src/main/java/org/luaj/vm3/ast/NameScope.java

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* of this software and associated documentation files (the "Software"), to deal
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package org.luaj.vm3.ast;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

public class NameScope {

	private static final Set<String> LUA_KEYWORDS = new HashSet<String>();

	static {
		String[] k = new String[] { "and", "break", "do", "else", "elseif", "end", "false", "for", "function", "if", "in", "local", "nil", "not", "or", "repeat", "return", "then", "true", "until", "while" };
		for (int i = 0; i < k.length; i++)
			LUA_KEYWORDS.add(k[i]);
	}

	public final Map<String, Variable> namedVariables = new HashMap<String, Variable>();

	public final NameScope outerScope;

	public int functionNestingCount;

	/** Construct default names scope */
	public NameScope() {
		this.outerScope = null;
		this.functionNestingCount = 0;
	}

	/** Construct name scope within another scope*/
	public NameScope(NameScope outerScope) {
		this.outerScope = outerScope;
		this.functionNestingCount = outerScope != null ? outerScope.functionNestingCount : 0;
	}

	/** Look up a name.  If it is a global name, then throw IllegalArgumentException. */
	public Variable find(String name) throws IllegalArgumentException {
		validateIsNotKeyword(name);
		for (NameScope n = this; n != null; n = n.outerScope)
			if (n.namedVariables.containsKey(name))
				return (Variable) n.namedVariables.get(name);
		Variable value = new Variable(name);
		this.namedVariables.put(name, value);
		return value;
	}

	/** Define a name in this scope.  If it is a global name, then throw IllegalArgumentException. */
	public Variable define(String name) throws IllegalStateException, IllegalArgumentException {
		validateIsNotKeyword(name);
		Variable value = new Variable(name, this);
		this.namedVariables.put(name, value);
		return value;
	}

	private void validateIsNotKeyword(String name) {
		if (LUA_KEYWORDS.contains(name))
			throw new IllegalArgumentException("name is a keyword: '" + name + "'");
	}
}