reimplement #eof. fixes #66.

mrblib/io.rb

@@ -133,20 +133,12 @@ class IO
   end
 
   def eof?
-    return true if @buf && @buf.size > 0
-
-    ret = false
-    char = ''
-
     begin
-      char = sysread(1)
-    rescue EOFError => e
-      ret = true
-    ensure
-      _ungets(char)
+      buf = _read_buf
+      return buf.size == 0
+    rescue EOFError
+      return true
     end
-
-    ret
   end
   alias_method :eof, :eof?
 
@@ -176,24 +168,17 @@ class IO
     @buf = sysread(BUF_SIZE)
   end
 
-  def _ungets(substr)
+  def ungetc(substr)
     raise TypeError.new "expect String, got #{substr.class}" unless substr.is_a?(String)
-    raise IOError if @pos == 0 || @pos.nil?
     @pos -= substr.size
     if @buf.empty?
-      @buf = substr
+      @buf = substr.dup
     else
       @buf = substr + @buf
     end
     nil
   end
 
-  def ungetc(char)
-    raise IOError if @pos == 0 || @pos.nil?
-    _ungets(char)
-    nil
-  end
-
   def read(length = nil)
     unless length.nil?
       unless length.is_a? Fixnum

test/io.rb

@@ -70,14 +70,29 @@ end
 #assert('IO#each_line', '15.2.20.5.5') do
 
 assert('IO#eof?', '15.2.20.5.6') do
+  if false  # XXX: not implemented yet
+    io = IO.new(IO.sysopen($mrbtest_io_wfname, 'w'), 'w')
+    assert_raise(IOError) do
+      io.eof?
+    end
+  end
+
+  # empty file
+  io = IO.open(IO.sysopen($mrbtest_io_wfname, 'w'), 'w')
+  io.close
+  io = IO.open(IO.sysopen($mrbtest_io_wfname, 'r'), 'r')
+  assert_true io.eof?
+  io.close
+
+  # nonempty file
   io = IO.new(IO.sysopen($mrbtest_io_rfname))
-  $mrbtest_io_msg.each_char { |ch|
-    # XXX
-    #assert_false io.eof?
-    io.getc
-  }
+  assert_false io.eof?
+  io.readchar
+  assert_false io.eof?
+  io.read
   assert_true io.eof?
   io.close
+
   true
 end