Begin a parser implementation from HTML into an internal representation.

src/domain/session/room/timeline/FORMATTED.md

@@ -4,6 +4,12 @@
   inspiration from [Pandoc's AST](https://hackage.haskell.org/package/pandoc-types-1.22/docs/Text-Pandoc-Definition.html#t:Block).
   Then, much like Pandoc AST, we can turn our representation into
   markdown in the editor, or HTML in the view.
+  * This is good for both serialization and deserialization.
+    We can use the representation when going input -> formatted
+    message, which would allow other, non-web platforms
+    to rely on non-Markdown input types. We can also
+    use it going formatted message -> display, since a frontend
+    can then choose to use non-HTML output (GTK JS bindings?).
 * As such, we represent formatting by nesting parts
   (we'd have a `ItalicsPart`, `BoldPart`, etc.)
 * We keep the "inline"/"block" distinction, but only

src/domain/session/room/timeline/MessageBody.js

@@ -12,7 +12,7 @@ export function parsePlainBody(body) {
     // create callback outside of loop
     const linkifyCallback = (text, isLink) => {
         if (isLink) {
-            parts.push(new LinkPart(text, text));
+            parts.push(new LinkPart(text, [new TextPart(text)]));
         } else {
             parts.push(new TextPart(text));
         }
@@ -36,65 +36,63 @@ export function stringAsBody(body) {
     return new MessageBody(body, [new TextPart(body)]);
 }
 
-class HeaderBlock {
+export class HeaderBlock {
     constructor(level, inlines) {
         this.level = level;
         this.inlines = inlines;
     }
 
     get type() { return "header"; }
-    isBlock() { return true; }
 }
 
-class CodeBlock {
-    constructor(text) {
+export class CodeBlock {
+    constructor(language, text) {
+        this.language = language;
         this.text = text;
     }
 
     get type() { return "codeblock"; }
-    isBlock() { return true; }
 }
 
-class NewLinePart {
+export class ListBlock {
+    constructor(startOffset, items) {
+        this.items = items;
+        this.startOffset = startOffset;
+    }
+}
+
+export class RulePart {
+    get type( ) { return "rule"; }
+}
+
+export class NewLinePart {
     get type() { return "newline"; }
-    isBlock() { return false; }
 }
 
-class EmphPart {
-    constructor(wraps) {
-        this.wraps = wraps;
+export class FormatPart {
+    constructor(format, children) {
+        this.format = format;
+        this.children = children;
     }
 
-    get type() { return "emph"; }
-    isBlock() { return false; }
+    get type() { return "format"; }
 }
 
-class CodePart {
-    constructor(text) {
-        this.text = text;
-    }
-
-    get type() { return "code"; }
-    isBlock() { return false; }
-}
-
-class LinkPart {
-    constructor(url, text) {
+export class LinkPart {
+    constructor(url, inlines) {
         this.url = url;
-        this.text = text;
+        this.inlines = inlines;
     }
 
     get type() { return "link"; }
-    isBlock() { return false; }
 }
 
-class TextPart {
+export class TextPart {
     constructor(text) {
         this.text = text;
     }
 
     get type() { return "text"; }
-    isBlock() { return false; }
 }
 
 class MessageBody {

src/platform/web/dom/deserialize.js

@@ -0,0 +1,108 @@
+import { HeaderBlock, ListBlock, CodeBlock, FormatPart, NewLinePart, RulePart, TextPart, LinkPart } from "../../../domain/session/room/timeline/MessageBody.js"
+
+
+/* At the time of writing (Jul 1 2021), Matrix Spec recommends
+ * allowing the following HTML tags:
+ *     font, del, h1, h2, h3, h4, h5, h6, blockquote, p, a, ul, ol, sup, sub, li, b, i, u,
+ *     strong, em, strike, code, hr, br, div, table, thead, tbody, tr, th, td, caption, pre, span, img
+ */
+
+const basicNodes = ["EM", "STRONG", "CODE", "DEL", "P", "DIV", "SPAN" ]
+
+function basicWrapper(tag) {
+    return (_, children) => new FormatPart(tag, children);
+}
+
+function headerWrapper(level) {
+    return (_, children) => new HeaderBlock(level, children);
+}
+
+function parseLink(node, children) {
+    return new LinkPart(node.href, children);
+}
+
+function parseList(node) {
+    const start = node.getAttribute("start") || 1;
+    const nodes = [];
+    const len = node.childNodes.length;
+    for (let i = 0; i < len; i += 1) {
+        const child = node.childNodes[i];
+        if (child.tagName !== "LI") {
+            continue;
+        }
+        nodes.push(parseNodes(child.childNodes));
+    }
+    return new ListBlock(start, nodes);
+}
+
+function parseCodeBlock(node) {
+    let codeNode;
+    if (!((codeNode = node.firstChild) && codeNode.nodeName == "CODE")) {
+        return null;
+    }
+    let language = "";
+    for (const clname of codeNode.classList) {
+        if (clname.startsWith("language-") && !clname.startsWith("language-_")) {
+            language = clname.substring(9) // "language-".length
+            break;
+        }
+    }
+    return new CodeBlock(language, codeNode.textContent);
+}
+
+function parseImage(node) {
+    return null;
+}
+
+function buildNodeMap() {
+    let map = {
+        A: { descend: true, parsefn: parseLink },
+        UL: { descend: false, parsefn: parseList },
+        OL: { descend: false, parsefn: parseList },
+        PRE: { descend: false, parsefn: parseCodeBlock },
+        BR: { descend: false, parsefn: () => new NewLinePart() },
+        HR: { descend: false, parsefn: () => new RulePart() },
+        IMG: { descend: false, parsefn: parseImage }
+    }
+    for (const tag of basicNodes) {
+        map[tag] = { descend: true, parsefn: basicWrapper(tag) }
+    }
+    for (let level = 1; level <= 6; level++) {
+        const tag = "h" + level;
+        map[tag] = { descend: true, parsefn: headerWrapper(level) }
+    }
+    return map;
+}
+
+const nodes = buildNodeMap();
+
+function parseNode(node) {
+    if (node.nodeType === Node.TEXT_NODE) {
+        return new TextPart(node.nodeValue);
+    } else if (node.nodeType == Node.ELEMENT_NODE) {
+        const f = nodes[node.nodeName];
+        if (!f) {
+            return null;
+        }
+        let result = f.parsefn(node, f.descend ? parseNodes(node.childNodes) : null);
+        return result;
+    }
+    return null;
+}
+
+function parseNodes(nodes) {
+    const len = nodes.length;
+    const parsed = [];
+    for (let i = 0; i < len; i ++) {
+        let node = parseNode(nodes[i]);
+        if (node) {
+            parsed.push(node);
+        }
+    }
+    return parsed;
+}
+
+export function parse(html) {
+    const rootNode = new DOMParser().parseFromString(html, "text/html").body;
+    return parseNodes(rootNode.childNodes);
+}

src/platform/web/ui/session/room/timeline/TextMessageView.js

@@ -38,10 +38,10 @@ export class TextMessageView extends BaseMessageView {
 const formatFunction = {
     header: headerBlock => tag["h" + Math.min(6,headerBlock.level)]({}, renderParts(headerBlock.inlines)),
     codeblock: codeBlock => tag.pre({}, tag.code({}, text(codeBlock.text))),
-    emph: emphPart => tag.em({}, [renderPart(emphPart.wraps)]),
+    emph: emphPart => tag.em({}, renderPart(emphPart.inlines)),
     code: codePart => tag.code({}, text(codePart.text)),
     text: textPart => text(textPart.text),
-    link: linkPart => tag.a({ href: linkPart.url, target: "_blank", rel: "noopener" }, [linkPart.text]),
+    link: linkPart => tag.a({ href: linkPart.url, target: "_blank", rel: "noopener" }, renderParts(linkPart.inlines)),
     newline: () => tag.br()
 };