Added pattern guards to sail

Introduces a when keyword for case statements, as the Pat_when constructor for pexp's in the AST. This allows us to write things like:

typedef T = const union { int C1; int C2 }

function int test ((int) x, (T) y) =
  switch y {
    case (C1(z)) when z == 0 -> 0
    case (C1(z)) when z != 0 -> x quot z
    case (C2(z)) -> z
  }

this should make translation from ASL's patterns much more straightforward

1 files changed, 6 insertions, 2 deletions

diff --git a/src/pretty_print_sail.ml b/src/pretty_print_sail.ml
index 6826087a..a484bd1f 100644
--- a/src/pretty_print_sail.ml
+++ b/src/pretty_print_sail.ml
@@ -364,8 +364,12 @@ let doc_exp, doc_let =
 
   and doc_fexp (FE_aux(FE_Fexp(id,e),_)) = doc_op equals (doc_id id) (exp e)
 
-  and doc_case (Pat_aux(Pat_exp(pat,e),_)) =
-    doc_op arrow (separate space [string "case"; doc_atomic_pat pat]) (group (exp e))
+  and doc_case (Pat_aux (pexp, _)) =
+    match pexp with
+    | Pat_exp(pat, e) ->
+       doc_op arrow (separate space [string "case"; doc_atomic_pat pat]) (group (exp e))
+    | Pat_when(pat, guard, e) ->
+       doc_op arrow (separate space [string "case"; doc_atomic_pat pat; string "when"; exp guard]) (group (exp e))
 
   (* lexps are parsed as eq_exp - we need to duplicate the precedence
    * structure for them *)