me.jaimegarza.syntax.algorithm

Enum Algorithm

java.lang.Object

java.lang.Enum<Algorithm>

me.jaimegarza.syntax.algorithm.Algorithm

All Implemented Interfaces:

Serializable, Comparable<Algorithm>

public enum Algorithm
extends Enum<Algorithm>

Describes the algorithm supported by the compiler-compiler.

• SLR stands for Simple LR parser. It is based on the computation of the sets of first and follow sets associated to non terminal symbols. It constructs a compact number of states.
• LALR stands for Look Ahead LR parser. Similar to the SLR parser except that it eliminates follow sets in favor of examining the reduced follow sets in a specific point of the rules where they appear. Follow sets in SLR are computed for a non-terminal based on ALL the rules where they appear.

It is worth noting that SLR requires more reduce actions to produce an error because of the generic follow sets. Errors are only produced on Shift attempts.

Also, of importance is that when packed parsers are produced, reduces are forced to make the packing smaller. In that sense, a LALR parser can degenerate into a similar packed SLR. The major difference is that LALR can support certain parsers by producing less conflict on the generation phase due to the smaller assumptions of follow sets.

The less restrictive cannonical LR or simply LR parser allows for more context free grammars, but I have not found much use to that so far in pragmatic situations. Implementing this algorithm would not be too hard. It uses no follow up sets at all. Produced parsers are more extensive, errors are detected quicker. However, non packed parsers are too sparse in memory, and when packing occurs the tables degenerate as well. LR parsers can indeed be impractically too large.

TODO: P4-Add LR mode TODO: P5-Add Honalee algorithm

Author:

jaimegarza@gmail.com

See Also:

for the creation of follow ups

Enum Constant Summary

Enum Constants

Enum Constant and Description
LALR
SLR

Method Summary

Modifier and Type	Method and Description
static Algorithm	valueOf(String name) Returns the enum constant of this type with the specified name.
static Algorithm[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

LALR

public static final Algorithm LALR

SLR

public static final Algorithm SLR

Method Detail

values

public static Algorithm[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (Algorithm c : Algorithm.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static Algorithm valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null