Fix #3278 - Handle UTF-8 in URI encoding/decoding

autoload/ale/uri.vim

@@ -1,9 +1,18 @@
-" This probably doesn't handle Unicode characters well.
+function! s:EncodeChar(char) abort
+    let l:result = ''
+
+    for l:index in range(strlen(a:char))
+        let l:result .= printf('%%%02x', char2nr(a:char[l:index]))
+    endfor
+
+    return l:result
+endfunction
+
 function! ale#uri#Encode(value) abort
     return substitute(
     \   a:value,
     \   '\([^a-zA-Z0-9\\/$\-_.!*''(),]\)',
-    \   '\=printf(''%%%02x'', char2nr(submatch(1)))',
+    \   '\=s:EncodeChar(submatch(1))',
     \   'g'
     \)
 endfunction
@@ -12,7 +21,7 @@ function! ale#uri#Decode(value) abort
     return substitute(
     \   a:value,
     \   '%\(\x\x\)',
-    \   '\=nr2char(''0x'' . submatch(1))',
+    \   '\=printf("%c", str2nr(submatch(1), 16))',
     \   'g'
     \)
 endfunction

test/test_path_uri.vader

@@ -1,3 +1,6 @@
+Before:
+  scriptencoding utf-8
+
 Execute(ale#path#ToURI should work for Windows paths):
   AssertEqual 'file:///C:/foo/bar/baz.tst', ale#path#ToURI('C:\foo\bar\baz.tst')
   AssertEqual 'foo/bar/baz.tst', ale#path#ToURI('foo\bar\baz.tst')
@@ -62,3 +65,9 @@ Execute(ale#path#ToURI should percent encode unsafe characters):
 
 Execute(ale#path#FromURI should decode percent encodings):
   AssertEqual ' +:?&=', ale#path#FromURI('%20%2b%3a%3f%26%3d')
+
+Execute(ale#path#ToURI should handle UTF-8):
+  AssertEqual 'file:///T%c3%a9l%c3%a9chargement', ale#path#ToURI('/Téléchargement')
+
+Execute(ale#path#FromURI should handle UTF-8):
+  AssertEqual '/Téléchargement', ale#path#FromURI('file:///T%C3%A9l%C3%A9chargement')