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.