1 files changed, 186 insertions, 0 deletions
diff --git a/remote/shared/Format.sys.mjs b/remote/shared/Format.sys.mjs
new file mode 100644
index 0000000000..95e9ff339f
--- /dev/null
+++ b/remote/shared/Format.sys.mjs
@@ -0,0 +1,186 @@
+/* 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/. */
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  Log: "chrome://remote/content/shared/Log.sys.mjs",
+});
+
+XPCOMUtils.defineLazyGetter(lazy, "logger", () => lazy.Log.get());
+
+XPCOMUtils.defineLazyPreferenceGetter(
+  lazy,
+  "truncateLog",
+  "remote.log.truncate",
+  false
+);
+
+const ELEMENT_NODE = 1;
+const MAX_STRING_LENGTH = 250;
+
+/**
+ * Pretty-print values passed to template strings.
+ *
+ * Usage::
+ *
+ *     let bool = {value: true};
+ *     pprint`Expected boolean, got ${bool}`;
+ *     => 'Expected boolean, got [object Object] {"value": true}'
+ *
+ *     let htmlElement = document.querySelector("input#foo");
+ *     pprint`Expected element ${htmlElement}`;
+ *     => 'Expected element <input id="foo" class="bar baz" type="input">'
+ *
+ *     pprint`Current window: ${window}`;
+ *     => '[object Window https://www.mozilla.org/]'
+ */
+export function pprint(ss, ...values) {
+  function pretty(val) {
+    let proto = Object.prototype.toString.call(val);
+    if (
+      typeof val == "object" &&
+      val !== null &&
+      "nodeType" in val &&
+      val.nodeType === ELEMENT_NODE
+    ) {
+      return prettyElement(val);
+    } else if (["[object Window]", "[object ChromeWindow]"].includes(proto)) {
+      return prettyWindowGlobal(val);
+    } else if (proto == "[object Attr]") {
+      return prettyAttr(val);
+    }
+    return prettyObject(val);
+  }
+
+  function prettyElement(el) {
+    let attrs = ["id", "class", "href", "name", "src", "type"];
+
+    let idents = "";
+    for (let attr of attrs) {
+      if (el.hasAttribute(attr)) {
+        idents += ` ${attr}="${el.getAttribute(attr)}"`;
+      }
+    }
+
+    return `<${el.localName}${idents}>`;
+  }
+
+  function prettyWindowGlobal(win) {
+    let proto = Object.prototype.toString.call(win);
+    return `[${proto.substring(1, proto.length - 1)} ${win.location}]`;
+  }
+
+  function prettyAttr(obj) {
+    return `[object Attr ${obj.name}="${obj.value}"]`;
+  }
+
+  function prettyObject(obj) {
+    let proto = Object.prototype.toString.call(obj);
+    let s = "";
+    try {
+      s = JSON.stringify(obj);
+    } catch (e) {
+      if (e instanceof TypeError) {
+        s = `<${e.message}>`;
+      } else {
+        throw e;
+      }
+    }
+    return `${proto} ${s}`;
+  }
+
+  let res = [];
+  for (let i = 0; i < ss.length; i++) {
+    res.push(ss[i]);
+    if (i < values.length) {
+      let s;
+      try {
+        s = pretty(values[i]);
+      } catch (e) {
+        lazy.logger.warn("Problem pretty printing:", e);
+        s = typeof values[i];
+      }
+      res.push(s);
+    }
+  }
+  return res.join("");
+}
+
+/**
+ * Template literal that truncates string values in arbitrary objects.
+ *
+ * Given any object, the template will walk the object and truncate
+ * any strings it comes across to a reasonable limit.  This is suitable
+ * when you have arbitrary data and data integrity is not important.
+ *
+ * The strings are truncated in the middle so that the beginning and
+ * the end is preserved.  This will make a long, truncated string look
+ * like "X <...> Y", where X and Y are half the number of characters
+ * of the maximum string length from either side of the string.
+ *
+ *
+ * Usage::
+ *
+ *     truncate`Hello ${"x".repeat(260)}!`;
+ *     // Hello xxx ... xxx!
+ *
+ * Functions named `toJSON` or `toString` on objects will be called.
+ */
+export function truncate(strings, ...values) {
+  function walk(obj) {
+    const typ = Object.prototype.toString.call(obj);
+
+    switch (typ) {
+      case "[object Undefined]":
+      case "[object Null]":
+      case "[object Boolean]":
+      case "[object Number]":
+        return obj;
+
+      case "[object String]":
+        if (lazy.truncateLog && obj.length > MAX_STRING_LENGTH) {
+          let s1 = obj.substring(0, MAX_STRING_LENGTH / 2);
+          let s2 = obj.substring(obj.length - MAX_STRING_LENGTH / 2);
+          return `${s1} ... ${s2}`;
+        }
+        return obj;
+
+      case "[object Array]":
+        return obj.map(walk);
+
+      // arbitrary object
+      default:
+        if (
+          Object.getOwnPropertyNames(obj).includes("toString") &&
+          typeof obj.toString == "function"
+        ) {
+          return walk(obj.toString());
+        }
+
+        let rv = {};
+        for (let prop in obj) {
+          rv[prop] = walk(obj[prop]);
+        }
+        return rv;
+    }
+  }
+
+  let res = [];
+  for (let i = 0; i < strings.length; ++i) {
+    res.push(strings[i]);
+    if (i < values.length) {
+      let obj = walk(values[i]);
+      let t = Object.prototype.toString.call(obj);
+      if (t == "[object Array]" || t == "[object Object]") {
+        res.push(JSON.stringify(obj));
+      } else {
+        res.push(obj);
+      }
+    }
+  }
+  return res.join("");
+}