feat: dot notation on integer literals (#5620)

Parse num.id as `num dot id`, not `float id`, allowing `0.range(9)` etc
without spurious whitespace or brackets.

Introduces new token `NUM_DOT_ID` to lexer and dedicated pseudo
production to grammar

Author: crusso

src/gen-grammar/grammar.sed

@@ -14,6 +14,7 @@ s/<id>/ID/g
 /^<typ_dec> ::=/,+2d
 /^<parse_stab_sig> ::=/,+5d
 /.*PRIM.*/d
+/.*NUM_DOT_ID.*/d
 /^<bl> ::=/,+2d
 /^<ob> ::=/,+2d
 s/<start> //g

src/mo_frontend/error_reporting.ml

@@ -60,6 +60,7 @@ let terminal2token (type a) (symbol : a terminal) : token =
       | T_NOT -> NOT
       | T_NEQOP -> NEQOP
       | T_NAT -> NAT "<nat>"
+      | T_NUM_DOT_ID -> NUM_DOT_ID ("<num>","<id>")
       | T_MULOP -> MULOP
       | T_MULASSIGN -> MULASSIGN
       | T_MODULE -> MODULE

src/mo_frontend/parser.mly

@@ -246,6 +246,7 @@ and objblock eo s id ty dec_fields =
 %token TRANSIENT PERSISTENT
 %token<string> DOT_NUM
 %token<string> NAT
+%token<string * string> NUM_DOT_ID
 %token<string> FLOAT
 %token<Mo_values.Value.unicode> CHAR
 %token<bool> BOOL
@@ -673,6 +674,20 @@ exp_post(B) :
     { ProjE (e, int_of_string s) @? at $sloc }
   | e=exp_post(B) DOT x=id
     { DotE(e, x, ref None) @? at $sloc }
+  | nid = NUM_DOT_ID
+    { let (num, id) = nid in
+      let {left; right} = at $sloc in
+      let e =
+	LitE(ref (PreLit (num, Type.Nat))) @?
+	{ left;
+	  right = { right with column = left.column + String.length num }}
+      in
+      let x =
+	id @@
+	{ left = { left with column = right.column - String.length id };
+	  right } in
+      DotE(e, x, ref None) @? at $sloc
+    }
   | e1=exp_post(B) inst=inst e2=exp_arg
     {
       let e2, sugar = e2 in

src/mo_frontend/printers.ml

@@ -94,6 +94,7 @@ let repr_of_symbol : xsymbol -> (string * string) =
   | X (T T_OR) -> simple_token "or"
   | X (T T_OBJECT) -> simple_token "object"
   | X (T T_NULL) -> simple_token "null"
+  | X (T T_NUM_DOT_ID) -> simple_token "num.id"
   | X (T T_NOT) -> simple_token "not"
   | X (T T_NEQOP) -> binop "!="
   | X (T T_NAT) -> "<nat>", "0"

src/mo_frontend/source_lexer.mll

@@ -113,6 +113,8 @@ let char = '\'' (character | byte+) '\''
 let text = '"' character* '"'
 let id = ((letter  | '_') ((letter | digit | '_')*))
 let privileged_id = "@" id
+let num_dot_ident =
+    num '.' id
 
 let reserved = ([^'\"''('')'';'] # space)+  (* hack for table size *)
 
@@ -181,6 +183,11 @@ rule token mode = parse
 
   | '.' (num as s) { DOT_NUM s }
   | nat as s { NAT s }
+  | num_dot_ident as s {
+      match Lib.String.split s '.' with
+      | [n; id] -> NUM_DOT_ID (n, id)
+      | _ -> assert false
+    }
   | float as s { FLOAT s }
   | char as s { CHAR (char lexbuf s) }
   | text as s { TEXT (text lexbuf s) }

src/mo_frontend/source_token.ml

@@ -116,6 +116,7 @@ type token =
   | ROTRASSIGN
   | NULL
   | DOT_NUM of string
+  | NUM_DOT_ID of string * string
   | NAT of string
   | FLOAT of string
   | CHAR of Mo_values.Value.unicode
@@ -251,6 +252,7 @@ let to_parser_token :
   | ROTLASSIGN -> Ok Parser.ROTLASSIGN
   | ROTRASSIGN -> Ok Parser.ROTRASSIGN
   | NULL -> Ok Parser.NULL
+  | NUM_DOT_ID (ns, id) -> Ok (Parser.NUM_DOT_ID (ns, id))
   | DOT_NUM s -> Ok (Parser.DOT_NUM s)
   | NAT s -> Ok (Parser.NAT s)
   | FLOAT s -> Ok (Parser.FLOAT s)
@@ -388,6 +390,7 @@ let string_of_parser_token = function
   | Parser.ROTLASSIGN -> "ROTLASSIGN"
   | Parser.ROTRASSIGN -> "ROTRASSIGN"
   | Parser.NULL -> "NULL"
+  | Parser.NUM_DOT_ID _ -> "NUM_DOT_IDENT of string * string"
   | Parser.DOT_NUM _ -> "DOT_NUM of string"
   | Parser.NAT _ -> "NAT of string"
   | Parser.FLOAT _ -> "FLOAT of string"

test/fail/nat-dot.mo

@@ -0,0 +1,35 @@
+// test parsing dot notation on integral literals works
+module Nat {
+
+  public func toText(self : Nat) : Text { "" };
+
+};
+
+module Int {
+
+  public func toText(self : Int) : Text { "" };
+
+};
+
+module Float {
+
+  public func toText(self : Float) : Text { "" };
+
+};
+
+
+ignore 0.toText(); // Nat.toText()
+
+ignore 0 .toText(); // Nat.toText()
+
+ignore (+0).toText(); // Int.toText()
+
+ignore (-0).toText(); // Int.toText()
+
+ignore 0.0.toText(); // Float.toText()
+
+ignore 0..toText(); // Float.toText()
+
+
+ignore +0 .toText(); // dubious (error)
+ignore -0 .toText(); // dubious (error)

test/fail/ok/nat-dot.tc.ok

@@ -0,0 +1,4 @@
+nat-dot.mo:34.8-34.20: type error [M0059], operator is not defined for operand type
+  Text
+nat-dot.mo:35.8-35.20: type error [M0059], operator is not defined for operand type
+  Text

test/fail/ok/nat-dot.tc.ret.ok

@@ -0,0 +1 @@
+Return code 1