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Fluent query implementation for JPA repositories
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package co.streamx.fluent.JPA;
import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Executable;
import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.stream.Collectors;
import co.streamx.fluent.JPA.spi.impl.SQLConfiguratorImpl;
import co.streamx.fluent.extree.expression.BinaryExpression;
import co.streamx.fluent.extree.expression.ConstantExpression;
import co.streamx.fluent.extree.expression.Expression;
import co.streamx.fluent.extree.expression.ExpressionType;
import co.streamx.fluent.extree.expression.InvocableExpression;
import co.streamx.fluent.extree.expression.InvocationExpression;
import co.streamx.fluent.extree.expression.LambdaExpression;
import co.streamx.fluent.extree.expression.MemberExpression;
import co.streamx.fluent.extree.expression.NewArrayInitExpression;
import co.streamx.fluent.extree.expression.ParameterExpression;
import co.streamx.fluent.extree.expression.SimpleExpressionVisitor;
import co.streamx.fluent.extree.expression.UnaryExpression;
import co.streamx.fluent.notation.Literal;
import co.streamx.fluent.notation.Local;
import co.streamx.fluent.notation.Notation;
import co.streamx.fluent.notation.ViewDeclaration;
import lombok.SneakyThrows;
class Normalizer extends SimpleExpressionVisitor {
private static final String COMPARE_TO = "compareTo";
private static final Method compareToMethod = initializeCompareToMethod();
public static Normalizer get() {
return new Normalizer();
}
@SneakyThrows
private static Method initializeCompareToMethod() {
return Comparable.class.getMethod(COMPARE_TO, Object.class);
}
private static boolean isFunctionalInterfaceCall(Member member) {
Class declaringClass = member.getDeclaringClass();
return declaringClass.isInterface() && declaringClass.isAnnotationPresent(FunctionalInterface.class);
}
@Override
@SneakyThrows
public Expression visit(MemberExpression e) {
Member member = e.getMember();
if (!(member instanceof Method)) {
if (member instanceof Field && Modifier.isStatic(member.getModifiers())) {
Field f = (Field) member;
Object value;
try {
value = f.get(null);
} catch (IllegalAccessException iae) {
throw new RuntimeException("Cannot access: " + f.getName() + ". " + iae.getMessage(), iae);
}
Class clazz = value.getClass();
if (clazz.isAnnotationPresent(Literal.class))
value = value.toString();
ConstantExpression c = Expression.constant(value, clazz);
return c;
}
return super.visit(e);
}
Method method = (Method) member;
if (isNotation(method))
return super.visit(e);
if (Modifier.isStatic(method.getModifiers()) || method.isDefault()) {
Expression instance = e.getInstance();
LambdaExpression parsed = LambdaExpression.parseMethod(method, instance);
if (instance != null) {
List args = getContextArguments();
if (!args.isEmpty())
args.add(0, instance.accept(this));
}
return visit(parsed);
}
if (isFunctionalInterfaceCall(method)) {
Expression instance = e.getInstance();
if (instance != null && instance.getExpressionType() == ExpressionType.Parameter) {
int index = ((ParameterExpression) instance).getIndex();
return super.visit(Expression.delegate(e.getResultType(),
Expression.parameter(LambdaExpression.class, index), e.getParameters()));
}
}
return super.visit(e);
}
@Override
public Expression visit(InvocationExpression e) {
InvocableExpression target = e.getTarget();
if (!(target instanceof MemberExpression))
return super.visit(e);
MemberExpression memberExpression = (MemberExpression) target;
Member member = memberExpression.getMember();
if (!(member instanceof Executable))
return super.visit(e);
Executable method = (Executable) member;
if (method.isAnnotationPresent(Local.class)) {
Object result = LambdaExpression.compile(target)
.apply(new Object[] { null, contextArgumentsArray(e.getArguments()) });
boolean isSynthetic = result != null && isFunctional(result.getClass());
if (isSynthetic) {
LambdaExpression parsed = LambdaExpression.parse(result);
return visit(parsed);
}
return Expression.constant(result);
}
Map>> substitutions = SQLConfiguratorImpl.getSubstitutions();
Map> subByName = substitutions.get(method.getName());
if (subByName != null) {
for (Executable m : subByName.keySet()) {
if (isSameOrDerived(m, method)) {
LambdaExpression substition = subByName.get(m);
Expression instance = memberExpression.getInstance();
List args = e.getArguments();
if (instance != null) {
List newArgs = new ArrayList<>();
newArgs.add(instance);
newArgs.addAll(args);
args = newArgs;
}
e = Expression.invoke(substition, args);
break;
}
}
}
InvocationExpression visited = (InvocationExpression) super.visit(e);
if (method.isAnnotationPresent(ViewDeclaration.class)) {
Expression entity = visited.getArguments().get(0);
List args = Collections.singletonList(entity);
NewArrayInitExpression aliases = (NewArrayInitExpression) visited.getArguments().get(1);
List resolvedAliases = aliases.getInitializers()
.stream()
.map(ex -> Expression.invoke((LambdaExpression) ex, args))
.collect(Collectors.toList());
aliases = Expression.newArrayInit(aliases.getComponentType(), resolvedAliases);
visited = Expression.invoke(target, entity, aliases);
}
return visited;
}
@Override
public Expression visit(LambdaExpression e) {
return super.visit(e.parseMethodRef());
}
private static boolean isFunctional(Class clazz) {
if (clazz.isSynthetic())
return true;
for (Class i : clazz.getInterfaces())
if (i.isAnnotationPresent(FunctionalInterface.class))
return true;
return false;
}
private Object[] contextArgumentsArray(List args) {
if (args.isEmpty())
return null;
return args.stream().map(e -> {
Expression x = removeCast(e);
if (x instanceof ParameterExpression)
x = resolveContextParameter((ParameterExpression) x);
if (!(x instanceof ConstantExpression))
throw TranslationError.REQUIRES_EXTERNAL_PARAMETER.getError(x);
return ((ConstantExpression) x).getValue();
}).toArray();
}
private static Expression removeCast(Expression x) {
return (x != null && x.getExpressionType() == ExpressionType.Convert)
? removeCast(((UnaryExpression) x).getFirst())
: x;
}
private static boolean isNotation(AnnotatedElement annotated) {
for (Annotation a : annotated.getDeclaredAnnotations())
if (a.annotationType().isAnnotationPresent(Notation.class))
return true;
return false;
}
@Override
public Expression visit(BinaryExpression e) {
int type = e.getExpressionType();
switch (type) {
case ExpressionType.LessThan:
case ExpressionType.LessThanOrEqual:
case ExpressionType.Equal:
case ExpressionType.NotEqual:
case ExpressionType.GreaterThan:
case ExpressionType.GreaterThanOrEqual:
if (isZero(e.getFirst()) && isCompareTo(e.getSecond())) {
Expression comparison = createComparison(e.getExpressionType(), e.getSecond());
return type == ExpressionType.Equal || type == ExpressionType.NotEqual ? comparison
: Expression.logicalNot(comparison);
}
if (isZero(e.getSecond()) && isCompareTo(e.getFirst()))
return createComparison(type, e.getFirst());
}
return super.visit(e);
}
private Expression createComparison(int expressionType,
Expression e) {
InvocationExpression ie = (InvocationExpression) e;
MemberExpression m = (MemberExpression) ie.getTarget();
return Expression.binary(expressionType, m.getInstance(), ie.getArguments().get(0));
}
private boolean isCompareTo(Expression e) {
if (!(e instanceof InvocationExpression))
return false;
InvocableExpression target = ((InvocationExpression) e).getTarget();
if (!(target instanceof MemberExpression))
return false;
Member member = ((MemberExpression) target).getMember();
return member instanceof Method && isSameOrDerived(compareToMethod, (Method) member);
}
private static boolean isZero(Expression e) {
return e instanceof ConstantExpression && Objects.equals(0, ((ConstantExpression) e).getValue());
}
private static boolean isSameOrDerived(Executable base,
Executable derived) {
return Modifier.isStatic(base.getModifiers()) == Modifier.isStatic(derived.getModifiers())
&& base.getDeclaringClass().isAssignableFrom(derived.getDeclaringClass())
&& base.getName().equals(derived.getName()) && base.getParameterCount() == derived.getParameterCount();
}
}