Adding extensions using Groovy

It is possible to write extensions inline using a Groovy DSL. Two approaches are supported: inline strings and files.

Groovy

import org.asciidoctor.gradle.model5.jvm.extensions.AsciidoctorjGroovyDslExtension

asciidoc {
    toolchains {
        aciidoctorj {
            asciidocExtensions {
                groovydsl(AsciidoctorjGroovyDslExtension) {
                    fromString (''' (1)
                        block(name: "BIG", contexts: [":paragraph"]) {
                            parent, reader, attributes ->
                            def upperLines = reader.readLines()
                                .collect {it.toUpperCase()}
                                .inject("") {a, b -> a + '\n' + b}

                            createBlock(parent, "paragraph", [upperLines], attributes, [:])
                        }
                    ''')

                    fromFile('src/docs/asciidoc/myExtension.groovy') (2)
                }
            }
        }
    }
}

1	Add an inline extension. Anything that can be lazy-evaluated as a string can be passed.
2	An extension in a Groovy source file. Anything that can be lazy-evaluated to a file can be passed.

In versions prior to 4.0, there was a way of using closures to define extensions. With advancements in Gradle, it has actually become problematic to serialize those closures over classloader boundaries. The second problem is that it unnecessarily drags in a number of dependencies onto the build plugin classpath. These are the two reasons why we no longer support the closure approach for inline extensions.