Android-scaex
This library provides some expressions, IF, Match like Scala.
IF enables java if-statement to return a value as Scala if-expression.
Match also enables java to use pattern-match expression.
Setup
dependencies {
compile 'net.petitviolet.android:scaex:<latest-version>
}
Interface
IF
/** returns primitive value pattern **/ // if ~ else if ~ else String result = IF.<String>x(false).then("hoge")
.ElseIf(false).then("foo")
.Else("bar");
assert result == "bar"; // if ~ else if ~ String result2 = IF.<String>x(true).then("hoge")
.ElseIf(false).then("foo")
.get();
assert result2 == "hoge"; // not matched String result3 = IF.<String>x(false).then("hoge").get() assert result3 == null;
/** returns value the result of given method invoked **/ String result4 = IF.<String>x(false).then(new Action<String>() {
@Override
public String run() {
return "hoge";
}
}
).ElseIf(true).then(new Action<String>() {
@Override
public String run() {
return "foo";
}
}
).Else(new Action<String>() {
@Override
public String run() {
Log.d(TAG, "in else condition!");
return "bar";
}
}
);
assert result4 == "foo"; // with lambda expression String result5 = IF.<String>x(false).then(() -> "hoge")
.ElseIf(true).then(() -> "foo")
.Else(() -> {
Log.d(TAG, "in else condition!");
return "bar";
}
);
assert result5 == "foo";Match
/** pattern match by value condition **/ int target = 100; String result1 = Match.<String, Integer>x(target)
.Case(target < 100).then("down")
.Case(target > 100).then("up")
.Case(target == 100).then("draw")
.eval();
assert result1.equals("draw") == true; /** pattern match by class **/ int result2 = Match.<Integer, Object>x(100)
.Case(String.class).then(1)
.Case(Boolean.class).then(2)
.Case(Integer.class).then(3)
.eval();
assert result2 == 3; /** lazy pattern-match using Function interface in Case **/ int result3 = Match.<Integer, Object>x(100)
.Case(String.class).then(1)
.Case(Boolean.class).then(2)
.Case(new Function.F1<Object, Boolean>() {
@Override
public Boolean apply(Object integer) {
return integer == 100;
}
}
).then(3)
.Case(new Function.F1<Object, Boolean>() {
@Override
public Boolean apply(Object integer) {
// not evaluate
return integer == 999;
}
}
).then(4)
.Case(Integer.class).then(5)
.eval();
assert result3 == 3; /** with lambda expression **/ String result4 = Match.<String, String>x("hoge")
.Case(TextUtils::isEmpty).then("empty")
.Case((s) -> s.length() < 3).then("short")
.eval("long");
assert result4 == "long";For
// for(Integer i: inputs) {
i -> action(i)
}
List<Integer> inputs = Arrays.asList(1, 2, 3);
For.x(inputs).action(new Action.A1<Integer>() {
@Override
public void run(Integer integer) {
Log.i(Tag, s"result ->" + integer * 2);
}
}
);
// for statement with returning value // result = for(String s: strings) {
s -> function(s)
}
List<String> result = For.x(Arrays.asList("a", "b", "c")).apply(new Function.F1<String, String>() {
@Override
public String apply(String s) {
return "x" + s;
}
}
);
// for(int i = 0; i <= 10; i++) {
//
}
// `x(0).to(10).by(1)` List<Integer> result = For.x(0).to(10).by(1).apply(new Function.F1<Integer, Integer>() {
@Override
public Integer apply(Integer integer) {
return integer;
}
}
);
// for(int i = 1; i < 10; i = i + 2 {
//
}
// `x(1).until(10).by(2)` List<Integer> result = For.x(1).until(10).by(2).apply(new Function.F1<Integer, Integer>() {
@Override
public Integer apply(Integer integer) {
return integer;
}
}
);
// example using lambda // like foreach For.x(inputs).action(s -> Log.i(String.format("testFor: %s", input), s));
// like map List<String> results = For.x(inputs).apply(s -> String.format("applied: %s: %s", input, s));
Lisence
This code is licensed under the Apache Software License 2.0.