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Simple library for generating code.
There is a newer version: 5.25.1
/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.codegen;

import static java.util.Objects.requireNonNull;
import static org.neo4j.codegen.Parameter.NO_PARAMETERS;
import static org.neo4j.codegen.TypeReference.NO_TYPES;
import static org.neo4j.codegen.TypeReference.typeReference;

import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MethodTemplate {
    public static Builder method(Class returnType, String name, Parameter... parameters) {
        return method(typeReference(returnType), name, parameters);
    }

    public static Builder method(final TypeReference returnType, final String name, Parameter... parameters) {
        try {
            return new Builder(parameters) {
                @Override
                public MethodTemplate build() {
                    return buildMethod(this, returnType, name);
                }

                @Override
                MethodDeclaration.Builder declaration() {
                    return MethodDeclaration.method(returnType, name, parameters);
                }
            };
        } catch (IllegalArgumentException | NullPointerException e) {
            throw new IllegalArgumentException("Invalid signature for " + name + ": " + e.getMessage(), e);
        }
    }

    public static ConstructorBuilder constructor(Parameter... parameters) {
        try {
            return new ConstructorBuilder(parameters);
        } catch (IllegalArgumentException | NullPointerException e) {
            throw new IllegalArgumentException("Invalid constructor signature: " + e.getMessage(), e);
        }
    }

    public static class ConstructorBuilder extends Builder {
        ConstructorBuilder(Parameter[] parameters) {
            super(parameters);
        }

        public Builder invokeSuper() {
            return expression(
                    ExpressionTemplate.invokeSuperConstructor(new ExpressionTemplate[] {}, TypeReference.NO_TYPES));
        }

        public Builder invokeSuper(ExpressionTemplate[] parameters, Class[] parameterTypes) {
            TypeReference[] references = new TypeReference[parameterTypes.length];
            for (int i = 0; i < parameterTypes.length; i++) {
                references[i] = typeReference(parameterTypes[i]);
            }

            return invokeSuper(parameters, references);
        }

        public Builder invokeSuper(ExpressionTemplate[] parameters, TypeReference[] parameterTypes) {
            return expression(ExpressionTemplate.invokeSuperConstructor(parameters, parameterTypes));
        }

        @Override
        public MethodTemplate build() {
            return buildConstructor(this);
        }

        @Override
        MethodDeclaration.Builder declaration() {
            return MethodDeclaration.constructor(parameters);
        }
    }

    public abstract static class Builder {
        final Parameter[] parameters;
        private final Map locals = new HashMap<>();
        private final List statements = new ArrayList<>();
        private int modifiers = Modifier.PUBLIC;

        Builder(Parameter[] parameters) {
            if (parameters == null || parameters.length == 0) {
                this.parameters = NO_PARAMETERS;
            } else {
                this.parameters = Arrays.copyOf(parameters, parameters.length);
            }
            for (int i = 0; i < this.parameters.length; i++) {
                Parameter parameter = requireNonNull(this.parameters[i], "Parameter " + i);
                if (null != locals.put(parameter.name(), parameter.type())) {
                    throw new IllegalArgumentException("Duplicate parameters named \"" + parameter.name() + "\".");
                }
            }
        }

        public abstract MethodTemplate build();

        public Builder expression(ExpressionTemplate expression) {
            statements.add(Statement.expression(expression));
            return this;
        }

        public Builder put(
                ExpressionTemplate target, Class fieldType, String fieldName, ExpressionTemplate expression) {
            return put(target, typeReference(fieldType), fieldName, expression);
        }

        public Builder put(
                ExpressionTemplate target, TypeReference fieldType, String fieldName, ExpressionTemplate expression) {
            statements.add(Statement.put(target, Lookup.field(fieldType, fieldName), expression));
            return this;
        }

        public Builder modifiers(int modifiers) {
            this.modifiers = modifiers;
            return this;
        }

        public Builder returns(ExpressionTemplate value) {
            statements.add(Statement.returns(value));
            return this;
        }

        abstract MethodDeclaration.Builder declaration();
    }

    public TypeReference returnType() {
        return returnType;
    }

    public String name() {
        return name;
    }

    public int modifiers() {
        return modifiers;
    }

    public TypeReference[] parameterTypes() {
        if (parameters.length == 0) {
            return NO_TYPES;
        }
        TypeReference[] result = new TypeReference[parameters.length];
        for (int i = 0; i < result.length; i++) {
            result[i] = parameters[i].type();
        }
        return result;
    }

    MethodDeclaration declaration(ClassHandle handle) {
        return declaration.build(handle);
    }

    void generate(CodeBlock generator) {
        for (Statement statement : statements) {
            statement.generate(generator);
        }
    }

    private static MethodTemplate buildMethod(Builder builder, TypeReference returnType, String name) {
        return new MethodTemplate(builder, returnType, name);
    }

    private static MethodTemplate buildConstructor(Builder builder) {
        return new MethodTemplate(builder, TypeReference.VOID, "");
    }

    private final MethodDeclaration.Builder declaration;
    private final Parameter[] parameters;
    private final Statement[] statements;
    private final TypeReference returnType;
    private final String name;
    private final int modifiers;

    private MethodTemplate(Builder builder, TypeReference returnType, String name) {
        this.returnType = returnType;
        this.name = name;
        this.declaration = builder.declaration();
        this.parameters = builder.parameters;
        this.statements = builder.statements.toArray(new Statement[0]);
        this.modifiers = builder.modifiers;
    }
}