#1095 Cache the sorting of patterns for g:ale_pattern_options

autoload/ale/pattern_options.vim

@@ -1,6 +1,10 @@
 " Author: w0rp <devw0rp@gmail.com>
 " Description: Set options in files based on regex patterns.
 
+" These variables are used to cache the sorting of patterns below.
+let s:last_pattern_options = {}
+let s:sorted_items = []
+
 function! s:CmpPatterns(left_item, right_item) abort
     if a:left_item[0] < a:right_item[0]
         return -1
@@ -18,13 +22,19 @@ function! ale#pattern_options#SetOptions(buffer) abort
         return
     endif
 
+    " The items will only be sorted whenever the patterns change.
+    if g:ale_pattern_options != s:last_pattern_options
+        let s:last_pattern_options = deepcopy(g:ale_pattern_options)
+        " The patterns are sorted, so they are applied consistently.
+        let s:sorted_items = sort(
+        \   items(g:ale_pattern_options),
+        \   function('s:CmpPatterns')
+        \)
+    endif
+
     let l:filename = expand('#' . a:buffer . ':p')
 
-    " The patterns are sorted, so they are applied consistently.
-    for [l:pattern, l:options] in sort(
-    \   items(g:ale_pattern_options),
-    \   function('s:CmpPatterns')
-    \)
+    for [l:pattern, l:options] in s:sorted_items
         if match(l:filename, l:pattern) >= 0
             for [l:key, l:value] in items(l:options)
                 call setbufvar(a:buffer, l:key, l:value)

test/test_pattern_options.vader

@@ -74,3 +74,19 @@ Execute(Patterns should not be applied when the setting is disabled):
   call ale#pattern_options#SetOptions(bufnr(''))
 
   AssertEqual 0, b:some_option
+
+" This test is important for making sure we update the sorted items.
+Execute(Patterns should be applied after the Dictionary changes):
+  call ale#test#SetFilename('foobar.js')
+
+  let g:ale_pattern_options = {}
+
+  call ale#pattern_options#SetOptions(bufnr(''))
+
+  AssertEqual 0, b:some_option
+
+  let g:ale_pattern_options['foo'] = {'some_option': 666}
+
+  call ale#pattern_options#SetOptions(bufnr(''))
+
+  AssertEqual 666, b:some_option