Add translate command for key mappings.

Under *Custom key mappings* (on the options page), this implements:

    translate x y

Whenever the users types `x` in normal mode or in visual mode, the `x`
is replaced by `y`.

For example:

    map ç l

(which apparently would be helpful on Brazilian keyboards).

Issues:

- Do we want yet another hack like this?  This would be documented only on
  the wiki.

- If we allowed `translate <c-c> <c-[>` (and extended `isEscape()` to
  use the translation), then we'd get the `exitMode` command for free
  (#2253).

- Alternatively, instead of adding a new "command" called `translate`,
  we could overload the existing `map` command.  Since these are
  single-key mappings, there's no ambiguity.  (Although, I guess there's
  a risk some user has junk in their key mappings and would be taken by
  surprise).

Inspired by isssue posted by @vhoyer (#2305).

Fixes #2305.

2 files changed, 17 insertions, 0 deletions

diff --git a/background_scripts/commands.coffee b/background_scripts/commands.coffee
index 7a4526c2..17c05f90 100644
--- a/background_scripts/commands.coffee
+++ b/background_scripts/commands.coffee
@@ -9,6 +9,7 @@ Commands =
     @clearKeyMappingsAndSetDefaults()
     @parseCustomKeyMappings customKeyMappings
     @generateKeyStateMapping()
+    chrome.storage.local.set keyTranslationRegistry: @keyTranslationRegistry
 
   availableCommands: {}
   keyToCommandRegistry: {}
@@ -84,6 +85,12 @@ Commands =
           when "unmapAll"
             @keyToCommandRegistry = {}
 
+          when "translate"
+            if tokens.length == 3
+              fromChar = @parseKeySequence tokens[1]
+              toChar = @parseKeySequence tokens[2]
+              @keyTranslationRegistry[fromChar[0]] = toChar[0] if fromChar.length == toChar.length == 1
+
     # Push the key mapping for passNextKey into Settings so that it's available in the front end for insert
     # mode.  We exclude single-key mappings (that is, printable keys) because when users press printable keys
     # in insert mode they expect the character to be input, not to be droppped into some special Vimium
@@ -109,6 +116,7 @@ Commands =
 
   clearKeyMappingsAndSetDefaults: ->
     @keyToCommandRegistry = {}
+    @keyTranslationRegistry = {}
     for own key, command of defaultKeyMappings
       keySequence = @parseKeySequence key
       key = keySequence.join ""
diff --git a/content_scripts/mode_key_handler.coffee b/content_scripts/mode_key_handler.coffee
index 8c0ae4b8..7904d801 100644
--- a/content_scripts/mode_key_handler.coffee
+++ b/content_scripts/mode_key_handler.coffee
@@ -33,8 +33,16 @@ class KeyHandlerMode extends Mode
       # We cannot track keyup events if we lose the focus.
       blur: (event) => @alwaysContinueBubbling => @keydownEvents = {} if event.target == window
 
+    @keyTranslationRegistry = {}
+    chrome.storage.local.get "keyTranslationRegistry", (obj) =>
+      @keyTranslationRegistry = obj.keyTranslationRegistry
+      chrome.storage.onChanged.addListener (changes, area) =>
+        if area == "local" and changes.keyTranslationRegistry?.newValue?
+          @keyTranslationRegistry = changes.keyTranslationRegistry.newValue
+
   onKeydown: (event) ->
     keyChar = KeyboardUtils.getKeyCharString event
+    keyChar = @keyTranslationRegistry[keyChar] ? keyChar
     isEscape = KeyboardUtils.isEscape event
     if isEscape and (@countPrefix != 0 or @keyState.length != 1)
       @keydownEvents[event.keyCode] = true
@@ -61,6 +69,7 @@ class KeyHandlerMode extends Mode
 
   onKeypress: (event) ->
     keyChar = KeyboardUtils.getKeyCharString event
+    keyChar = @keyTranslationRegistry[keyChar] ? keyChar
     if @isMappedKey keyChar
       @handleKeyChar keyChar
     else if @isCountKey keyChar