kemitix/conditional: Functional-style if-then-else

Functional-style if-then-else

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Paul Campbell 3fcd5450bf Merge branch 'release/0.2.0' * release/0.2.0: pom.xml: version set to 0.2.0 README.adoc: add documentation for Value Value: clean up unneeded generics type parameters Value: add javadoc ValueTest: remove ambiguity on then() and otherwise() parameters Value: rewrite using strong chaining logic Value: add initial implementation ConditionalTest: more tests for whereNot(), andNot() and orNot() Condition: remove use of 'if' internaly ConditionalTest: more tests ConditionalTest: clean up helper methods pom.xml: version set to 0.2.0-SNAPSHOT		2017-04-23 21:45:06 +01:00
src	Value: clean up unneeded generics type parameters	2017-04-23 17:55:08 +01:00
.gitignore	Initial commit	2017-04-21 10:55:11 +01:00
.travis.yml	.travis.yml: add TravisCI configuration	2017-04-21 14:42:45 +01:00
LICENSE.txt	Initial commit	2017-04-21 10:55:11 +01:00
pom.xml	pom.xml: version set to 0.2.0	2017-04-23 21:44:55 +01:00
README.adoc	README.adoc: add documentation for Value	2017-04-23 21:37:22 +01:00

README.adoc

# Conditional

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* link:#_condition[Condition]
* link:#_value[Value]

## Condition

If-then-else in a functional-style.

### if-then

[[source,java]]
----
if (isTrue()) {
    doSomething();
}
----

[[source,java]]
----
Condition.where(isTrue())
         .then(() -> doSomething());
----

### if-then-else

[[source,java]]
----
if (isTrue()) {
    doSomething();
} else {
    doSomethingElse();
}
----

[[source,java]]
----
Condition.where(isTrue())
         .then(() -> doSomething())
         .otherwise(() -> doSomethingElse());
----

### if-and-then-else

[[source,java]]
----
if (isTrue() && isAlsoTrue()) {
    doSomething();
} else {
    doSomethingElse();
}
----

[[source,java]]
----
Condition.where(isTrue())
         .and(isAlsoTrue())
         .then(() -> doSomething())
         .otherwise(() -> doSomethingElse());
----

### if-or-then-else

[[source,java]]
----
if (isTrue() || alternativeIsTrue()) {
    doSomething();
} else {
    doSomethingElse();
}
----

[[source,java]]
----
Condition.where(isTrue())
         .or(alternativeIsTrue())
         .then(() -> doSomething())
         .otherwise(() -> doSomethingElse());
----

### if-not-then-else

[[source,java]]
----
if (!isFalse()) {
    doSomething();
} else {
    doSomethingElse();
}
----

[[source,java]]
----
Condition.whereNot(isFalse())
         .then(() -> doSomething())
         .otherwise(() -> doSomethingElse());
----

### if-and-not-then-else

[[source,java]]
----
if (isTrue() || !isFalse()) {
    doSomething();
} else {
    doSomethingElse();
}
----

[[source,java]]
----
Condition.where(isTrue())
         .andNot(isFalse())
         .then(() -> doSomething())
         .otherwise(() -> doSomethingElse());
----

### if-or-not-then-else

[[source,java]]
----
if (isFalse() || !isAlsoFalse()) {
    doSomething();
} else {
    doSomethingElse();
}
----

[[source,java]]
----
Condition.where(isFalse())
         .orNot(isAlsoFalse())
         .then(() -> doSomething())
         .otherwise(() -> doSomethingElse());
----

### if-then-else-if

[[source,java]]
----
if (isFalse()) {
    doSomething();
} else if (isTrue()) {
    doSomethingElse();
}
----

[[source,java]]
----
Condition.where(isFalse())
         .then(() -> doSomething())
         .otherwise(isTrue())
         .then(() -> doSomethingElse());
----

### if-then-if-then

[[source,java]]
----
if (isTrue()) {
    doSomething();
    if (isAlsoTrue()) {
        doSomethingElse();
    }
}
----

[[source,java]]
----
Condition.where(isTrue())
         .then(() -> doSomething())
         .and(isAlsoTrue())
         .then(() -> doSomethingElse());
----

## Value

Values from an if-then-else in a functional-style.

Functional, and verbose, alternative to the ternary operator (`?:`).

### if-then-else

[[source,java]]
----
String result;
if (isTrue()) {
    result = TRUE;
} else {
    result = FALSE;
}
----

[[source,java]]
----
String result = isTrue() ? TRUE : FALSE;
----

[[source,java]]
----
final String result = Value.<String>where(isTrue()).then(() -> TRUE)
                                                   .otherwise(() -> FALSE);
----

### if-not-then-else

[[source,java]]
----
String result;
if (!isTrue()) {
    result = TRUE;
} else {
    result = FALSE;
}
----

[[source,java]]
----
final String result = Value.<String>whereNot(isTrue()).then(() -> TRUE)
                                                      .otherwise(() -> FALSE);
----

### if-and-then-else

[[source,java]]
----
String result;
if (isTrue() && alternativeIsTrue()) {
    result = TRUE;
} else {
    result = FALSE;
}
----

[[source,java]]
----
final String result = Value.<String>where(isTrue()).and(alternativeIsTrue())
                                                   .then(() -> TRUE)
                                                   .otherwise(() -> FALSE);
----

### if-and-not-then-else

[[source,java]]
----
String result;
if (isTrue() && !alternativeIsFalse()) {
    result = TRUE;
} else {
    result = FALSE;
}
----

[[source,java]]
----
final String result = Value.<String>where(isTrue()).andNot(alternativeIsFalse())
                                                   .then(() -> TRUE)
                                                   .otherwise(() -> FALSE);
----

### if-or-then-else

[[source,java]]
----
String result;
if (isTrue() || alternativeIsTrue()) {
    result = TRUE;
} else {
    result = FALSE;
}
----

[[source,java]]
----
final String result = Value.<String>where(isTrue()).or(alternativeIsTrue())
                                                   .then(() -> TRUE)
                                                   .otherwise(() -> FALSE);
----

### if-or-not-then-else

[[source,java]]
----
String result;
if (isTrue() || !isFalse()) {
    result = TRUE;
} else {
    result = FALSE;
}
----

[[source,java]]
----
final String result = Value.<String>where(isTrue()).orNot(isFalse())
                                                   .then(() -> TRUE)
                                                   .otherwise(() -> FALSE);
----