Added file-header pattern support to `syntax`

data/core/doc/init.lua

···
 
 
 function Doc:reset_syntax()
-  local syn = syntax.get(self.filename or "")
+  local header = self:get_text(1, 1, self:position_offset(1, 1, 128))
+  local syn = syntax.get(self.filename or "", header)
   if self.syntax ~= syn then
     self.syntax = syn
     self.highlighter:reset()

data/core/syntax.lua

···
 end
 
 
-function syntax.get(filename)
+local function find(string, field)
   for i = #syntax.items, 1, -1 do
     local t = syntax.items[i]
-    if common.match_pattern(filename, t.files) then
+    if common.match_pattern(string, t[field] or {}) then
       return t
     end
   end
-  return plain_text_syntax
+end
+
+function syntax.get(filename, header)
+  return find(filename, "files")
+      or find(header, "headers")
+      or plain_text_syntax
 end
 
 

data/plugins/language_lua.lua

···
 
 syntax.add {
   files = "%.lua$",
+  headers = "^#!.*[ /]lua",
   comment = "--",
   patterns = {
     { pattern = { '"', '"', '\\' },       type = "string"   },

data/plugins/language_python.lua

···
 
 syntax.add {
   files = "%.py$",
+  headers = "^#!.*[ /]python",
   comment = "#",
   patterns = {
     { pattern = { "#", "\n" },            type = "comment"  },

data/plugins/language_xml.lua

···
 
 syntax.add {
   files = { "%.xml$", "%.html?$" },
+  headers = "<%?xml",
   patterns = {
     { pattern = { "<!%-%-", "%-%->" },     type = "comment"  },
     { pattern = { '%f[^>][^<]', '%f[<]' }, type = "normal"   },