lib/rus3/parser.rb in rus3-0.1.2 vs lib/rus3/parser.rb in rus3-0.2.0

@@ -1,71 +1,87 @@
 # frozen_string_literal: true
 
+require "readline"
+
 module Rus3
 
   module Parser
-    require "readline"
-    require_relative "parser/lexer"
 
     # Indicates the version of the parser module.
-    VERSION = "0.1.0"
+    VERSION = "0.2.0"
 
     # A base class to derived a parser.
     class Parser
 
       # Holds a prompt string.  It is intended to be set in the REPL
       # loop.
-      attr_accessor :prompt
+      attr_reader :prompt
 
+      # Constructs the version string.
+
+      def version
+        "parser-module :version #{VERSION}"
+      end
+
       def initialize
         @prompt = ""
       end
 
-      # Constructs the version string.
-
-      def version
-        "Parser version #{VERSION}"
+      def prompt=(str)
+        index = str.index(">")
+        class_name = self.class.name.split("::")[-1]
+        parser_name = class_name.delete_suffix("Parser").downcase
+        @prompt = str[0...index] + "(#{parser_name})" + str[index..-1]
       end
 
-      # Reads an expression from the passed IO instance.  Returns nil
-      # when reaches to EOF.
+      # Reads program source from the passed IO instance, then returns
+      # the AST (abstract syntax tree).  Returns nil when reaches to
+      # EOF.
 
       def read(io = STDIN)
-        exp = Readline::readline(@prompt, true)
-        exp.nil? ? nil : parse(exp)
+        program_source = nil
+        if io == STDIN
+          program_source = Readline::readline(@prompt, true)
+        else
+          program_source = io.readlines(chomp: true).join(" ")
+        end
+        program_source.nil? ? nil : parse(program_source)
       end
 
       protected
 
-      # Parses the passed expression, then returns the processed
-      # expression to be evaluated by an evaluator.  How to process
-      # depends on each derived parser class.
+      # Parses the passed program source, then returns the AST to be
+      # evaluated by an evaluator.  How to process depends on each
+      # derived parser class.
 
-      def parse(exp)
+      def parse(program_source)
         nil
       end
 
     end
 
     require_relative "parser/scheme_parser"
 
-    DEFAULT_PARSER = SchemeParser # :nodoc:
-
     # :stopdoc:
 
     class PassthroughParser < Parser
-      PARSER_VERSION = "0.1.0"
+      PARSER_VERSION = "0.2.0"
 
       def version
-        super + " (Pass Through Parser version: #{PARSER_VERSION})"
+        vmsg = "(pass-through-parser version: #{PARSER_VERSION})"
+        vmsg += " #{Lexer.version}"
+        super + " (#{vmsg})"
       end
-    end
 
-    def parse(exp)
-      exp
+      def parse(program_source)
+        [Lexer.new(program_source).map {|tk| tk.to_s}]
+      end
+
     end
 
     # :startdoc:
+
+    DEFAULT_PARSER = SchemeParser # :nodoc:
 
   end
 
 end