Factor error message generation into a separate file; add '-tc' flag to domtool-client

[hcoop/domtool2.git] / src / describe.sml

diff --git a/src/describe.sml b/src/describe.sml
new file mode 100644 (file)
index 0000000..a39faeb
--- /dev/null
+++ b/src/describe.sml
@@ -0,0 +1,125 @@
+(* HCoop Domtool (http://hcoop.sourceforge.net/)
+ * Copyright (c) 2006-2007, Adam Chlipala
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *)
+
+(* Error message generation *)
+
+structure Describe :> DESCRIBE = struct
+
+open Ast Print
+
+structure SM = StringMap
+
+exception UnequalDomains
+         
+fun eqRecord f (r1, r2) =
+    (SM.appi (fn (k, v1) =>
+                case SM.find (r2, k) of
+                    NONE => raise UnequalDomains
+                  | SOME v2 =>
+                    if f (v1, v2) then
+                        ()
+                    else
+                        raise UnequalDomains) r1;
+     SM.appi (fn (k, v2) =>
+                case SM.find (r1, k) of
+                    NONE => raise UnequalDomains
+                  | SOME v1 =>
+                    if f (v1, v2) then
+                        ()
+                    else
+                        raise UnequalDomains) r2;
+     true)
+    handle UnequalDomains => false
+
+fun eqPred ((p1, _), (p2, _)) =
+    case (p1, p2) of
+       (CRoot, CRoot) => true
+      | (CConst s1, CConst s2) => s1 = s2
+      | (CPrefix p1, CPrefix p2) => eqPred (p1, p2)
+      | (CNot p1, CNot p2) => eqPred (p1, p2)
+      | (CAnd (p1, q1), CAnd (p2, q2)) =>
+       eqPred (p1, p2) andalso eqPred (q1, q2)
+
+      | _ => false
+
+fun eqTy (t1All as (t1, _), t2All as (t2, _)) =
+    case (t1, t2) of
+       (TBase s1, TBase s2) => s1 = s2
+      | (TList t1, TList t2) => eqTy (t1, t2)
+      | (TArrow (d1, r1), TArrow (d2, r2)) =>
+       eqTy (d1, d2) andalso eqTy (r1, r2)
+
+      | (TAction (p1, d1, r1), TAction (p2, d2, r2)) =>
+       eqPred (p1, p2) andalso eqRecord eqTy (d1, d2)
+       andalso eqRecord eqTy (r1, r2)
+
+      | (TNested (p1, q1), TNested (p2, q2)) =>
+       eqPred (p1, p2) andalso eqTy (q1, q2)
+
+      | (TUnif (_, ref (SOME t1)), _) => eqTy (t1, t2All)
+      | (_, TUnif (_, ref (SOME t2))) => eqTy (t1All, t2)
+
+      | (TUnif (_, r1), TUnif (_, r2)) => r1 = r2
+
+      | (TError, TError) => true
+
+      | _ => false
+
+fun describe_unification_error t ue =
+    case ue of
+       UnifyPred (p1, p2) =>
+       (print "Reason: Incompatible contexts.\n";
+        preface ("Have:", p_pred p1);
+        preface ("Need:", p_pred p2))
+      | UnifyTyp (t1, t2) =>
+       if eqTy (t, t1) then
+           ()
+       else
+           (print "Reason: Incompatible types.\n";
+            preface ("Have:", p_typ t1);
+            preface ("Need:", p_typ t2))
+      | UnifyOccurs (name, t') =>
+       if eqTy (t, t') then
+           ()
+       else
+           (print "Reason: Occurs check failed for ";
+            print name;
+            print " in:\n";
+            printd (p_typ t))
+
+fun describe_type_error loc te =
+    case te of
+       WrongType (place, e, t1, t2, ueo) =>
+       (ErrorMsg.error (SOME loc) (place ^ " has wrong type.");
+        preface (" Expression:", p_exp e);
+        preface ("Actual type:", p_typ t1);
+        preface ("Needed type:", p_typ t2);
+        Option.app (describe_unification_error t1) ueo)
+      |        WrongForm (place, form, e, t, ueo) =>
+       (ErrorMsg.error (SOME loc) (place ^ " has a non-" ^ form ^ " type.");
+        preface ("Expression:", p_exp e);
+        preface ("      Type:", p_typ t);
+        Option.app (describe_unification_error t) ueo)
+      | UnboundVariable name =>
+       ErrorMsg.error (SOME loc) ("Unbound variable " ^ name ^ ".\n")
+      |        WrongPred (place, p1, p2) =>
+       (ErrorMsg.error (SOME loc) ("Context incompatibility for " ^ place ^ ".");
+        preface ("Have:", p_pred p1);
+        preface ("Need:", p_pred p2))
+
+end