CraftTweaker/ZenScript/src/main/java/stanhebben/zenscript/expression/ExpressionJavaLambda.java

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package stanhebben.zenscript.expression;

import java.lang.reflect.Method;
import java.util.List;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import stanhebben.zenscript.compiler.EnvironmentClass;
import stanhebben.zenscript.compiler.IEnvironmentMethod;
import stanhebben.zenscript.compiler.EnvironmentMethod;
import stanhebben.zenscript.compiler.IEnvironmentClass;
import stanhebben.zenscript.definitions.ParsedFunctionArgument;
import stanhebben.zenscript.statements.Statement;
import stanhebben.zenscript.symbols.SymbolArgument;
import stanhebben.zenscript.type.ZenType;
import stanhebben.zenscript.util.MethodOutput;
import stanhebben.zenscript.util.ZenPosition;
import static stanhebben.zenscript.util.ZenTypeUtil.descriptor;
import static stanhebben.zenscript.util.ZenTypeUtil.internal;

/**
 *
 * @author Stanneke
 */
public class ExpressionJavaLambda extends Expression {
	private final Class interfaceClass;
	private final List<ParsedFunctionArgument> arguments;
	private final List<Statement> statements;

	private final ZenType type;

	public ExpressionJavaLambda(
			ZenPosition position,
			Class interfaceClass,
			List<ParsedFunctionArgument> arguments,
			List<Statement> statements,
			ZenType type) {
		super(position);

		this.interfaceClass = interfaceClass;
		this.arguments = arguments;
		this.statements = statements;

		this.type = type;
	}

	@Override
	public ZenType getType() {
		return type;
	}

	@Override
	public void compile(boolean result, IEnvironmentMethod environment) {
		if (!result)
			return;

		Method method = interfaceClass.getMethods()[0];

		// generate class
		String clsName = environment.makeClassName();

		ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
		cw.visit(Opcodes.V1_6, Opcodes.ACC_PUBLIC, clsName, null, "java/lang/Object", new String[] { internal(interfaceClass) });

		MethodOutput constructor = new MethodOutput(cw, Opcodes.ACC_PUBLIC, "<init>", "()V", null, null);
		constructor.start();
		constructor.loadObject(0);
		constructor.invokeSpecial("java/lang/Object", "<init>", "()V");
		constructor.ret();
		constructor.end();

		MethodOutput output = new MethodOutput(cw, Opcodes.ACC_PUBLIC, method.getName(), descriptor(method), null, null);

		IEnvironmentClass environmentClass = new EnvironmentClass(cw, environment);
		IEnvironmentMethod environmentMethod = new EnvironmentMethod(output, environmentClass);

		for (int i = 0; i < arguments.size(); i++) {
			environmentMethod.putValue(
					arguments.get(i).getName(),
					new SymbolArgument(i + 1, environment.getType(method.getGenericParameterTypes()[i])),
					getPosition());
		}

		output.start();
		for (Statement statement : statements) {
			statement.compile(environmentMethod);
		}
		output.end();

		environment.putClass(clsName, cw.toByteArray());

		// make class instance
		environment.getOutput().newObject(clsName);
		environment.getOutput().dup();
		environment.getOutput().construct(clsName);
	}
}