The PlantUML extension for AsciiDoc renderering

server/modules/rendering/asciidoc-core/definition.yml

@@ -18,3 +18,15 @@ props:
       - safe
       - server
       - secure
+  enablePlantuml:
+    type: Boolean
+    default: false
+    title: enable plantuml extension
+    hint: 'enable rendering for [plantuml] block'
+    order: 2
+  plantumlServer:
+    type: String
+    default: https://plantuml.requarks.io
+    title: PlantUML Server
+    hint: PlantUML server used for image generation
+    order: 3

server/modules/rendering/asciidoc-core/renderer.js

@@ -1,15 +1,42 @@
 const asciidoctor = require('asciidoctor')()
 const cheerio = require('cheerio')
+const deflateRawSync = require('zlib').deflateRawSync
+
+// asciidoctor.js extensions
+// https://docs.asciidoctor.org/asciidoctor.js/latest/extend/extensions/block-processor/
+
+function plantuml_ext(registry, server) {
+  registry.block(function () {
+    this.named("plantuml");
+    this.onContext(["paragraph", "listing"]);
+    this.process(function (parent, reader) {
+      const lines = reader.getLines();
+      const zippedCode = encode64(
+        deflateRawSync(lines.join("\n")).toString("binary")
+      );
+      return this.createImageBlock(parent, {
+        target: `${server}/svg/${zippedCode}`,
+      });
+    });
+  });
+}
+
 
 module.exports = {
   async render() {
+    let registry = undefined
+    if(this.config.enablePlantuml && this.config.plantumlServer) {
+        registry = asciidoctor.Extensions.create();
+        plantuml_ext(registry, this.config.plantumlServer);
+    }
     const html = asciidoctor.convert(this.input, {
       standalone: false,
       safe: this.config.safeMode,
       attributes: {
         showtitle: true,
         icons: 'font'
-      }
+      },
+      extension_registry: registry
     })
 
     const $ = cheerio.load(html, {
@@ -24,3 +51,58 @@ module.exports = {
     return $.html()
   }
 }
+
+
+function encode64(data) {
+  let r = "";
+  for (let i = 0; i < data.length; i += 3) {
+    if (i + 2 === data.length) {
+      r += append3bytes(data.charCodeAt(i), data.charCodeAt(i + 1), 0);
+    } else if (i + 1 === data.length) {
+      r += append3bytes(data.charCodeAt(i), 0, 0);
+    } else {
+      r += append3bytes(
+        data.charCodeAt(i),
+        data.charCodeAt(i + 1),
+        data.charCodeAt(i + 2)
+      );
+    }
+  }
+  return r;
+}
+
+function append3bytes(b1, b2, b3) {
+  let c1 = b1 >> 2;
+  let c2 = ((b1 & 0x3) << 4) | (b2 >> 4);
+  let c3 = ((b2 & 0xf) << 2) | (b3 >> 6);
+  let c4 = b3 & 0x3f;
+  let r = "";
+  r += encode6bit(c1 & 0x3f);
+  r += encode6bit(c2 & 0x3f);
+  r += encode6bit(c3 & 0x3f);
+  r += encode6bit(c4 & 0x3f);
+  return r;
+}
+
+function encode6bit(raw) {
+  let b = raw;
+  if (b < 10) {
+    return String.fromCharCode(48 + b);
+  }
+  b -= 10;
+  if (b < 26) {
+    return String.fromCharCode(65 + b);
+  }
+  b -= 26;
+  if (b < 26) {
+    return String.fromCharCode(97 + b);
+  }
+  b -= 26;
+  if (b === 0) {
+    return "-";
+  }
+  if (b === 1) {
+    return "_";
+  }
+  return "?";
+}