# HG changeset patch
# User Anton Shestakov <av6@dwimlabs.net>
# Date 1587483911 -28800
# Node ID 2d48fc2c47fc29cb8b8fd1a3cc102a2e4807898b
# Parent  b117e47326562b228510adf88ab5962c7276bf4e
obslog: add preliminary support for showing predecessors

This functionality is not yet used right now, but will be in the next patch.

diff -r b117e4732656 -r 2d48fc2c47fc hgext3rd/evolve/obshistory.py
--- a/hgext3rd/evolve/obshistory.py	Fri Apr 24 01:15:38 2020 +0800
+++ b/hgext3rd/evolve/obshistory.py	Tue Apr 21 23:45:11 2020 +0800
@@ -112,8 +112,10 @@
     b"presentnode": TEMPLATE_PRESENT_NODE,
     b"missingnode": TEMPLATE_MISSING_NODE
 }
+TEMPLATE_PREDNODES = b"""{label("evolve.node", join(prednodes % "{prednode|short}", ", "))}"""
 TEMPLATE_SUCCNODES = b"""{label("evolve.node", join(succnodes % "{succnode|short}", ", "))}"""
-TEMPLATE_NODES = b"""{if(succnodes, "as %(succnodes)s")}""" % {
+TEMPLATE_NODES = b"""{if(prednodes, "from %(prednodes)s")}{if(succnodes, "as %(succnodes)s")}""" % {
+    b"prednodes": TEMPLATE_PREDNODES,
     b"succnodes": TEMPLATE_SUCCNODES
 }
 TEMPLATE_REWRITE = b"""{label("evolve.verb", verb)}{if(effects, "({join(effects, ", ")})")}"""
@@ -606,10 +608,14 @@
              label=b"evolve.node evolve.missing_change_ctx")
     fm.plain(b'\n')
 
-def displaymarkers(ui, fm, succnodes, markers, node, repo, includediff=False):
+def displaymarkers(ui, fm, nodes, markers, node, repo, includediff=False,
+                   successive=True):
     fm.startitem()
 
-    verb = _successorsetverb(succnodes, markers)[b"verb"]
+    if successive:
+        verb = _successorsetverb(nodes, markers)[b"verb"]
+    else:
+        verb = _predecessorsverb(nodes, markers)
 
     fm.data(verb=verb)
 
@@ -618,10 +624,14 @@
         fmteffects = fm.formatlist(effects, b'effect', sep=b', ')
         fm.data(effects=fmteffects)
 
-    if len(succnodes) > 0:
-        hexnodes = (nodemod.hex(succnode) for succnode in sorted(succnodes))
-        nodes = fm.formatlist(hexnodes, b'succnode')
-        fm.data(succnodes=nodes)
+    if len(nodes) > 0:
+        hexnodes = (nodemod.hex(node) for node in sorted(nodes))
+        if successive:
+            nodelist = fm.formatlist(hexnodes, b'succnode')
+            fm.data(succnodes=nodelist)
+        else:
+            nodelist = fm.formatlist(hexnodes, b'prednode')
+            fm.data(prednodes=nodelist)
 
     # Operations
     operations = obsutil.markersoperations(markers)
@@ -643,22 +653,27 @@
 
     # Patch display
     if includediff is True:
-        _patchavailable = patchavailable(node, repo, succnodes)
+        _patchavailable = patchavailable(node, repo, nodes,
+                                         successive=successive)
 
         if _patchavailable[0] is True:
-            succ = _patchavailable[1]
+            diffnode = _patchavailable[1]
 
-            basectx = repo[node]
-            succctx = repo[succ]
+            if successive:
+                actx = repo[node]
+                bctx = repo[diffnode]
+            else:
+                actx = repo[diffnode]
+                bctx = repo[node]
             # Description patch
             descriptionpatch = getmarkerdescriptionpatch(repo,
-                                                         basectx.description(),
-                                                         succctx.description())
+                                                         actx.description(),
+                                                         bctx.description())
 
             if descriptionpatch:
                 # add the diffheader
                 diffheader = b"diff -r %s -r %s changeset-description\n" %\
-                             (basectx, succctx)
+                             (actx, bctx)
                 descriptionpatch = diffheader + descriptionpatch
 
                 def tolist(text):
@@ -678,8 +693,8 @@
             matchfn = scmutil.matchall(repo)
             firstline = True
             linestart = True
-            for chunk, label in patch.diffui(repo, node, succ, matchfn,
-                                             opts=diffopts):
+            for chunk, label in patch.diffui(repo, actx.node(), bctx.node(),
+                                             matchfn, opts=diffopts):
                 if firstline:
                     ui.write(b'\n')
                     firstline = False