allow byvar access to non constant List and Tuples

qlasskit/ast2ast/astrewriter.py

@@ -161,6 +161,53 @@ def visit_Subscript(self, node):  # noqa: C901
         if isinstance(_sval, ast.Name) and _sval.id in self.const:
             node.slice = self.const[_sval.id]
 
+        # Handle inner access L[i]
+        elif (
+            isinstance(node, ast.Subscript)
+            and isinstance(node.value, ast.Name)
+            and isinstance(node.slice, ast.Name)
+        ):
+            nname = node.value.id
+            iname = node.slice.id
+
+            def create_if_exp(i, max_i):
+                if i == max_i:
+                    return ast.Subscript(
+                            value=ast.Name(id=nname, ctx=ast.Load()),
+                            slice=ast.Constant(value=i),
+                            ctx=ast.Load(),
+                        )
+                else:
+                    next_i = i + 1
+                    return ast.IfExp(
+                        test=ast.Compare(
+                                    left=ast.Name(id=iname, ctx=ast.Load()),
+                                    ops=[ast.Eq()],
+                                    comparators=[ast.Constant(value=i)],
+
+                        ),
+                        body=ast.Subscript(
+                                value=ast.Name(id=nname, ctx=ast.Load()),
+                                slice=ast.Constant(value=i),
+                                ctx=ast.Load(),
+                            ),
+                        orelse=create_if_exp(next_i, max_i),
+                    )
+
+            # Infer i and j sizes from env['a']
+            a_type = self.env[nname]
+
+            # self.env[nname] is a constant
+            if isinstance(a_type, ast.Tuple):
+                max_i = len(a_type.elts) - 1
+            # self.env[nname] is a type annotation
+            else:
+                outer_tuple = a_type.slice
+                max_i = len(outer_tuple.elts) - 1
+
+            # Create the IfExp structure
+            return create_if_exp(0,  max_i)
+
         # Handle inner access L[i][j]
         elif (
             isinstance(node, ast.Subscript)

test/qlassf/test_list.py

@@ -95,10 +95,6 @@ def test_list_access_with_var(self):
         compute_and_compare_results(self, qf)
 
     def test_list_access_with_var_on_tuple(self):
-        # TODO: this fails on internal compiler
-        if self.compiler == "internal":
-            return
-
         f = (
             "def test(ab: Tuple[Qint[2], Qint[2]]) -> Qint[2]:\n\tc = [1,2,3,2]\n\tai,bi = ab\n"
             "\td = c[ai] + c[bi]\n\treturn d"
@@ -107,10 +103,6 @@ def test_list_access_with_var_on_tuple(self):
         compute_and_compare_results(self, qf)
 
     def test_list_access_with_var_on_tuple2(self):
-        # TODO: this fails on internal compiler
-        if self.compiler == "internal":
-            return
-
         f = (
             "def test(ab: Tuple[Qint[2], Qint[2]]) -> Qint[2]:\n\tc = [1,2,3,2]\n"
             "\td = c[ab[0]] + c[ab[1]]\n\treturn d"
@@ -146,3 +138,11 @@ def test_list_of_tuple_of_tuple2(self):
         ttable = [(False, False), (True, False), (False, True), (True, True)]
         tt = list(map(lambda e: (e[0], e[1], e[0] or e[1]), ttable))
         qf.bind(io_list=tt)
+
+    def test_list_var_access(self):
+        f = (
+            "def test(a: Qlist[bool, 4], i: Qint[2]) -> bool:\n"
+            "\treturn a[i]"
+        )
+        qf = qlassf(f, to_compile=COMPILATION_ENABLED, compiler=self.compiler)
+        compute_and_compare_results(self, qf)

test/qlassf/test_tuple.py

@@ -207,3 +207,11 @@ def test_tuple_of_tuple_var_access(self):
         )
         qf = qlassf(f, to_compile=COMPILATION_ENABLED, compiler=self.compiler)
         compute_and_compare_results(self, qf)
+
+    def test_tuple_var_access(self):
+        f = (
+            "def test(a: Tuple[bool, bool, bool, bool], i: Qint[2]) -> bool:\n"
+            "\treturn a[i]"
+        )
+        qf = qlassf(f, to_compile=COMPILATION_ENABLED, compiler=self.compiler)
+        compute_and_compare_results(self, qf)