initial commit

src/html.ts

@@ -0,0 +1,104 @@
+/**
+ * Copyright (c) 2025 xwra
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import { type Chunk, ChunkedWriter } from "./http.ts";
+import { ChunkedStream } from "./stream.ts";
+
+type Attrs = Record<string, string | number | boolean>;
+
+const SELF_CLOSING_TAGS = new Set([
+  "br",
+  "embed",
+  "hr",
+  "img",
+  "input",
+  "link",
+  "meta",
+  "track",
+  "source",
+]);
+
+export function escape(input: string): string {
+  return input
+    .replace(/&/g, "&amp;")
+    .replace(/</g, "&lt;")
+    .replace(/>/g, "&gt;")
+    .replace(/"/g, "&quot;")
+    .replace(/'/g, "&#039;");
+}
+
+function attrsToString(
+  attrs: Attrs | undefined,
+  escape: (str: string) => string,
+): string {
+  if (!attrs) return "";
+  const pairs = Object.entries(attrs)
+    .filter(([_, value]) => value !== undefined && value !== null)
+    .map(([key, value]) => {
+      if (value === true) return key;
+      if (value === false) return "";
+      return `${key}="${escape(String(value))}"`;
+    })
+    .filter(Boolean);
+  return pairs.length ? " " + pairs.join(" ") : "";
+}
+
+type TagFunction = {
+  (attrs: Attrs, ...children: Chunk[]): Promise<void>;
+  (...children: Chunk[]): Promise<void>;
+};
+
+type HtmlBuilder = {
+  [K: string]: TagFunction;
+};
+
+export function html(
+  chunks: ChunkedStream<string>,
+  write: ChunkedWriter,
+): HtmlBuilder {
+  const tags = new Map<string, (...args: any[]) => Promise<void>>();
+
+  const handler: ProxyHandler<Record<string, TagFunction>> = {
+    get(_, tag: string) {
+      if (tags.has(tag)) {
+        return tags.get(tag);
+      }
+
+      const fn = async (...args: (Chunk | Attrs)[]) => {
+        const isTemplate = args.length === 1 && Array.isArray(args[0]) &&
+          "raw" in args[0];
+        const hasAttrs = !isTemplate && args.length &&
+          typeof args[0] === "object";
+
+        const attrs: Attrs | undefined = hasAttrs
+          ? args.shift() as Attrs
+          : undefined;
+        const children: Chunk[] = args as Chunk[];
+
+        const attributes = attrsToString(attrs, escape);
+        const isSelfClosing = SELF_CLOSING_TAGS.has(tag.toLowerCase());
+        if (!isSelfClosing && !children.length) return;
+        chunks.write(`<${tag}${attributes}${isSelfClosing ? " /" : ""}>`);
+
+        if (!isSelfClosing) {
+          if (isTemplate) {
+            await (write as any)(...children);
+          } else {
+            for (const child of children) {
+              typeof child === "function"
+                ? await (child as any)()
+                : chunks.write(String(await child));
+            }
+          }
+          chunks.write(`</${tag}>`);
+        }
+      };
+
+      tags.set(tag, fn);
+      return fn;
+    },
+  };
+  return new Proxy({}, handler);
+}