net.wpm.codegen.PredicateDefCmp Maven / Gradle / Ivy

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/*
 * Copyright (C) 2015 SoftIndex LLC.
 *
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.wpm.codegen;

import org.objectweb.asm.Label;
import org.objectweb.asm.Type;
import org.objectweb.asm.commons.GeneratorAdapter;
import org.objectweb.asm.commons.Method;

import net.wpm.codegen.Context;
import net.wpm.codegen.Expression;
import net.wpm.codegen.PredicateDef;
import net.wpm.codegen.PredicateDefCmp;
import net.wpm.codegen.utils.Preconditions;

import static net.wpm.codegen.PredicateDefCmp.Operation.*;
import static net.wpm.codegen.Utils.isPrimitiveType;
import static org.objectweb.asm.Type.BOOLEAN_TYPE;
import static org.objectweb.asm.Type.INT_TYPE;

/**
 * Defines methods for comparing functions
 */
public final class PredicateDefCmp implements PredicateDef {
	private Expression left;
	private Expression right;
	private Operation operation = EQ;

	public enum Operation {
		EQ(GeneratorAdapter.EQ, "=="),
		NE(GeneratorAdapter.NE, "!="),
		LT(GeneratorAdapter.LT, "<"),
		GT(GeneratorAdapter.GT, ">"),
		LE(GeneratorAdapter.LE, "<="),
		GE(GeneratorAdapter.GE, ">=");

		private final int opCode;
		private final String symbol;

		Operation(int opCode, String symbol) {
			this.opCode = opCode;
			this.symbol = symbol;
		}

		public static Operation operation(String symbol) {
			for (Operation operation : values()) {
				if (operation.symbol.equals(symbol)) {
					return operation;
				}
			}
			throw new IllegalArgumentException();
		}
	}

	PredicateDefCmp(Operation operation, Expression left, Expression right) {
		this.left = left;
		this.right = right;
		this.operation = operation;
	}

	@Override
	public final Type type(Context ctx) {
		return BOOLEAN_TYPE;
	}

	@Override
	public Type load(Context ctx) {
		GeneratorAdapter g = ctx.getGeneratorAdapter();
		Label labelTrue = new Label();
		Label labelExit = new Label();

		Type leftFieldType = left.type(ctx);
		Preconditions.check(leftFieldType.equals(right.type(ctx)));
		left.load(ctx);
		right.load(ctx);

		if (isPrimitiveType(leftFieldType)) {
			g.ifCmp(leftFieldType, operation.opCode, labelTrue);
		} else {
			if (operation == EQ || operation == NE) {
				g.invokeVirtual(leftFieldType, new Method("equals", BOOLEAN_TYPE, new Type[]{Type.getType(Object.class)}));
				g.push(operation == EQ);
				g.ifCmp(BOOLEAN_TYPE, GeneratorAdapter.EQ, labelTrue);
			} else {
				g.invokeVirtual(leftFieldType, new Method("compareTo", INT_TYPE, new Type[]{Type.getType(Object.class)}));
				if (operation == LT) {
					g.ifZCmp(GeneratorAdapter.LT, labelTrue);
				} else if (operation == GT) {
					g.ifZCmp(GeneratorAdapter.GT, labelTrue);
				} else if (operation == LE) {
					g.ifZCmp(GeneratorAdapter.LE, labelTrue);
				} else if (operation == GE) {
					g.ifZCmp(GeneratorAdapter.GE, labelTrue);
				}
			}
		}

		g.push(false);
		g.goTo(labelExit);

		g.mark(labelTrue);
		g.push(true);

		g.mark(labelExit);

		return BOOLEAN_TYPE;
	}

	@Override
	public boolean equals(Object o) {
		if (this == o) return true;
		if (o == null || getClass() != o.getClass()) return false;

		PredicateDefCmp that = (PredicateDefCmp) o;

		if (left != null ? !left.equals(that.left) : that.left != null) return false;
		if (operation != that.operation) return false;
		if (right != null ? !right.equals(that.right) : that.right != null) return false;

		return true;
	}

	@Override
	public int hashCode() {
		int result = left != null ? left.hashCode() : 0;
		result = 31 * result + (right != null ? right.hashCode() : 0);
		result = 31 * result + (operation != null ? operation.hashCode() : 0);
		return result;
	}

	public int getOperationOpCode() {
		return operation.opCode;
	}
}