wip

lib/propane/generator.rb

@@ -71,12 +71,14 @@ class Propane
         end
         tokens_by_name[token.name] = token
       end
-      # Check for user start rule.
-      unless @grammar.rules.find {|rule| rule.name == @grammar.start_rule}
-        raise Error.new("Start rule `#{@grammar.start_rule}` not found")
+      # Check for user start rules.
+      @grammar.start_rules.each_with_index do |start_rule, i|
+        unless @grammar.rules.find {|rule| rule.name == start_rule}
+          raise Error.new("Start rule `#{start_rule}` not found")
+        end
+        # Add "real" start rule.
+        @grammar.rules.unshift(Rule.new("$#{start_rule}", [start_rule, "$EOF"], nil, nil, nil))
       end
-      # Add "real" start rule.
-      @grammar.rules.unshift(Rule.new("$Start", [@grammar.start_rule, "$EOF"], nil, nil, nil))
       # Generate and add rules for optional components.
       generate_optional_component_rules!(tokens_by_name)
       # Build rule sets.
@@ -332,9 +334,9 @@ class Propane
     #
     # @return [Array<String>]
     #   Start rule parser value type name and type string.
-    def start_rule_type
+    def start_rule_type(start_rule_index = 0)
       start_rule = @grammar.rules.find do |rule|
-        rule.name == @grammar.start_rule
+        rule.name == @grammar.start_rules[start_rule_index]
       end
       [start_rule.ptypename, @grammar.ptypes[start_rule.ptypename]]
     end

lib/propane/grammar.rb

@@ -12,7 +12,7 @@ class Propane
     attr_reader :modulename
     attr_reader :patterns
     attr_reader :rules
-    attr_reader :start_rule
+    attr_reader :start_rules
     attr_reader :tokens
     attr_reader :code_blocks
     attr_reader :ptypes
@@ -20,7 +20,7 @@ class Propane
 
     def initialize(input)
       @patterns = []
-      @start_rule = "Start"
+      @start_rules = []
       @tokens = []
       @rules = []
       @code_blocks = {}
@@ -35,6 +35,7 @@ class Propane
       @ast_suffix = ""
       @free_token_node = nil
       parse_grammar!
+      @start_rules << "Start" if @start_rules.empty?
     end
 
     def ptype
@@ -242,7 +243,7 @@ class Propane
 
     def parse_start_statement!
       if md = consume!(/start\s+(\w+)\s*;/)
-        @start_rule = md[1]
+        @start_rules << md[1] unless @start_rules.include?(md[1])
       end
     end