/*
 * Copyright (C) 2010 The Project Lombok Authors.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package lombok.javac;

import java.util.HashSet;
import java.util.Set;

import javax.lang.model.element.Name;
import javax.lang.model.type.ArrayType;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.ErrorType;
import javax.lang.model.type.ExecutableType;
import javax.lang.model.type.NoType;
import javax.lang.model.type.NullType;
import javax.lang.model.type.PrimitiveType;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.type.TypeVariable;
import javax.lang.model.type.WildcardType;
import javax.lang.model.util.AbstractTypeVisitor6;

import com.sun.tools.javac.code.Type;

scanner (i.e. visits child nodes all the way to the leaves) that accumulates type variables. Call visit on any TypeMirror object with an instance to add all used type variable names such as T or E to the set that is returned by the getTypeVariables method. /**
 * scanner (i.e. visits child nodes all the way to the leaves) that accumulates type variables. Call {@code visit} on any {@code TypeMirror} object with an instance
 * to add all used type variable names such as {@code T} or {@code E} to the set that is returned by the {@link #getTypeVariables} method.
 */
public class FindTypeVarScanner extends AbstractTypeVisitor6<Void, Void> {
	private Set<String> typeVariables = new HashSet<String>();
	
	public Set<String> getTypeVariables() {
		return typeVariables;
	}
	
	private Void subVisit(TypeMirror mirror) {
		if (mirror == null) return null;
		return mirror.accept(this, null);
	}
	
	@Override public Void visitPrimitive(PrimitiveType t, Void p) {
		return null;
	}
	
	@Override public Void visitNull(NullType t, Void p) {
		return null;
	}
	
	
	@Override public Void visitNoType(NoType t, Void p) {
		return null;
	}
	
	@Override public Void visitUnknown(TypeMirror t, Void p) {
		return null;
	}
	
	@Override public Void visitError(ErrorType t, Void p) {
		return null;
	}
	
	@Override public Void visitArray(ArrayType t, Void p) {
		return subVisit(t.getComponentType());
	}
	
	@Override public Void visitDeclared(DeclaredType t, Void p) {
		for (TypeMirror subT : t.getTypeArguments()) subVisit(subT);
		return null;
	}
	
	@Override public Void visitTypeVariable(TypeVariable t, Void p) {
		Name name = null;
		try {
			name = ((Type) t).tsym.name;
		} catch (NullPointerException e) {}
		if (name != null) typeVariables.add(name.toString());
		subVisit(t.getLowerBound());
		subVisit(t.getUpperBound());
		return null;
	}
	
	@Override public Void visitWildcard(WildcardType t, Void p) {
		subVisit(t.getSuperBound());
		subVisit(t.getExtendsBound());
		return null;
	}
	
	@Override public Void visitExecutable(ExecutableType t, Void p) {
		subVisit(t.getReturnType());
		for (TypeMirror subT : t.getParameterTypes()) subVisit(subT);
		for (TypeMirror subT : t.getThrownTypes()) subVisit(subT);
		for (TypeVariable subT : t.getTypeVariables()) subVisit(subT);
		return null;
	}
}