histedit: move constraint verification to the 'action.verify' method

Action has a method dedicated to verifying its validity. So we move code
related to constrains into that method. This requires a bit more context to the
'verify' method in the same fashion we were passing the 'prev' argument.

This is an extra step before we can simplify the constraint handling code
further.

hgext/histedit.py

@@ -405,7 +405,7 b' class histeditaction(object):'
             raise error.ParseError("invalid changeset %s" % rulehash)
         return cls(state, rev)
 
-    def verify(self, prev):
+    def verify(self, prev, expected, seen):
         """ Verifies semantic correctness of the rule"""
         repo = self.repo
         ha = node.hex(self.node)
@@ -414,6 +414,27 b' class histeditaction(object):'
         except error.RepoError:
             raise error.ParseError(_('unknown changeset %s listed')
                               % ha[:12])
+        for constraint in self.constraints:
+            if constraint not in _constraints.known():
+                raise error.ParseError(_('unknown constraint "%s"') %
+                        constraint)
+
+        if self.node is not None:
+            constrs = self.constraints
+            if _constraints.noother in constrs and self.node not in expected:
+                raise error.ParseError(
+                    _('%s "%s" changeset was not a candidate')
+                     % (self.verb, node.short(self.node)),
+                    hint=_('only use listed changesets'))
+            if _constraints.forceother in constrs and self.node in expected:
+                raise error.ParseError(
+                    _('%s "%s" changeset was not an edited list candidate')
+                     % (self.verb, node.short(self.node)),
+                    hint=_('only use listed changesets'))
+            if _constraints.noduplicates in constrs and self.node in seen:
+                raise error.ParseError(_(
+                        'duplicated command for changeset %s') %
+                        node.short(self.node))
 
     def torule(self):
         """build a histedit rule line for an action
@@ -661,9 +682,9 b' class edit(histeditaction):'
 @action(['fold', 'f'],
         _('use commit, but combine it with the one above'))
 class fold(histeditaction):
-    def verify(self, prev):
+    def verify(self, prev, expected, seen):
         """ Verifies semantic correctness of the fold rule"""
-        super(fold, self).verify(prev)
+        super(fold, self).verify(prev, expected, seen)
         repo = self.repo
         if not prev:
             c = repo[self.node].parents()[0]
@@ -1377,29 +1398,9 b' def verifyactions(actions, state, ctxs):'
     seen = set()
     prev = None
     for action in actions:
-        action.verify(prev)
+        action.verify(prev, expected, seen)
         prev = action
-        constrs = action.constraints
-        for constraint in constrs:
-            if constraint not in _constraints.known():
-                raise error.ParseError(_('unknown constraint "%s"') %
-                        constraint)
-
         if action.node is not None:
-            if _constraints.noother in constrs and action.node not in expected:
-                raise error.ParseError(
-                    _('%s "%s" changeset was not a candidate')
-                     % (action.verb, node.short(action.node)),
-                    hint=_('only use listed changesets'))
-            if _constraints.forceother in constrs and action.node in expected:
-                raise error.ParseError(
-                    _('%s "%s" changeset was not an edited list candidate')
-                     % (action.verb, node.short(action.node)),
-                    hint=_('only use listed changesets'))
-            if _constraints.noduplicates in constrs and action.node in seen:
-                raise error.ParseError(_(
-                        'duplicated command for changeset %s') %
-                        node.short(action.node))
             seen.add(action.node)
     missing = sorted(expected - seen)  # sort to stabilize output