[nem-en] Late Binding in Nemerle

Snaury snaury at gmail.com
Fri Jul 21 20:25:48 CEST 2006


Or actually no, it's better to do it this way, because this seems the
really correct way to do this is to catch special expressions early:

Index: Late.n
===================================================================
--- Late.n	(revision 6459)
+++ Late.n	(working copy)
@@ -149,6 +149,22 @@
         else
           call

+    /// returns true is expr is of some special kind
+    /// and shouldn't be transformed by late rules
+    public special(expr : PExpr) : bool
+        | PExpr.This => true
+        | PExpr.Base => true
+        | _ => match(Util.QidOfExpr(expr))
+          | Some((id, name)) =>
+            def ctx = name.GetEnv(env)
+            if(ctx.LookupType(id) is Some(_))
+              true
+            else if(ctx.LookupMacro(id) is Some(_))
+              true
+            else
+              false
+          | _ => false
+
     /// returns expression that does all late invokes in chain
     /// expr_name is used to hold expr with each invoke
     public static build(expr_name : Name, expr : PExpr, chain :
list[LateCall]) : PExpr
@@ -168,30 +184,28 @@

     /// scans single expression and returns (expr, list[LateCall])
     /// returns (expr, []) if nothing in expression can be late bound
-    public static scan(expr : PExpr) : PExpr * list[LateCall]
+    public scan(expr : PExpr) : PExpr * list[LateCall]
       def loop(expr, r = [])
-        def can_be_late(expr)
-          | PExpr.This => false
-          | PExpr.Base => false
-          | _ when Macros.IsTypeName(expr) => false
-          | _ => true
         match(expr)
           | null => (expr, r)
-          | <[ $rest . $(id : name) [.. $args] = $value ]> when
can_be_late(rest) \
-          | <[ $rest . $(id : name) = $value ]> when
can_be_late(rest) with (args = []) \
-          | <[ $rest . [.. $args] = $value ]> when can_be_late(rest)
with(id = Name("")) \
-          | <[ $rest [.. $args] = $value ]> when can_be_late(rest)
with(id = Name("")) =>
+          | _ when special(expr) => (expr, r)
+          | <[ $rest (.. $_) ]> when special(rest) \
+          | <[ $rest [.. $_] ]> when special(rest) => (expr, r)
+          | <[ $rest . $(id : name) [.. $args] = $value ]> when
!special(rest) \
+          | <[ $rest . $(id : name) = $value ]> when !special(rest)
with (args = []) \
+          | <[ $rest . [.. $args] = $value ]> when !special(rest)
with(id = Name("")) \
+          | <[ $rest [.. $args] = $value ]> when !special(rest)
with(id = Name("")) =>
             when(id.Id == "" && args.Length == 0)
               Message.FatalError(expr.Location, "default indexer must
have parameters")
             loop(rest, LateCall.SetProperty(expr.Location,
CallInfo(id.Id, args, [value])) :: r)
-          | <[ $rest . $(id : name) [.. $args] ]> when can_be_late(rest) \
-          | <[ $rest . $(id : name) ]> when can_be_late(rest) with(args = []) \
-          | <[ $rest . [.. $args] ]> when can_be_late(rest) with(id =
Name("")) \
-          | <[ $rest [.. $args] ]> when can_be_late(rest) with(id =
Name("")) =>
+          | <[ $rest . $(id : name) [.. $args] ]> when !special(rest) \
+          | <[ $rest . $(id : name) ]> when !special(rest) with(args = []) \
+          | <[ $rest . [.. $args] ]> when !special(rest) with(id = Name("")) \
+          | <[ $rest [.. $args] ]> when !special(rest) with(id = Name("")) =>
             when(id.Id == "" && args.Length == 0)
               Message.FatalError(expr.Location, "default indexer must
have parameters")
             loop(rest, LateCall.GetProperty(expr.Location,
CallInfo(id.Id, args)) :: r)
-          | <[ $rest . $(id : name) (.. $args) ]> when can_be_late(rest) =>
+          | <[ $rest . $(id : name) (.. $args) ]> when !special(rest) =>
             loop(rest, LateCall.Method(expr.Location, CallInfo(id.Id,
args)) :: r)
           | _ => (expr, r)
       loop(expr)
@@ -245,6 +259,7 @@
       mutable expr'
       def result = match(expr)
         | null => null
+        | _ when special(expr) => expr
         | _ when latebound(expr, out expr', deep) => expr'
         | PExpr.Wildcard \
         | PExpr.Void => expr
@@ -265,18 +280,7 @@
             expr
           else
             PExpr.Member(loc, recurse(obj), mem)
-        | PExpr.Call(func, parms) =>
-          def ismacro = match (Util.QidOfExpr (func))
-            | Some ((id, name)) =>
-              def ctx = name.GetEnv (env)
-              match (ctx.LookupMacro (id))
-                | Some (_) => true
-                | None => false
-            | None => false
-          if (ismacro)
-            PExpr.Call(loc, func, parms.Map(recurse))
-          else
-            PExpr.Call(loc, recurse(func), parms.Map(recurse))
+        | PExpr.Call(func, parms) => PExpr.Call(loc, recurse(func),
parms.Map(recurse))
         | PExpr.GenericSpecifier(func, parms) =>
PExpr.GenericSpecifier(loc, recurse(func), parms.Map(recurse))
         | PExpr.ListLiteral(elems) => PExpr.ListLiteral(loc,
elems.Map(recurse))
         | PExpr.Assign(target, source) => PExpr.Assign(loc,
recurse(target), recurse(source))
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