[Perf] Remove getLoc from linesBetween() method

Author: mdevils

lib/js-file.js

@@ -647,6 +647,26 @@ JsFile.prototype = {
         return distance;
     },
 
+    getLineCountBetween(tokenBefore, tokenAfter) {
+        if (tokenBefore === tokenAfter) {
+            return 0;
+        }
+        tokenBefore = tokenBefore instanceof Token ? tokenBefore : tokenBefore.getLastToken();
+        tokenAfter = tokenAfter instanceof Token ? tokenAfter : tokenAfter.getFirstToken();
+
+        var currentToken = tokenBefore.getNextToken();
+        var lineCount = 0;
+        while (currentToken) {
+            if (currentToken === tokenAfter) {
+                break;
+            }
+
+            lineCount += currentToken.getNewlineCount();
+            currentToken = currentToken.getNextToken();
+        }
+        return lineCount;
+    },
+
     /**
      * Returns array of source lines for the file with comments removed.
      *

lib/rules/require-newline-before-single-statements-in-if.js

@@ -48,6 +48,13 @@ var assert = require('assert');
 
 module.exports = function() {};
 
+function getFirstStatement(node) {
+    if (node && node.type === 'BlockStatement') {
+        return node.body[0];
+    }
+    return node;
+}
+
 module.exports.prototype = {
 
     configure: function(value) {
@@ -80,13 +87,21 @@ module.exports.prototype = {
         }
 
         file.iterateNodesByType('IfStatement', function(node) {
-            var consequentNode = node.consequent;
-            var alternateNode = node.alternate;
+            var consequentNode = getFirstStatement(node.consequent);
+            var alternateNode = getFirstStatement(node.alternate);
 
-            assertDifferentLine(consequentNode, getToken(consequentNode, 'Keyword', 'previousSibling'));
+            if (consequentNode) {
+                assertDifferentLine(
+                    getToken(consequentNode, 'Keyword', 'previousSibling'),
+                    consequentNode
+                );
+            }
 
-            if (alternateNode) {
-                assertDifferentLine(alternateNode, getToken(alternateNode, 'Keyword', 'previousSibling'));
+            if (alternateNode && alternateNode.type !== 'IfStatement' && alternateNode.type !== 'BlockStatement') {
+                assertDifferentLine(
+                    getToken(alternateNode, 'Keyword', 'previousSibling'),
+                    alternateNode
+                );
             }
         });
     }

lib/token-assert.js

@@ -297,7 +297,7 @@ TokenAssert.prototype.linesBetween = function(options) {
     // as this prevents accidentally moving a valid token onto a line comment ed line
     var fixed = !options.token.getNextNonWhitespaceToken().isComment;
 
-    var linesBetween = Math.abs(token.getLoc().end.line - nextToken.getLoc().start.line);
+    var linesBetween = this._file.getLineCountBetween(token, nextToken);
 
     var emitError = function(countPrefix, lineCount) {
         var msgPrefix = token.value + ' and ' + nextToken.value;