/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2007 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package alterrs.asm.tree.analysis;

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

import alterrs.asm.Opcodes;
import alterrs.asm.Type;
import alterrs.asm.tree.AbstractInsnNode;
import alterrs.asm.tree.FieldInsnNode;
import alterrs.asm.tree.LdcInsnNode;
import alterrs.asm.tree.MethodInsnNode;

/**
 * An {@link Interpreter} for {@link SourceValue} values.
 * 
 * @author Eric Bruneton
 */
public class SourceInterpreter implements Opcodes, Interpreter {

	public Value newValue(final Type type) {
		if (type == Type.VOID_TYPE) {
			return null;
		}
		return new SourceValue(type == null ? 1 : type.getSize());
	}

	public Value newOperation(final AbstractInsnNode insn) {
		int size;
		switch (insn.getOpcode()) {
		case LCONST_0:
		case LCONST_1:
		case DCONST_0:
		case DCONST_1:
			size = 2;
			break;
		case LDC:
			Object cst = ((LdcInsnNode) insn).cst;
			size = cst instanceof Long || cst instanceof Double ? 2 : 1;
			break;
		case GETSTATIC:
			size = Type.getType(((FieldInsnNode) insn).desc).getSize();
			break;
		default:
			size = 1;
		}
		return new SourceValue(size, insn);
	}

	public Value copyOperation(final AbstractInsnNode insn, final Value value) {
		return new SourceValue(value.getSize(), insn);
	}

	public Value unaryOperation(final AbstractInsnNode insn, final Value value) {
		int size;
		switch (insn.getOpcode()) {
		case LNEG:
		case DNEG:
		case I2L:
		case I2D:
		case L2D:
		case F2L:
		case F2D:
		case D2L:
			size = 2;
			break;
		case GETFIELD:
			size = Type.getType(((FieldInsnNode) insn).desc).getSize();
			break;
		default:
			size = 1;
		}
		return new SourceValue(size, insn);
	}

	public Value binaryOperation(final AbstractInsnNode insn,
			final Value value1, final Value value2) {
		int size;
		switch (insn.getOpcode()) {
		case LALOAD:
		case DALOAD:
		case LADD:
		case DADD:
		case LSUB:
		case DSUB:
		case LMUL:
		case DMUL:
		case LDIV:
		case DDIV:
		case LREM:
		case DREM:
		case LSHL:
		case LSHR:
		case LUSHR:
		case LAND:
		case LOR:
		case LXOR:
			size = 2;
			break;
		default:
			size = 1;
		}
		return new SourceValue(size, insn);
	}

	public Value ternaryOperation(final AbstractInsnNode insn,
			final Value value1, final Value value2, final Value value3) {
		return new SourceValue(1, insn);
	}

	public Value naryOperation(final AbstractInsnNode insn, final List values) {
		int size;
		if (insn.getOpcode() == MULTIANEWARRAY) {
			size = 1;
		} else {
			size = Type.getReturnType(((MethodInsnNode) insn).desc).getSize();
		}
		return new SourceValue(size, insn);
	}

	public void returnOperation(final AbstractInsnNode insn, final Value value,
			final Value expected) {
	}

	public Value merge(final Value v, final Value w) {
		SourceValue dv = (SourceValue) v;
		SourceValue dw = (SourceValue) w;
		if (dv.insns instanceof SmallSet && dw.insns instanceof SmallSet) {
			Set s = ((SmallSet) dv.insns).union((SmallSet) dw.insns);
			if (s == dv.insns && dv.size == dw.size) {
				return v;
			} else {
				return new SourceValue(Math.min(dv.size, dw.size), s);
			}
		}
		if (dv.size != dw.size || !dv.insns.containsAll(dw.insns)) {
			Set s = new HashSet();
			s.addAll(dv.insns);
			s.addAll(dw.insns);
			return new SourceValue(Math.min(dv.size, dw.size), s);
		}
		return v;
	}
}
