Fix max-line-length column number for lines with urls

Closes #2286

lib/rules/max-line-length/README.md

@@ -10,7 +10,7 @@ a { color: red }
 
 Lines that exceed the maximum length but contain no whitespace (other than at the beginning of the line) are ignored.
 
-When evaluating the line length, `url(...)` functions are collapsed into just `url()`, because typically you have no control over the length of its argument. This means that long `url()` functions should not contribute to warnings.
+When evaluating the line length, the arguments of any `url(...)` functions are excluded from the calculation, because typically you have no control over the length of these arguments. This means that long `url()` functions should not contribute to warnings.
 
 ## Options
 
@@ -103,7 +103,7 @@ a { color: pink; }
 ```css
 /*
  * comment that is too long the max length
- * comment that is too long the max length 
+ * comment that is too long the max length
  *
  */
 a { color: pink; }

lib/rules/max-line-length/index.js

@@ -1,5 +1,6 @@
 "use strict"
 
+const execall = require("execall")
 const optionsMatches = require("../../utils/optionsMatches")
 const report = require("../../utils/report")
 const ruleMessages = require("../../utils/ruleMessages")
@@ -32,9 +33,7 @@ const rule = function (maxLength, options) {
       return
     }
 
-    // Collapse all urls into something nice and short,
-    // so they do not throw the game
-    const rootString = root.toString().replace(/url\(.*\)/ig, "url()")
+    const rootString = root.toString()
 
     const ignoreNonComments = optionsMatches(options, "ignore", "non-comments")
     const ignoreComments = optionsMatches(options, "ignore", "comments")
@@ -66,9 +65,16 @@ const rule = function (maxLength, options) {
         nextNewlineIndex = rootString.length
       }
 
+      const rawLineLength = nextNewlineIndex - match.endIndex
+      const lineText = rootString.slice(match.endIndex, nextNewlineIndex)
+      const urlValueLengths = execall(/url\((.*)\)/ig, lineText).reduce((result, match) => {
+        return result + _.get(match, "sub[0].length", 0)
+      }, 0)
+
       // If the line's length is less than or equal to the specified
-      // max, ignore it ... So anything below is liable to be complained about
-      if (nextNewlineIndex - match.endIndex <= maxLength) {
+      // max, ignore it ... So anything below is liable to be complained about.
+      // **Note that the length of any url values are excluded from the calculation.**
+      if (rawLineLength - urlValueLengths <= maxLength) {
         return
       }