From 84dc2d07fa19c237479c1681385a63d64fddcc74 Mon Sep 17 00:00:00 2001
From: Luke Granger-Brown <lukegb@google.com>
Date: Wed, 6 Jul 2016 13:28:29 +0100
Subject: [PATCH] [vim bindings] Make Backspace delete characters

In Replace mode (or Overwrite mode) it should still go backwards
without deleting characters.
---
 keymap/vim.js    | 19 ++++++++++++++++---
 test/vim_test.js | 28 +++++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/keymap/vim.js b/keymap/vim.js
index 9891eb5fcb..afed132e36 100644
--- a/keymap/vim.js
+++ b/keymap/vim.js
@@ -53,7 +53,6 @@
     { keys: '<Down>', type: 'keyToKey', toKeys: 'j' },
     { keys: '<Space>', type: 'keyToKey', toKeys: 'l' },
     { keys: '<BS>', type: 'keyToKey', toKeys: 'h', context: 'normal'},
-    { keys: '<BS>', type: 'motion', motion: 'moveByCharacters', motionArgs: { forward: false }, context: 'insert'},
     { keys: '<C-Space>', type: 'keyToKey', toKeys: 'W' },
     { keys: '<C-BS>', type: 'keyToKey', toKeys: 'B', context: 'normal' },
     { keys: '<S-Space>', type: 'keyToKey', toKeys: 'w' },
@@ -73,6 +72,7 @@
     { keys: '<PageUp>', type: 'keyToKey', toKeys: '<C-b>' },
     { keys: '<PageDown>', type: 'keyToKey', toKeys: '<C-f>' },
     { keys: '<CR>', type: 'keyToKey', toKeys: 'j^', context: 'normal' },
+    { keys: '<Ins>', type: 'action', action: 'toggleOverwrite', context: 'insert' },
     // Motions
     { keys: 'H', type: 'motion', motion: 'moveToTopLine', motionArgs: { linewise: true, toJumplist: true }},
     { keys: 'M', type: 'motion', motion: 'moveToMiddleLine', motionArgs: { linewise: true, toJumplist: true }},
@@ -277,6 +277,7 @@
 
     function cmKey(key, cm) {
       if (!cm) { return undefined; }
+      if (this[key]) { return this[key]; }
       var vimKey = cmKeyToVimKey(key);
       if (!vimKey) {
         return false;
@@ -289,7 +290,7 @@
     }
 
     var modifiers = {'Shift': 'S', 'Ctrl': 'C', 'Alt': 'A', 'Cmd': 'D', 'Mod': 'A'};
-    var specialKeys = {Enter:'CR',Backspace:'BS',Delete:'Del'};
+    var specialKeys = {Enter:'CR',Backspace:'BS',Delete:'Del',Insert:'Ins'};
     function cmKeyToVimKey(key) {
       if (key.charAt(0) == '\'') {
         // Keypress character binding of format "'a'"
@@ -2175,6 +2176,17 @@
         var registerName = actionArgs.selectedCharacter;
         macroModeState.enterMacroRecordMode(cm, registerName);
       },
+      toggleOverwrite: function(cm) {
+        if (!cm.state.overwrite) {
+          cm.toggleOverwrite(true);
+          cm.setOption('keyMap', 'vim-replace');
+          CodeMirror.signal(cm, "vim-mode-change", {mode: "replace"});
+        } else {
+          cm.toggleOverwrite(false);
+          cm.setOption('keyMap', 'vim-insert');
+          CodeMirror.signal(cm, "vim-mode-change", {mode: "insert"});
+        }
+      },
       enterInsertMode: function(cm, actionArgs, vim) {
         if (cm.getOption('readOnly')) { return; }
         vim.insertMode = true;
@@ -2220,7 +2232,6 @@
             return;
           }
         }
-        cm.setOption('keyMap', 'vim-insert');
         cm.setOption('disableInput', false);
         if (actionArgs && actionArgs.replace) {
           // Handle Replace-mode as a special case of insert mode.
@@ -2228,6 +2239,7 @@
           cm.setOption('keyMap', 'vim-replace');
           CodeMirror.signal(cm, "vim-mode-change", {mode: "replace"});
         } else {
+          cm.toggleOverwrite(false);
           cm.setOption('keyMap', 'vim-insert');
           CodeMirror.signal(cm, "vim-mode-change", {mode: "insert"});
         }
@@ -4779,6 +4791,7 @@
     };
 
     CodeMirror.keyMap['vim-replace'] = {
+      'Backspace': 'goCharLeft',
       fallthrough: ['vim-insert'],
       attach: attachVimMap,
       detach: detachVimMap,
diff --git a/test/vim_test.js b/test/vim_test.js
index fb612b1407..159114cecd 100644
--- a/test/vim_test.js
+++ b/test/vim_test.js
@@ -145,7 +145,7 @@ function testVim(name, run, opts, expectedFail) {
         for (var i = 0; i < arguments.length; i++) {
           var key = arguments[i];
           // Find key in keymap and handle.
-          var handled = CodeMirror.lookupKey(key, 'vim-insert', executeHandler);
+          var handled = CodeMirror.lookupKey(key, cm.getOption('keyMap'), executeHandler, cm);
           // Record for insert mode.
           if (handled == "handled" && cm.state.vim.insertMode && arguments[i] != 'Esc') {
             var lastChange = CodeMirror.Vim.getVimGlobalState_().macroModeState.lastInsertModeChanges;
@@ -1419,6 +1419,32 @@ testVim('i_repeat_delete', function(cm, vim, helpers) {
   eq('abe', cm.getValue());
   helpers.assertCursorAt(0, 1);
 }, { value: 'abcde' });
+testVim('insert', function(cm, vim, helpers) {
+  helpers.doKeys('i');
+  eq('vim-insert', cm.getOption('keyMap'));
+  eq(false, cm.state.overwrite);
+  helpers.doKeys('<Ins>');
+  eq('vim-replace', cm.getOption('keyMap'));
+  eq(true, cm.state.overwrite);
+  helpers.doKeys('<Ins>');
+  eq('vim-insert', cm.getOption('keyMap'));
+  eq(false, cm.state.overwrite);
+});
+testVim('i_backspace', function(cm, vim, helpers) {
+  cm.setCursor(0, 10);
+  helpers.doKeys('i');
+  helpers.doInsertModeKeys('Backspace');
+  helpers.assertCursorAt(0, 9);
+  eq('012345678', cm.getValue());
+}, { value: '0123456789'});
+testVim('i_overwrite_backspace', function(cm, vim, helpers) {
+  cm.setCursor(0, 10);
+  helpers.doKeys('i');
+  helpers.doKeys('<Ins>');
+  helpers.doInsertModeKeys('Backspace');
+  helpers.assertCursorAt(0, 9);
+  eq('0123456789', cm.getValue());
+}, { value: '0123456789'});
 testVim('A', function(cm, vim, helpers) {
   helpers.doKeys('A');
   helpers.assertCursorAt(0, lines[0].length);