org.stekikun.dolmen.automaton

Class Automata

java.lang.Object

org.stekikun.dolmen.automaton.Automata

public final class Automata
extends Object

An instance of Automata gathers all the deterministic finite automata implementing the various rules in a lexer definition.

The automata are described by the reunion of their cells and by a description of each sub-automaton associated to a lexer entry, providing its initial state, memory size for tag handling, initializer and finisher actions, etc.

Author:

Stéphane Lescuyer

See Also:

Determinize.lexer(org.stekikun.dolmen.syntax.Lexer, boolean)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Automata.Entry Represents automaton information for one lexer entry.

Field Summary

Fields

Modifier and Type	Field and Description
DFA.Cell[]	automataCells The cells of the various automata implementing the rules
List<Automata.Entry>	automataEntries The list of automata entries, one for each lexer rule
Extent	footer The location of this lexer's footer
Extent	header The location of this lexer's header
List<Located<String>>	imports The imports to be added to the generated lexer

Constructor Summary

Constructors

Constructor and Description
Automata(List<Located<String>> imports, Extent header, Extent footer, List<Automata.Entry> automataEntries, DFA.Cell[] automataCells) Builds the automata from the given entries and cells

Method Summary

Modifier and Type	Method and Description
List<IReport>	findProblems(Lexer lexer) Checks the automata which must correspond to the lexer description lexer for any problems and reports all of them in reporter.
boolean	needsEmptyMemories()
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

imports

public final List<Located<String>> imports

The imports to be added to the generated lexer

header

public final Extent header

The location of this lexer's header

automataEntries

public final List<Automata.Entry> automataEntries

The list of automata entries, one for each lexer rule

automataCells

public final DFA.Cell[] automataCells

The cells of the various automata implementing the rules

footer

public final Extent footer

The location of this lexer's footer

Constructor Detail

Automata

public Automata(List<Located<String>> imports,
                Extent header,
                Extent footer,
                List<Automata.Entry> automataEntries,
                DFA.Cell[] automataCells)

Builds the automata from the given entries and cells

Parameters:

imports -

header -

footer -

automataEntries -

automataCells -

Method Detail

needsEmptyMemories

public boolean needsEmptyMemories()

Returns:

true iff at least one of the entries in the automata requires a non-empty number of memory cells and at least one of the entries require none.

toString

public String toString()

Overrides:

toString in class Object

findProblems

public List<IReport> findProblems(Lexer lexer)

Checks the automata which must correspond to the lexer description lexer for any problems and reports all of them in reporter.

The following issues can be reported:

• clauses which are never used, i.e. those for which the semantic action is never performed;
• entries which can produce empty token exceptions.

Parameters:

lexer -

Returns:

the (potentially empty) list of reports for the problems found in this Automata instance