org.antlr.tool

Class FASerializer

java.lang.Object

org.antlr.tool.FASerializer

public class FASerializer
extends Object

An aspect of FA (finite automata) that knows how to dump them to serialized strings.

Field Summary

Fields

Modifier and Type	Field and Description
protected Grammar	grammar
protected Set<State>	markedStates To prevent infinite recursion when walking state machines, record which states we've visited.
protected int	stateCounter Each state we walk will get a new state number for serialization purposes.
protected Map<State,Integer>	stateNumberTranslator Rather than add a new instance variable to NFA and DFA just for serializing machines, map old state numbers to new state numbers by a State object → Integer new state number HashMap.

Constructor Summary

Constructors

Constructor and Description
FASerializer(Grammar grammar) This aspect is associated with a grammar; used to get token names

Method Summary

Methods

Modifier and Type	Method and Description
String	serialize(State s)
String	serialize(State s, boolean renumber) Return a string representation of a state machine.
protected void	walkFANormalizingStateNumbers(State s) In stateNumberTranslator, get a map from State to new, normalized state number.
protected void	walkSerializingFA(List<String> lines, State s)

Methods inherited from class java.lang.Object

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

Field Detail

markedStates

protected Set<State> markedStates

To prevent infinite recursion when walking state machines, record which states we've visited. Make a new set every time you start walking in case you reuse this object. Multiple threads will trash this shared variable. Use a different FASerializer per thread.

stateCounter

protected int stateCounter

Each state we walk will get a new state number for serialization purposes. This is the variable that tracks state numbers.

stateNumberTranslator

protected Map<State,Integer> stateNumberTranslator

Rather than add a new instance variable to NFA and DFA just for serializing machines, map old state numbers to new state numbers by a State object → Integer new state number HashMap.

grammar

protected Grammar grammar

Constructor Detail

FASerializer

public FASerializer(Grammar grammar)

This aspect is associated with a grammar; used to get token names

Method Detail

serialize

public String serialize(State s)

serialize

public String serialize(State s,
               boolean renumber)

Return a string representation of a state machine. Two identical NFAs or DFAs will have identical serialized representations. The state numbers inside the state are not used; instead, a new number is computed and because the serialization will walk the two machines using the same specific algorithm, then the state numbers will be identical. Accept states are distinguished from regular states.

walkFANormalizingStateNumbers

protected void walkFANormalizingStateNumbers(State s)

In stateNumberTranslator, get a map from State to new, normalized state number. Used by walkSerializingFA to make sure any two identical state machines will serialize the same way.

walkSerializingFA

protected void walkSerializingFA(List<String> lines,
                     State s)