From patchwork Wed Jun 25 23:22:09 2014
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Subject: [3,of,4,V3] tags: add mergemode flag to _readtags
From: Angel Ezquerra <angel.ezquerra@gmail.com>
X-Patchwork-Id: 5066
Message-Id: <488f01d33770c338ebe9.1403738529@ubuntu>
To: mercurial-devel@selenic.com
Date: Thu, 26 Jun 2014 01:22:09 +0200

# HG changeset patch
# User Angel Ezquerra <angel.ezquerra@gmail.com>
# Date 1403677632 -7200
#      Wed Jun 25 08:27:12 2014 +0200
# Node ID 488f01d33770c338ebe987b4efbd986b0ef91ed0
# Parent  10ffd0db8fea2e7324233136b262822e775c45a5
tags: add mergemode flag to _readtags

When this flag is enabled the output of the function changes in a way that will
make it easier to merge tags read using the _readtags function.

By default _readtags returns a sortdict of tags where each item in the sortdict
correponds to a two element tuple containing the current tag node and the node
history of the tag.

When the mergemode flag is enabled the output is a sortdict mapping each tag to
a list of [hexnode, line number] pairs. That is, each element is a pair where
the first item is a hex node and the second is the line number where that
hexnode was found on the tag file being read. Pairs are ordered from the oldest
to the most recent, current hexnode.

This is not used yet, but will be used on a follow up patch that will introduce
an automatic tag merge algorithm.

diff --git a/mercurial/tags.py b/mercurial/tags.py
--- a/mercurial/tags.py
+++ b/mercurial/tags.py
@@ -75,20 +75,25 @@
         recode=encoding.fromlocal)
     _updatetags(filetags, "local", alltags, tagtypes)
 
-def _readtags(ui, repo, lines, fn, recode=None):
+def _readtags(ui, repo, lines, fn, recode=None, mergemode=False):
     '''Read tag definitions from a file (or any source of lines).
-    Return a mapping from tag name to (node, hist): node is the node id
-    from the last line read for that name, and hist is the list of node
-    ids previously associated with it (in file order).  All node ids are
-    binary, not hex.'''
+    The output changes depending on the mergemode flag:
+    - When mergemode is False (the default), return a mapping from tag name to
+      (node, hist): node is the node id from the last line read for that name,
+      and hist is the list of node ids previously associated with it (in file
+      order).  All node ids are binary, not hex.
+    - When mergemode is True, return a mapping from tag name to a list of
+      [hexnode, line number] pairs, ordered from the oldest to the newest node.
+      hex node is hex not binary.
+      '''
 
-    filetags = util.sortdict()  # map tag name to (node, hist)
+    filetags = util.sortdict()
     count = 0
 
     def warn(msg):
         ui.warn(_("%s, line %s: %s\n") % (fn, count, msg))
 
-    for line in lines:
+    for nline, line in enumerate(lines):
         count += 1
         if not line:
             continue
@@ -108,6 +113,13 @@
 
         # update filetags
         hist = []
+        if mergemode:
+            # map tag name to list of [node, line number]
+            if name not in filetags:
+                filetags[name] = []
+            filetags[name].append([nodehex, nline])
+            continue
+        # map tag name to (node, hist)
         if name in filetags:
             n, hist = filetags[name]
             hist.append(n)