diff --git a/src/caoscrawler/crawl.py b/src/caoscrawler/crawl.py
index b0f576a2c73342cc1301ff0f27b74bb519768541..3a78392e56b55b152f10760b7bec9f9b205263af 100644
--- a/src/caoscrawler/crawl.py
+++ b/src/caoscrawler/crawl.py
@@ -49,12 +49,17 @@ from caosdb.apiutils import compare_entities, merge_entities
from copy import deepcopy
from jsonschema import validate
+from .macros import defmacro_constructor, macro_constructor
import importlib
SPECIAL_PROPERTIES_STRICT = ("description", "name", "id", "path")
SPECIAL_PROPERTIES_NOT_STRICT = ("file", "checksum", "size")
+# Register the macro functions from the submodule:
+yaml.SafeLoader.add_constructor("!defmacro", defmacro_constructor)
+yaml.SafeLoader.add_constructor("!macro", macro_constructor)
+
def check_identical(record1: db.Entity, record2: db.Entity, ignore_id=False):
"""
diff --git a/src/caoscrawler/macros/__init__.py b/src/caoscrawler/macros/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..0acfb1763039a3bb800bbf0e26d6940b49d045cf
--- /dev/null
+++ b/src/caoscrawler/macros/__init__.py
@@ -0,0 +1 @@
+from .macro_yaml_object import defmacro_constructor, macro_constructor
diff --git a/src/caoscrawler/macros/macro_yaml_object.py b/src/caoscrawler/macros/macro_yaml_object.py
new file mode 100644
index 0000000000000000000000000000000000000000..2022f518fe1e3d627fbdcb87595898561f825348
--- /dev/null
+++ b/src/caoscrawler/macros/macro_yaml_object.py
@@ -0,0 +1,120 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# ** header v3.0
+# This file is a part of the CaosDB Project.
+#
+# Copyright (C) 2022 Alexander Schlemmer
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program. If not, see <https://www.gnu.org/licenses/>.
+#
+# ** end header
+#
+
+# Function to expand a macro in yaml
+# A. Schlemmer, 05/2022
+
+from dataclasses import dataclass
+from typing import Any
+from copy import deepcopy
+from string import Template
+
+@dataclass
+class MacroDefinition:
+ """
+ Stores a macro definition.
+ name: Name of the macro
+ params: variables and default values to be substituted in keys or values
+ definition: A dictionary that will be substituted including parameters
+ """
+ name: str
+ params: dict[str, Any]
+ definition: Any
+
+# This dictionary stores the macro definitions
+macro_store: dict[str, MacroDefinition] = dict()
+
+
+def substitute(propvalue, values: dict):
+ """
+ Substitution of variables in strings using the variable substitution
+ library from python's standard library.
+ """
+ propvalue_template = Template(propvalue)
+ return propvalue_template.safe_substitute(**values)
+
+
+def substitute_dict(sourced: dict[str, Any], values: dict[str, Any]):
+ """
+ Create a copy of sourced.
+ Afterwards recursively do variable substitution on all keys and values.
+ """
+ d = deepcopy(sourced)
+ # Changes in keys:
+ replace: dict[str, str] = dict()
+ for k in d:
+ replacement = substitute(k, values)
+ if replacement != k:
+ replace[k] = replacement
+ for k, v in replace.items():
+ d[v] = d[k]
+ del d[k]
+ # Changes in values:
+ for k, v in d.items():
+ if isinstance(v, str):
+ d[k] = substitute(v, values)
+ elif isinstance(v, list):
+ subst_list = list()
+ for i in d[k]:
+ if isinstance(i, str):
+ subst_list.append(substitute(i, values))
+ else:
+ subst_list.append(i)
+ elif isinstance(v, dict):
+ d[k] = substitute_dict(v, values)
+ else:
+ pass
+ return d
+
+
+def defmacro_constructor(loader, node):
+ """
+ Function for registering macros in yaml files.
+
+ It can be registered in pyaml using:
+ yaml.SafeLoader.add_constructor("!defmacro", defmacro_constructor)
+ """
+ value = loader.construct_mapping(node, deep=True)
+ macro = MacroDefinition(
+ value["name"], value["params"],
+ value["definition"])
+ macro_store[macro.name] = macro
+ return {}
+
+
+def macro_constructor(loader, node):
+ """
+ Function for substituting macros in yaml files.
+
+ It can be registered in pyaml using:
+ yaml.SafeLoader.add_constructor("!macro", macro_constructor)
+ """
+ value = loader.construct_mapping(node, deep=True)
+ name = value["name"]
+ macro = macro_store[name]
+ params = deepcopy(macro.params)
+ params.update(value["params"])
+ definition = deepcopy(macro.definition)
+
+ return substitute_dict(definition, params)
diff --git a/unittests/test_macros.py b/unittests/test_macros.py
new file mode 100644
index 0000000000000000000000000000000000000000..2beced2f1f701535e70026e9cc760123ff965a0c
--- /dev/null
+++ b/unittests/test_macros.py
@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# ** header v3.0
+# This file is a part of the CaosDB Project.
+#
+# Copyright (C) 2022 Alexander Schlemmer
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program. If not, see <https://www.gnu.org/licenses/>.
+#
+# ** end header
+#
+
+from caoscrawler.macros import defmacro_constructor, macro_constructor
+import yaml
+
+def test_macros():
+ yaml.SafeLoader.add_constructor("!defmacro", defmacro_constructor)
+ yaml.SafeLoader.add_constructor("!macro", macro_constructor)
+ dat = yaml.load("""
+defs:
+- !defmacro
+ name: test
+ params:
+ a: 2
+ b: bla
+ c: $variable
+ definition:
+ expanded_$b:
+ blubb: ok$a
+ $b: $c
+
+testnode:
+ obl: !macro
+ name: test
+ params:
+ a: 4
+ b: yea
+""", Loader=yaml.SafeLoader)
+ assert dat["testnode"]["obl"]["expanded_yea"]["blubb"] == "ok4"
+ assert dat["testnode"]["obl"]["expanded_yea"]["yea"] == "$variable"
+ assert "expanded_bla" not in dat["testnode"]["obl"]
+ assert "bla" not in dat["testnode"]["obl"]["expanded_yea"]