2018.2 Groovy examples (Groovy 2.5 and 3.0)

.gitignore

@@ -4,3 +4,5 @@
 .idea/workspace.xml
 spring-tricks/target/
 standard-java/target/
+groovy/out
+groovy/build

groovy/build.gradle

@@ -1,15 +1,18 @@
-plugins {
-    id 'groovy'
-}
+apply plugin: 'groovy'
 
 group 'com.jetbrains'
 version '1.0-SNAPSHOT'
+sourceCompatibility = 8
 
 repositories {
     mavenCentral()
 }
 
 dependencies {
-    compile 'org.codehaus.groovy:groovy-all:2.3.11'
-    testCompile group: 'junit', name: 'junit', version: '4.12'
+//    compile 'org.codehaus.groovy:groovy-all:2.5.0'
+    compile 'org.codehaus.groovy:groovy-all:3.0.0-alpha-3'
+    compile 'javax.xml.bind:jaxb-api:2.3.0' // needed by Groovy
+    testCompile 'org.junit.jupiter:junit-jupiter-api:5.2.0'
+
+
 }

groovy/src/main/groovy/DefaultMethods.groovy

@@ -0,0 +1,28 @@
+interface Greetable {
+    String target()
+
+    default String salutation() {
+        'Greetings'
+    }
+
+    default String greet() {
+        "${salutation()}, ${target()}"
+    }
+}
+
+class Friend implements Greetable {
+    String name
+
+    @Override
+    String target() {
+        return name
+    }
+
+    @Override
+    String salutation() {
+        return 'Hi'
+    }
+}
+
+def friend = new Friend(name: 'Pat')
+println friend.greet()

groovy/src/main/groovy/ElvisAssignment.groovy

@@ -0,0 +1,14 @@
+import groovy.transform.ToString
+
+@ToString
+class Element {
+    String name
+    int atomicNumber
+}
+
+def he = new Element(name: 'Helium')
+he.with {
+    name = name ?: 'Hydrogen'   // existing Elvis operator
+    atomicNumber ?= 2           // new Elvis assignment shorthand
+}
+assert he.toString() == 'Element(Helium, 2)'

groovy/src/main/groovy/IdentityEquality.groovy

@@ -0,0 +1,15 @@
+
+
+class Creature { String type }
+
+def houseCat = new Creature(type: 'cat')
+def copyHouseCat = houseCat
+def lion = new Creature(type: 'cat')
+
+assert !houseCat.equals(lion) // Java logical equality
+assert houseCat != lion       // Groovy shorthand operator
+
+assert houseCat.is(copyHouseCat)  // Groovy identity
+assert houseCat === copyHouseCat  // operator shorthand
+assert houseCat !== lion          // negated operator shorthand
+

groovy/src/main/groovy/Macro.groovy

@@ -0,0 +1,38 @@
+import org.codehaus.groovy.ast.ClassNode
+import org.codehaus.groovy.ast.expr.ClassExpression
+import org.codehaus.groovy.ast.expr.ConstantExpression
+import org.codehaus.groovy.macro.transform.MacroClass
+
+def classNameMacro = macro(true) { getClass().name }
+
+
+def date = new ConstantExpression(new Date().toString())
+def version = new ConstantExpression(GroovySystem.version)
+def body = macro(true) {
+    """\
+    Name: ${getClass().name}
+    Compiled: ${$v { date }}
+    Using Groovy version: ${$v { version }}""".stripIndent()
+}
+
+
+
+ClassNode buildInfoClass(ClassNode reference) {
+    def date = new ConstantExpression(new Date().toString())
+    def vers = new ConstantExpression(GroovySystem.version)
+    def name = new ClassExpression(reference)
+    ClassNode infoClass = new MacroClass() {
+        class DummyName {
+            java.lang.String getName() { $v{ name }.name }
+            java.lang.String getVersion() { $v{ vers } }
+            java.lang.String getCompiled() { $v{ date } }
+        }
+    }
+    infoClass.name = reference.name + 'Info'
+    return infoClass
+}
+
+//@Info
+//class Foo {
+//
+//}

groovy/src/test/groovy/Groovy3Test.groovy

@@ -0,0 +1,38 @@
+import java.util.stream.Stream
+
+import static java.util.stream.Collectors.toList
+
+class Groovy3Test extends GroovyTestCase {
+    void testJavaDoWhile() {
+        def count = 5
+        do {
+            println "count = $count"
+        } while (count-- > 0)
+    }
+
+    void testMethodReferences() {
+        // class::staticMethod
+        assert ['1', '2', '3'] == Stream.of(1, 2, 3)
+                                        .map(String::valueOf)
+                                        .collect(toList())
+
+        // class::instanceMethod
+        assert [1, 2, 3] == ['a', 'bb', 'ccc'].stream()
+                                              .map(String::length)
+                                              .collect(toList())
+    }
+
+    void testNotInAndNotInstanceOf() {
+        assert 45 !instanceof Date
+
+        assert 4 !in [1, 3, 5, 7]
+    }
+
+    void testSafeIndexing() {
+        String[] array = null
+        assert null == array ?[1]     // return null for all index values
+        array ?[1] = 'c'              // quietly ignore attempt to set value
+        assert array == null
+    }
+
+}

groovy/src/test/groovy/MacroTest.groovy

@@ -0,0 +1,9 @@
+class MacroTest {
+
+
+    def body = macro(true) { getClass().name }
+
+
+
+}
+

groovy/src/test/groovy/NamedParamsTest.groovy

@@ -0,0 +1,17 @@
+import groovy.transform.NamedParam
+import groovy.transform.NamedVariant
+import org.junit.jupiter.api.Test
+
+class NamedParamsTest {
+
+    @NamedVariant
+    String fullName(String lastName, @NamedParam String firstName) {
+        "$firstName $lastName"
+    }
+
+    @Test
+    void testNamedParams() {
+        println fullName('Smith', firstName: 'Ash')
+    }
+}
+