org.simpleflatmapper.reflect.impl.BuilderInstantiatorDefinitionFactory Maven / Gradle / Ivy

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Java library to map flat record - ResultSet, csv - to java object with minimum configuration and low footprint.
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package org.simpleflatmapper.reflect.impl;

import org.simpleflatmapper.reflect.BuilderInstantiatorDefinition;
import org.simpleflatmapper.reflect.instantiator.ExecutableInstantiatorDefinition;
import org.simpleflatmapper.reflect.InstantiatorDefinition;
import org.simpleflatmapper.reflect.setter.SetterHelper;
import org.simpleflatmapper.util.ConstantPredicate;
import org.simpleflatmapper.util.Predicate;
import org.simpleflatmapper.util.TypeHelper;

import java.lang.reflect.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class BuilderInstantiatorDefinitionFactory {

    public static final Predicate GOOGLE_PROTO_EXCLUDE = new Predicate() {
        Set excludeMethod = new HashSet(Arrays.asList(
                "setUnknownFields", 
                "clearField", "mergeUnknownFields", "mergeFrom", "clearOneof", "mergeFrom",
                "parseFrom", "parseDelimitedFrom", "parsePartialFrom", 
                "newBuilderForField",
                "getField",
                "getFieldBuilder"
        ));
        @Override
        public boolean test(Method method) {
            String name = method.getName();
            return excludeMethod.contains(name);
        }
    };

    public static List extractDefinitions(Type target) {

        List instantiatorDefinitions = new ArrayList();
        Class clazz = TypeHelper.toClass(target);

        for(Method m : clazz.getDeclaredMethods()) {
            if (isPotentialBuilderMethod(m)) {
                BuilderInstantiatorDefinition def = getDefinitionForBuilderFromMethod(m, target);
                if (def != null) {
                    instantiatorDefinitions.add(def);
                }
            }
        }



        return instantiatorDefinitions;
    }

    private static boolean isPotentialBuilderMethod(Method m) {
        return
                Modifier.isStatic(m.getModifiers())
                        && m.getParameterTypes().length == 0
                && ! Void.TYPE.equals(m.getReturnType())
                && ! TypeHelper.areEquals(m.getReturnType(), m.getDeclaringClass());
    }

    private static BuilderInstantiatorDefinition getDefinitionForBuilderFromMethod(Method m, Type target) {
        if (Modifier.isStatic(m.getModifiers())
                && Modifier.isPublic(m.getModifiers())
                && m.getParameterTypes().length == 0
                && !(Void.TYPE.equals(m.getReturnType()))) {
            return  getDefinitionForBuilder(m , target);
        }
        return null;
    }

    public static BuilderInstantiatorDefinition getDefinitionForBuilder(Member e, Type target) {
        ExecutableInstantiatorDefinition def = new ExecutableInstantiatorDefinition(e);
        Type builderType;
        if (e instanceof Constructor) {
            builderType = ((Constructor)e).getDeclaringClass();
        } else {
            builderType = ((Method)e).getGenericReturnType();

        }
        return getDefinitionForBuilder(def, builderType, target);
    }


    private static BuilderInstantiatorDefinition getDefinitionForBuilder(ExecutableInstantiatorDefinition def,
                                                                         Type builderType, Type target) {
        Map setters = new HashMap();
        List buildMethods = new ArrayList();

        int i = 0;

        
        Class builderClass = TypeHelper.toClass(builderType);
        
        if (ignoreBuilderClass(builderClass)) {
            return null;
        }
        
        Predicate excludeMethod = getExcludeMethodPredicateFor(builderClass);
        for(Method m : builderClass.getMethods()) {
            if (excludeMethod.test(m)) continue;
            if (!Modifier.isStatic(m.getModifiers()) && Object.class != m.getDeclaringClass()) {
                Type returnType = m.getGenericReturnType();
                if ((TypeHelper.areEquals(returnType, void.class)
                    ||TypeHelper.isAssignable(returnType, builderType)) && m.getParameterTypes().length == 1) {
                    org.simpleflatmapper.reflect.Parameter p = new org.simpleflatmapper.reflect.Parameter(i++, SetterHelper.getPropertyNameFromBuilderMethodName(m.getName()), m.getParameterTypes()[0], m.getGenericParameterTypes()[0]);
                    setters.put(p, m);
                } else if (TypeHelper.isAssignable(target, returnType) && m.getParameterTypes().length == 0) {
                    // build function
                    buildMethods.add(m);
                }
            }
        }
        
        Method buildMethod = selectBuildMethod(buildMethods);

        if (!setters.isEmpty() && buildMethod != null) {
            return new BuilderInstantiatorDefinition(def, setters, buildMethod);
        }
        return null;
    }

    private static boolean ignoreBuilderClass(Class builderClass) {
        return "com.google.protobuf.Parser".equals(builderClass.getName());
    }

    private static Predicate getExcludeMethodPredicateFor(Class builderClass) {
        if (builderClass.getSuperclass() != null 
                && builderClass.getSuperclass().getName().equals("com.google.protobuf.GeneratedMessageV3$Builder")) {
            return GOOGLE_PROTO_EXCLUDE;
        }
        return ConstantPredicate.falsePredicate();
    }

    private static Method selectBuildMethod(List buildMethods) {
        if (buildMethods.isEmpty()) 
            return null;
        
        if (buildMethods.size() == 1)
            return buildMethods.get(0);

        for(Method m : buildMethods) {
            if (m.getName().equals("build")) {
                return m;
            }
        }

        throw new IllegalStateException("Multiple potential build methods candidate " + buildMethods + ", cannot use the builder on that object");
    }
}