[PATCH 2/2] python/notmuch2: add bindings for the database config strings

[Anton Khirnov]

---
 bindings/python-cffi/notmuch2/_build.py    | 17 +++++
 bindings/python-cffi/notmuch2/_config.py   | 84 ++++++++++++++++++++++
 bindings/python-cffi/notmuch2/_database.py | 23 ++++++
 3 files changed, 124 insertions(+)
 create mode 100644 bindings/python-cffi/notmuch2/_config.py

diff --git a/bindings/python-cffi/notmuch2/_build.py b/bindings/python-cffi/notmuch2/_build.py
index 5e1fcac1..f269f2a1 100644
--- a/bindings/python-cffi/notmuch2/_build.py
+++ b/bindings/python-cffi/notmuch2/_build.py
@@ -314,6 +314,23 @@ ffibuilder.cdef(
     notmuch_indexopts_get_decrypt_policy (const notmuch_indexopts_t *indexopts);
     void
     notmuch_indexopts_destroy (notmuch_indexopts_t *options);
+
+    notmuch_status_t
+    notmuch_database_set_config (notmuch_database_t *db, const char *key, const char *value);
+    notmuch_status_t
+    notmuch_database_get_config (notmuch_database_t *db, const char *key, char **value);
+    notmuch_status_t
+    notmuch_database_get_config_list (notmuch_database_t *db, const char *prefix, notmuch_config_list_t **out);
+    notmuch_bool_t
+    notmuch_config_list_valid (notmuch_config_list_t *config_list);
+    const char *
+    notmuch_config_list_key (notmuch_config_list_t *config_list);
+    const char *
+    notmuch_config_list_value (notmuch_config_list_t *config_list);
+    void
+    notmuch_config_list_move_to_next (notmuch_config_list_t *config_list);
+    void
+    notmuch_config_list_destroy (notmuch_config_list_t *config_list);
     """
 )
 
diff --git a/bindings/python-cffi/notmuch2/_config.py b/bindings/python-cffi/notmuch2/_config.py
new file mode 100644
index 00000000..58383c16
--- /dev/null
+++ b/bindings/python-cffi/notmuch2/_config.py
@@ -0,0 +1,84 @@
+import collections.abc
+
+import notmuch2._base as base
+import notmuch2._capi as capi
+import notmuch2._errors as errors
+
+__all__ = ['ConfigMapping']
+
+class ConfigIter(base.NotmuchIter):
+    def __init__(self, parent, iter_p):
+        super().__init__(
+            parent, iter_p,
+            fn_destroy=capi.lib.notmuch_config_list_destroy,
+            fn_valid=capi.lib.notmuch_config_list_valid,
+            fn_get=capi.lib.notmuch_config_list_key,
+            fn_next=capi.lib.notmuch_config_list_move_to_next)
+
+    def __next__(self):
+        item = super().__next__()
+        return base.BinString.from_cffi(item)
+
+class ConfigMapping(base.NotmuchObject, collections.abc.MutableMapping):
+    """The config key/value pairs stored in the database.
+
+    The entries are exposed as a :class:`collections.abc.MutableMapping` object.
+    Note that setting a value to an empty string is the same as deleting it.
+
+    :param parent: the parent object
+    :param ptr_name: the name of the attribute on the parent which will
+       return the memory pointer.  This allows this object to
+       access the pointer via the parent's descriptor and thus
+       trigger :class:`MemoryPointer`'s memory safety.
+    """
+
+    def __init__(self, parent, ptr_name):
+        self._parent = parent
+        self._ptr = lambda: getattr(parent, ptr_name)
+
+    @property
+    def alive(self):
+        return self._parent.alive
+
+    def _destroy(self):
+        pass
+
+    def __getitem__(self, key):
+        if isinstance(key, str):
+            key = key.encode('utf-8')
+        val_pp = capi.ffi.new('char**')
+        ret = capi.lib.notmuch_database_get_config(self._ptr(), key, val_pp)
+        if ret != capi.lib.NOTMUCH_STATUS_SUCCESS:
+            raise errors.NotmuchError(ret)
+        if val_pp[0] == "":
+            capi.lib.free(val_pp[0])
+            raise KeyError
+        val = base.BinString.from_cffi(val_pp[0])
+        capi.lib.free(val_pp[0])
+        return val
+
+    def __setitem__(self, key, val):
+        if isinstance(key, str):
+            key = key.encode('utf-8')
+        if isinstance(val, str):
+            val = val.encode('utf-8')
+        ret = capi.lib.notmuch_database_set_config(self._ptr(), key, val)
+        if ret != capi.lib.NOTMUCH_STATUS_SUCCESS:
+            raise errors.NotmuchError(ret)
+
+    def __delitem__(self, key):
+        self[key] = ""
+
+    def __iter__(self):
+        """Return an iterator over the config items.
+
+        :raises NullPointerError: If the iterator can not be created.
+        """
+        configlist_pp = capi.ffi.new('notmuch_config_list_t**')
+        ret = capi.lib.notmuch_database_get_config_list(self._ptr(), b'', configlist_pp)
+        if ret != capi.lib.NOTMUCH_STATUS_SUCCESS:
+            raise errors.NotmuchError(ret)
+        return ConfigIter(self._parent, configlist_pp[0])
+
+    def __len__(self):
+        return sum(1 for t in self)
diff --git a/bindings/python-cffi/notmuch2/_database.py b/bindings/python-cffi/notmuch2/_database.py
index f14eac78..fc55fea8 100644
--- a/bindings/python-cffi/notmuch2/_database.py
+++ b/bindings/python-cffi/notmuch2/_database.py
@@ -7,6 +7,7 @@ import pathlib
 import weakref
 
 import notmuch2._base as base
+import notmuch2._config as config
 import notmuch2._capi as capi
 import notmuch2._errors as errors
 import notmuch2._message as message
@@ -536,6 +537,28 @@ class Database(base.NotmuchObject):
             self._cached_tagset = weakref.ref(tagset)
         return tagset
 
+    @property
+    def config(self):
+        """Return a mutable mapping with the settings stored in this database.
+
+        This returns an mutable dict-like object implementing the
+        collections.abc.MutableMapping Abstract Base Class.
+
+        :rtype: Config
+
+        :raises ObjectDestroyedError: if used after destroyed.
+        """
+        try:
+            ref = self._cached_config
+        except AttributeError:
+            config_mapping = None
+        else:
+            config_mapping = ref()
+        if config_mapping is None:
+            config_mapping = config.ConfigMapping(self, '_db_p')
+            self._cached_config = weakref.ref(config_mapping)
+        return config_mapping
+
     def _create_query(self, query, *,
                       omit_excluded=EXCLUDE.TRUE,
                       sort=SORT.UNSORTED,  # Check this default
-- 
2.20.1