merge: add state extras merge state data

In future commits we will want to store more data related to each file in the
merge state. This patch adds an optional record for storing a dictionary of
extras for each file.

mercurial/merge.py

@@ -65,6 +65,7 b' class mergestate(object):'
        (experimental)
     m: the external merge driver defined for this merge plus its run state
        (experimental)
+    f: a (filename, dictonary) tuple of optional values for a given file
     X: unsupported mandatory record type (used in tests)
     x: unsupported advisory record type (used in tests)
 
@@ -102,6 +103,7 b' class mergestate(object):'
 
     def reset(self, node=None, other=None):
         self._state = {}
+        self._stateextras = {}
         self._local = None
         self._other = None
         for var in ('localctx', 'otherctx'):
@@ -126,6 +128,7 b' class mergestate(object):'
         of on disk file.
         """
         self._state = {}
+        self._stateextras = {}
         self._local = None
         self._other = None
         for var in ('localctx', 'otherctx'):
@@ -152,6 +155,16 b' class mergestate(object):'
             elif rtype in 'FDC':
                 bits = record.split('\0')
                 self._state[bits[0]] = bits[1:]
+            elif rtype == 'f':
+                filename, rawextras = record.split('\0', 1)
+                extraparts = rawextras.split('\0')
+                extras = {}
+                i = 0
+                while i < len(extraparts):
+                    extras[extraparts[i]] = extraparts[i + 1]
+                    i += 2
+
+                self._stateextras[filename] = extras
             elif not rtype.islower():
                 unsupported.add(rtype)
         self._results = {}
@@ -336,6 +349,10 b' class mergestate(object):'
                 records.append(('C', '\0'.join([d] + v)))
             else:
                 records.append(('F', '\0'.join([d] + v)))
+        for filename, extras in sorted(self._stateextras.iteritems()):
+            rawextras = '\0'.join('%s\0%s' % (k, v) for k, v in
+                                  extras.iteritems())
+            records.append(('f', '%s\0%s' % (filename, rawextras)))
         return records
 
     def _writerecords(self, records):
@@ -423,6 +440,9 b' class mergestate(object):'
             if entry[0] == 'd':
                 yield f
 
+    def extras(self, filename):
+        return self._stateextras.setdefault(filename, {})
+
     def _resolve(self, preresolve, dfile, wctx, labels=None):
         """rerun merge process for file path `dfile`"""
         if self[dfile] in 'rd':
@@ -462,6 +482,7 b' class mergestate(object):'
         if r is None:
             # no real conflict
             del self._state[dfile]
+            self._stateextras.pop(dfile, None)
             self._dirty = True
         elif not r:
             self.mark(dfile, 'r')