Add command to inc/dec number under cursor (#1027)

* Add command to inc/dec number under cursor

With the cursor over a number in normal mode, Ctrl + A will increment the
number and Ctrl + X will decrement the number. It works with binary, octal,
decimal, and hexidecimal numbers. Here are some examples.

0b01110100
0o1734
-24234
0x1F245

If the number isn't over a number it will try to find a number after the
cursor on the same line.

* Move several functions to helix-core

* Change to work based on word under selection

* It no longer finds the next number if the cursor isn't already over
  a number.
* It only matches numbers that are part of words with other characters
  like "foo123bar".
* It now works with multiple selections.

* Add some unit tests

* Fix for clippy

* Simplify some things

* Keep previous selection after incrementing

* Use short word instead of long word

This change requires us to manually handle minus sign.

* Don't pad decimal numbers if no leading zeros

* Handle numbers with `_` separators

* Refactor and add tests

* Move most of the code into core
* Add tests for the incremented output

* Use correct range

* Formatting

* Rename increment functions

* Make docs more specific

* This is easier to read

* This is clearer

* Type can be inferred

1 files changed, 3 insertions, 0 deletions

diff --git a/helix-term/src/keymap.rs b/helix-term/src/keymap.rs
index fdf43d87..bf3b594e 100644
--- a/helix-term/src/keymap.rs
+++ b/helix-term/src/keymap.rs
@@ -698,6 +698,9 @@ impl Default for Keymaps {
             "A-!" => shell_append_output,
             "$" => shell_keep_pipe,
             "C-z" => suspend,
+
+            "C-a" => increment,
+            "C-x" => decrement,
         });
         let mut select = normal.clone();
         select.merge_nodes(keymap!({ "Select mode"