Typed metavar (part 2, sgrep part) for literals.

.gitignore

@@ -22,7 +22,7 @@ dist/
 downloads/
 eggs/
 .eggs/
-lib/
+#lib/ pad: used for ocaml
 lib64/
 parts/
 sdist/

lib/generic_vs_generic.ml

@@ -449,6 +449,12 @@ and m_expr a b =
      when MV.is_metavar_name str ->
       envf (str, tok) (B.E (e2))
 
+  (* metavar: typed! *)
+  | A.TypedMetavar ((str, tok), _, t), e2 
+      when MV.is_metavar_name str && 
+           Typechecking_generic.compatible_type t e2 ->
+      envf (str, tok) (B.E e2)
+
   (* dots: should be patterned-match before in arguments, or statements,
    * but this is useful for keyword parameters, as in f(..., foo=..., ...)
    *)
@@ -593,6 +599,7 @@ and m_expr a b =
   | A.Yield _, _  | A.Await _, _  | A.Cast _, _  | A.Seq _, _  | A.Ref _, _
   | A.DeRef _, _  | A.OtherExpr _, _
   | A.SliceAccess _, _
+  | A.TypedMetavar _, _
    -> fail ()
 
 

lib/typechecking_generic.ml

@@ -0,0 +1,45 @@
+(* Yoann Padioleau
+ *
+ * Copyright (C) 2020 r2c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License (GPL)
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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
+ * file license.txt for more details.
+ *)
+open Ast_generic
+
+(*****************************************************************************)
+(* Prelude *)
+(*****************************************************************************)
+(* Poor's man typechecker on literals (for now).
+ *
+ * todo: 
+ *  - local type inference on AST generic? good coverage?
+ *  - we could allow metavars on the type itself, as in
+ *    foo($X: $T) ... $T x; ...
+ *    which would require to transform the code in the generic_vs_generic
+ *    style as typechecking could also bind metavariables in the process
+ *)
+
+(*****************************************************************************)
+(* Entry point *)
+(*****************************************************************************)
+
+(* very Python specific for now where the type is currently an OT_Expr
+ * TODO: fill Ast_generic.expr_to_type at least.
+ *)
+let compatible_type t e =
+  match t, e with
+  | OtherType (OT_Expr, [E (Name ((("int", _tok), _nameinfo), _idinfo))]),
+    L (Int _) -> true
+  | OtherType (OT_Expr, [E (Name ((("float", _tok), _nameinfo), _idinfo))]),
+    L (Float _) -> true
+  | OtherType (OT_Expr, [E (Name ((("str", _tok), _nameinfo), _idinfo))]),
+    L (String _) -> true
+
+  | _ -> false

lib/typechecking_generic.mli

@@ -0,0 +1,2 @@
+
+val compatible_type: Ast_generic.type_ -> Ast_generic.expr -> bool

tests/python/metavar_typed.py

@@ -0,0 +1,5 @@
+def foo():
+  #ERROR: match
+  foo(1)
+  foo(1.0)
+  foo("")

tests/python/metavar_typed.sgrep

@@ -0,0 +1 @@
+foo($X: int)