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package prompto.compiler;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class LocalVariableTableAttribute implements IAttribute {

	Utf8Constant attributeName = new Utf8Constant("LocalVariableTable");
	private Map entries = new HashMap<>();

	public int numLocals() {
		return entries.size();
	}
	
	public List getEntries() {
		return entries.values().stream()
				.sorted((a, b)->
					Short.compare(a.getIndex(), b.getIndex()))
				.collect(Collectors.toList());
	}
	
	/* a work-around to get a unique transient variable name */
	/* the real solution is to manage variable scope */
	public String nextTransientName(String core) {
		int i = 0;
		while(true) {
			String name = String.format("%%%s-%03d%%", core, i++);
			if(!entries.containsKey(name))
				return name;
		}
	}

	public StackLocal registerLocal(StackLocal local) {
		String name = local.getName();
		StackLocal current = entries.get(name);
		if(current!=null)
			return current;
		int idx = entries.size();
		local.setIndex((short)idx);
		entries.put(name, local);
		return local;
	}
		
	public void unregisterLocal(StackLocal local) {
		int index = local.getIndex();
		if(index!=entries.size()-1)
			throw new CompilerException("Can only unregister top local!");
		entries.remove(local.getName());
	}

	public StackLocal getRegisteredLocal(String name) {
		return entries.get(name);
	}
	
	@Override
	public void register(ConstantsPool pool) {
		throw new UnsupportedOperationException(); // TODO
	}
	
	@Override
	public int lengthWithoutHeader() {
		throw new UnsupportedOperationException(); // TODO
	}
	
	@Override
	public void writeTo(ByteWriter writer) {
		throw new UnsupportedOperationException(); // TODO
	}



}