content: /*
   * Copyright (C) 2020 ActiveJ 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 io.activej.codegen.expression.impl;
  
  import io.activej.codegen.Context;
  import io.activej.codegen.expression.Expression;
  import io.activej.common.annotation.ExposedInternals;
  import org.objectweb.asm.Label;
  import org.objectweb.asm.Type;
  import org.objectweb.asm.commons.GeneratorAdapter;
  import org.objectweb.asm.commons.Method;
  
  import java.util.List;
  
  import static io.activej.codegen.util.TypeChecks.checkType;
  import static io.activej.codegen.util.TypeChecks.isAssignable;
  import static io.activej.codegen.util.Utils.*;
  import static org.objectweb.asm.Type.getType;
  import static org.objectweb.asm.commons.Method.getMethod;
  
  /**
   * Defines methods which allow to concat arguments into a string
   */
  @ExposedInternals
  public final class Concat implements Expression {
  	public final List<Expression> arguments;
  
  	public Concat(List<Expression> arguments) {
  		this.arguments = arguments;
  	}
  
  	@Override
  	public Type load(Context ctx) {
  		GeneratorAdapter g = ctx.getGeneratorAdapter();
  
  		g.newInstance(getType(StringBuilder.class));
  		g.dup();
  		g.invokeConstructor(getType(StringBuilder.class), getMethod("void <init> ()"));
  
  		for (Expression expression : arguments) {
  			g.dup();
  			Type type = expression.load(ctx);
  			checkType(type, isAssignable());
  
  			if (isPrimitiveType(type)) {
  				g.invokeStatic(wrap(type), new Method("toString", getType(String.class), new Type[]{type}));
  			} else {
  				Label nullLabel = new Label();
  				Label afterToString = new Label();
  				g.dup();
  				g.ifNull(nullLabel);
  				invokeVirtualOrInterface(ctx, type, getMethod("String toString()"));
  				g.goTo(afterToString);
  				g.mark(nullLabel);
  				g.pop();
  				g.push("null");
  				g.mark(afterToString);
  			}
  			g.invokeVirtual(getType(StringBuilder.class), getMethod("StringBuilder append(String)"));
  			g.pop();
  		}
  
  		g.invokeVirtual(getType(StringBuilder.class), getMethod("String toString()"));
  		return getType(String.class);
  	}
  }
  