PreProcessor

A Gradle plugin for preprocessing code. Based on ToCraft's PreProcessor which is based on RePlayMod's PreProcessor.

Build File

Here's how you can apply the plugin in a build.gradle file:

plugins {
    id 'java'
    id 'net.william278.preprocessor' version '1.0'
}

The Kotlin implementation for a build.gradle.kts file looks similar:

plugins {
    id("org.jetbrains.kotlin.jvm") version "2.0.0"
    id("net.william278.preprocessor") version "1.0"
}

Now, you'll need to define variables so the preprocessor can evaluate the if-statements.

preprocess {
    vars.put("a", "1")
}

This sets the value of the variable a to 1. You can define any value object you want as long as the key is a String.

Gradle Tasks

By default, the plugin registers the following tasks per source set:

• preProcessJava & applyPreProcessJava, if the source set contains java sources
• preProcessKotlin & applyPreProcessKotlin, if the source set contains kotlin sources
• preProcessResources & applyPreProcessResources, if the source set contains resources

It automatically adapts the tasks compileJava, compileKotlin and processResources to use the outputs of the above tasks. The applyPreProcess*-tasks cause the plugin to update the sources and comment lines with //$$ that won't run since their if-condition is false. This is not required for the plugin to preprocess, but for better code readability. {:.note}

The plugin also registers one task simply called applyPreProcess, which automatically applies every applyPreProcess* task for every source set in this build file.

Code Example

An example Java test class looks like this;

package test;

class Test {
    public static void main(String... args) {
        //#if a
        //$$ System.out.println("Test succeeded.");
        //#else
        System.out.println("Test failed.");
        //#endif
    }
}

This will be preprocessed to the following, if a exists:

package test;

class Test {
    public static void main(String... args) {
        //#if a
        System.out.println("Test succeeded.");
        //#else
        //$$ System.out.println("Test failed.");
        //#endif
    }
}

Keywords

You'll notice the //#if, //#$$, //#else and //#endif. There is also a //#elseif keyword. These will work as if-statements. Every if-statement must start with //#if and must end with //#endif.

You can change these keywords with the following build.gradle structure:

preprocess {
    keywords.put("json", new Keywords("//#if","//#elseif","//#endif","//\$\$"))
}

This will add custom keywords for every file ending with json.

Possible Conditions

Now, this condition is true, if a exists and is not 0 or null:

//#if a

You can also chain conditions:

//#if a && b || c

Of course you can also compare integer values with ==, !=, >=, <=, > and <.

//#if a == 1