Moved StringStream to rlib

Signed-off-by: Stefan Marr <git@stefan-marr.de>

src/rlib/string_stream.py

+from rpython.rlib.streamio import Stream, StreamError
+
+class StringStream(Stream):
+    def __init__(self, string):
+        self._string = string
+        self.pos     = 0
+        self.max     = len(string) - 1
+
+    def write(self, data):
+        raise StreamError("StringStream is not writable")
+    def truncate(self, size):
+        raise StreamError("StringStream is immutable")
+
+    def peek(self):
+        if self.pos < self.max:
+            return self._string[self.pos:]
+        else:
+            return ''
+
+    def tell(self):
+        return self.pos
+
+    def seek(self, offset, whence):
+        if whence == 0:
+            self.pos = max(0, offset)
+        elif whence == 1:
+            self.pos = max(0, self.pos + offset)
+        elif whence == 2:
+            self.pos = max(0, self.max + offset)
+        else:
+            raise StreamError("seek(): whence must be 0, 1 or 2")
+
+    def read(self, n):
+        assert isinstance(n, int)
+        end = self.pos + n
+        data = self._string[self.pos:end]
+        self.pos += len(data)
+        return data
\ No newline at end of file

src/som/compiler/sourcecode_compiler.py

 import os
 
-from rpython.rlib.streamio import open_file_as_stream, Stream, StreamError
+from rpython.rlib.streamio import open_file_as_stream
+
+from rlib.string_stream import StringStream
 
 from som.compiler.parser                   import Parser
 from som.compiler.class_generation_context import ClassGenerationContext
 
-
-class _StringStream(Stream):
-    def __init__(self, string):
-        self._string = string
-        self.pos     = 0
-        self.max     = len(string) - 1
-
-    def write(self, data):
-        raise StreamError("StringStream is not writable")
-    def truncate(self, size):
-        raise StreamError("StringStream is immutable")
-
-    def peek(self):
-        if self.pos < self.max:
-            return self._string[self.pos:]
-        else:
-            return ''
-
-    def tell(self):
-        return self.pos
-
-    def seek(self, offset, whence):
-        if whence == 0:
-            self.pos = max(0, offset)
-        elif whence == 1:
-            self.pos = max(0, self.pos + offset)
-        elif whence == 2:
-            self.pos = max(0, self.max + offset)
-        else:
-            raise StreamError("seek(): whence must be 0, 1 or 2")
-
-    def read(self, n):
-        assert isinstance(n, int)
-        end = self.pos + n
-        data = self._string[self.pos:end]
-        self.pos += len(data)
-        return data
-
 def compile_class_from_file(path, filename, system_class, universe):
     return _SourcecodeCompiler().compile(path, filename, system_class, universe)
 
@@ -64,7 +28,7 @@ class _SourcecodeCompiler(object):
                 result = self._compile(system_class, universe)
             finally:
                 input_file.close()
-        except OSError as e:
+        except OSError:
             raise IOError()
 
         cname = result.get_name()
@@ -76,7 +40,7 @@ class _SourcecodeCompiler(object):
         return result
 
     def compile_class_string(self, stream, system_class, universe):
-        self._parser = Parser(_StringStream(stream), universe)
+        self._parser = Parser(StringStream(stream), universe)
 
         result = self._compile(system_class, universe)
         return result