dirstate: add a `set_tracked` method for "hg add"-like usage

dirstate: add a `set_tracked` method for "hg add"-like usage

This is a step further toward clarifying the semantic of various dirstate call.

Having a dedicated function comes with a couple of benefits:

1) we can move duplicated logic about how to handle the previous state within
the dirstate. Since we are sure this is always called in the same situation, we
can implement that logic once in the dirstate.

2) having a dedicated method for this case unlock also having a dedicated
method for the other case and recording more information at that time. All this
leading having more code within the dirstate and higher level API that are less
error prone.

Differential Revision: https://phab.mercurial-scm.org/D11013

--- a/hgext/largefiles/lfutil.py	Sat Jul 10 23:31:51 2021 +0200
+++ b/hgext/largefiles/lfutil.py	Thu Jul 08 03:03:34 2021 +0200
@@ -162,6 +162,9 @@
     def __getitem__(self, key):
         return super(largefilesdirstate, self).__getitem__(unixpath(key))
 
+    def set_tracked(self, f):
+        return super(largefilesdirstate, self).set_tracked(unixpath(f))
+
     def normal(self, f):
         return super(largefilesdirstate, self).normal(unixpath(f))
 

--- a/hgext/narrow/narrowdirstate.py	Sat Jul 10 23:31:51 2021 +0200
+++ b/hgext/narrow/narrowdirstate.py	Thu Jul 08 03:03:34 2021 +0200
@@ -38,6 +38,10 @@
             return super(narrowdirstate, self).normal(*args, **kwargs)
 
         @_editfunc
+        def set_tracked(self, *args):
+            return super(narrowdirstate, self).set_tracked(*args)
+
+        @_editfunc
         def add(self, *args):
             return super(narrowdirstate, self).add(*args)
 

--- a/hgext/sparse.py	Sat Jul 10 23:31:51 2021 +0200
+++ b/hgext/sparse.py	Thu Jul 08 03:03:34 2021 +0200
@@ -256,6 +256,7 @@
     # Prevent adding files that are outside the sparse checkout
     editfuncs = [
         b'normal',
+        b'set_tracked',
         b'add',
         b'normallookup',
         b'copy',

--- a/mercurial/dirstate.py	Sat Jul 10 23:31:51 2021 +0200
+++ b/mercurial/dirstate.py	Thu Jul 08 03:03:34 2021 +0200
@@ -83,6 +83,17 @@
     return wrap
 
 
+def requires_no_parents_change(func):
+    def wrap(self, *args, **kwargs):
+        if not self.pendingparentchange():
+            msg = 'calling `%s` inside of a parentchange context'
+            msg %= func.__name__
+            raise error.ProgrammingError(msg)
+        return func(self, *args, **kwargs)
+
+    return wrap
+
+
 @interfaceutil.implementer(intdirstate.idirstate)
 class dirstate(object):
     def __init__(
@@ -451,6 +462,24 @@
     def copies(self):
         return self._map.copymap
 
+    @requires_no_parents_change
+    def set_tracked(self, filename):
+        """a "public" method for generic code to mark a file as tracked
+
+        This function is to be called outside of "update/merge" case. For
+        example by a command like `hg add X`.
+
+        return True the file was previously untracked, False otherwise.
+        """
+        entry = self._map.get(filename)
+        if entry is None:
+            self._add(filename)
+            return True
+        elif not entry.tracked:
+            self.normallookup(filename)
+            return True
+        return False
+
     @requires_parents_change
     def update_file_reference(
         self,