From 924f400ba60425a5516ff65b486b2ab59ea5d63c Mon Sep 17 00:00:00 2001
From: Jeremy Maitin-Shepard <jeremy@jeremyms.com>
Date: Thu, 9 Oct 2008 18:00:22 -0700
Subject: [PATCH] Add generic label mechanism

---
 modules/conkeror.js |  1 +
 modules/labels.js   | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 modules/labels.js

diff --git a/modules/conkeror.js b/modules/conkeror.js
index b3fda86..6826382 100644
--- a/modules/conkeror.js
+++ b/modules/conkeror.js
@@ -8,6 +8,7 @@
 var start_time = Date.now ();
 
 require("keywords.js"); // not required to be listed as dep.
+require("labels.js"); // not required to be listed as a dep.
 require("coroutine.js"); // not required to be listed as dep.
 
 require("hook.js");
diff --git a/modules/labels.js b/modules/labels.js
new file mode 100644
index 0000000..ac0be16
--- /dev/null
+++ b/modules/labels.js
@@ -0,0 +1,85 @@
+/**
+ * (C) Copyright 2008 Jeremy Maitin-Shepard
+ *
+ * Use, modification, and distribution are subject to the terms specified in the
+ * COPYING file.
+**/
+
+require_later("help.js"); // for pretty_print_value
+
+/**
+ * @param name specifies the name of the label to be defined
+ *
+ * The remaining arguments should be strings, specifying the names of
+ * required arguments. Additionally, the last additional argument can
+ * be `null', which indicates that unlimited optional arguments can
+ * follow. If `null' is not specified as the last argument, then it is
+ * assumed that all optional arguments are keyword arguments. The
+ * optional arguments are stored as an array in a member called $.
+ */
+function define_label(name) {
+    var allow_optional = false;
+    var required_args = [];
+    for (let i = 1; i < arguments.length; ++i) {
+        if (arguments[i] === null) {
+            allow_optional = true;
+            if (i + 1 != arguments.length)
+                throw new Error("null must be the last argument");
+        } else {
+            required_args.push(arguments[i]);
+        }
+    }
+    function toString() {
+        let optional = this.$;
+        if (optional == null)
+            optional = [];
+        let printed_args = [];
+        let seen_defined_yet = false;
+        for (let i = required_args.length - 1; i >= 0; --i) {
+            let arg = required_args[i];
+            if (seen_defined_yet || this[arg] !== undefined) {
+                printed_args.unshift(arg + " = " + pretty_print_value(this[arg]));
+                seen_defined_yet = true;
+            }
+        }
+        printed_args.push.apply(null, optional.map(pretty_print_value));
+        for (let i in this) {
+            if (i.length > 1 && i[0] == "$")
+                printed_args.push(i + " = " + this[i]);
+        }
+        if (printed_args.length > 0)
+            printed_args = "(" + printed_args.join(", ") + ")";
+        else
+            printed_args = "";
+        return this._name + printed_args;
+    }
+    var result;
+    result = function () {
+        var o = {_name: name, toString: toString, _id: result, __is_label: true, toSource: toString};
+        let max_req_arg = arguments.length;
+        if (max_req_arg > required_args.length)
+            max_req_arg = required_args.length;
+        for (let i = 0; i < max_req_arg; ++i)
+            o[required_args[i]] = arguments[i];
+        if (allow_optional)
+            o.$ = Array.prototype.slice.call(arguments, required_args.length);
+        else {
+            write_keywords(o, arguments, required_args.length);
+        }
+        return o;
+    }
+    result._name = name;
+    result._id = result;
+    result.$ = [];
+    for (let i in required_args)
+        result[i] = undefined;
+    result.toString = toString;
+    result.__is_label = true;
+    conkeror[name] = result;
+}
+
+function label_id(value) {
+    if (value == null)
+        return null;
+    return value._id;
+}
-- 
2.11.4.GIT