Implement a preview window for selecting locations to open

autoload/ale/preview.vim

@@ -2,13 +2,16 @@
 " Description: Preview windows for showing whatever information in.
 
 " Open a preview window and show some lines in it.
-function! ale#preview#Show(lines) abort
+" An optional second argument can set an alternative filetype for the window.
+function! ale#preview#Show(lines, ...) abort
+    let l:filetype = get(a:000, 0, 'ale-preview')
+
     silent pedit ALEPreviewWindow
     wincmd P
     setlocal modifiable
     setlocal noreadonly
     setlocal nobuflisted
-    setlocal filetype=ale-preview
+    let &l:filetype = l:filetype
     setlocal buftype=nofile
     setlocal bufhidden=wipe
     :%d
@@ -16,3 +19,50 @@ function! ale#preview#Show(lines) abort
     setlocal nomodifiable
     setlocal readonly
 endfunction
+
+" Show a location selection preview window, given some items.
+" Each item should have 'filename', 'line', and 'column' keys.
+function! ale#preview#ShowSelection(item_list) abort
+    let l:lines = []
+
+    " Create lines to display to users.
+    for l:item in a:item_list
+        call add(
+        \   l:lines,
+        \   l:item.filename
+        \       . ':' . l:item.line
+        \       . ':' . l:item.column,
+        \)
+    endfor
+
+    call ale#preview#Show(l:lines, 'ale-preview-selection')
+    let b:ale_preview_item_list = a:item_list
+endfunction
+
+function! s:Open(open_in_tab) abort
+    let l:item_list = get(b:, 'ale_preview_item_list', [])
+    let l:item = get(l:item_list, getcurpos()[1] - 1, {})
+
+    if empty(l:item)
+        return
+    endif
+
+    if !a:open_in_tab
+        :q!
+    endif
+
+    call ale#util#Open(
+    \   l:item.filename,
+    \   l:item.line,
+    \   l:item.column,
+    \   {'open_in_tab': a:open_in_tab},
+    \)
+endfunction
+
+function! ale#preview#OpenSelectionInBuffer() abort
+    call s:Open(0)
+endfunction
+
+function! ale#preview#OpenSelectionInTab() abort
+    call s:Open(1)
+endfunction