DFA (ANTLR 3 Runtime 3.5.3 API)

java.lang.Object
- org.antlr.runtime.DFA

```
public class DFA
extends Object
```
A DFA implemented as a set of transition tables. Any state that has a semantic predicate edge is special; those states are generated with if-then-else structures in a specialStateTransition() which is generated by cyclicDFA template. There are at most 32767 states (16-bit signed short). Could get away with byte sometimes but would have to generate different types and the simulation code too. For a point of reference, the Java lexer's Tokens rule DFA has 326 states roughly.

Field Summary

Fields
Modifier and Type	Field	Description
`protected short[]`	`accept`
`static boolean`	`debug`
`protected int`	`decisionNumber`
`protected short[]`	`eof`
`protected short[]`	`eot`
`protected char[]`	`max`
`protected char[]`	`min`
`protected BaseRecognizer`	`recognizer`	Which recognizer encloses this DFA? Needed to check backtracking
`protected short[]`	`special`
`protected short[][]`	`transition`

Constructor Summary

Constructors
Constructor Description

DFA()

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected void`	`error(NoViableAltException nvae)`	A hook for debugging interface
`String`	`getDescription()`
`protected void`	`noViableAlt(int s, IntStream input)`
`int`	`predict(IntStream input)`	From the input stream, predict what alternative will succeed using this DFA (representing the covering regular approximation to the underlying CFL).
`int`	`specialStateTransition(int s, IntStream input)`
`static short[]`	`unpackEncodedString(String encodedString)`	Given a String that has a run-length-encoding of some unsigned shorts like "\1\2\3\9", convert to short[] {2,9,9,9}.
`static char[]`	`unpackEncodedStringToUnsignedChars(String encodedString)`	Hideous duplication of code, but I need different typed arrays out :(

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

eot
```
protected short[] eot
```

eof
```
protected short[] eof
```

min
```
protected char[] min
```

max
```
protected char[] max
```

accept
```
protected short[] accept
```

special
```
protected short[] special
```

transition
```
protected short[][] transition
```

decisionNumber
```
protected int decisionNumber
```

recognizer
```
protected BaseRecognizer recognizer
```
Which recognizer encloses this DFA? Needed to check backtracking

debug
```
public static final boolean debug
```
See Also:

Constant Field Values

Constructor Detail
- DFA
```
public DFA()
```

Method Detail
- predict
```
public int predict(IntStream input)
            throws RecognitionException
```
  From the input stream, predict what alternative will succeed using this DFA (representing the covering regular approximation to the underlying CFL). Return an alternative number 1..n. Throw an exception upon error.
  
  Throws:
  
  RecognitionException
- noViableAlt
```
protected void noViableAlt(int s,
                           IntStream input)
                    throws NoViableAltException
```
  Throws:
  
  NoViableAltException
- error
```
protected void error(NoViableAltException nvae)
```
  A hook for debugging interface
- specialStateTransition
```
public int specialStateTransition(int s,
                                  IntStream input)
                           throws NoViableAltException
```
  Throws:
  
  NoViableAltException
- getDescription
```
public String getDescription()
```
- unpackEncodedString
```
public static short[] unpackEncodedString(String encodedString)
```
  Given a String that has a run-length-encoding of some unsigned shorts like "\1\2\3\9", convert to short[] {2,9,9,9}. We do this to avoid static short[] which generates so much init code that the class won't compile. :(
- unpackEncodedStringToUnsignedChars
```
public static char[] unpackEncodedStringToUnsignedChars(String encodedString)
```
  Hideous duplication of code, but I need different typed arrays out :(