Rewrite sys.inspect to be more reliable and handle crazy edge cases.

lib/sys.js

@@ -21,9 +21,99 @@ exports.error = function (x) {
  * in the best way possible given the different types.
  *
  * @param {Object} value The object to print out
+ * @param {Boolean} showHidden Flag that shows hidden (not enumerable) properties of objects.
  */
-exports.inspect = function (value) {
+exports.inspect = function (obj, showHidden) {
-  return formatter(value, '', []);
+  var seen = [];
+  function format(value) {
+    var keys, visible_keys, base, type, braces;
+    // Primitive types cannot have properties
+    switch (typeof value) {
+      case 'undefined': return 'undefined';
+      case 'string':    return JSON.stringify(value);
+      case 'number':    return '' + value;
+      case 'boolean':   return '' + value;
+    }
+    // For some reason typeof null is "object", so special case here.
+    if (value === null) {
+      return 'null';
+    }
+
+    // Look up the keys of the object.
+    keys = showHidden ? Object.getOwnPropertyNames(value).map(function (key) {
+      return '' + key;
+    }) : Object.keys(value);
+    visible_keys = Object.keys(value);
+
+    // Functions without properties can be shortcutted.
+    if (typeof value === 'function' && keys.length === 0) {
+      if (value instanceof RegExp) {
+        return '' + value;
+      } else {
+        return '[Function]';
+      }
+    }
+
+    // Determine the object type
+    if (value instanceof Array) {
+      type = 'Array';
+      braces = ["[", "]"];
+    } else {
+      type = 'Object';
+      braces = ["{", "}"];
+    }
+
+    // Make functions say that they are functions
+    if (typeof value === 'function') {
+      base = (value instanceof RegExp) ? ' ' + value : ' [Function]';
+    } else {
+      base = "";
+    }
+
+    seen.push(value);
+
+    if (keys.length === 0) {
+      return braces[0] + base + braces[1];
+    }
+
+    return braces[0] + base + "\n" + (keys.map(function (key) {
+      var name, str;
+      if (value.__lookupGetter__) {
+        if (value.__lookupGetter__(key)) {
+          if (value.__lookupSetter__(key)) {
+            str = "[Getter/Setter]";
+          } else {
+            str = "[Getter]";
+          }
+        } else {
+          if (value.__lookupSetter__(key)) {
+            str = "[Setter]";
+          }
+        }
+      }
+      if (visible_keys.indexOf(key) < 0) {
+        name = "[" + key + "]";
+      }
+      if (!str) {
+        if (seen.indexOf(value[key]) < 0) {
+          str = format(value[key]);
+        } else {
+          str = '[Circular]';
+        }
+      }
+      if (typeof name === 'undefined') {
+        if (type === 'Array' && key.match(/^\d+$/)) {
+          return str;
+        }
+        name = JSON.stringify('' + key);
+      }
+
+      return name + ": " + str;
+    }).join(",\n")).split("\n").map(function (line) {
+      return ' ' + line;
+    }).join('\n') + "\n" + braces[1];
+  }
+  return format(obj);
 };
 
 exports.p = function (x) {
@@ -70,76 +160,4 @@ exports.exec = function (command) {
  */
 exports.inherits = process.inherits;
 
-/**
+// Object.create(null, {name: {value: "Tim", enumerable: true}})
- * A recursive function to format an object - used by inspect.
- *
- * @param {Object} value
- *   the value to format
- * @param {String} indent
- *   the indent level of any nested objects, since they are formatted over
- *   more than one line
- * @param {Array} parents
- *   contains all objects above the current one in the heirachy, used to
- *   prevent getting stuck in a loop on circular references
- */
-var formatter = function(value, indent, parents) {
-  switch(typeof(value)) {
-    case 'string':    return JSON.stringify(value);
-    case 'number':    return '' + value;
-    case 'function':  return '[Function]';
-    case 'boolean':   return '' + value;
-    case 'undefined': return 'undefined';
-    case 'object':
-      if (value == null) return 'null';
-      if (parents.indexOf(value) >= 0) return '[Circular]';
-      parents.push(value);
-
-      if (value instanceof Array && Object.keys(value).length === value.length) {
-        return formatObject(value, indent, parents, '[]', function(x, f) {
-          return f(value[x]);
-        });
-      } else {
-        return formatObject(value, indent, parents, '{}', function(x, f) {
-          var child;
-          if (value.__lookupGetter__(x)) {
-            if (value.__lookupSetter__(x)) {
-              child = "[Getter/Setter]";
-            } else {
-              child = "[Getter]";
-            }
-          } else {
-            if (value.__lookupSetter__(x)) {
-              child = "[Setter]";
-            } else {
-              child = f(value[x]);
-            }
-          }
-          return f(x) + ': ' + child;
-        });
-      }
-      return buffer;
-    default:
-      throw('inspect unimplemented for ' + typeof(value));
-  }
-}
-
-/**
- * Helper function for formatting either an array or an object, used internally by formatter
- */
-var formatObject = function(obj, indent, parents, parenthesis, entryFormatter) {
-  var buffer = parenthesis[0];
-  var values = [];
-  var x;
-
-  var localFormatter = function(value) {
-    return formatter(value, indent + ' ', parents);
-  };
-  for (x in obj) {
-    values.push(indent + ' ' + entryFormatter(x, localFormatter));
-  }
-  if (values.length > 0) {
-    buffer += "\n" + values.join(",\n") + "\n" + indent;
-  }
-  buffer += parenthesis[1];
-  return buffer;
-}

test/mjsunit/test-sys.js

@@ -9,6 +9,7 @@ assert.equal('"hello"', inspect("hello"));
 assert.equal("[Function]", inspect(function() {}));
 assert.equal('undefined', inspect(undefined));
 assert.equal('null', inspect(null));
+assert.equal('/foo(bar\\n)?/gi', inspect(/foo(bar\n)?/gi));
 
 assert.equal("\"\\n\\u0001\"", inspect("\n\u0001"));
 
@@ -23,6 +24,24 @@ assert.equal('{\n "a": [Function]\n}', inspect({a: function() {}}));
 assert.equal('{\n "a": 1,\n "b": 2\n}', inspect({a: 1, b: 2}));
 assert.equal('{\n "a": {}\n}', inspect({'a': {}}));
 assert.equal('{\n "a": {\n  "b": 2\n }\n}', inspect({'a': {'b': 2}}));
+assert.equal('[\n 1,\n 2,\n 3,\n [length]: 3\n]', inspect([1,2,3], true));
+assert.equal("{\n \"visible\": 1\n}",
+  inspect(Object.create({}, {visible:{value:1,enumerable:true},hidden:{value:2}}))
+);
+assert.equal("{\n [hidden]: 2,\n \"visible\": 1\n}",
+  inspect(Object.create({}, {visible:{value:1,enumerable:true},hidden:{value:2}}), true)
+);
+
+// Objects without prototype
+assert.equal(
+  "{\n [hidden]: \"secret\",\n \"name\": \"Tim\"\n}",
+  inspect(Object.create(null, {name: {value: "Tim", enumerable: true}, hidden: {value: "secret"}}), true)
+);
+assert.equal(
+  "{\n \"name\": \"Tim\"\n}",
+  inspect(Object.create(null, {name: {value: "Tim", enumerable: true}, hidden: {value: "secret"}}))
+);
+
 
 // Dynamic properties
 assert.equal(
@@ -35,12 +54,28 @@ value['a'] = value;
 assert.equal('{\n "a": [Circular]\n}', inspect(value));
 value = Object.create([]);
 value.push(1);
-assert.equal('{\n "0": 1,\n "length": 1\n}', inspect(value));
+assert.equal("[\n 1,\n \"length\": 1\n]", inspect(value));
 
 // Array with dynamic properties
 value = [1,2,3];
 value.__defineGetter__('growingLength', function () { this.push(true); return this.length; });
 assert.equal(
-  "{\n \"0\": 1,\n \"1\": 2,\n \"2\": 3,\n \"growingLength\": [Getter]\n}",
+  "[\n 1,\n 2,\n 3,\n \"growingLength\": [Getter]\n]",
   inspect(value)
-);
+);
+
+// Function with properties
+value = function () {};
+value.aprop = 42;
+assert.equal(
+  "{ [Function]\n \"aprop\": 42\n}",
+  inspect(value)
+);
+
+// Regular expressions with properties
+value = /123/ig;
+value.aprop = 42;
+assert.equal(
+  "{ /123/gi\n \"aprop\": 42\n}",
+  inspect(value)
+);