Support falling back to 1-char from 2-char mode.

Relates to hadronized#166.

README.md

@@ -106,6 +106,9 @@ to any.
 
 ![](https://phaazon.net/media/uploads/hop_char2_mode.gif)
 
+Note that it’s possible to _fallback to 1-char mode_ if you hit a special key as second key. This key can be controlled
+via the user configuration. `:h hop-config-char2_fallback_key`.
+
 ## Pattern mode (`:HopPattern`)
 
 Akin to `/`, this mode prompts you for a pattern (regex) to search. Occurrences will be highlighted, allowing you to

doc/hop.txt

@@ -262,6 +262,9 @@ Most of the functions and values you need to know about are in `hop`.
     Let the user type a bigram (two concatenated keys) and immediately hint
     all of its occurrences.
 
+    This function can behave like |hop.hint_char1| in some cases. See
+    |hop-config-char2_fallback_key|.
+
     Arguments:~
         {opts}  Hop options.
 
@@ -680,6 +683,17 @@ below.
     Defaults:~
         `uppercase_labels = false`
 
+`char2_fallback_key`                               *hop-config-char2_fallback_key*
+    Enable a special key that breaks |hop.hint_char2| if only one key is
+    pressed, falling back to the same behavior as |hop.hint_char1|. It is
+    recommended that, if you set this option, you not use a key that is in
+    your |hop-config-keys| (because it would make those keys unreachable), and
+    not a character that you might jump to. A good fallback key could be
+    `<esc>` or `<cr>`, for instance.
+
+    Defaults:~
+        `char2_fallback_key = nil`
+
 `extensions`                                               *hop-config-extensions*
     List-table of extensions to enable (names). As described in |hop-extension|,
     extensions for which the name is in that list must have a `register(opts)`

lua/hop/init.lua

@@ -335,7 +335,13 @@ function M.hint_char2(opts)
     return
   end
 
-  local pattern = vim.fn.nr2char(a) .. vim.fn.nr2char(b)
+  local pattern = vim.fn.nr2char(a)
+
+  -- if we have a fallback key defined in the opts, if the second character is that key, we then fallback to the same
+  -- behavior as hint_char1()
+  if opts.char2_fallback_key == nil or b ~= vim.fn.char2nr(vim.api.nvim_replace_termcodes(opts.char2_fallback_key, true, false, true)) then
+    pattern = pattern .. vim.fn.nr2char(b)
+  end
 
   local generator
   if opts.current_line_only then