🐐 Unpacking arrays

tests.py

@@ -11,8 +11,8 @@ from fractions import Fraction
 
 from centvrion.ast_nodes import (
   ArrayIndex, Bool, BinOp, BuiltIn, DataArray, DataRangeArray, Defini,
-  Continva, Designa, DesignaIndex, DumStatement, Erumpe, ExpressionStatement, ID,
-  Invoca, ModuleCall, Nullus, Numeral, PerStatement,
+  Continva, Designa, DesignaDestructure, DesignaIndex, DumStatement, Erumpe,
+  ExpressionStatement, ID, Invoca, ModuleCall, Nullus, Numeral, PerStatement,
   Program, Redi, SiStatement, String, UnaryMinus, UnaryNot,
   Fractio, frac_to_fraction, fraction_to_frac,
   num_to_int, int_to_num, make_string,
@@ -298,6 +298,57 @@ class TestAssignment(unittest.TestCase):
     run_test(self, source, nodes, value)
 
 
+# --- Destructuring ---
+
+destructuring_tests = [
+  # basic: unpack multi-return function
+  (
+    "DEFINI pair (a, b) VT { REDI (a, b) }\nDESIGNA x, y VT INVOCA pair (III, VII)\nx + y",
+    Program([], [
+      Defini(ID("pair"), [ID("a"), ID("b")], [Redi([ID("a"), ID("b")])]),
+      DesignaDestructure([ID("x"), ID("y")], Invoca(ID("pair"), [Numeral("III"), Numeral("VII")])),
+      ExpressionStatement(BinOp(ID("x"), ID("y"), "SYMBOL_PLUS")),
+    ]),
+    ValInt(10),
+  ),
+  # unpack array literal
+  (
+    "DESIGNA a, b VT [I, II]\na + b",
+    Program([], [
+      DesignaDestructure([ID("a"), ID("b")], DataArray([Numeral("I"), Numeral("II")])),
+      ExpressionStatement(BinOp(ID("a"), ID("b"), "SYMBOL_PLUS")),
+    ]),
+    ValInt(3),
+  ),
+  # three variables
+  (
+    "DESIGNA a, b, c VT [X, XX, XXX]\na + b + c",
+    Program([], [
+      DesignaDestructure([ID("a"), ID("b"), ID("c")], DataArray([Numeral("X"), Numeral("XX"), Numeral("XXX")])),
+      ExpressionStatement(BinOp(BinOp(ID("a"), ID("b"), "SYMBOL_PLUS"), ID("c"), "SYMBOL_PLUS")),
+    ]),
+    ValInt(60),
+  ),
+  # destructure into individual use
+  (
+    "DEFINI pair (a, b) VT { REDI (a, b) }\nDESIGNA x, y VT INVOCA pair (V, II)\nDICE(x)\nDICE(y)",
+    Program([], [
+      Defini(ID("pair"), [ID("a"), ID("b")], [Redi([ID("a"), ID("b")])]),
+      DesignaDestructure([ID("x"), ID("y")], Invoca(ID("pair"), [Numeral("V"), Numeral("II")])),
+      ExpressionStatement(BuiltIn("DICE", [ID("x")])),
+      ExpressionStatement(BuiltIn("DICE", [ID("y")])),
+    ]),
+    ValStr("II"),
+    "V\nII\n",
+  ),
+]
+
+class TestDestructuring(unittest.TestCase):
+  @parameterized.expand(destructuring_tests)
+  def test_destructuring(self, source, nodes, value, output=""):
+    run_test(self, source, nodes, value, output)
+
+
 # --- Control flow ---
 
 control_tests = [
@@ -539,6 +590,9 @@ error_tests = [
   ("NON I", CentvrionError),                                               # NON on integer
   ("DESIGNA z VT I - I\nNON z", CentvrionError),                          # NON on zero integer
   ('NON "hello"', CentvrionError),                                         # NON on string
+  ("DESIGNA a, b VT III", CentvrionError),                                 # destructure non-array
+  ("DESIGNA a, b VT [I]", CentvrionError),                                # destructure length mismatch: too many targets
+  ("DESIGNA a, b VT [I, II, III]", CentvrionError),                       # destructure length mismatch: too few targets
 ]
 
 class TestErrors(unittest.TestCase):