From 4168cda2363f3d796d0b9922852e249aac3131ba Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 4 Dec 2020 08:39:35 +0200
Subject: Mark Buildfile functions as pure or impure

---
 libbuild2/function.cxx | 111 ++++++++++++++++++++++---------------------------
 1 file changed, 50 insertions(+), 61 deletions(-)

(limited to 'libbuild2/function.cxx')

diff --git a/libbuild2/function.cxx b/libbuild2/function.cxx
index 25dacf9..eaf3f9e 100644
--- a/libbuild2/function.cxx
+++ b/libbuild2/function.cxx
@@ -80,21 +80,6 @@ namespace build2
     return i != map_.end () && i->first.compare (0, n, name) == 0;
   }
 
-  auto function_map::
-  insert (string name, function_overload f) -> iterator
-  {
-    // Sanity checks.
-    //
-    assert (f.arg_min <= f.arg_max &&
-            f.arg_types.size () <= f.arg_max &&
-            f.impl != nullptr);
-
-    auto i (map_.emplace (move (name), move (f)));
-
-    i->second.name = i->first.c_str ();
-    return i;
-  }
-
   pair<value, bool> function_map::
   call (const scope* base,
         const string& name,
@@ -120,16 +105,17 @@ namespace build2
     // See the overall function machinery description for the ranking
     // semantics.
     //
-    auto ip (map_.equal_range (name));
+    const function_overloads* all_ovls (find (name));
 
     size_t rank (~0);
     small_vector<const function_overload*, 2> ovls;
+    if (all_ovls != nullptr)
     {
       size_t count (args.size ());
 
-      for (auto it (ip.first); it != ip.second; ++it)
+      for (auto it (all_ovls->begin ()); it != all_ovls->end (); ++it)
       {
-        const function_overload& f (it->second);
+        const function_overload& f (*it);
 
         // Argument count match.
         //
@@ -257,8 +243,11 @@ namespace build2
 
         dr << fail (loc) << "unmatched call to "; print_call (dr.os);
 
-        for (auto i (ip.first); i != ip.second; ++i)
-          dr << info << "candidate: " << i->second;
+        if (all_ovls != nullptr)
+        {
+          for (auto i (all_ovls->begin ()); i != all_ovls->end (); ++i)
+            dr << info << "candidate: " << *i;
+        }
 
         // If this is an unqualified name, then also print qualified
         // functions that end with this name. But skip functions that we
@@ -271,14 +260,20 @@ namespace build2
           for (auto i (begin ()); i != end (); ++i)
           {
             const string& q (i->first);
-            const function_overload& f (i->second);
 
-            if ((f.alt_name == nullptr || f.alt_name != name) &&
-                q.size () > n)
+            if (q.size () > n)
             {
-              size_t p (q.size () - n);
-              if (q[p - 1] == '.' && q.compare (p, n, name) == 0)
-                dr << info << "candidate: " << i->second;
+              for (auto j (i->second.begin ()); j != i->second.end (); ++j)
+              {
+                const function_overload& f (*j);
+
+                if (f.alt_name == nullptr || f.alt_name != name)
+                {
+                  size_t p (q.size () - n);
+                  if (q[p - 1] == '.' && q.compare (p, n, name) == 0)
+                    dr << info << "candidate: " << f;
+                }
+              }
             }
           }
         }
@@ -300,30 +295,8 @@ namespace build2
     }
   }
 
-  value function_family::
-  default_thunk (const scope* base,
-                 vector_view<value> args,
-                 const function_overload& f)
-  {
-    // Call the cast thunk.
-    //
-    struct cast_data // Prefix of function_cast::data.
-    {
-      value (*const thunk) (const scope*, vector_view<value>, const void*);
-    };
-
-    auto d (reinterpret_cast<const cast_data*> (&f.data));
-    return d->thunk (base, move (args), d);
-  }
-
-#if !defined(_WIN32)
-  constexpr const optional<const value_type*>* function_args<>::types;
-#else
-  const optional<const value_type*>* const function_args<>::types = nullptr;
-#endif
-
-  void function_family::entry::
-  insert (string n, function_overload f) const
+  auto function_family::
+  insert (string n, bool pure) const -> entry
   {
     // Figure out qualification.
     //
@@ -332,31 +305,47 @@ namespace build2
 
     if (p == string::npos)
     {
-      if (!qual.empty ())
+      if (!qual_.empty ())
       {
-        qn = qual;
+        qn = qual_;
         qn += '.';
         qn += n;
       }
     }
     else if (p == 0)
     {
-      assert (!qual.empty ());
-      n.insert (0, qual);
+      assert (!qual_.empty ());
+      n.insert (0, qual_);
     }
 
-    auto i (qn.empty () ? map_.end () : map_.insert (move (qn), f));
-    auto j (map_.insert (move (n), move (f)));
+    return entry {
+      map_.insert (move (n), pure),
+      qn.empty () ? nullptr : &map_.insert (move (qn), pure),
+      thunk_};
+  }
 
-    // If we have both, then set alternative names.
+  value function_family::
+  default_thunk (const scope* base,
+                 vector_view<value> args,
+                 const function_overload& f)
+  {
+    // Call the cast thunk.
     //
-    if (i != map_.end ())
+    struct cast_data // Prefix of function_cast::data.
     {
-      i->second.alt_name = j->first.c_str ();
-      j->second.alt_name = i->first.c_str ();
-    }
+      value (*const thunk) (const scope*, vector_view<value>, const void*);
+    };
+
+    auto d (reinterpret_cast<const cast_data*> (&f.data));
+    return d->thunk (base, move (args), d);
   }
 
+#if !defined(_WIN32)
+  constexpr const optional<const value_type*>* function_args<>::types;
+#else
+  const optional<const value_type*>* const function_args<>::types = nullptr;
+#endif
+
   // Static-initialize the function map and populate with builtin functions.
   //
 
-- 
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