Modularize lazy loading of polyglot parts

scripts/build

@@ -13,8 +13,11 @@ Dir.chdir(File.dirname(__dir__))
 BASE_URL = 'https://raw.githubusercontent.com/github/linguist/master'
 
 def read_section(name)
-  "\" Please do not edit this file directly, instead modify polyglot.vim or scripts/build\n\n" +
-  File.read('polyglot.vim').match(/""" #{Regexp.escape(name)}\n*(.*)\n(?=\n""")/m)[1]
+  section = File.read('polyglot.vim').split('""" ').find { |e| e.start_with?(name) }
+  if section.nil?
+    raise StandardError.new("Section not found: #{name}")
+  end
+  "\" Please do not edit this file directly, instead modify polyglot.vim or scripts/build\n" + section[(section.index("\n") + 1)..-1]
 end
 
 def camelize(str)
@@ -390,10 +393,17 @@ def rule_to_code(rule)
     EOS
   end
 
+  if rule.has_key?("shebang")
+    return <<~EOS
+      if polyglot#shebang#Detect() | return | endif
+      #{indent(rule_to_code(except(rule, "shebang")), 0)}
+    EOS
+  end
+
   if rule.has_key?("filetype")
     if rule.has_key?("fallback")
       return <<~EOS
-        set ft=#{rule["filetype"]} | au! BufWritePost <buffer> ++once call polyglot#Detect#{camelize(rule["extensions"].first)}Filetype()
+        set ft=#{rule["filetype"]} | au! BufWritePost <buffer> ++once call polyglot#detect##{camelize(rule["extensions"].first)}()
         return
       EOS
     end
@@ -489,6 +499,8 @@ def extract(packages)
 end
 
 def generate_ftdetect(packages, heuristics)
+  FileUtils.mkdir_p('autoload/polyglot')
+
   output = "\n"
 
   all_filetypes = packages.flat_map { |f| f["filetypes"] || [] }
@@ -561,7 +573,7 @@ def generate_ftdetect(packages, heuristics)
 
     for heuristic in package_heuristics.uniq
       extensions = heuristic["extensions"].map { |e| "*.#{e}" }
-      autocommands << "  au! BufNewFile,BufRead #{extensions.join(",")} call polyglot#Detect#{camelize(heuristic["extensions"].first)}Filetype()\n"
+      autocommands << "  au! BufNewFile,BufRead #{extensions.join(",")} call polyglot#detect##{camelize(heuristic["extensions"].first)}()\n"
     end
 
     if autocommands != ""
@@ -580,6 +592,18 @@ def generate_ftdetect(packages, heuristics)
      ftdetect.gsub('" scripts/build inserts here filetype detection autocommands') { output }
   )
 
+  output = []
+
+  for heuristic in heuristics
+    output << <<~EOS
+      func! polyglot#detect##{camelize(heuristic["extensions"].first)}()
+      #{indent(rules_to_code(heuristic), 2)}
+      endfunc
+    EOS
+  end
+
+  File.write('autoload/polyglot/detect.vim', output.join("\n"))
+
   output = <<~EOS
     let s:interpreters = {
     EOS
@@ -590,24 +614,10 @@ def generate_ftdetect(packages, heuristics)
       end
     end
 
-  output << <<~EOS
-      \\ }
+  output << "  \\ }"
 
-  EOS
-
-  for heuristic in heuristics
-    output << <<~EOS
-      func! polyglot#Detect#{camelize(heuristic["extensions"].first)}Filetype()
-      #{indent(rules_to_code(heuristic), 2)}
-      endfunc
-
-    EOS
-  end
-
-  autoload_script = read_section('autoload/polyglot.vim')
-  autoload_script["\" scripts/build generates heuristics functions here\n"] = output
-
-  File.write('autoload/polyglot.vim', autoload_script)
+  autoload_script = read_section('autoload/polyglot/shebang.vim')
+  File.write('autoload/polyglot/shebang.vim', autoload_script + "\n\n" + output)
 end
 
 def generate_tests(packages)
@@ -744,13 +754,13 @@ def generate_plugins(packages)
 
 
   output << <<~EOS
-    func! sleuth#GlobForFiletype(type)
+    func! polyglot#sleuth#GlobForFiletype(type)
       return get(s:globs, a:type, '')
     endfunc
   EOS
 
 
-  File.write('autoload/sleuth.vim', output)
+  File.write('autoload/polyglot/sleuth.vim', output)
 end
 
 def process_list(list, extras)