net.percederberg.grammatica.parser
Class Parser

java.lang.Object
  net.percederberg.grammatica.parser.Parser

Direct Known Subclasses:

RecursiveDescentParser

public abstract class Parser
extends java.lang.Object

A base parser class. This class provides the standard parser interface, as well as token handling.

Method Summary

void	addPattern(ProductionPattern pattern) Adds a new production pattern to the parser.
Analyzer	getAnalyzer() Returns the analyzer in use by this parser.
Tokenizer	getTokenizer() Returns the tokenizer in use by this parser.
protected Analyzer	newAnalyzer() Creates a new analyzer for this parser.
protected Production	newProduction(ProductionPattern pattern) Factory method to create a new production node.
protected Tokenizer	newTokenizer(java.io.Reader input) Creates a new tokenizer for this parser.
Node	parse() Parses the token stream and returns a parse tree.
protected abstract Node	parseStart() Parses the token stream and returns a parse tree.
void	prepare() Initializes the parser.
void	reset(java.io.Reader input) Resets this parser for usage with another input stream.
java.lang.String	toString() Returns a string representation of this parser.

Methods inherited from class java.lang.Object

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

Method Detail

newTokenizer

protected Tokenizer newTokenizer(java.io.Reader input)
                          throws ParserCreationException

Creates a new tokenizer for this parser. Can be overridden by a subclass to provide a custom implementation.

Parameters:

input - the input stream to read from

Returns:

the tokenizer created

Throws:

ParserCreationException - if the tokenizer couldn't be initialized correctly

Since:

1.5

newAnalyzer

protected Analyzer newAnalyzer()

Creates a new analyzer for this parser. Can be overridden by a subclass to provide a custom implementation.

Returns:

the analyzer created

Since:

1.5

getTokenizer

public Tokenizer getTokenizer()

Returns the tokenizer in use by this parser.

Returns:

the tokenizer in use by this parser

Since:

1.4

getAnalyzer

public Analyzer getAnalyzer()

Returns the analyzer in use by this parser.

Returns:

the analyzer in use by this parser

Since:

1.4

addPattern

public void addPattern(ProductionPattern pattern)
                throws ParserCreationException

Adds a new production pattern to the parser. The first pattern added is assumed to be the starting point in the grammar. The patterns added may be validated to some extent.

Parameters:

pattern - the pattern to add

Throws:

ParserCreationException - if the pattern couldn't be added correctly to the parser

prepare

public void prepare()
             throws ParserCreationException

Initializes the parser. All the added production patterns will be analyzed for ambiguities and errors. This method also initializes internal data structures used during the parsing.

Throws:

ParserCreationException - if the parser couldn't be initialized correctly

reset

public void reset(java.io.Reader input)

Resets this parser for usage with another input stream. The associated tokenizer and analyzer will also be reset. This method will clear all the internal state and the error log in the parser. It is normally called in order to reuse a parser and tokenizer pair with multiple input streams, thereby avoiding the cost of re-analyzing the grammar structures.

Parameters:

input - the new input stream to read

Since:

1.5

See Also:

Tokenizer.reset(java.io.Reader), Analyzer.reset()

parse

public Node parse()
           throws ParserCreationException,
                  ParserLogException

Parses the token stream and returns a parse tree. This method will call prepare() if not previously called. It will also call the reset() method, to making sure that only the Tokenizer.reset() method must be explicitly called in order to reuse a parser for multiple input streams. In case of a parse error, the parser will attempt to recover and throw all the errors found in a parser log exception at the end of the parsing.

Returns:

the parse tree

Throws:

ParserCreationException - if the parser couldn't be initialized correctly

ParserLogException - if the input couldn't be parsed correctly

See Also:

prepare(), reset(java.io.Reader), Tokenizer.reset(java.io.Reader)

parseStart

protected abstract Node parseStart()
                            throws ParseException

Parses the token stream and returns a parse tree.

Returns:

the parse tree

Throws:

ParseException - if the input couldn't be parsed correctly

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

toString

public java.lang.String toString()

Returns a string representation of this parser. The string will contain all the production definitions and various additional information.

Overrides:

toString in class java.lang.Object

Returns:

a detailed string representation of this parser