lexer.rb in tracksperanto-1.6.7

- old
+ new

@@ -1,15 +1,25 @@
 module Tracksperanto::ShakeGrammar
   # Since Shake uses a C-like language for it's scripts we rig up a very sloppy
   # but concise C-like lexer to cope
   class Lexer
     
+    # Parsed stack
     attr_reader :stack
     
-    def initialize(with_io)
-      @io, @stack, @buf  = with_io, [], ''
-      parse until (@io.eof? || @stop)
+    # Access to the sentinel object
+    attr_reader :sentinel
+    
+    STOP_TOKEN = :__stop #:nodoc:
+    
+    # The first argument is the IO handle to the data of the Shake script.
+    # The second argument is a "sentinel" that is going to be passed
+    # to the downstream lexers instantiated for nested data structures.
+    # You can use the sentinel to collect data from child nodes for example.
+    def initialize(with_io, sentinel = nil)
+      @io, @stack, @buf, @sentinel  = with_io, [], '', sentinel
+      catch(STOP_TOKEN) { parse until @io.eof? }
       in_comment? ? consume_comment("\n") : consume_atom!
     end
     
     private
     
@@ -29,18 +39,18 @@
     def parse
       c = @io.read(1)
       return consume_comment(c) if in_comment? 
       
       if !@buf.empty? && (c == "(") # Funcall
-        push([:funcall, @buf.strip] + self.class.new(@io).stack)
+        push([:funcall, @buf.strip] + self.class.new(@io, @sentinel).stack)
         @buf = ''
       elsif c == "[" # Array, booring
         push([:arr] + self.class.new(@io).stack)
       elsif (c == "]" || c == ")")
         # Funcall end, and when it happens assume we are called as
         # a subexpression.
         consume_atom!
-        @stop = true
+        throw STOP_TOKEN
       elsif (c == ",")
         consume_atom!
       elsif (c == ";" || c == "\n")
         # Skip these - the subexpression already is expanded anyway
       elsif (c == "=")
\ No newline at end of file