          int pos)
                   throws ParseException

Returns a child at the specified position. If either the node or the child node is null, this method will throw a parse exception with the internal error type.

Parameters:

node - the parent node

pos - the child position

Returns:

the child node

Throws:

ParseException - if either the node or the child node was null

getChildWithId

protected Node getChildWithId(Node node,
                              int id)
                       throws ParseException

Returns the first child with the specified id. If the node is null, or no child with the specified id could be found, this method will throw a parse exception with the internal error type.

Parameters:

node - the parent node

id - the child node id

Returns:

the child node

Throws:

ParseException - if the node was null, or a child node couldn't be found

getValue

protected java.lang.Object getValue(Node node,
                                    int pos)
                             throws ParseException

Returns the node value at the specified position. If either the node or the value is null, this method will throw a parse exception with the internal error type.

Parameters:

node - the parse tree node

pos - the child position

Returns:

the value object

Throws:

ParseException - if either the node or the value was null

getIntValue

protected int getIntValue(Node node,
                          int pos)
                   throws ParseException

Returns the node integer value at the specified position. If either the node is null, or the value is not an instance of the Integer class, this method will throw a parse exception with the internal error type.

Parameters:

node - the parse tree node

pos - the child position

Returns:

the value object

Throws:

ParseException - if either the node was null, or the value wasn't an integer

getStringValue

protected java.lang.String getStringValue(Node node,
                                          int pos)
                                   throws ParseException

Returns the node string value at the specified position. If either the node is null, or the value is not an instance of the String class, this method will throw a parse exception with the internal error type.

Parameters:

node - the parse tree node

pos - the child position

Returns:

the value object

Throws:

ParseException - if either the node was null, or the value wasn't a string

getChildValues

protected java.util.ArrayList getChildValues(Node node)

Returns all the node values for all child nodes.

Parameters:

node - the parse tree node

Returns:

a list with all the child node values

Since:

1.3