Data structures builtins

processing issue https://git.scc.kit.edu/jk7683/vre-language/-/issues/8

constraints/substitute.py

+"""functions related to variable substitutions in expressions"""
+from copy import deepcopy
+from textx import get_children_of_type, get_children
+from textx import get_metamodel
+from textx import textx_isinstance
+
+
+def subst(caller, func, params):
+    """
+    substitute dummy identifiers (bound variables) with their parameters
+    caller: the object of which the new returned expression will become a child
+    func: object of type FunctionDefinition or Lambda that contain expr
+    params: an iterable with the parameters in the order of substitution
+    """
+    expr = deepcopy(func.expr)
+    new_objs = get_children(lambda x: True, expr)
+    for new_obj in new_objs:
+        if new_obj is not expr:
+            new_obj.parent = new_obj.parent.last_copy
+    expr.parent = caller
+    meta = get_metamodel(caller)
+    vrefs = get_children_of_type('VarReference', expr)
+    for vref in filter(lambda x: textx_isinstance(x.ref, meta['Dummy']), vrefs):
+        if hasattr(vref.ref, 'name'):
+            for par, arg in zip(params, func.args):
+                if vref.ref.name == arg.name:
+                    if textx_isinstance(par, meta['VarReference']):
+                        vref.ref = par.ref
+                    else:
+                        vref.ref = par
+                    break
+    return expr