# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1252967576 -7200
# Node ID d8b4b6f1a5d94f184d0c18db624692b8ae1e1f90
# Parent  8d41e2d063e91164d0d0ea9b187030c70e617a8a
Added a cache offset attribute to better track available cached data.

diff -r 8d41e2d063e9 -r d8b4b6f1a5d9 iixr/files.py
--- a/iixr/files.py	Tue Sep 15 00:15:58 2009 +0200
+++ b/iixr/files.py	Tue Sep 15 00:32:56 2009 +0200
@@ -137,12 +137,20 @@
 
     def __init__(self, f):
         File.__init__(self, f)
-        self.reset_cache()
+        self.reset_cache(0)
 
-    def reset_cache(self):
+    def reset_cache(self, offset):
         self.cache = ""
         self.cache_length = 0
         self.cache_start = 0
+        self.cache_offset = offset
+        self.f.seek(offset)
+
+    def resize_cache(self, next_start):
+        self.cache = self.cache[next_start:]
+        self.cache_length = len(self.cache)
+        self.cache_start = 0
+        self.cache_offset += next_start
 
     def read_number(self):
 
@@ -217,31 +225,28 @@
         return s
 
     def tell(self):
-        return self.f.tell() - self.cache_length + self.cache_start
+        return self.cache_offset + self.cache_start
 
     def seek(self, offset):
         current = self.tell()
-        self.f.seek(offset)
 
         # If seeking forward, attempt to navigate the cache.
 
         if offset >= current:
             self._seek_cache(offset - current)
         else:
-            self.reset_cache()
+            self.reset_cache(offset)
 
     def _seek_cache(self, delta):
         next_start = self.cache_start + delta
 
         if next_start > 0 and next_start >= len(self.cache):
-            self.reset_cache()
+            self.reset_cache(self.cache_offset + next_start)
 
         # If the cache is too big, resize it.
 
         elif next_start > READ_CACHE_RESIZE:
-            self.cache = self.cache[next_start:]
-            self.cache_length = len(self.cache)
-            self.cache_start = 0
+            self.resize_cache(next_start)
 
         # Otherwise, just reference the next part of the cache.