sjm.parse
Class Terminal

java.lang.Object
  |
  +--sjm.parse.Parser
        |
        +--sjm.parse.Terminal

Direct Known Subclasses:

Char, Digit, Letter, Literal, Num, QuotedString, SpecificChar, SpecificTerminal, Symbol, Word

public class Terminal

extends Parser

A Terminal is a parser that is not a composition of other parsers. Terminals are "terminal" because they do not pass matching work on to other parsers. The criterion that terminals use to check a match is something other than another parser. Terminals are also the only parsers that advance an assembly.

Version:

1.0

Author:

Steven J. Metsker

Field Summary

protected boolean

discard

Fields inherited from class sjm.parse.Parser

assembler, name

Constructor Summary

Terminal()
Constructs an unnamed terminal.

Terminal(java.lang.String name)
Constructs a terminal with the given name.

Method Summary

void	accept(ParserVisitor pv, java.util.Vector visited) Accept a "visitor" and a collection of previously visited parsers.
Terminal	discard() A convenience method that sets discarding to be true.
java.util.Vector	match(java.util.Vector in) Given a collection of assemblies, this method matches this terminal against all of them, and returns a new collection of the assemblies that result from the matches.
protected Assembly	matchOneAssembly(Assembly in) Returns an assembly equivalent to the supplied assembly, except that this terminal will have been removed from the front of the assembly.
protected boolean	qualifies(java.lang.Object o) The mechanics of matching are the same for many terminals, except for the check that the next element on the assembly qualifies as the type of terminal this terminal looks for.
java.util.Vector	randomExpansion(int maxDepth, int depth)
Terminal	setDiscard(boolean discard) By default, terminals push themselves upon a assembly's stack, after a successful match.
protected java.lang.String	unvisitedString(java.util.Vector visited)

Methods inherited from class sjm.parse.Parser

accept, add, best, bestMatch, completeMatch, elementClone, getName, matchAndAssemble, randomInput, setAssembler, toString, toString

Methods inherited from class java.lang.Object

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

Field Detail

discard

protected boolean discard

Constructor Detail

Terminal

public Terminal()

Constructs an unnamed terminal.

Terminal

public Terminal(java.lang.String name)

Constructs a terminal with the given name.

Parameters:

String - A name to be known by.

Method Detail

accept

public void accept(ParserVisitor pv,
                   java.util.Vector visited)

Accept a "visitor" and a collection of previously visited parsers.

Overrides:

accept in class Parser

Parameters:

ParserVisitor - the visitor to accept

Vector - a collection of previously visited parsers

discard

public Terminal discard()

A convenience method that sets discarding to be true.

Returns:

this

match

public java.util.Vector match(java.util.Vector in)

Given a collection of assemblies, this method matches this terminal against all of them, and returns a new collection of the assemblies that result from the matches.

Overrides:

match in class Parser

Parameters:

Vector - a vector of assemblies to match against

Returns:

a Vector of assemblies that result from matching against a beginning set of assemblies

matchOneAssembly

protected Assembly matchOneAssembly(Assembly in)

Returns an assembly equivalent to the supplied assembly, except that this terminal will have been removed from the front of the assembly. As with any parser, if the match succeeds, this terminal's assembler will work on the assembly. If the match fails, this method returns null.

Parameters:

Assembly - the assembly to match against

Returns:

a copy of the incoming assembly, advanced by this terminal

qualifies

protected boolean qualifies(java.lang.Object o)

The mechanics of matching are the same for many terminals, except for the check that the next element on the assembly qualifies as the type of terminal this terminal looks for. This method performs that check.

Parameters:

Object - an element from a assembly

Returns:

true, if the object is the kind of terminal this parser seeks

randomExpansion

public java.util.Vector randomExpansion(int maxDepth,
                                        int depth)

Overrides:

randomExpansion in class Parser

setDiscard

public Terminal setDiscard(boolean discard)

By default, terminals push themselves upon a assembly's stack, after a successful match. This routine will turn off (or turn back on) that behavior.

Parameters:

boolean - true, if this terminal should push itself on a assembly's stack

Returns:

this

unvisitedString

protected java.lang.String unvisitedString(java.util.Vector visited)

Overrides:

unvisitedString in class Parser