Groovy 4.0 的發行說明

def result
switch(i) {
  case 0: result = 'zero'; break
  case 1: result = 'one'; break
  case 2: result = 'two'; break
  default: throw new IllegalStateException('unknown number')
}

def stringify(int i) {
  switch(i) {
    case 0: return 'zero'
    case 1: return 'one'
    case 2: return 'two'
    default: throw new IllegalStateException('unknown number')
  }
}

def result = stringify(i)

def result = switch(i) {
    case 0 -> 'zero'
    case 1 -> 'one'
    case 2 -> 'two'
    default -> throw new IllegalStateException('unknown number')
}

    case 0 -> { def a = 'ze'; def b = 'ro'; a + b }

def result = switch(i) {
    case 0:
        def a = 'ze'
        def b = 'ro'
        if (true) yield a + b
        else yield b + a
    case 1:
        yield 'one'
    case 2:
        yield 'two'
    default:
        throw new IllegalStateException('unknown number')
}

class Custom {
  def isCase(o) { o == -1 }
}

class Coord {
  int x, y
}

def items = [10, -1, 5, null, 41, 3.5f, 38, 99, new Coord(x: 4, y: 5), 'foo']
def result = items.collect { a ->
  switch(a) {
    case null -> 'null'
    case 5 -> 'five'
    case new Custom() -> 'custom'
    case 0..15 -> 'range'
    case [37, 41, 43] -> 'prime'
    case Float -> 'float'
    case { it instanceof Number && it % 2 == 0 } -> 'even'
    case Coord -> a.with { "x: $x, y: $y" }
    case ~/../ -> 'two chars'
    default -> 'none of the above'
  }
}

assert result == ['range', 'custom', 'five', 'null', 'prime', 'float',
                  'even', 'two chars', 'x: 4, y: 5', 'none of the above']

import groovy.transform.Immutable

interface Expr { }
@Immutable class IntExpr implements Expr { int i }
@Immutable class NegExpr implements Expr { Expr n }
@Immutable class AddExpr implements Expr { Expr left, right }
@Immutable class MulExpr implements Expr { Expr left, right }

int eval(Expr e) {
    e.with {
        switch(it) {
            case IntExpr -> i
            case NegExpr -> -eval(n)
            case AddExpr -> eval(left) + eval(right)
            case MulExpr -> eval(left) * eval(right)
            default -> throw new IllegalStateException()
        }
    }
}

@Newify(pattern=".*Expr")
def test() {
    def exprs = [
        IntExpr(4),
        NegExpr(IntExpr(4)),
        AddExpr(IntExpr(4), MulExpr(IntExpr(3), IntExpr(2))), // 4 + (3*2)
        MulExpr(IntExpr(4), AddExpr(IntExpr(3), IntExpr(2)))  // 4 * (3+2)
    ]
    assert exprs.collect { eval(it) } == [4, -4, 10, 20]
}

test()

import groovy.transform.*

@Sealed interface Tree<T> {}
@Singleton final class Empty implements Tree {
    String toString() { 'Empty' }
}
@Canonical final class Node<T> implements Tree<T> {
    T value
    Tree<T> left, right
}

Tree<Integer> tree = new Node<>(42, new Node<>(0, Empty.instance, Empty.instance), Empty.instance)
assert tree.toString() == 'Node(42, Node(0, Empty, Empty), Empty)'

sealed abstract class Weather { }
class Rainy extends Weather { Integer rainfall }
class Sunny extends Weather { Integer temp }
class Cloudy extends Weather { Integer uvIndex }
def threeDayForecast = [
    new Rainy(rainfall: 12),
    new Sunny(temp: 35),
    new Cloudy(uvIndex: 6)
]

record Cyclist(String firstName, String lastName) { }

@groovy.transform.RecordType
class Cyclist {
    String firstName
    String lastName
}

def richie = new Cyclist('Richie', 'Porte')

@RecordBase
@RecordOptions
@TupleConstructor(namedVariant = true, force = true, defaultsMode = DefaultsMode.AUTO)
@PropertyOptions
@KnownImmutable
@POJO
@CompileStatic

def newYearsEve = '2020-12-31'
def matcher = newYearsEve =~ /(\d{4})-(\d{1,2})-(\d{1,2}/

import groovy.transform.TypeChecked

@TypeChecked(extensions = 'groovy.typecheckers.RegexChecker')
def whenIs2020Over() {
    def newYearsEve = '2020-12-31'
    def matcher = newYearsEve =~ /(\d{4})-(\d{1,2})-(\d{1,2}/
}

1 compilation error:
[Static type checking] - Bad regex: Unclosed group near index 26
(\d{4})-(\d{1,2})-(\d{1,2}
 at line: 6, column: 19

def num = 42
def list = [1 ,2, 3]
def range = 0..5
def string = 'foo'

println SV(num, list, range, string)

num=42, list=[1, 2, 3], range=[0, 1, 2, 3, 4, 5], string=foo

println SVI(range)

range=0..5

println SVD(range)

range=<groovy.lang.IntRange@14 from=0 to=5 reverse=false inclusiveRight=true inclusiveLeft=true modCount=0>

def r = NV(range)
assert r instanceof NamedValue
assert r.name == 'range' && r.val == 0..5

def nsl = NVL(num, string)
assert nsl*.name == ['num', 'string']
assert nsl*.val == [42, 'foo']

import org.apache.groovy.util.JavaShell
def opts = ['--enable-preview', '--release', '14']
def src = 'record Coord(int x, int y) {}'
Class coordClass = new JavaShell().compile('Coord', opts, src)
assert coordClass.newInstance(5, 10).toString() == 'Coord[x=5, y=10]'

@CompileStatic
@POJO
@Canonical(includeNames = true)
class Point {
    Integer x, y
}

@CompileStatic
@POJO
class PointList {
    @Delegate
    List<Point> points
}

Predicate<Point> xNeqY = p -> p.getX() != p.getY();  // (1)

Point p13 = new Point(1, 3);
List<Point> pts = List.of(p13, new Point(2, 2), new Point(3, 1));
PointList list = new PointList();
list.setPoints(pts);

System.out.println(list.size());
System.out.println(list.contains(p13));

list.forEach(System.out::println);

long count = list.stream().filter(xNeqY).collect(counting());  // (2)
System.out.println(count);

3
true
Point(x:1, y:3)
Point(x:2, y:2)
Point(x:3, y:1)
2

import groovy.contracts.*

@Invariant({ speed() >= 0 })
class Rocket {
    int speed = 0
    boolean started = true

    @Requires({ isStarted() })
    @Ensures({ old.speed < speed })
    def accelerate(inc) { speed += inc }

    def isStarted() { started }

    def speed() { speed }
}

def r = new Rocket()
r.accelerate(5)

from p in persons
leftjoin c in cities on p.city.name == c.name
where c.name == 'Shanghai'
select p.name, c.name as cityName

from p in persons
groupby p.gender
having p.gender == 'Male'
select p.gender, max(p.age)

from p in persons
orderby p.age in desc, p.name
select p.name

from n in numbers
where n > 0 && n <= 3
select n * 2

from n1 in nums1
innerjoin n2 in nums2 on n1 == n2
select n1 + 1, n2

import groovy.json.JsonSlurper
def json = new JsonSlurper().parseText('''
{
    "prices": [
        {"name": "Kakuda plum",      "price": 13},
        {"name": "Camu camu",        "price": 25},
        {"name": "Acerola cherries", "price": 39},
        {"name": "Guava",            "price": 2.5},
        {"name": "Kiwifruit",        "price": 0.4},
        {"name": "Orange",           "price": 0.4}
    ],
    "vitC": [
        {"name": "Kakuda plum",      "conc": 5300},
        {"name": "Camu camu",        "conc": 2800},
        {"name": "Acerola cherries", "conc": 1677},
        {"name": "Guava",            "conc": 228},
        {"name": "Kiwifruit",        "conc": 144},
        {"name": "Orange",           "conc": 53}
    ]
}
''')

assert GQ {
    from p in json.prices
    join c in json.vitC on c.name == p.name
    orderby c.conc / p.price in desc
    limit 2
    select p.name
}.toList() == ['Kakuda plum', 'Kiwifruit']

import groovy.xml.XmlSlurper
def root = new XmlSlurper().parseText('''
<root>
    <prices>
        <price name="Kakuda plum">13</price>
        <price name="Camu camu">25</price>
        <price name="Acerola cherries">39</price>
        <price name="Guava">2.5</price>
        <price name="Kiwifruit">0.4</price>
        <price name="Orange">0.4</price>
    </prices>
    <vitaminC>
        <conc name="Kakuda plum">5300</conc>
        <conc name="Camu camuum">2800</conc>
        <conc name="Acerola cherries">1677</conc>
        <conc name="Guava">228</conc>
        <conc name="Kiwifruit">144</conc>
        <conc name="Orange">53</conc>
    </vitaminC>
</root>
''')

assert GQ {
    from p in root.prices.price
    join c in root.vitaminC.conc on c.@name == p.@name
    orderby c.toInteger() / p.toDouble() in desc
    limit 2
    select p.@name
}.toList() == ['Kakuda plum', 'Kiwifruit']

// ... create sql connection ...
def price = sql.rows('SELECT * FROM Price')
def vitC = sql.rows('SELECT * FROM VitaminC')
assert GQ {
    from p in price
    join c in vitC on c.name == p.name
    orderby c.per100g / p.per100g in desc
    limit 2
    select p.name
}.toList() == ['Kakuda plum', 'Kiwifruit']
// ... close connection ...

def builder = new TomlBuilder()
builder.records {
    car {
        name 'HSV Maloo'
        make 'Holden'
        year 2006
        country 'Australia'
        homepage new URL('http://example.org')
        record {
            type 'speed'
            description 'production pickup truck with speed of 271kph'
        }
    }
}

def ts = new TomlSlurper()
def toml = ts.parseText(builder.toString())

assert 'HSV Maloo' == toml.records.car.name
assert 'Holden' == toml.records.car.make
assert 2006 == toml.records.car.year
assert 'Australia' == toml.records.car.country
assert 'http://example.org' == toml.records.car.homepage
assert 'speed' == toml.records.car.record.type
assert 'production pickup truck with speed of 271kph' == toml.records.car.record.description

def now = java.time.LocalDateTime.now()
def gs = "integer: ${1}, double: ${1.2d}, string: ${'x'}, class: ${Map.class}, boolean: ${true}, date: ${now}"
long b = System.currentTimeMillis()
for (int i = 0; i < 10000000; i++) {
    gs.toString()
}
long e = System.currentTimeMillis()
println "${e - b}ms"

def half = .5
def otherHalf = 0.5  // leading zero remains supported
double third = .333d
float quarter = .25f
def fractions = [.1, .2, .3]

// can be used for ranges too (with a rare edge case you might want to avoid)
def range1 = -1.5..<.5    // okay here
def range2 = -1.5.. .5    // space is okay but harder for humans (1)
def range3 = -1.5..0.5    // leading zero edge case (1)
assert range3 == [-1.5, -.5, .5]

@Grab('net.jqwik:jqwik:1.5.5')
import net.jqwik.api.*
import net.jqwik.api.constraints.*

class PropertyBasedTests {
    @Property
    def uniqueInList(@ForAll @Size(5) @UniqueElements List<@IntRange(min = 0, max = 10) Integer> aList) {
        assert aList.size() == aList.toSet().size()
        assert aList.every{ anInt -> anInt >= 0 && anInt <= 10 }
    }
}

@Grab('org.hibernate.validator:hibernate-validator:7.0.1.Final')
@Grab('org.hibernate.validator:hibernate-validator-cdi:7.0.1.Final')
@Grab('org.glassfish:jakarta.el:4.0.0')
import jakarta.validation.constraints.*
import jakarta.validation.*
import groovy.transform.*

@Canonical
class Car {
    @NotNull @Size(min = 2, max = 14) String make
    @Min(1L) int seats
    List<@NotBlank String> owners
}

def validator = Validation.buildDefaultValidatorFactory().validator

def violations = validator.validate(new Car(make: 'T', seats: 1))
assert violations*.message == ['size must be between 2 and 14']

violations = validator.validate(new Car(make: 'Tesla', owners: ['']))
assert violations*.message.toSet() == ['must be greater than or equal to 1', 'must not be blank'] as Set

violations = validator.validate(new Car(make: 'Tesla', owners: ['Elon'], seats: 2))
assert !violations