stream: Offer string-backed input streams.

Signed-off-by: Jean-Christophe Beaupré <jcbrinfo@users.noreply.github.com>

diff --git a/lib/standard/stream.nit b/lib/standard/stream.nit
index 6b70e21..6765305 100644 (file)
--- a/lib/standard/stream.nit
+++ b/lib/standard/stream.nit
@@ -1,13 +1,11 @@
 # This file is part of NIT ( http://www.nitlanguage.org ).
 #
-# Copyright 2004-2008 Jean Privat <jean@pryen.org>
-#
-# This file is free software, which comes along with NIT.  This software is
+# This file is free software, which comes along with NIT. This software is
 # distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
-# without  even  the implied warranty of  MERCHANTABILITY or  FITNESS FOR A 
-# PARTICULAR PURPOSE.  You can modify it is you want,  provided this header
+# without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+# PARTICULAR PURPOSE. You can modify it is you want, provided this header
 # is kept unaltered, and a notification of the changes is added.
-# You  are  allowed  to  redistribute it and sell it, alone or is a part of
+# You are allowed to redistribute it and sell it, alone or is a part of
 # another product.
 
 # Input and output streams of characters
@@ -209,7 +207,7 @@ abstract class BufferedIStream
                        fill_buffer
                end
                return s.to_s
-       end   
+       end
 
        redef fun append_line_to(s)
        do
@@ -258,7 +256,7 @@ abstract class BufferedIStream
        # Fill the buffer
        protected fun fill_buffer is abstract
 
-       # Is the last fill_buffer reach the end 
+       # Is the last fill_buffer reach the end
        protected fun end_reached: Bool is abstract
 
        # Allocate a `_buffer` for a given `capacity`.
@@ -399,7 +397,9 @@ redef interface Object
        `}
 end
 
-# Stream to a String. Mainly used for compatibility with OStream type and tests.
+# Stream to a String.
+#
+# Mainly used for compatibility with OStream type and tests.
 class StringOStream
        super OStream
 
@@ -415,3 +415,33 @@ class StringOStream
        protected var closed = false
        redef fun close do closed = true
 end
+
+# Stream from a String.
+#
+# Mainly used for compatibility with IStream type and tests.
+class StringIStream
+       super IStream
+
+       # The string to read from.
+       var source: String
+
+       # The current position in the string.
+       private var cursor: Int = 0
+
+       redef fun read_char do
+               if cursor < source.length then
+                       var c = source[cursor].ascii
+
+                       cursor += 1
+                       return c
+               else
+                       return -1
+               end
+       end
+
+       redef fun close do
+               source = ""
+       end
+
+       redef fun eof do return cursor >= source.length
+end