Echo string format (#76)

* Implement an option to configure the echoed message, #48

Via `g:ale_echo_msg_format` where:
- `%s` is the error message itself
- `%linter%` is the linter name
- `%severity` is the severity type

e.g
let g:ale_echo_msg_fomat = '[%linter%] [%severity%] %s'

* Add new options for defining the string used for errors in echoed
message

`g:ale_echo_msg_error_str` and `g:ale_echo_msg_warning_str`

* Change text output of some linters

Now that the echoed message can be customized, no need to add the type
to the text variable.

* Update README & documentation file

* Fix some typos
* Sort the table of options alphabetically (except echo_msg_x_str options)

* Added echo warning str option to the doc

2 files changed, 29 insertions, 1 deletions

diff --git a/plugin/ale/aaflags.vim b/plugin/ale/aaflags.vim
index 10d82128..f18dcc43 100644
--- a/plugin/ale/aaflags.vim
+++ b/plugin/ale/aaflags.vim
@@ -48,3 +48,12 @@ let g:ale_sign_column_always = get(g:, 'ale_sign_column_always', 0)
 let g:ale_statusline_format = get(g:, 'ale_statusline_format', 
 \   ['%d error(s)', '%d warning(s)', 'OK']
 \)
+
+" String format for the echoed message
+" A %s is mandatory
+" It can contain 2 handlers: %linter%, %severity%
+let g:ale_echo_msg_format = get(g:, 'ale_echo_msg_format', '%s')
+
+" Strings used for severity in the echoed message
+let g:ale_echo_msg_error_str = get(g:, 'ale_echo_msg_error_str', 'Error')
+let g:ale_echo_msg_warning_str = get(g:, 'ale_echo_msg_warning_str', 'Warning')
diff --git a/plugin/ale/cursor.vim b/plugin/ale/cursor.vim
index e0751a8c..24f1f183 100644
--- a/plugin/ale/cursor.vim
+++ b/plugin/ale/cursor.vim
@@ -7,6 +7,23 @@ endif
 
 let g:loaded_ale_cursor = 1
 
+" Return a formatted message according to g:ale_echo_msg_format variable
+function! s:GetMessage(linter, type, text) abort
+    let msg = g:ale_echo_msg_format
+    let type = a:type ==# 'E'
+    \   ? g:ale_echo_msg_error_str
+    \   : g:ale_echo_msg_warning_str
+    " Capitalize the 1st character
+    let text = toupper(a:text[0]) . a:text[1:-1]
+
+    " Replace handlers if they exist
+    for [k, v] in items({'linter': a:linter, 'severity': type})
+        let msg = substitute(msg, '\V%' . k . '%', v, '')
+    endfor
+
+    return printf(msg, text)
+endfunction
+
 " This function will perform a binary search to find a message from the
 " loclist to echo when the cursor moves.
 function! s:BinarySearch(loclist, line, column)
@@ -81,7 +98,9 @@ function! ale#cursor#EchoCursorWarning(...)
     let index = s:BinarySearch(loclist, pos[1], pos[2])
 
     if index >= 0
-        call ale#cursor#TruncatedEcho(loclist[index]['text'])
+        let l = loclist[index]
+        let msg = s:GetMessage(l.linter_name, l.type, l.text)
+        call ale#cursor#TruncatedEcho(msg)
     else
         echo
     endif