gi
Class SLR1_Grammar

java.lang.Object
  gi.Lexicon
      gi.Grammar
          gi.LR0_Grammar
              gi.SLR1_Grammar

public class SLR1_Grammar

extends LR0_Grammar

This class implements an SLR(1) parser around a Grammar. The parser adapts to changes in the underlying Grammar. Semantics in a phrase are evaluated during a bottom-up parse, from left to right after all subtrees rooted in the phrase have been constructed. Attributes throughout the phrase are available during evaluation. SLR(1) parsing is more space- and time-efficient than LR(1) parsing; however, SLR(1) parsing is more easily confused than LR(1) parsing, since it considers lookahead terminals generally following a nonterminal (rather than specifically following it in a context) to choose between applicable phrases.

Version:

1.2

Author:

© 1999-2004 Craig A. Rich <carich@csupomona.edu>

Nested Class Summary

Nested classes inherited from class gi.LR0_Grammar

LR0_Grammar.Context, LR0_Grammar.Contexts

Nested classes inherited from class gi.Grammar

Grammar.ParseTree, Grammar.Production, Grammar.Semantics

Nested classes inherited from class gi.Lexicon

Lexicon.Alphabet, Lexicon.Concatenation, Lexicon.Exception, Lexicon.Expression, Lexicon.Match, Lexicon.NonMatch, Lexicon.PosixClass, Lexicon.Range, Lexicon.Repetition, Lexicon.Set, Lexicon.Singleton, Lexicon.Stack, Lexicon.UnicodeCategory, Lexicon.Union

Field Summary

Fields inherited from class gi.LR0_Grammar

S$, states, trees

Fields inherited from class gi.Grammar

CONFLICT, FIRST_FOLLOW, P, PARSE_TREE, S, SYNTAX

Fields inherited from class gi.Lexicon

$, debug, LEXICAL, TERMINALS, VERBOSE

Constructor Summary

protected	SLR1_Grammar() Constructs an SLR(1) parser around a new empty Grammar.
protected	SLR1_Grammar(Grammar G) Constructs an SLR(1) parser around an existing Grammar.

Method Summary

(package private) Lexicon.Set	expected(LR0_Grammar.Contexts C) Computes the terminals expected in a set of LR(0) Contexts.
(package private) Grammar.Production	parse(LR0_Grammar.Contexts C, Object a) Computes the Production to use in a reverse rightmost derivation.
String	toString() Returns the string representation of this parser, specifically "SLR(1)".

Methods inherited from class gi.LR0_Grammar

closure, initial, interpret, transition

Methods inherited from class gi.Grammar

first, first, first, follow, grab, interpret, nonterminal, put, put, terminal

Methods inherited from class gi.Lexicon

expression, interpret, interpret, interpret, interpret, interpret, interpret, put, word

Methods inherited from class java.lang.Object

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

Constructor Detail

SLR1_Grammar

protected SLR1_Grammar()

Constructs an SLR(1) parser around a new empty Grammar.

SLR1_Grammar

protected SLR1_Grammar(Grammar G)

Constructs an SLR(1) parser around an existing Grammar.

Parameters:

G - the Grammar around which the parser is constructed.

Method Detail

expected

Lexicon.Set expected(LR0_Grammar.Contexts C)

Computes the terminals expected in a set of LR(0) Contexts.

Overrides:

expected in class LR0_Grammar

Parameters:

C - the set of LR(0) Contexts.

Returns:

the terminals matching a shift or reduce Context in C.

parse

Grammar.Production parse(LR0_Grammar.Contexts C,
                         Object a)

Computes the Production to use in a reverse rightmost derivation.

Overrides:

parse in class LR0_Grammar

Parameters:

C - the set of LR(0) Contexts.

a - the lookahead terminal.

Returns:

the highest priority Production underlying an applicable reduce Context in C; returns null if none.

toString

public String toString()

Returns the string representation of this parser, specifically "SLR(1)".

Overrides:

toString in class LR0_Grammar

Returns:

the string representation of this parser, specifically "SLR(1)".

Since:

1.1