Added variable assingment

ziffers/classes.py

@@ -270,6 +270,16 @@ class Function(Event):
 
     run: str = field(default=None)
 
+@dataclass(kw_only=True)
+class VariableAssignment(Item):
+    """Class for defining variables"""
+    variable: str
+    value: Item
+
+@dataclass(kw_only=True)
+class Variable(Item):
+    """Class for using variables"""
+    name: str
 
 @dataclass(kw_only=True)
 class Sequence(Meta):
@@ -334,6 +344,12 @@ class Sequence(Meta):
                     yield item
                 else:
                     yield from item.evaluate_tree(options)
+            elif isinstance(item, VariableAssignment):
+                options[item.variable.name] = item.value
+            elif isinstance(item, Variable):
+                if options[item.name]:
+                    variable = options[item.name]
+                    yield from _resolve_item(variable, options)
             elif isinstance(item, Range):
                 yield from item.evaluate(options)
             elif isinstance(item, Cyclic):

ziffers/mapper.py

@@ -28,6 +28,8 @@ from .classes import (
     Integer,
     Euclid,
     RepeatedSequence,
+    VariableAssignment,
+    Variable
 )
 from .common import flatten, sum_dict
 from .defaults import DEFAULT_DURS, OPERATORS
@@ -255,6 +257,17 @@ class ZiffersTransformer(Transformer):
         val = token[0].value
         return Atom(value=val, text=val)
 
+
+    # Variable assignment
+
+    def assignment(self, items):
+        var = items[0]
+        content = items[1]
+        return VariableAssignment(variable=var, value=content, text=var.text+"="+content.text)
+
+    def variable(self, items):
+        return Variable(name=items[0].value, text=items[0].value)
+
     # List rules
 
     def list(self, items):

ziffers/spec/ziffers.lark

@@ -1,6 +1,6 @@
     // Root for the rules    
     ?root: sequence -> start
-    sequence: (pitch_class | rest | dur_change | oct_mod | oct_change | WS | chord | named_roman | cycle | random_integer | random_pitch | random_percent | range | list | repeated_list | lisp_operation | list_op | subdivision | eval | euclid | repeat)*
+    sequence: (pitch_class | assignment | variable | rest | dur_change | oct_mod | oct_change | WS | chord | named_roman | cycle | random_integer | random_pitch | random_percent | range | list | repeated_list | lisp_operation | list_op | subdivision | eval | euclid | repeat)*
     
     // Pitch classes
     pitch_class: prefix* pitch
@@ -11,6 +11,10 @@
     octave: /[_^]+/
     modifier: /[#b]/
 
+    // Variable assignment
+    assignment: variable "=" (list | pitch_class | random_integer | random_pitch | cycle | list_op)
+    variable: /[A-Z]/
+
     // Durations
     // TODO: Refactor dchar as: /([mklpdcwyhnqaefsxtgujzo](\.)*)(?=\d)/
     duration_chars: dotted_dur+