Support code blocks and inline code for GFM format (#2485)

Fixes #2477.

Inline code, text that is nested within a pair of backquotes,
is now converted into GitHub Flavored Markdown (gfm) without
stripping out the backquotes. For example:

    The parameter `sum` must be a non-negative real number.

Code blocks, which are any number of lines of literal text
between triple-backquotes, and an optional programming language
name, are now preserved. If absent, the programming language
is assumed to be "kotlin". This follows the behavior of the
html renderer. For example:

    Here is an example of calling the function:
    ```kotlin
    val sum = addThemUp(left, right)
    ```

1 files changed, 36 insertions, 0 deletions

diff --git a/plugins/base/src/main/kotlin/translators/documentables/PageContentBuilder.kt b/plugins/base/src/main/kotlin/translators/documentables/PageContentBuilder.kt
index 7b6fbc7a..363b6a3f 100644
--- a/plugins/base/src/main/kotlin/translators/documentables/PageContentBuilder.kt
+++ b/plugins/base/src/main/kotlin/translators/documentables/PageContentBuilder.kt
@@ -363,6 +363,42 @@ open class PageContentBuilder(
             contents += ContentGroup(content, DCI(mainDRI, kind), sourceSets.toDisplaySourceSets(), styles, extra)
         }
 
+        fun codeBlock(
+            language: String = "",
+            kind: Kind = ContentKind.Main,
+            sourceSets: Set<DokkaSourceSet> = mainSourcesetData,
+            styles: Set<Style> = mainStyles,
+            extra: PropertyContainer<ContentNode> = mainExtra,
+            block: DocumentableContentBuilder.() -> Unit
+        ) {
+            contents += ContentCodeBlock(
+                contentFor(mainDRI, sourceSets, kind, styles, extra, block).children,
+                language,
+                DCI(mainDRI, kind),
+                sourceSets.toDisplaySourceSets(),
+                styles,
+                extra
+            )
+        }
+
+        fun codeInline(
+            language: String,
+            kind: Kind = ContentKind.Main,
+            sourceSets: Set<DokkaSourceSet> = mainSourcesetData,
+            styles: Set<Style> = mainStyles,
+            extra: PropertyContainer<ContentNode> = mainExtra,
+            block: DocumentableContentBuilder.() -> Unit
+        ) {
+            contents += ContentCodeInline(
+                contentFor(mainDRI, sourceSets, kind, styles, extra, block).children,
+                language,
+                DCI(mainDRI, kind),
+                sourceSets.toDisplaySourceSets(),
+                styles,
+                extra
+            )
+        }
+
         fun firstParagraphComment(
             content: DocTag,
             kind: Kind = ContentKind.Comment,