feat: add the fixer function to eslint/rules/vars-order

PR-URL: #3224
Closes: #3222

Co-authored-by: Philipp Burckhardt <pburckhardt@outlook.com>
Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>
Signed-off-by: Muhammad Haris <101793258+headlessNode@users.noreply.github.com>

Author: headlessNode

lib/node_modules/@stdlib/_tools/eslint/rules/vars-order/lib/main.js

@@ -81,19 +81,88 @@ function main( context ) {
 		break;
 	}
 
+	/**
+	* Sorts the variable declarations by name length.
+	*
+	* @private
+	* @param {Object} a - input object
+	* @param {Object} b - comparison object
+	* @returns {number} number indicating sort order
+	*/
+	function sortVars( a, b ) {
+		if ( fun( a.name.length, b.name.length ) ) {
+			return 1;
+		}
+		return -1;
+	}
+
 	/**
 	* Reports the error message.
 	*
 	* @private
 	* @param {string} msg - error message
-	* @param {Object} loc - lines of code (object with `start` and `end` properties)
+	* @param {ASTNode} node - node to fix
 	*/
-	function report( msg, loc ) {
+	function report( msg, node ) {
 		context.report({
 			'node': null,
 			'message': msg,
-			'loc': loc
+			'loc': node.loc,
+			'fix': fix
 		});
+
+		/**
+		* Fixes the lint error by reordering the variable declarations inside of the function.
+		*
+		* @private
+		* @param {Function} fixer - ESLint fixer
+		* @returns {(Object|null)} fix or null
+		*/
+		function fix( fixer ) {
+			var replacingText;
+			var declarations;
+			var startRange;
+			var endRange;
+			var source;
+			var elem;
+			var body;
+			var i;
+			var j;
+
+			declarations = [];
+			replacingText = '';
+			body = node.body.body;
+			source = context.getSourceCode();
+
+			for ( i = 0; i < body.length; i++ ) {
+				elem = body[ i ];
+				if ( elem.type === 'VariableDeclaration' && elem.kind === 'var' ) {
+					declarations.push({
+						'text': source.getText( elem ),
+						'name': elem.declarations[ 0 ].id.name,
+						'col': elem.loc.start.column
+					});
+					if ( declarations.length === 1 ) {
+						startRange = elem.range[ 0 ] - elem.loc.start.column;
+					}
+					endRange = elem.range[ 1 ];
+				}
+			}
+
+			declarations.sort( sortVars );
+
+			for ( i = 0; i < declarations.length; i++ ) {
+				for ( j = 0; j < declarations[ i ].col; j++ ) {
+					replacingText += '\t';
+				}
+				replacingText += declarations[ i ].text;
+				if ( i !== declarations.length -1 ) {
+					replacingText += '\n';
+				}
+			}
+
+			return fixer.replaceTextRange( [ startRange, endRange ], replacingText ); // eslint-disable-line max-len
+		}
 	}
 
 	/**
@@ -117,7 +186,7 @@ function main( context ) {
 			if ( elem.type === 'VariableDeclaration' && elem.kind === 'var' ) {
 				name = elem.declarations[ 0 ].id.name;
 				if ( prevLength && !fun( name.length, prevLength ) ) {
-					return report( 'Variable declarations inside of function are not ordered by length (in '+ order +' order)', node.loc );
+					return report( 'Variable declarations inside of function are not ordered by length (in '+ order +' order)', node );
 				}
 				prevLength = name.length;
 			}
@@ -135,9 +204,11 @@ function main( context ) {
 
 rule = {
 	'meta': {
+		'type': 'layout',
 		'docs': {
 			'description': 'require variable declarations inside of functions to be ordered by length'
 		},
+		'fixable': 'code',
 		'schema': [
 			{
 				'order': [ 'increasing', 'decreasing' ]