Class ThompsonCompiler

java.lang.Object
  ThompsonCompiler

All Implemented Interfaces:

ExpressionCompiler

public class ThompsonCompiler

extends java.lang.Object

implements ExpressionCompiler

Compiles a rational expression into an automaton of the class NFA by Thompson's algorithm. Uses a top-down analysis for the grammar
E -> E+T | T ,
T -> TF | F ,
F -> G | G* ,
G -> (E) | char .

Constructor Summary

ThompsonCompiler()

Method Summary

void	advance() Implements the function Advance() of Section 1.6.1.
char	current() Implements the function Current() of Section 1.6.1.
LinkedNFA	evalExp() Implements the function EvalExp() of Section 1.6.1.
LinkedNFA	evalFact() Implements the function EvalFact() of Section 1.6.1.
LinkedNFA	evalTerm() Implements the function EvalTerm() of Section 1.6.1.
LinkedNFA	toLinkedNFA()
NFA	toNFA(java.lang.String s) Compiles the expression into a nondeterministic finite automaton.

Methods inherited from class java.lang.Object

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

Constructor Detail

ThompsonCompiler

public ThompsonCompiler()

Method Detail

current

public char current()

Implements the function Current() of Section 1.6.1. Returns the current character of the input expression.

advance

public void advance()

Implements the function Advance() of Section 1.6.1. Advances to the next character in the input expression.

evalExp

public LinkedNFA evalExp()

Implements the function EvalExp() of Section 1.6.1. Returns a LinkedNFA recognizing the expression.

evalTerm

public LinkedNFA evalTerm()

Implements the function EvalTerm() of Section 1.6.1.

evalFact

public LinkedNFA evalFact()

Implements the function EvalFact() of Section 1.6.1.

toLinkedNFA

public LinkedNFA toLinkedNFA()

toNFA

public NFA toNFA(java.lang.String s)

Compiles the expression into a nondeterministic finite automaton. Internally, the function computes an automaton of the class LinkedNFA and then converts it into an NFA.

Specified by:

toNFA in interface ExpressionCompiler