[Wisp-cvs] wisp/users/dig bits.py,1.1,1.2

[<di...@us...>]

Update of /cvsroot/wisp/wisp/users/dig
In directory sc8-pr-cvs1:/tmp/cvs-serv3871

Modified Files:
	bits.py 
Log Message:
introduced Bits.__getitem__

Index: bits.py
===================================================================
RCS file: /cvsroot/wisp/wisp/users/dig/bits.py,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -d -r1.1 -r1.2
--- bits.py	26 Apr 2003 17:36:17 -0000	1.1
+++ bits.py	26 Apr 2003 20:56:56 -0000	1.2
@@ -8,23 +8,23 @@
 
 from array import array
 from struct import pack, unpack
+from types import SliceType
 
 class Bits (object):
-    __slots__ = ['_contents', '_skipped']
+    __slots__ = ['_contents', '_skipped', '_byte_order',
+                 'emit_wyde', 'emit_tetra']
     def __init__ (this, byte_order = None):
         this._contents = array('c')
         if byte_order == None: pass
         elif byte_order == '<':
             this.emit_wyde = this.emit_lewyde
             this.emit_tetra = this.emit_letetra
-            this.add_wyde = this.add_lewyde
-            this.add_tetra = this.add_letetra
         elif byte_order == '>':
             this.emit_wyde = this.emit_bewyde
             this.emit_tetra = this.emit_betetra
-            this.add_wyde = this.add_bewyde
-            this.add_tetra = this.add_betetra
         else: raise "Unknown byte order", byte_order
+        this._skipped = 0
+        this._byte_order = byte_order
     def emit_byte (this, b):
         if this._skipped <> 0: raise "Events out of order", this
         this._contents.append(chr(b & 0xff))
@@ -51,9 +51,19 @@
         datum, = unpack(tpl, this._contents[ofs : ofs + size])
         datum += value
         datum %= 1L << (size << 3)
-        this._contents[ofs : ofs + size] = array('c', pack(tpl, datum))
-    def add_lewyde (this, ofs, value): this._add(ofs, value, 2, '<H')
-    def add_bewyde (this, ofs, value): this._add(ofs, value, 2, '>H')
-    def add_letetra (this, ofs, value): this._add(ofs, value, 4, '<L')
-    def add_betetra (this, ofs, value): this._add(ofs, value, 4, '>L')
+        this._contents[ofs : ofs + size] = \
+            array('c', pack(this._byte_order + tpl, datum))
+    def add_wyde (this, ofs, value): this._add(ofs, value, 2, 'H')
+    def add_tetra (this, ofs, value): this._add(ofs, value, 4, 'L')
 
+    def __getitem__ (this, index):
+        if isinstance(index, SliceType):
+            if index.start == None or index.stop != None or \
+                    not index.step in (1, 2, 4):
+                raise 'Bad slice for Bits.__getitem__', index
+            if index.step == 1: return ord(this._contents[index.start])
+            else:
+                data = this._contents[index.start : index.start + index.step]
+                tpl = this._byte_order + {2: 'H', 4: 'L'}[index.step]
+                return unpack(tpl, data)
+        else: return ord(this._contents[index])