Errors: ability to suppress errors via inline comments.

Fixes jscs-dev#335 and Fixes jscs-dev#486

README.md

@@ -160,6 +160,51 @@ Values: A single file extension or an Array of file extensions, beginning with a
 "fileExtensions": [".js"]
 ```
 
+## Error Suppression
+
+### Inline Comments
+
+You can disable and reenable rules inline with two special comments: `//jscs:disable` and `//jscs:enable`. You can use them to disable rules in 3 ways.
+
+#### Disabling All Rules
+
+Simply using `//jscs:disable` or `//jscs:enable` will disable all rules.
+```
+var a = b;
+//jscs:disable
+var c = d; // all errors on this line will be ignored
+//jscs:enable
+var e = f; // all errors on this line will be reported
+```
+
+#### Disabling Specific Rules
+
+Including a comma separated list of rules to modify after `//jscs:disable` or `//jscs:enable` will modify only those rules.
+```
+//jscs:disable requireCurlyBraces
+if (x) y(); // all errors from requireCurlyBraces on this line will be ignored
+//jscs:enable requireCurlyBraces
+if (z) a(); // all errors, including from requireCurlyBraces, on this line will be reported
+```
+
+You can enable all rules after disabling a specific rule, and that rule becomes reenabled as well.
+```
+//jscs:disable requireCurlyBraces
+if (x) y(); // all errors from requireCurlyBraces on this line will be ignored
+//jscs:enable
+if (z) a(); // all errors, even from requireCurlyBraces, will be reported
+```
+
+You can disable multiple rules at once and progressively reeanble them.
+```
+//jscs:disable requireCurlyBraces, requireDotNotation
+if (x['a']) y(); // all errors from requireCurlyBraces OR requireDotNotation on this line will be ignored
+//jscs:enable requireCurlyBraces
+if (z['a']) a(); // all errors from requireDotNotation, but not requireCurlyBraces, will be ignored
+//jscs:enable requireDotNotation
+if (z['a']) a(); // all errors will be reported
+```
+
 ## Rules
 
 ### requireCurlyBraces

lib/errors.js

@@ -27,6 +27,11 @@ Errors.prototype = {
             column = line.column;
             line = line.line;
         }
+
+        if (!this._file.isEnabledRule(this._currentRule, line)) {
+            return;
+        }
+
         this._errorList.push({
             rule: this._currentRule,
             message: this._verbose ? this._currentRule + ': ' + message : message,

lib/js-file.js

@@ -36,6 +36,8 @@ var JsFile = function(filename, source, tree) {
         }
     });
 
+    this._buildDisabledRuleIndex();
+
     // Part of temporary esprima fix.
     function convertKeywordToIdentifierIfRequired(node) {
         var tokenPos = _this.getTokenPosByRangeStart(node.range[0]);
@@ -49,6 +51,77 @@ var JsFile = function(filename, source, tree) {
 };
 
 JsFile.prototype = {
+    /**
+     * Builds an index of disabled rules by starting line for error suppression.
+     */
+    _buildDisabledRuleIndex: function() {
+        this._disabledRuleIndex = [];
+
+        var comments = this.getComments() || [];
+        var commentRe = /(jscs:(en|dis)able)(.*)/;
+
+        comments.forEach(function(comment) {
+            var enabled;
+            var parsed = commentRe.exec(comment.value.trim());
+
+            if (!parsed || parsed.index !== 0) {
+                return;
+            }
+
+            enabled = parsed[2] === 'en';
+            this._addToDisabledRuleIndex(enabled, parsed[3], comment.loc.start.line);
+        }, this);
+    },
+
+    /**
+     * returns whether a specific rule is disabled on the given line.
+     *
+     * @param {String} rule the rule name being tested
+     * @param {Number} line the line number being tested
+     * @returns {Boolean} true if the rule is enabled
+     */
+    isEnabledRule: function(rule, line) {
+        var enabled = true;
+        this._disabledRuleIndex.some(function(region) {
+            if (region.line > line) {
+                return true;
+            }
+
+            if (region.rule === rule || region.rule === '*') {
+                enabled = region.enabled;
+            }
+        }, this);
+
+        return enabled;
+    },
+
+    /**
+     * Adds rules to the disabled index given a string containing rules (or '' for all).
+     *
+     * @param {Boolean} enabled whether the rule is disabled or enabled on this line
+     * @param {String} rulesStr the string containing specific rules to en/disable
+     * @param {Number} line the line the comment appears on
+     */
+    _addToDisabledRuleIndex: function(enabled, rulesStr, line) {
+        rulesStr = rulesStr || '*';
+
+        rulesStr.split(',').forEach(function(rule) {
+            var ruleLength;
+
+            rule = rule.trim();
+
+            if (!rule) {
+                return;
+            }
+
+            this._disabledRuleIndex.push({
+                rule: rule,
+                enabled: enabled,
+                line: line
+            });
+        }, this);
+    },
+
     /**
      * Builds token index by starting pos for futher navigation.
      */

test/errors.js

@@ -20,4 +20,50 @@ describe('modules/errors', function() {
 
         assert.ok(error.rule === 'disallowQuotedKeysInObjects');
     });
+
+    it('should suppress errors with disable comment', function() {
+        var errors = checker.checkString('//jscs:disable\n\tvar x = { "a": 1 }');
+        assert.ok(errors.isEmpty());
+    });
+
+    it('should not suppress errors with disable followed by enable comment', function() {
+        var errors = checker.checkString('//jscs:disable\n//jscs:enable\n\tvar x = { "a": 1 }');
+        assert.ok(!errors.isEmpty());
+    });
+
+    it('should suppress errors with disable comment followed by enable comment after error location', function() {
+        var errors = checker.checkString('//jscs:disable\n\tvar x = { "a": 1 };\n//jscs:enable');
+        assert.ok(errors.isEmpty());
+    });
+
+    it('should suppress errors when specific rule is disabled', function() {
+        var errors = checker.checkString('//jscs:disable disallowQuotedKeysInObjects\n\tvar x = { "a": 1 }');
+        assert.ok(errors.isEmpty());
+    });
+
+    it('should not suppress errors when other rule is disabled', function() {
+        var errors = checker.checkString('//jscs:disable someRuleName\n\tvar x = { "a": 1 }');
+        assert.ok(!errors.isEmpty());
+    });
+
+    it('should not suppress errors with disable followed by specific enable comment', function() {
+        var errors = checker.checkString('//jscs:disable\n ' +
+            '//jscs:enable disallowQuotedKeysInObjects\n\tvar x = { "a": 1 }');
+
+        assert.ok(!errors.isEmpty());
+    });
+
+    it('should suppress errors with disable followed by specific enable other comment', function() {
+        var errors = checker.checkString('//jscs:disable\n ' +
+            '//jscs:enable someRuleName\n\tvar x = { "a": 1 }');
+
+        assert.ok(errors.isEmpty());
+    });
+
+    it('should not suppress errors with disable followed by specific enable other comment', function() {
+        var errors = checker.checkString('//jscs:disable\n ' +
+            '//jscs:enable someRuleName, disallowQuotedKeysInObjects\n\tvar x = { "a": 1 }');
+
+        assert.ok(!errors.isEmpty());
+    });
 });