[vim mode] Added yank command to yank the current line

Author: Bharad

keymap/vim.js

@@ -226,6 +226,7 @@
     { name: 'sort', shortName: 'sor' },
     { name: 'substitute', shortName: 's', possiblyAsync: true },
     { name: 'nohlsearch', shortName: 'noh' },
+    { name: 'yank', shortName: 'y' },
     { name: 'delmarks', shortName: 'delm' },
     { name: 'registers', shortName: 'reg', excludeFromCommandHistory: true },
     { name: 'global', shortName: 'g' }
@@ -4522,6 +4523,13 @@
       nohlsearch: function(cm) {
         clearSearchHighlight(cm);
       },
+      yank: function (cm) {
+        var cur = copyCursor(cm.getCursor());
+        var line = cur.line;
+        var lineText = cm.getLine(line);
+        vimGlobalState.registerController.pushText(
+          '0', 'yank', lineText, true, true);
+      },
       delmarks: function(cm, params) {
         if (!params.argString || !trim(params.argString)) {
           showConfirm(cm, 'Argument required');

test/vim_test.js

@@ -3725,6 +3725,14 @@ testVim('ex_noh_clearSearchHighlight', function(cm, vim, helpers) {
   helpers.doKeys('n');
   helpers.assertCursorAt(0, 11,'can\'t resume search after clearing highlighting');
 }, { value: 'match nope match \n nope Match' });
+testVim('ex_yank', function (cm, vim, helpers) {
+  var curStart = makeCursor(3, 0);
+  cm.setCursor(curStart);
+  helpers.doEx('y');
+  var register = helpers.getRegisterController().getRegister();
+  var line = cm.getLine(3);
+  eq(line + '\n', register.toString());
+});
 testVim('set_boolean', function(cm, vim, helpers) {
   CodeMirror.Vim.defineOption('testoption', true, 'boolean');
   // Test default value is set.