/*

***** BEGIN LICENSE BLOCK *****

* Version: CPL 1.0/GPL 2.0/LGPL 2.1

*

* The contents of this file are subject to the Common Public

* License Version 1.0 (the "License"); you may not use this file

* except in compliance with the License. You may obtain a copy of

* the License at http://www.eclipse.org/legal/cpl-v10.html

*

* Software distributed under the License is distributed on an "AS

* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or

* implied. See the License for the specific language governing

* rights and limitations under the License.

*

* Copyright (C) 2002 Benoit Cerrina <b.cerrina@wanadoo.fr>

* Copyright (C) 2002 Jan Arne Petersen <jpetersen@uni-bonn.de>

* Copyright (C) 2002-2004 Anders Bengtsson <ndrsbngtssn@yahoo.se>

* Copyright (C) 2004 Thomas E Enebo <enebo@acm.org>

* Copyright (C) 2004 Stefan Matthias Aust <sma@3plus4.de>

*

* Alternatively, the contents of this file may be used under the terms of

* either of the GNU General Public License Version 2 or later (the "GPL"),

* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),

* in which case the provisions of the GPL or the LGPL are applicable instead

* of those above. If you wish to allow use of your version of this file only

* under the terms of either the GPL or the LGPL, and not to allow others to

* use your version of this file under the terms of the CPL, indicate your

* decision by deleting the provisions above and replace them with the notice

* and other provisions required by the GPL or the LGPL. If you do not delete

* the provisions above, a recipient may use your version of this file under

* the terms of any one of the CPL, the GPL or the LGPL.

***** END LICENSE BLOCK *****/

package org.jruby.ast;

import java.util.List;

import org.jruby.Ruby;

import org.jruby.RubyBoolean;

import org.jruby.ast.visitor.NodeVisitor;

import org.jruby.lexer.yacc.ISourcePosition;

import org.jruby.runtime.Block;

import org.jruby.runtime.DynamicScope;

import org.jruby.runtime.ThreadContext;

import org.jruby.runtime.builtin.IRubyObject;

/**

* A Range in a boolean expression (named after a FlipFlop component in electronic?).

*/

public class FlipNode extends Node {

private final Node beginNode;

private final Node endNode;

private final boolean exclusive;

// A scoped location of this variable (high 16 bits is how many scopes down and low 16 bits

// is what index in the right scope to set the value.

private final int location;

public FlipNode(ISourcePosition position, Node beginNode, Node endNode, boolean exclusive, int location) {

super(position);

assert beginNode != null : "beginNode is not null";

assert endNode != null : "endNode is not null";

this.beginNode = beginNode;

this.endNode = endNode;

this.exclusive = exclusive;

this.location = location;

}

public NodeType getNodeType() {

return NodeType.FLIPNODE;

}

/**

* Accept for the visitor pattern.

* @param iVisitor the visitor

**/

public Object accept(NodeVisitor iVisitor) {

return iVisitor.visitFlipNode(this);

}

/**

* Gets the beginNode.

* beginNode will set the FlipFlop the first time it is true

* @return Returns a Node

*/

public Node getBeginNode() {

return beginNode;

}

/**

* Gets the endNode.

* endNode will reset the FlipFlop when it is true while the FlipFlop is set.

* @return Returns a Node

*/

public Node getEndNode() {

return endNode;

}

/**

* Gets the exclusive.

* if the range is a 2 dot range it is false if it is a three dot it is true

* @return Returns a boolean

*/

public boolean isExclusive() {

return exclusive;

}

/**

* How many scopes should we burrow down to until we need to set the block variable value.

*

* @return 0 for current scope, 1 for one down, ...

*/

public int getDepth() {

return location >> 16;

}

/**

* Gets the index within the scope construct that actually holds the eval'd value

* of this local variable

*

* @return Returns an int offset into storage structure

*/

public int getIndex() {

return location & 0xffff;

}

public List<Node> childNodes() {

return Node.createList(beginNode, endNode);

}

@Override

public IRubyObject interpret(Ruby runtime, ThreadContext context, IRubyObject self, Block aBlock) {

DynamicScope scope = context.getCurrentScope();

IRubyObject nil = runtime.getNil();

int index = getIndex();

// Make sure the appropriate scope has proper size. See JRUBY-2046.

DynamicScope flipScope = scope.getFlipScope();

flipScope.growIfNeeded();

IRubyObject result = flipScope.getValueDepthZeroOrNil(index, nil);

if (exclusive) {

if (result == null || !result.isTrue()) {

result = trueIfTrue(runtime, beginNode.interpret(runtime, context, self, aBlock));

flipScope.setValueDepthZero(result, index);

return result;

} else {

if (endNode.interpret(runtime, context, self, aBlock).isTrue()) {

flipScope.setValueDepthZero(runtime.getFalse(), index);

}

return runtime.getTrue();

}

} else {

if (result == null || !result.isTrue()) {

if (beginNode.interpret(runtime, context, self, aBlock).isTrue()) {

flipScope.setValueDepthZero(falseIfTrue(runtime, endNode.interpret(runtime, context, self, aBlock)), index);

return runtime.getTrue();

}

return runtime.getFalse();

} else {

if (endNode.interpret(runtime, context, self, aBlock).isTrue()) {

flipScope.setValueDepthZero(runtime.getFalse(), index);

}

return runtime.getTrue();

}

}

}

private static RubyBoolean trueIfTrue(Ruby runtime, IRubyObject truish) {

return truish.isTrue() ? runtime.getTrue() : runtime.getFalse();

}

private static RubyBoolean falseIfTrue(Ruby runtime, IRubyObject truish) {

return truish.isTrue() ? runtime.getFalse() : runtime.getTrue();

}

}