1 files changed, 130 insertions, 0 deletions
diff --git a/services/blog/nuldoc-src/renderers/xml.ts b/services/blog/nuldoc-src/renderers/xml.ts
new file mode 100644
index 00000000..77cc1574
--- /dev/null
+++ b/services/blog/nuldoc-src/renderers/xml.ts
@@ -0,0 +1,130 @@
+import { Element, forEachChild, Node, Text } from "../dom.ts";
+
+export function renderXml(root: Node): string {
+  return `<?xml version="1.0" encoding="utf-8"?>\n` + nodeToXmlText(root, {
+    indentLevel: 0,
+  });
+}
+
+type Context = {
+  indentLevel: number;
+};
+
+type Dtd = { type: "block" | "inline" };
+
+function getDtd(name: string): Dtd {
+  switch (name) {
+    case "feed":
+    case "entry":
+    case "author":
+      return { type: "block" };
+    default:
+      return { type: "inline" };
+  }
+}
+
+function isInlineNode(n: Node): boolean {
+  if (n.kind === "text") {
+    return true;
+  }
+  return getDtd(n.name).type === "inline";
+}
+
+function isBlockNode(n: Node): boolean {
+  return !isInlineNode(n);
+}
+
+function nodeToXmlText(n: Node, ctx: Context): string {
+  if (n.kind === "text") {
+    if (n.raw) {
+      return n.content;
+    } else {
+      return textNodeToXmlText(n);
+    }
+  } else {
+    return elementNodeToXmlText(n, ctx);
+  }
+}
+
+function textNodeToXmlText(t: Text): string {
+  const s = encodeSpecialCharacters(t.content);
+
+  // TODO: 日本語で改行するときはスペースを入れない
+  return s.replaceAll(/\n */g, " ");
+}
+
+function encodeSpecialCharacters(s: string): string {
+  return s.replaceAll(/&(?!\w+;)/g, "&amp;")
+    .replaceAll(/</g, "&lt;")
+    .replaceAll(/>/g, "&gt;")
+    .replaceAll(/'/g, "&apos;")
+    .replaceAll(/"/g, "&quot;");
+}
+
+function elementNodeToXmlText(e: Element, ctx: Context): string {
+  let s = "";
+
+  s += indent(ctx);
+  s += `<${e.name}`;
+  const attributes = getElementAttributes(e);
+  if (attributes.length > 0) {
+    s += " ";
+    for (let i = 0; i < attributes.length; i++) {
+      const [name, value] = attributes[i];
+      s += `${name}="${encodeSpecialCharacters(value)}"`;
+      if (i !== attributes.length - 1) {
+        s += " ";
+      }
+    }
+  }
+  s += ">";
+  if (isBlockNode(e)) {
+    s += "\n";
+  }
+  ctx.indentLevel += 1;
+
+  forEachChild(e, (c) => {
+    s += nodeToXmlText(c, ctx);
+  });
+
+  ctx.indentLevel -= 1;
+  if (isBlockNode(e)) {
+    s += indent(ctx);
+  }
+  s += `</${e.name}>`;
+  s += "\n";
+
+  return s;
+}
+
+function indent(ctx: Context): string {
+  return "  ".repeat(ctx.indentLevel);
+}
+
+function getElementAttributes(e: Element): [string, string][] {
+  return [...e.attributes.entries()]
+    .filter((a) => !a[0].startsWith("--"))
+    .sort(
+      (a, b) => {
+        // Special rules:
+        if (e.name === "link") {
+          if (a[0] === "href" && b[0] === "rel") {
+            return 1;
+          }
+          if (a[0] === "rel" && b[0] === "href") {
+            return -1;
+          }
+          if (a[0] === "href" && b[0] === "type") {
+            return 1;
+          }
+          if (a[0] === "type" && b[0] === "href") {
+            return -1;
+          }
+        }
+        // General rules:
+        if (a[0] > b[0]) return 1;
+        else if (a[0] < b[0]) return -1;
+        else return 0;
+      },
+    );
+}