me.jaimegarza.syntax.generator

Class StructuralAnalyzer

java.lang.Object

me.jaimegarza.syntax.generator.AbstractPhase

me.jaimegarza.syntax.generator.StructuralAnalyzer

public class StructuralAnalyzer
extends AbstractPhase

Phases:

1. Code Parser
2. Structural Analysis (This Phase)
3. Table Generation
4. Writing Code

This phase computes the first & follow sets for symbols

Author:

jaimegarza@gmail.com

Field Summary

Fields inherited from class me.jaimegarza.syntax.generator.AbstractPhase

environment, runtimeData

Constructor Summary

Constructors

Constructor and Description
StructuralAnalyzer(Environment environment) Construct an analizer given an environment

Method Summary

Modifier and Type	Method and Description
void	execute()
Set<Integer>	getFirst(int nonTerminalId) The first is the set of terminal symbols that a given non-terminal can start with.

Methods inherited from class me.jaimegarza.syntax.generator.AbstractPhase

indent, left, right, span, span

Methods inherited from class java.lang.Object

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

Constructor Detail

StructuralAnalyzer

public StructuralAnalyzer(Environment environment)

Construct an analizer given an environment

Parameters:

environment - the Environment, shared between phases.

Method Detail

getFirst

public Set<Integer> getFirst(int nonTerminalId)

The first is the set of terminal symbols that a given non-terminal can start with.

Look at the left side of all rules and, if the rule left hand matches the desired symbol, find the non-terminals that the symbol can start with. This is recursive. In addition, empty non-terminals appearing at the beginning of the rule require the review of the second one, etc.

given

 ri: α → β 
 

First(α) = ∪ First(β)
∀ α ∈ N ∧ r_i ∈ (R ∈ G)

In addition, for β = λδ

First (β):

1. if λ ∈ N then First (β) = First(λ)

   if ∃ r_j: λ → ∅ then First(β) = First(λ) ∪ First(δ)

2. if λ ∈ T then First(λ) = { λ }

Parameters:

nonTerminalId - is the non terminal to compute

Returns:

the set of first for a given symbol, traversing all rules left hand symbol.

execute

public void execute()
             throws AnalysisException

Throws:

AnalysisException