From 94703081971636db5bcdbb46ecebec234f4760e4 Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adamc@hcoop.net>
Date: Thu, 25 Mar 2010 16:06:04 -0400
Subject: Subquery FROM items

---
 lib/ur/basis.urs  |  3 +++
 src/monoize.sml   | 17 +++++++++++++++--
 src/urweb.grm     |  8 ++++++++
 tests/subquery.ur | 13 +++++++++++--
 4 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/lib/ur/basis.urs b/lib/ur/basis.urs
index 98390555..c75eea1b 100644
--- a/lib/ur/basis.urs
+++ b/lib/ur/basis.urs
@@ -295,6 +295,9 @@ con sql_from_items :: {{Type}} -> {{Type}} -> Type
 val sql_from_table : free ::: {{Type}} -> t ::: Type -> fs ::: {Type}
                      -> fieldsOf t fs -> name :: Name
                      -> t -> sql_from_items free [name = fs]
+val sql_from_query : free ::: {{Type}} -> fs ::: {Type} -> name :: Name
+                     -> sql_query free [] fs
+                     -> sql_from_items free [name = fs]
 val sql_from_comma : free ::: {{Type}} -> tabs1 ::: {{Type}} -> tabs2 ::: {{Type}}
                      -> [tabs1 ~ tabs2]
     => sql_from_items free tabs1 -> sql_from_items free tabs2
diff --git a/src/monoize.sml b/src/monoize.sml
index 9e5e1b38..5aebad63 100644
--- a/src/monoize.sml
+++ b/src/monoize.sml
@@ -1882,7 +1882,7 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
                                            strcatComma (map (fn (x, t) =>
                                                                 strcat [
                                                                 (L'.EField (gf "SelectExps", x), loc),
-                                                                sc (" AS _" ^ x)
+                                                                sc (" AS uw_" ^ x)
                                                             ]) sexps
                                                         @ map (fn (x, xts) =>
                                                                   strcatComma
@@ -2059,6 +2059,19 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
                                    (L'.EPrim (Prim.String (" AS T_" ^ name)), loc)]), loc),
                  fm)
             end
+          | L.ECApp ((L.ECApp ((L.ECApp ((L.EFfi ("Basis", "sql_from_query"), _), _),
+                                          _), _), _),
+                     (L.CName name, _)) =>
+            let
+                val s = (L'.TFfi ("Basis", "string"), loc)
+                fun sc s = (L'.EPrim (Prim.String s), loc)
+            in
+                ((L'.EAbs ("q", s, s,
+                           strcat [sc "(",
+                                   (L'.ERel 0, loc),
+                                   sc (") AS T_" ^ name)]), loc),
+                 fm)
+            end
           | L.ECApp ((L.ECApp ((L.ECApp ((L.EFfi ("Basis", "sql_from_comma"), _), _), _), _), _), _) =>
             let
                 val s = (L'.TFfi ("Basis", "string"), loc)
@@ -2317,7 +2330,7 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
                _), _),
               _), _),
              _), _),
-            (L.CName nm, _)) => ((L'.EPrim (Prim.String ("_" ^ lowercaseFirst nm)), loc), fm)
+            (L.CName nm, _)) => ((L'.EPrim (Prim.String ("uw_" ^ lowercaseFirst nm)), loc), fm)
 
           | L.ECApp (
             (L.ECApp (
diff --git a/src/urweb.grm b/src/urweb.grm
index f11c3cd5..995d4664 100644
--- a/src/urweb.grm
+++ b/src/urweb.grm
@@ -1629,6 +1629,14 @@ fitem  : table'                         ([#1 table'], #2 table')
                                              (#1 fitem1 @ #1 fitem2,
                                               (EApp (e, sqlexp), loc))
                                          end)
+       | LPAREN query RPAREN AS tname   (let
+                                             val loc = s (LPARENleft, RPARENright)
+                                                       
+                                             val e = (EVar (["Basis"], "sql_from_query", Infer), loc)
+                                             val e = (ECApp (e, tname), loc)
+                                         in
+                                             ([tname], (EApp (e, query), loc))
+                                         end)
 
 tname  : CSYMBOL                        (CName CSYMBOL, s (CSYMBOLleft, CSYMBOLright))
        | LBRACE cexp RBRACE             (cexp)
diff --git a/tests/subquery.ur b/tests/subquery.ur
index 302175e5..b7881817 100644
--- a/tests/subquery.ur
+++ b/tests/subquery.ur
@@ -6,5 +6,14 @@ fun main () =
                   WHERE t.B = (SELECT MAX(U.B) AS M
                                FROM t AS U
                                WHERE U.A = t.A))
-         (fn r => <xml>{[r.A]},{[r.C]};</xml>);
-    return <xml>{v}</xml>
+                 (fn r => <xml>{[r.A]},{[r.C]};</xml>);
+    v' <- queryX1 (SELECT t.A, t.C
+                   FROM (SELECT t.A AS A, MAX(t.B) AS B
+                         FROM t
+                         GROUP BY t.A) AS Maxes
+                   JOIN t ON t.A = Maxes.A AND t.B = Maxes.B)
+                  (fn r => <xml>{[r.A]},{[r.C]};</xml>);
+    return <xml><body>
+      {v}<br/>
+      {v'}
+    </body></xml>
-- 
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