lib/string: privatize `StringCharView` and cie.

Since there is no additional services in `StringCharView`, then exposing
the classes just add unneeded complexity.

`Text::chars` and cie. could just returns abtract Seuquence types.

Also remove the less useful virtual type `SELFVIEW`.

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/lib/standard/string.nit b/lib/standard/string.nit
index c685f92..e1efccd 100644 (file)
--- a/lib/standard/string.nit
+++ b/lib/standard/string.nit
@@ -32,16 +32,13 @@ abstract class Text
 
        redef type OTHER: Text
 
-       # Type of the view on self (.chars)
-       type SELFVIEW: StringCharView
-
        # Type of self (used for factorization of several methods, ex : substring_from, empty...)
        type SELFTYPE: Text
 
        # Gets a view on the chars of the Text object
        #
        #     assert "hello".chars.to_a == ['h', 'e', 'l', 'l', 'o']
-       fun chars: SELFVIEW is abstract
+       fun chars: SequenceRead[Char] is abstract
 
        # Number of characters contained in self.
        #
@@ -574,7 +571,7 @@ end
 
 # Abstract class for the SequenceRead compatible
 # views on String and Buffer objects
-abstract class StringCharView
+private abstract class StringCharView
        super SequenceRead[Char]
 
        type SELFTYPE: Text
@@ -597,7 +594,7 @@ end
 
 # View on Buffer objects, extends Sequence
 # for mutation operations
-abstract class BufferCharView
+private abstract class BufferCharView
        super StringCharView
        super Sequence[Char]
 
@@ -627,7 +624,7 @@ class FlatString
        # Indes in _items of the last item of the string
        private var index_to: Int
 
-       redef var chars: SELFVIEW = new FlatStringCharView(self)
+       redef var chars: SequenceRead[Char] = new FlatStringCharView(self)
 
        ################################################
        #       AbstractString specific methods        #
@@ -960,7 +957,6 @@ end
 abstract class Buffer
        super Text
 
-       redef type SELFVIEW: BufferCharView
        redef type SELFTYPE: Buffer
 
        # Specific implementations MUST set this to `true` in order to invalidate caches
@@ -1002,6 +998,9 @@ abstract class Buffer
                return super
        end
 
+       # In Buffers, the internal sequence of character is mutable
+       # Thus, `chars` can be used to modify the buffer.
+       redef fun chars: Sequence[Char] is abstract
 end
 
 # Mutable strings of characters.
@@ -1011,7 +1010,7 @@ class FlatBuffer
 
        redef type SELFTYPE: FlatBuffer
 
-       redef var chars: SELFVIEW = new FlatBufferCharView(self)
+       redef var chars: Sequence[Char] = new FlatBufferCharView(self)
 
        private var capacity: Int