xml: T5218: add operations on xml cache

2 files changed, 292 insertions, 0 deletions

diff --git a/python/vyos/xml_ref/__init__.py b/python/vyos/xml_ref/__init__.py
new file mode 100644
index 000000000..66525865c
--- /dev/null
+++ b/python/vyos/xml_ref/__init__.py
@@ -0,0 +1,58 @@
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+from vyos.xml_ref import definition
+
+def load_reference(cache=[]):
+    if cache:
+        return cache[0]
+
+    xml = definition.Xml()
+
+    try:
+        from vyos.xml_ref.cache import reference
+        xml.define(reference)
+        cache.append(xml)
+    except Exception:
+        raise ImportError('no xml reference cache !!')
+
+    return xml
+
+def is_tag(path: list) -> bool:
+    return load_reference().is_tag(path)
+
+def is_tag_value(path: list) -> bool:
+    return load_reference().is_tag_value(path)
+
+def is_multi(path: list) -> bool:
+    return load_reference().is_multi(path)
+
+def is_valueless(path: list) -> bool:
+    return load_reference().is_valueless(path)
+
+def is_leaf(path: list) -> bool:
+    return load_reference().is_leaf(path)
+
+def component_version() -> dict:
+    return load_reference().component_version()
+
+def multi_to_list(rpath: list, conf: dict) -> dict:
+    return load_reference().multi_to_list(rpath, conf)
+
+def get_defaults(path: list, get_first_key=False) -> dict:
+    return load_reference().get_defaults(path, get_first_key=get_first_key)
+
+def merge_defaults(path: list, conf: dict) -> dict:
+    return load_reference().merge_defaults(path, conf)
diff --git a/python/vyos/xml_ref/definition.py b/python/vyos/xml_ref/definition.py
new file mode 100644
index 000000000..64a33e4d0
--- /dev/null
+++ b/python/vyos/xml_ref/definition.py
@@ -0,0 +1,234 @@
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+from typing import Union, Optional, Any
+from vyos.configdict import dict_merge
+
+class Xml:
+    def __init__(self):
+        self.ref = {}
+
+    def define(self, ref: dict):
+        self.ref = ref
+
+    def _get_ref_node_data(self, node: dict, data: str) -> Union[bool, str]:
+        res = node.get('node_data', {})
+        if not res:
+            raise ValueError("non-existent node data")
+        if data not in res:
+            raise ValueError("non-existent data field")
+
+        return res.get(data)
+
+    def _get_ref_path(self, path: list) -> dict:
+        ref_path = path.copy()
+        d = self.ref
+        while ref_path and d:
+            d = d.get(ref_path[0], {})
+            ref_path.pop(0)
+            if self._is_tag_node(d) and ref_path:
+                ref_path.pop(0)
+
+        return d
+
+    def _is_tag_node(self, node: dict) -> bool:
+        res = self._get_ref_node_data(node, 'node_type')
+        return res == 'tag'
+
+    def is_tag(self, path: list) -> bool:
+        ref_path = path.copy()
+        d = self.ref
+        while ref_path and d:
+            d = d.get(ref_path[0], {})
+            ref_path.pop(0)
+            if self._is_tag_node(d) and ref_path:
+                if len(ref_path) == 1:
+                    return False
+                ref_path.pop(0)
+
+        return self._is_tag_node(d)
+
+    def is_tag_value(self, path: list) -> bool:
+        if len(path) < 2:
+            return False
+
+        return self.is_tag(path[:-1])
+
+    def _is_multi_node(self, node: dict) -> bool:
+        b = self._get_ref_node_data(node, 'multi')
+        assert isinstance(b, bool)
+        return b
+
+    def is_multi(self, path: list) -> bool:
+        d = self._get_ref_path(path)
+        return  self._is_multi_node(d)
+
+    def _is_valueless_node(self, node: dict) -> bool:
+        b = self._get_ref_node_data(node, 'valueless')
+        assert isinstance(b, bool)
+        return b
+
+    def is_valueless(self, path: list) -> bool:
+        d = self._get_ref_path(path)
+        return  self._is_valueless_node(d)
+
+    def _is_leaf_node(self, node: dict) -> bool:
+        res = self._get_ref_node_data(node, 'node_type')
+        return res == 'leaf'
+
+    def is_leaf(self, path: list) -> bool:
+        d = self._get_ref_path(path)
+        return self._is_leaf_node(d)
+
+    def component_version(self) -> dict:
+        d = {}
+        for k, v in self.ref['component_version']:
+            d[k] = int(v)
+        return d
+
+    def multi_to_list(self, rpath: list, conf: dict) -> dict:
+        if rpath and rpath[-1] in list(conf):
+            raise ValueError('rpath should be disjoint from conf keys')
+
+        res = {}
+
+        for k in list(conf):
+            d = self._get_ref_path(rpath + [k])
+            if self._is_leaf_node(d):
+                if self._is_multi_node(d) and not isinstance(conf[k], list):
+                    res[k] = [conf[k]]
+                else:
+                    res[k] = conf[k]
+            else:
+                res[k] = self.multi_to_list(rpath + [k], conf[k])
+
+        return res
+
+    def _get_default_value(self, node: dict):
+        return self._get_ref_node_data(node, "default_value")
+
+    def get_defaults(self, path: list, get_first_key=False) -> dict:
+        """Return dict containing default values below path
+
+        Note that descent below path will not proceed beyond an encountered
+        tag node, as no tag node value is known. For a default dict relative
+        to an existing config dict containing tag node values, see function:
+        'relative_defaults'
+        """
+        res: Any = {}
+        d = self._get_ref_path(path)
+        if self._is_leaf_node(d):
+            default_value = self._get_default_value(d)
+            if default_value is not None:
+                res = default_value
+                if self._is_multi_node(d) and not isinstance(res, list):
+                    res = [res]
+        elif self.is_tag(path):
+            # tag node defaults are used as suggestion, not default value;
+            # should this change, append to path and continue recursion
+            pass
+        else:
+            for k in list(d):
+                if k in ('node_data', 'component_version') :
+                    continue
+                pos = self.get_defaults(path + [k])
+                res |= pos
+        if res:
+            if get_first_key or not path:
+                if not isinstance(res, dict):
+                    raise TypeError("Cannot get_first_key as data under node is not of type dict")
+                return res
+            return {path[-1]: res}
+
+        return {}
+
+    def _relative_defaults(self, rpath: list, conf: Optional[dict] = None,
+                          get_first_key=False) -> dict:
+        # Return dict containing defaults along paths of a config dict
+
+        # Note that for conf argument {} or None, this function returns the
+        # same result as 'get_defaults' above; for clarity, the functions
+        # are individually defined.
+
+        if conf is None:
+            conf = {}
+        if rpath and rpath[-1] in list(conf):
+            raise ValueError('rpath should be disjoint from conf keys')
+        res: Any = {}
+        d = self._get_ref_path(rpath)
+        if self._is_leaf_node(d):
+            default_value = self._get_default_value(d)
+            if default_value is not None:
+                res = default_value
+                if self._is_multi_node(d) and not isinstance(res, list):
+                    res = [res]
+        elif self.is_tag(rpath):
+            for k in list(conf):
+                pos = self._relative_defaults(rpath + [k], conf[k])
+                res |= pos
+        else:
+            for k in list(d):
+                if k in ('node_data', 'component_version') :
+                    continue
+                pos = self._relative_defaults(rpath + [k], conf.get(k, {}))
+                res |= pos
+        if res:
+            if get_first_key or not rpath:
+                if not isinstance(res, dict):
+                    raise TypeError("Cannot get_first_key as data under node is not of type dict")
+                return res
+            return {rpath[-1]: res}
+
+        return {}
+
+    def _defines_config_path(self, path: list, conf: dict) -> bool:
+        # test disjoint path + conf for sensible config paths
+        def walk(c):
+            return [next(iter(c.keys()))] if c else []
+        try:
+            tmp = walk(conf)
+            if self.is_tag_value(path + tmp):
+                c = conf[tmp[0]]
+                if not isinstance(c, dict):
+                    raise ValueError
+                tmp = tmp + walk(c)
+                self._get_ref_path(path + tmp)
+            else:
+                self._get_ref_path(path + tmp)
+        except ValueError:
+            return False
+        return True
+
+    def merge_defaults(self, path: list, conf: dict) -> dict:
+        """Return config dict with defaults non-destructively merged
+        """
+        if not path:
+            path = [next(iter(conf.keys()))]
+        if path[-1] in list(conf):
+            config = conf[path[-1]]
+            if not isinstance(config, dict):
+                raise ValueError('conf at path is not of type dict')
+            first = False
+        else:
+            config = conf
+            first = True
+
+        if not self._defines_config_path(path, config):
+            print('path + conf do not define config paths; conf returned unchanged')
+            return conf
+
+        d = self._relative_defaults(path, conf=config, get_first_key=first)
+        d = dict_merge(d, conf)
+        return d