Improve django filetype detection, closes #560

autoload/polyglot.vim

@@ -4,13 +4,6 @@
 let s:cpo_save = &cpo
 set cpo&vim
 
-func! polyglot#ObserveShebang()
-  augroup polyglot-observer
-    au! CursorHold,CursorHoldI,BufWritePost <buffer>
-      \ if polyglot#Shebang() | au! polyglot-observer CursorHold,CursorHoldI,BufWritePost | endif
-  augroup END
-endfunc
-
 func! polyglot#Shebang()
   if getline(1) =~# "^#!"
     let ft = polyglot#ShebangFiletype()
@@ -392,7 +385,8 @@ func! polyglot#DetectHtmlFiletype()
       set ft=xhtml | return
     endif
   endfor
-  set ft=html | return
+  set ft=html | au! BufWritePost <buffer> ++once call polyglot#DetectHtmlFiletype()
+  return
 endfunc
 
 
@@ -411,6 +405,14 @@ if exists('g:polyglot_test')
   autocmd!
 endif
 
+func! polyglot#Observe(fn)
+  let b:polyglot_observe = a:fn
+  augroup polyglot-observer
+    au! CursorHold,CursorHoldI,BufWritePost <buffer>
+      \ execute('if polyglot#' . b:polyglot_observe . '() | au! polyglot-observer | endif')
+  augroup END
+endfunc
+
 let s:disabled_packages = {}
 let s:new_polyglot_disabled = []
 
@@ -497,7 +499,7 @@ au! BufNewFile,BufRead,StdinReadPost * if expand("<afile>") !~ g:ft_ignore_pat |
   \ call polyglot#Shebang() | endif
 
 au BufEnter * if &ft == "" && expand("<afile>") !~ g:ft_ignore_pat |
-      \ call polyglot#ObserveShebang() | endif
+      \ call polyglot#Observe('Shebang') | endif
 
 augroup END
 

ftdetect/polyglot.vim

@@ -9,6 +9,14 @@ if exists('g:polyglot_test')
   autocmd!
 endif
 
+func! polyglot#Observe(fn)
+  let b:polyglot_observe = a:fn
+  augroup polyglot-observer
+    au! CursorHold,CursorHoldI,BufWritePost <buffer>
+      \ execute('if polyglot#' . b:polyglot_observe . '() | au! polyglot-observer | endif')
+  augroup END
+endfunc
+
 let s:disabled_packages = {}
 let s:new_polyglot_disabled = []
 
@@ -2021,7 +2029,7 @@ au! BufNewFile,BufRead,StdinReadPost * if expand("<afile>") !~ g:ft_ignore_pat |
   \ call polyglot#Shebang() | endif
 
 au BufEnter * if &ft == "" && expand("<afile>") !~ g:ft_ignore_pat |
-      \ call polyglot#ObserveShebang() | endif
+      \ call polyglot#Observe('Shebang') | endif
 
 augroup END
 

heuristics.yaml

@@ -69,7 +69,6 @@ rules:
     filetype: glsl
 - override: true
 - filetype: forth
-  fallback: true
 ---
 extensions: [re]
 rules:

polyglot.vim

@@ -4,13 +4,6 @@
 let s:cpo_save = &cpo
 set cpo&vim
 
-func! polyglot#ObserveShebang()
-  augroup polyglot-observer
-    au! CursorHold,CursorHoldI,BufWritePost <buffer>
-      \ if polyglot#Shebang() | au! polyglot-observer CursorHold,CursorHoldI,BufWritePost | endif
-  augroup END
-endfunc
-
 func! polyglot#Shebang()
   if getline(1) =~# "^#!"
     let ft = polyglot#ShebangFiletype()
@@ -84,6 +77,14 @@ if exists('g:polyglot_test')
   autocmd!
 endif
 
+func! polyglot#Observe(fn)
+  let b:polyglot_observe = a:fn
+  augroup polyglot-observer
+    au! CursorHold,CursorHoldI,BufWritePost <buffer>
+      \ execute('if polyglot#' . b:polyglot_observe . '() | au! polyglot-observer | endif')
+  augroup END
+endfunc
+
 let s:disabled_packages = {}
 let s:new_polyglot_disabled = []
 
@@ -170,7 +171,7 @@ au! BufNewFile,BufRead,StdinReadPost * if expand("<afile>") !~ g:ft_ignore_pat |
   \ call polyglot#Shebang() | endif
 
 au BufEnter * if &ft == "" && expand("<afile>") !~ g:ft_ignore_pat |
-      \ call polyglot#ObserveShebang() | endif
+      \ call polyglot#Observe('Shebang') | endif
 
 augroup END
 

scripts/build

@@ -126,10 +126,6 @@ def transform_patterns(heuristics)
   patterns_mapping = Hash[patterns.zip(patterns_to_vim_patterns(patterns))]
   each_hash(heuristics) do |h|
     if h.has_key?("pattern")
-      if h["pattern"].include?("#import")
-        puts h["pattern"]
-        puts patterns_mapping.fetch(h["pattern"])
-      end
       h["pattern"] = patterns_mapping.fetch(h["pattern"])
     end
   end
@@ -326,8 +322,18 @@ def rule_to_code(rule)
     EOS
   end
 
-  if (rule.keys - ["filetype", "override", "set", "extensions", "fallback"]).size > 0
+  if rule.has_key?("filetype")
-    raise "Unknown rule: #{JSON.generate(rule)}"
+    if rule.has_key?("fallback")
+      return <<~EOS
+        set ft=#{rule["filetype"]} | au! BufWritePost <buffer> ++once call polyglot#Detect#{camelize(rule["extensions"].first)}Filetype()
+        return
+      EOS
+    end
+
+    return <<~EOS
+      set ft=#{rule["filetype"]} | return
+      #{indent(rule_to_code(except(rule, "filetype")), 0)}
+    EOS
   end
 
   if rule.has_key?("override")
@@ -339,20 +345,8 @@ def rule_to_code(rule)
     EOS
   end
 
-  if rule.has_key?("filetype")
+  if (rule.keys - ["extensions"]).size > 0
-    return "set ft=#{rule["filetype"]} | return"
+    raise "Unknown rule: #{JSON.generate(rule)}"
-  end
-
-  if rule.has_key?("filetype")
-    if rule.has_key?("fallback")
-      return "set ft=#{rule["filetype"]} | return"
-    else
-      return "setf FALLBACK #{rule["filetype"]} | return"
-    end
-  end
-
-  if rule.has_key?("extensions")
-    return ""
   end
   
   return ""