1 files changed, 139 insertions, 0 deletions
diff --git a/tools/ts/build_xpcom.js b/tools/ts/build_xpcom.js
new file mode 100644
index 0000000000..d09b18fb69
--- /dev/null
+++ b/tools/ts/build_xpcom.js
@@ -0,0 +1,139 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+/**
+ * Build: <objdir>/dist/@types/lib.gecko.xpcom.d.ts,
+ *
+ * from:  <objdir>/config/makefiles/xpidl/*.d.json type definition files,
+ *        generated by a previous build step.
+ */
+
+const fs = require("fs");
+const URL = "https://searchfox.org/mozilla-central/source/";
+
+const HEADER = `/**
+ * NOTE: Do not modify this file by hand.
+ * Content was generated from source XPCOM .idl files.
+ */
+`;
+
+// Emit a typescript interface, along with any related enums.
+function ts_interface(iface) {
+  let lines = [];
+  let base = iface.base;
+  iface.class = iface.id;
+
+  // Make QueryInterface optional, enable plain objects to pass as nsISupports.
+  let partial = iface.id === "nsISupports" ? "?" : "";
+
+  let enums = iface.enums.map(e => `typeof ${iface.id}.${e.id}`).join(" & ");
+  if (enums) {
+    base += `, Enums<${enums}>`;
+    iface.class += `, ${enums}`;
+
+    // Close the global scope, avoid polluting it with the namespace value.
+    lines.push("}  // global\n");
+    lines.push(`declare namespace ${iface.id} {\n`);
+
+    for (let e of iface.enums) {
+      lines.push(`enum ${e.id} {`);
+      for (let v of e.variants) {
+        lines.push(`  ${v.name} = ${v.value},`);
+      }
+      lines.push("}\n");
+    }
+
+    lines.push("}\n");
+    lines.push("declare global {\n");
+  }
+
+  // Handle [function] interfaces.
+  if (iface.callable) {
+    lines.push(`type ${iface.id} = Callable<{`);
+  } else {
+    lines.push(`interface ${iface.id} ${base ? `extends ${base} ` : ""}{`);
+  }
+
+  for (let c of iface.consts) {
+    lines.push(`  readonly ${c.name}: ${c.value};`);
+  }
+
+  if (iface.consts.length && iface.members.length) {
+    // For style points.
+    lines.push("");
+  }
+
+  for (let m of iface.members) {
+    if (!m.args) {
+      lines.push(`  ${m.readonly ? "readonly " : ""}${m.name}: ${m.type};`);
+    } else {
+      let args = [];
+      for (let arg of m.args) {
+        // If this is the generic parameter, adjust its type.
+        let type = arg.name === m.iid_is ? "T" : arg.type;
+        args.push(`${arg.name}${arg.optional ? "?" : ""}: ${type}`);
+      }
+      let type = `(${args.join(", ")}): ${m.type}`;
+      // Adjust signature if this is a generic method.
+      let signature = m.iid_is ? `<T extends nsIID>${type}<T>` : type;
+      lines.push(`  ${m.name}${partial}${signature};`);
+    }
+  }
+
+  lines.push(iface.callable ? "}>\n" : "}\n");
+  return lines;
+}
+
+// Link all generated .d.json files into a self-contained ts typelib.
+function ts_link(dir, files) {
+  let lines = [HEADER, "declare global {\n"];
+  let typedefs = {};
+  let iids = [];
+
+  for (let djson of files) {
+    let modules = JSON.parse(fs.readFileSync(`${dir}/${djson}`, "utf8"));
+
+    for (let mod of modules) {
+      lines.push(`// ${URL}${mod.path}\n`);
+      Object.assign(typedefs, Object.fromEntries(mod.typedefs ?? []));
+
+      for (let iface of mod.interfaces ?? []) {
+        if (iface.id !== "nsIXPCComponents_Interfaces") {
+          lines = lines.concat(ts_interface(iface));
+          iids.push(`  ${iface.id}: nsJSIID<${iface.class}>;`);
+        }
+      }
+    }
+  }
+
+  lines.push("interface nsIXPCComponents_Interfaces {");
+  lines = lines.concat(iids);
+  lines.push("}\n");
+
+  lines.push("}  // global\n");
+
+  lines.push("// Typedefs from xpidl.");
+  for (let [id, type] of Object.entries(typedefs).sort()) {
+    lines.push(`type ${id} = ${type};`);
+  }
+  lines.push("");
+
+  // Include xpcom builtins.
+  lines.push(fs.readFileSync(`${__dirname}/fixtures/intrinsics.d.ts`, "utf8"));
+  return lines;
+}
+
+// For testing.
+module.exports = { ts_link };
+
+function main(lib_dts, djson_dir, ...djson_files) {
+  let dts = ts_link(djson_dir, djson_files).join("\n");
+  console.log(`[INFO] ${lib_dts} (${dts.length.toLocaleString()} bytes)`);
+  fs.writeFileSync(lib_dts, dts);
+}
+
+if (require.main === module) {
+  main(...process.argv.slice(2));
+}