Add loops and document optionnal else in conditional

Syntax:
foreach id from exp (to|downto) exp (by exp)? exp

foreach and by are keywords; from, to and downto aren't.

4 files changed, 26 insertions, 2 deletions

diff --git a/src/ast.ml b/src/ast.ml
index 356248ac..3ef45b12 100644
--- a/src/ast.ml
+++ b/src/ast.ml
@@ -233,6 +233,7 @@ and 'a exp_aux =  (* Expression *)
  | E_app_infix of 'a exp * id * 'a exp (* infix function application *)
  | E_tuple of ('a exp) list (* tuple *)
  | E_if of 'a exp * 'a exp * 'a exp (* conditional *)
+ | E_for of id * 'a exp * 'a exp * 'a exp * 'a exp (* loop *)
  | E_vector of ('a exp) list (* vector (indexed from 0) *)
  | E_vector_indexed of ((int * 'a exp)) list (* vector (indexed consecutively) *)
  | E_vector_access of 'a exp * 'a exp (* vector access *)
diff --git a/src/lexer.mll b/src/lexer.mll
index 3bd4d5a1..0024b2b8 100644
--- a/src/lexer.mll
+++ b/src/lexer.mll
@@ -60,6 +60,7 @@ let kw_table =
     [
      ("and",                     (fun _ -> And));
      ("as",                      (fun _ -> As));
+     ("by",                      (fun _ -> By));
      ("case",			 (fun _ -> Case));
      ("clause",                  (fun _ -> Clause));
      ("const",			 (fun _ -> Const));
@@ -71,6 +72,7 @@ let kw_table =
      ("else",                    (fun _ -> Else));
      ("false",                   (fun _ -> False));
      ("forall",                  (fun _ -> Forall));
+     ("foreach",                  (fun _ -> Foreach));
      ("function",                (fun x -> Function_));
      ("if",                      (fun x -> If_));
      ("in",			 (fun x -> In));
diff --git a/src/parse_ast.ml b/src/parse_ast.ml
index e24294ae..f527c402 100644
--- a/src/parse_ast.ml
+++ b/src/parse_ast.ml
@@ -195,6 +195,7 @@ exp_aux =  (* Expression *)
  | E_app_infix of exp * id * exp (* infix function application *)
  | E_tuple of (exp) list (* tuple *)
  | E_if of exp * exp * exp (* conditional *)
+ | E_for of id * exp * exp * exp * exp (* loop *)
  | E_vector of (exp) list (* vector (indexed from 0) *)
  | E_vector_indexed of ((int * exp)) list (* vector (indexed consecutively) *)
  | E_vector_access of exp * exp (* vector access *)
diff --git a/src/parser.mly b/src/parser.mly
index 84afecda..60969ebd 100644
--- a/src/parser.mly
+++ b/src/parser.mly
@@ -120,8 +120,8 @@ let star = "*"
 
 /*Terminals with no content*/
 
-%token And As Bits Case Clause Const Default Dec Effect Effects End Enum Else False
-%token Forall Function_ If_ In IN Inc Let_ Member Nat Order Pure Rec Register
+%token And As Bits By Case Clause Const Default Dec Effect Effects End Enum Else False
+%token Forall Foreach Function_ If_ In IN Inc Let_ Member Nat Order Pure Rec Register
 %token Scattered Struct Switch Then True Type TYPE Typedef Union With Val
 
 /* Avoid shift/reduce conflict - see right_atomic_exp rule */
@@ -505,6 +505,26 @@ right_atomic_exp:
     { eloc (E_if($2,$4,$6)) }
   | If_ exp Then exp
     { eloc (E_if($2,$4, eloc (E_lit(lloc L_unit)))) }
+  | Foreach id Id atomic_exp Id atomic_exp By atomic_exp exp
+    { if $3 <> "from" then
+       raise (Parse_error_locn ((loc ()),"Missing \"from\" in foreach loop"));
+      if $5 <> "to" && $5 <> "downto" then
+       raise (Parse_error_locn ((loc ()),"Missing \"to\" or \"downto\" in foreach loop"));
+      let step =
+        if $5 = "to"
+        then $8
+        else eloc (E_app_infix(eloc (E_lit(lloc (L_num 0))), idl (Id "-"), $8)) in
+      eloc (E_for($2,$4,$6,step,$9)) }
+  | Foreach id Id atomic_exp Id atomic_exp exp
+    { if $3 <> "from" then
+       raise (Parse_error_locn ((loc ()),"Missing \"from\" in foreach loop"));
+      if $5 <> "to" && $5 <> "downto" then
+       raise (Parse_error_locn ((loc ()),"Missing \"to\" or \"downto\" in foreach loop"));
+      let step =
+        if $5 = "to"
+        then eloc (E_lit(lloc (L_num 1)))
+        else eloc (E_lit(lloc (L_num (-1)))) in
+      eloc (E_for($2,$4,$6,step,$7)) }
   | letbind In exp
     { eloc (E_let($1,$3)) }