javaparser-symbol-solver-testing/src/test/java/com/github/javaparser/symbolsolver/resolution/LambdaResolutionTest.java

/*
 * Copyright 2016 Federico Tomassetti
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.github.javaparser.symbolsolver.resolution;

import com.github.javaparser.ast.CompilationUnit;
import com.github.javaparser.ast.body.MethodDeclaration;
import com.github.javaparser.ast.expr.Expression;
import com.github.javaparser.ast.expr.LambdaExpr;
import com.github.javaparser.ast.expr.MethodCallExpr;
import com.github.javaparser.ast.stmt.ReturnStmt;
import com.github.javaparser.resolution.types.ResolvedType;
import com.github.javaparser.symbolsolver.javaparser.Navigator;
import com.github.javaparser.symbolsolver.javaparsermodel.JavaParserFacade;
import com.github.javaparser.symbolsolver.resolution.typesolvers.ReflectionTypeSolver;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertEquals;

class LambdaResolutionTest extends AbstractResolutionTest {

    @Test
    void lambdaMapParameter() {
        CompilationUnit cu = parseSample("Lambda");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "lambdaMap");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        MethodCallExpr methodCallExpr = (MethodCallExpr) returnStmt.getExpression().get();
        Expression expression = methodCallExpr.getArguments().get(0);

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type = javaParserFacade.getType(expression);
        assertEquals("java.util.function.Function<? super java.lang.String, ? extends java.lang.String>", type.describe());
    }

    @Test
    void personsStream() {
        CompilationUnit cu = parseSample("Lambda");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "lambdaMap");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        Expression expression = returnStmt.getExpression().get();
        expression = Navigator.findMethodCall(expression, "stream").get();

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type = javaParserFacade.getType(expression);
        assertEquals("java.util.stream.Stream<java.lang.String>", type.describe());
    }

    @Test
    void lambdaMap() {
        CompilationUnit cu = parseSample("Lambda");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration m1 = Navigator.demandMethod(clazz, "lambdaMap");
        MethodDeclaration m2 = Navigator.demandMethod(clazz, "lambdaMap2");
        ReturnStmt returnStmt1 = Navigator.findReturnStmt(m1);
        ReturnStmt returnStmt2 = Navigator.findReturnStmt(m2);
        Expression e1 = returnStmt1.getExpression().get();
        Expression e2 = returnStmt2.getExpression().get();

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type1 = javaParserFacade.getType(e1);
        ResolvedType type2 = javaParserFacade.getType(e2);
        assertEquals("java.util.stream.Stream<java.lang.String>", type1.describe());
        assertEquals("java.util.stream.Stream<java.util.stream.IntStream>", type2.describe());
    }

    @Test
    void lambdaReduce() {
        CompilationUnit cu = parseSample("Lambda");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "reduce");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        Expression expr = returnStmt.getExpression().get();

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type1 = javaParserFacade.getType(expr);
        assertEquals("java.util.Optional<java.lang.Integer>", type1.describe());
    }

    @Test
    void lambdaPrint() {
        CompilationUnit cu = parseSample("Lambda");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "print");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        Expression expr = returnStmt.getExpression().get();

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type1 = javaParserFacade.getType(expr);
        assertEquals("void", type1.describe());
    }

    @Test
    void lambdaBifunc() {
        CompilationUnit cu = parseSample("Lambda");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "bifunc");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        Expression expr = returnStmt.getExpression().get();

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type1 = javaParserFacade.getType(expr);
        assertEquals("double", type1.describe());
    }

    @Test
    void lambdaCollectParam() {
        CompilationUnit cu = parseSample("LambdaCollect");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "lambdaMap");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        MethodCallExpr methodCallExpr = (MethodCallExpr) returnStmt.getExpression().get();
        // Collectors.toList()
        Expression expression = methodCallExpr.getArguments().get(0);

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type = javaParserFacade.getType(expression);
        assertEquals("java.util.stream.Collector<T, ? extends java.lang.Object, java.util.List<T>>", type.describe());
    }

    @Test
    void lambdaCollect() {
        CompilationUnit cu = parseSample("LambdaCollect");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "lambdaMap");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        Expression expression = returnStmt.getExpression().get();

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type = javaParserFacade.getType(expression);
        assertEquals("java.util.List<java.lang.String>", type.describe());
    }

    @Test
    void lambdaBlockExplicitReturn() {
        CompilationUnit cu = parseSample("LambdaMulti");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "lambdaSingleReturn");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        Expression expression = returnStmt.getExpression().get();

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type = javaParserFacade.getType(expression);
        assertEquals("java.lang.String", type.describe());
    }

    @Test
    void lambdaBlockMultiLineReturn() {
        CompilationUnit cu = parseSample("LambdaMulti");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "multiLineReturn");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        Expression expression = returnStmt.getExpression().get();

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type = javaParserFacade.getType(expression);
        assertEquals("java.lang.String", type.describe());
    }

    @Test
    void typeOfVoidLambda() {
        CompilationUnit cu = parseSample("LambdaVoid");
        com.github.javaparser.ast.body.ClassOrInterfaceDeclaration clazz = Navigator.demandClass(cu, "Agenda");
        MethodDeclaration method = Navigator.demandMethod(clazz, "lambdaEmpty");
        ReturnStmt returnStmt = Navigator.findReturnStmt(method);
        Expression expression = returnStmt.getExpression().get();
        LambdaExpr lambdaExpr = Navigator.findNodeOfGivenClass(expression, LambdaExpr.class);

        JavaParserFacade javaParserFacade = JavaParserFacade.get(new ReflectionTypeSolver());
        ResolvedType type = javaParserFacade.getType(lambdaExpr);
        assertEquals("void", type.describe());
    }


}