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The latte-lang compiler project, which contains compiler and runtime required library.
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package lt.runtime;
import lt.compiler.LtBug;
import lt.dependencies.asm.ClassWriter;
import lt.dependencies.asm.FieldVisitor;
import lt.dependencies.asm.MethodVisitor;
import lt.dependencies.asm.Opcodes;
import lt.lang.function.Function;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Map;
import java.util.NoSuchElementException;
/**
* it's used to generate for an implementation for a functional interface or abstract class
*/
public class LambdaGen {
private static final String FUNC_FIELD_NAME = "func";
private static final String F_FIELD_NAME = "f";
private static final String FIELD_DESC = "Ljava/lang/reflect/Field;";
public static Map.Entry gen(Function f, Class targetType) {
Method abstractMethod = Dynamic.findAbstractMethod(targetType);
Method funcMethod = f.getClass().getDeclaredMethods()[0];
final String className = getLambdaName(targetType);
String functionInternal = typeToInternalName(f.getClass().getInterfaces()[0]);
String functionDesc = "L" + functionInternal + ";";
// class X
final ClassWriter classVisitor = new ClassWriter(ClassWriter.COMPUTE_MAXS);
String superClass;
String[] interfaces;
if (targetType.isInterface()) {
superClass = "java/lang/Object";
interfaces = new String[]{typeToInternalName(targetType)};
} else {
superClass = typeToInternalName(targetType);
interfaces = new String[0];
}
classVisitor.visit(Opcodes.V1_6, Opcodes.ACC_PUBLIC, className, null, superClass, interfaces);
// func (field)
FieldVisitor funcVisitor = classVisitor.visitField(Opcodes.ACC_PRIVATE, FUNC_FIELD_NAME, functionDesc, null, null);
funcVisitor.visitEnd();
// f (field Field)
FieldVisitor fVisitor = classVisitor.visitField(Opcodes.ACC_PRIVATE, F_FIELD_NAME, typeToDesc(Field.class), null, null);
fVisitor.visitEnd();
MethodVisitor constructorVisitor = classVisitor.visitMethod(Opcodes.ACC_PUBLIC, "", "(" + functionDesc + ")V", null, null);
constructorVisitor.visitCode();
// this
visitThis(constructorVisitor);
// invoke super
constructorVisitor.visitMethodInsn(Opcodes.INVOKESPECIAL, superClass, "", "()V", false);
// this
visitThis(constructorVisitor);
// func (local)
constructorVisitor.visitVarInsn(Opcodes.ALOAD, 1);
// this.func = func
constructorVisitor.visitFieldInsn(Opcodes.PUTFIELD, className, FUNC_FIELD_NAME, functionDesc);
// invoke var1.getClass()
constructorVisitor.visitVarInsn(Opcodes.ALOAD, 1);
constructorVisitor.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Object", "getClass", "()Ljava/lang/Class;", false);
// getField('self')
constructorVisitor.visitLdcInsn("self");
constructorVisitor.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Class", "getField", "(Ljava/lang/String;)Ljava/lang/reflect/Field;", false);
// this.f = (field)
visitThis(constructorVisitor);
constructorVisitor.visitInsn(Opcodes.SWAP);
constructorVisitor.visitFieldInsn(Opcodes.PUTFIELD, className, F_FIELD_NAME, FIELD_DESC);
// return
constructorVisitor.visitInsn(Opcodes.RETURN);
constructorVisitor.visitMaxs(0, 0);
constructorVisitor.visitEnd();
// method
MethodVisitor implMethod = classVisitor.visitMethod(Opcodes.ACC_PUBLIC, abstractMethod.getName(), getDescFromMethod(abstractMethod), null, null);
implMethod.visitCode();
// this.f
visitThis(implMethod);
implMethod.visitFieldInsn(Opcodes.GETFIELD, className, F_FIELD_NAME, FIELD_DESC);
// setAccessible(true)
implMethod.visitLdcInsn(true);
try {
implMethod.visitMethodInsn(Opcodes.INVOKEVIRTUAL, typeToInternalName(Field.class), "setAccessible", getDescFromMethod(Field.class.getMethod("setAccessible", boolean.class)), false);
} catch (NoSuchMethodException e) {
throw new LtBug(e);
}
// this.f
visitThis(implMethod);
implMethod.visitFieldInsn(Opcodes.GETFIELD, className, F_FIELD_NAME, FIELD_DESC);
// set(this.func, this)
visitThis(implMethod);
implMethod.visitFieldInsn(Opcodes.GETFIELD, className, FUNC_FIELD_NAME, functionDesc);
visitThis(implMethod);
try {
implMethod.visitMethodInsn(Opcodes.INVOKEVIRTUAL, typeToInternalName(Field.class), "set", getDescFromMethod(Field.class.getMethod("set", Object.class, Object.class)), false);
} catch (NoSuchMethodException e) {
throw new LtBug(e);
}
// this.func
visitThis(implMethod);
implMethod.visitFieldInsn(Opcodes.GETFIELD, className, FUNC_FIELD_NAME, functionDesc);
// each param
for (int i = 1; i <= abstractMethod.getParameterTypes().length; ++i) {
visitLocal(implMethod, abstractMethod, i);
Class param = abstractMethod.getParameterTypes()[i - 1];
if (param.isPrimitive()) {
try {
boxPrimitive(param, implMethod);
} catch (NoSuchMethodException e) {
throw new LtBug(e);
}
}
}
// invoke
implMethod.visitMethodInsn(Opcodes.INVOKEINTERFACE, functionInternal, funcMethod.getName(), getDescFromMethod(funcMethod), true);
// return?void?
if (abstractMethod.getReturnType() == void.class) {
// void
implMethod.visitInsn(Opcodes.POP);
implMethod.visitInsn(Opcodes.RETURN);
} else {
// return
if (abstractMethod.getReturnType().isPrimitive()) {
Class returnType = abstractMethod.getReturnType();
castToPrimitive(returnType, implMethod);
if (returnType == long.class) {
implMethod.visitInsn(Opcodes.LRETURN);
} else if (returnType == float.class) {
implMethod.visitInsn(Opcodes.FRETURN);
} else if (returnType == double.class) {
implMethod.visitInsn(Opcodes.DRETURN);
} else {
implMethod.visitInsn(Opcodes.IRETURN);
}
} else {
// check type
if (abstractMethod.getReturnType().equals(Object.class)) {
implMethod.visitInsn(Opcodes.ARETURN);
} else {
checkcast(abstractMethod.getReturnType(), implMethod);
implMethod.visitInsn(Opcodes.ARETURN);
}
}
}
implMethod.visitMaxs(0, 0);
implMethod.visitEnd();
classVisitor.visitEnd();
return new Map.Entry() {
@Override
public String getKey() {
return className;
}
@Override
public byte[] getValue() {
return classVisitor.toByteArray();
}
@Override
public byte[] setValue(byte[] bytes) {
throw new UnsupportedOperationException();
}
};
}
private static void castToPrimitive(Class c, MethodVisitor visitor) throws NoSuchElementException {
String name = "castTo";
if (c == int.class) {
name += "Int";
} else if (c == short.class) {
name += "Short";
} else if (c == byte.class) {
name += "Byte";
} else if (c == boolean.class) {
name += "Bool";
} else if (c == float.class) {
name += "Float";
} else if (c == long.class) {
name += "Long";
} else if (c == double.class) {
name += "Double";
} else if (c == char.class) {
name += "Char";
} else {
throw new LtBug("unknown primitive " + c);
}
visitor.visitMethodInsn(Opcodes.INVOKESTATIC,
typeToInternalName(LtRuntime.class), name,
"(Ljava/lang/Object;)" + typeToDesc(c), false);
}
private static void checkcast(Class c, MethodVisitor visitor) {
visitor.visitTypeInsn(Opcodes.CHECKCAST, typeToDesc(c));
}
private static void boxPrimitive(Class c, MethodVisitor visitor) throws NoSuchMethodException {
String owner;
String name = "valueOf";
String desc;
if (c == int.class) {
owner = "java/lang/Integer";
desc = getDescFromMethod(Integer.class.getMethod(name, int.class));
} else if (c == float.class) {
owner = "java/lang/Float";
desc = getDescFromMethod(Float.class.getMethod(name, float.class));
} else if (c == long.class) {
owner = "java/lang/Long";
desc = getDescFromMethod(Long.class.getMethod(name, long.class));
} else if (c == double.class) {
owner = "java/lang/Double";
desc = getDescFromMethod(Double.class.getMethod(name, double.class));
} else if (c == byte.class) {
owner = "java/lang/Byte";
desc = getDescFromMethod(Byte.class.getMethod(name, byte.class));
} else if (c == short.class) {
owner = "java/lang/Short";
desc = getDescFromMethod(Short.class.getMethod(name, short.class));
} else if (c == boolean.class) {
owner = "java/lang/Boolean";
desc = getDescFromMethod(Boolean.class.getMethod(name, boolean.class));
} else if (c == char.class) {
owner = "java/lang/Character";
desc = getDescFromMethod(Character.class.getMethod(name, char.class));
} else {
throw new LtBug("unknown primitive type " + c);
}
visitor.visitMethodInsn(Opcodes.INVOKESTATIC, owner, name, desc, false);
}
private static String typeToInternalName(Class type) {
return type.getName().replace('.', '/');
}
private static String typeToDesc(Class type) {
StringBuilder sb = new StringBuilder();
if (type.isPrimitive()) {
if (type == int.class) sb.append("I");
else if (type == long.class) sb.append("J");
else if (type == short.class) sb.append("S");
else if (type == byte.class) sb.append("B");
else if (type == boolean.class) sb.append("Z");
else if (type == float.class) sb.append("F");
else if (type == double.class) sb.append("D");
else if (type == char.class) sb.append("C");
else if (type == void.class) sb.append("V"); // java 1.8 void is primitive
else throw new LtBug("unknown primitive: " + type);
} else if (type.isArray()) {
Class tmp = type;
while (tmp.isArray()) {
sb.append("[");
tmp = tmp.getComponentType();
}
sb.append(typeToDesc(tmp));
} else if (type == void.class) {
sb.append("V"); // java 1.6 void is not primitive
} else {
// object L...;
sb.append("L").append(typeToInternalName(type)).append(";");
}
return sb.toString();
}
private static String getDescFromMethod(Method method) {
StringBuilder sb = new StringBuilder("(");
for (Class cls : method.getParameterTypes()) {
sb.append(typeToDesc(cls));
}
sb.append(")").append(typeToDesc(method.getReturnType()));
return sb.toString();
}
private static void visitLocal(MethodVisitor visitor, Method method, int local) {
Class c = method.getParameterTypes()[local - 1];
if (c.isPrimitive()) {
int code;
if (c == float.class) {
code = Opcodes.FLOAD;
} else if (c == double.class) {
code = Opcodes.DLOAD;
} else if (c == long.class) {
code = Opcodes.LLOAD;
} else {
code = Opcodes.ILOAD;
}
visitor.visitVarInsn(code, local);
} else {
visitor.visitVarInsn(Opcodes.ALOAD, local);
}
}
private static void visitThis(MethodVisitor visitor) {
visitor.visitVarInsn(Opcodes.ALOAD, 0);
}
private static synchronized String getLambdaName(Class targetType) {
int i = 0;
while (true) {
try {
Class.forName(targetType.getSimpleName() + "$Latte$lambda$" + i);
} catch (ClassNotFoundException e) {
break;
}
}
return targetType.getSimpleName() + "$Latte$lambda$" + i;
}
}
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