build: ensure existing link definitions are not duplicated

Author: Planeshifter

lib/node_modules/@stdlib/_tools/remark/plugins/remark-stdlib-related/lib/transformer.js

@@ -80,6 +80,31 @@ function removeLinks( tree ) {
 	return found;
 }
 
+/**
+* Collects existing link definitions into an object.
+*
+* @private
+* @param {Node} node - reference node
+* @returns {Object} object mapping link identifiers to `true`
+*/
+function collectExistingLinks( node ) {
+	var existingLinks = {};
+	visit( node, 'definition', onDefinition );
+	return existingLinks;
+
+	/**
+	* Callback invoked upon encountering a link definition.
+	*
+	* @private
+	* @param {Node} definition - reference node
+	* @returns {void}
+	*/
+	function onDefinition( definition ) {
+		var identifier = definition.identifier;
+		existingLinks[ identifier ] = true;
+	}
+}
+
 
 // MAIN //
 
@@ -91,10 +116,12 @@ function removeLinks( tree ) {
 * @param {File} file - virtual file
 */
 function transformer( tree, file ) {
+	var existingLinks;
 	var found;
 	debug( 'Processing virtual file...' );
 
 	found = removeLinks( tree );
+	existingLinks = collectExistingLinks( tree );
 	visit( tree, 'html', insertSeeAlso );
 
 	/**
@@ -142,7 +169,9 @@ function transformer( tree, file ) {
 				content += '<span class="delimiter">: </span>';
 				content += '<span class="description">' + description + '</span>';
 				content += '\n';
-				links.push( '['+related[ i ]+']: https://github.com/stdlib-js/stdlib' );
+				if ( !existingLinks[ related[ i ] ] ) {
+					links.push( '['+related[ i ]+']: https://github.com/stdlib-js/stdlib' );
+				}
 			}
 			content += '\n';
 			content += '</section>';