From ffa0839de796fbefc48bacc4777648ff19b3fee6 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 8 Sep 2017 16:16:11 +0200
Subject: Add ability to pass scope to buildfile functions, add
 $install.resolve()

---
 build2/function.cxx               |  36 +++++-
 build2/function.hxx               | 232 ++++++++++++++++++++++++++++++++++----
 build2/functions-path.cxx         |   6 +-
 build2/install/functions.cxx      |  27 +++++
 build2/install/init.cxx           |  11 +-
 build2/parser.cxx                 |   6 +-
 build2/version/rule.cxx           |   4 +-
 tests/function/install/buildfile  |   5 +
 tests/function/install/testscript |  33 ++++++
 unit-tests/function/driver.cxx    |  20 +++-
 10 files changed, 342 insertions(+), 38 deletions(-)
 create mode 100644 build2/install/functions.cxx
 create mode 100644 tests/function/install/buildfile
 create mode 100644 tests/function/install/testscript

diff --git a/build2/function.cxx b/build2/function.cxx
index f7de749..2d04b30 100644
--- a/build2/function.cxx
+++ b/build2/function.cxx
@@ -58,6 +58,29 @@ namespace build2
     return os;
   }
 
+  bool function_map::
+  defined (const string& name) const
+  {
+    assert (!name.empty ());
+
+    // If this is a qualified function name then check if it is already
+    // defined.
+    //
+    if (name.back () != '.')
+      return map_.find (name) != map_.end ();
+
+    // If any function of the specified family is already defined, then one of
+    // them should be the first element that is greater than the dot-terminated
+    // family name. Here we rely on the fact that the dot character is less
+    // than any character of unqualified function and family names.
+    //
+    size_t n (name.size ());
+    assert (n > 1);
+
+    auto i (map_.upper_bound (name));
+    return i != map_.end () && i->first.compare (0, n, name) == 0;
+  }
+
   auto function_map::
   insert (string name, function_overload f) -> iterator
   {
@@ -74,7 +97,8 @@ namespace build2
   }
 
   pair<value, bool> function_map::
-  call (const string& name,
+  call (const scope& base,
+        const string& name,
         vector_view<value> args,
         const location& loc,
         bool fa) const
@@ -174,7 +198,7 @@ namespace build2
             }));
 
         auto f (r.back ());
-        return make_pair (f->impl (move (args), *f), true);
+        return make_pair (f->impl (base, move (args), *f), true);
       }
     case 0:
       {
@@ -231,18 +255,20 @@ namespace build2
   }
 
   value function_family::
-  default_thunk (vector_view<value> args, const function_overload& f)
+  default_thunk (const scope& base,
+                 vector_view<value> args,
+                 const function_overload& f)
   try
   {
     // Call the cast thunk.
     //
     struct cast_data // Prefix of function_cast::data.
     {
-      value (*const thunk) (vector_view<value>, const void*);
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
     };
 
     auto d (reinterpret_cast<const cast_data*> (&f.data));
-    return d->thunk (move (args), d);
+    return d->thunk (base, move (args), d);
   }
   catch (const invalid_argument& e)
   {
diff --git a/build2/function.hxx b/build2/function.hxx
index 0e592b1..96bf401 100644
--- a/build2/function.hxx
+++ b/build2/function.hxx
@@ -5,9 +5,9 @@
 #ifndef BUILD2_FUNCTION_HXX
 #define BUILD2_FUNCTION_HXX
 
+#include <map>
 #include <utility>       // index_sequence
 #include <type_traits>   // aligned_storage
-#include <unordered_map>
 
 #include <build2/types.hxx>
 #include <build2/utility.hxx>
@@ -45,6 +45,9 @@ namespace build2
   // expected to issue diagnostics and throw failed. Note that the arguments
   // are conceptually "moved" and can be reused by the implementation.
   //
+  // A function can also optionally receive the current scope by having the
+  // first argument of the const scope& type.
+  //
   // Normally functions come in families that share a common qualification
   // (e.g., string. or path.). The function_family class is a "registrar"
   // that simplifies handling of function families. For example:
@@ -64,7 +67,9 @@ namespace build2
   //
   struct function_overload;
 
-  using function_impl = value (vector_view<value>, const function_overload&);
+  using function_impl = value (const scope&,
+                               vector_view<value>,
+                               const function_overload&);
 
   struct function_overload
   {
@@ -134,7 +139,7 @@ namespace build2
   class function_map
   {
   public:
-    using map_type = std::unordered_multimap<string, function_overload>;
+    using map_type = std::multimap<string, function_overload>;
     using iterator = map_type::iterator;
     using const_iterator = map_type::const_iterator;
 
@@ -145,9 +150,12 @@ namespace build2
     erase (iterator i) {map_.erase (i);}
 
     value
-    call (const string& name, vector_view<value> args, const location& l) const
+    call (const scope& base,
+          const string& name,
+          vector_view<value> args,
+          const location& l) const
     {
-      return call (name, args, l, true).first;
+      return call (base, name, args, l, true).first;
     }
 
     // As above but do not fail if no match was found (but still do if the
@@ -156,11 +164,12 @@ namespace build2
     // functions.
     //
     pair<value, bool>
-    try_call (const string& name,
+    try_call (const scope& base,
+              const string& name,
               vector_view<value> args,
               const location& l) const
     {
-      return call (name, args, l, false);
+      return call (base, name, args, l, false);
     }
 
     iterator
@@ -175,9 +184,20 @@ namespace build2
     const_iterator
     end () const {return map_.end ();}
 
+    // Return true if the function with this name is already defined. If the
+    // name ends with '.', then instead check if any function with this prefix
+    // (which we call a family) is already defined.
+    //
+    bool
+    defined (const string&) const;
+
   private:
     pair<value, bool>
-    call (const string&, vector_view<value>, const location&, bool fail) const;
+    call (const scope&,
+          const string&,
+          vector_view<value>,
+          const location&,
+          bool fail) const;
 
     map_type map_;
   };
@@ -195,7 +215,7 @@ namespace build2
     // exceptions), you would normally call the default implementation.
     //
     static value
-    default_thunk (vector_view<value>, const function_overload&);
+    default_thunk (const scope&, vector_view<value>, const function_overload&);
 
     // A function family uses a common qualification (though you can pass
     // empty string to supress it). For an unqualified name (doesn't not
@@ -212,6 +232,13 @@ namespace build2
     entry
     operator[] (string name) const;
 
+    static bool
+    defined (string qual)
+    {
+      qual += '.';
+      return functions.defined (qual);
+    }
+
   private:
     const string qual_;
     function_impl* thunk_;
@@ -392,12 +419,12 @@ namespace build2
     //
     struct data
     {
-      value (*const thunk) (vector_view<value>, const void*);
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
       R (*const impl) (A...);
     };
 
     static value
-    thunk (vector_view<value> args, const void* d)
+    thunk (const scope&, vector_view<value> args, const void* d)
     {
       return thunk (move (args),
                     static_cast<const data*> (d)->impl,
@@ -417,6 +444,39 @@ namespace build2
     }
   };
 
+  // Specialization for functions that expect the current scope as a first
+  // argument.
+  //
+  template <typename R, typename... A>
+  struct function_cast<R, const scope&, A...>
+  {
+    struct data
+    {
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
+      R (*const impl) (const scope&, A...);
+    };
+
+    static value
+    thunk (const scope& base, vector_view<value> args, const void* d)
+    {
+      return thunk (base, move (args),
+                    static_cast<const data*> (d)->impl,
+                    std::index_sequence_for<A...> ());
+    }
+
+    template <size_t... i>
+    static value
+    thunk (const scope& base, vector_view<value> args,
+           R (*impl) (const scope&, A...),
+           std::index_sequence<i...>)
+    {
+      return value (
+        impl (base,
+              function_arg<A>::cast (
+                i < args.size () ? &args[i] : nullptr)...));
+    }
+  };
+
   // Specialization for void return type. In this case we return NULL value.
   //
   template <typename... A>
@@ -424,12 +484,12 @@ namespace build2
   {
     struct data
     {
-      value (*const thunk) (vector_view<value>, const void*);
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
       void (*const impl) (A...);
     };
 
     static value
-    thunk (vector_view<value> args, const void* d)
+    thunk (const scope&, vector_view<value> args, const void* d)
     {
       thunk (move (args),
              static_cast<const data*> (d)->impl,
@@ -447,6 +507,35 @@ namespace build2
     }
   };
 
+  template <typename... A>
+  struct function_cast<void, const scope&, A...>
+  {
+    struct data
+    {
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
+      void (*const impl) (const scope&, A...);
+    };
+
+    static value
+    thunk (const scope& base, vector_view<value> args, const void* d)
+    {
+      thunk (base, move (args),
+             static_cast<const data*> (d)->impl,
+             std::index_sequence_for<A...> ());
+      return value (nullptr);
+    }
+
+    template <size_t... i>
+    static void
+    thunk (const scope& base, vector_view<value> args,
+           void (*impl) (const scope&, A...),
+           std::index_sequence<i...>)
+    {
+      impl (base,
+            function_arg<A>::cast (i < args.size () ? &args[i] : nullptr)...);
+    }
+  };
+
   // Customization for coerced lambdas (see below).
   //
 #if defined(__GNUC__) && !defined(__clang__) && __GNUC__ < 6
@@ -455,12 +544,12 @@ namespace build2
   {
     struct data
     {
-      value (*const thunk) (vector_view<value>, const void*);
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
       R (L::*const impl) (A...) const;
     };
 
     static value
-    thunk (vector_view<value> args, const void* d)
+    thunk (const scope&, vector_view<value> args, const void* d)
     {
       return thunk (move (args),
                     static_cast<const data*> (d)->impl,
@@ -482,17 +571,49 @@ namespace build2
     }
   };
 
+  template <typename L, typename R, typename... A>
+  struct function_cast_lamb<L, R, const scope&, A...>
+  {
+    struct data
+    {
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
+      R (L::*const impl) (const scope&, A...) const;
+    };
+
+    static value
+    thunk (const scope& base, vector_view<value> args, const void* d)
+    {
+      return thunk (base, move (args),
+                    static_cast<const data*> (d)->impl,
+                    std::index_sequence_for<A...> ());
+    }
+
+    template <size_t... i>
+    static value
+    thunk (const scope& base, vector_view<value> args,
+           R (L::*impl) (const scope&, A...) const,
+           std::index_sequence<i...>)
+    {
+      const L* l (nullptr); // Undefined behavior.
+
+      return value (
+        (l->*impl) (base,
+                    function_arg<A>::cast (
+                      i < args.size () ? &args[i] : nullptr)...));
+    }
+  };
+
   template <typename L, typename... A>
   struct function_cast_lamb<L, void, A...>
   {
     struct data
     {
-      value (*const thunk) (vector_view<value>, const void*);
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
       void (L::*const impl) (A...) const;
     };
 
     static value
-    thunk (vector_view<value> args, const void* d)
+    thunk (const scope&, vector_view<value> args, const void* d)
     {
       thunk (move (args),
              static_cast<const data*> (d)->impl,
@@ -512,6 +633,37 @@ namespace build2
           i < args.size () ? &args[i] : nullptr)...);
     }
   };
+
+  template <typename L, typename... A>
+  struct function_cast_lamb<L, void, const scope&, A...>
+  {
+    struct data
+    {
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
+      void (L::*const impl) (const scope&, A...) const;
+    };
+
+    static value
+    thunk (const scope& base, vector_view<value> args, const void* d)
+    {
+      thunk (base, move (args),
+             static_cast<const data*> (d)->impl,
+             std::index_sequence_for<A...> ());
+      return value (nullptr);
+    }
+
+    template <size_t... i>
+    static void
+    thunk (const scope& base, vector_view<value> args,
+           void (L::*impl) (const scope&, A...) const,
+           std::index_sequence<i...>)
+    {
+      const L* l (nullptr);
+      (l->*impl) (base,
+                  function_arg<A>::cast (
+                    i < args.size () ? &args[i] : nullptr)...);
+    }
+  };
 #endif
 
   // Customization for member functions.
@@ -521,12 +673,12 @@ namespace build2
   {
     struct data
     {
-      value (*const thunk) (vector_view<value>, const void*);
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
       R (T::*const impl) () const;
     };
 
     static value
-    thunk (vector_view<value> args, const void* d)
+    thunk (const scope&, vector_view<value> args, const void* d)
     {
       auto mf (static_cast<const data*> (d)->impl);
       return value ((function_arg<T>::cast (&args[0]).*mf) ());
@@ -538,12 +690,12 @@ namespace build2
   {
     struct data
     {
-      value (*const thunk) (vector_view<value>, const void*);
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
       void (T::*const impl) () const;
     };
 
     static value
-    thunk (vector_view<value> args, const void* d)
+    thunk (const scope&, vector_view<value> args, const void* d)
     {
       auto mf (static_cast<const data*> (d)->impl);
       (function_arg<T>::cast (args[0]).*mf) ();
@@ -558,12 +710,12 @@ namespace build2
   {
     struct data
     {
-      value (*const thunk) (vector_view<value>, const void*);
+      value (*const thunk) (const scope&, vector_view<value>, const void*);
       R T::*const impl;
     };
 
     static value
-    thunk (vector_view<value> args, const void* d)
+    thunk (const scope&, vector_view<value> args, const void* d)
     {
       auto dm (static_cast<const data*> (d)->impl);
       return value (move (function_arg<T>::cast (&args[0]).*dm));
@@ -593,6 +745,23 @@ namespace build2
                 typename cast::data {&cast::thunk, impl}));
     }
 
+    template <typename R, typename... A>
+    void
+    operator= (R (*impl) (const scope&, A...)) &&
+    {
+      using args = function_args<A...>;
+      using cast = function_cast<R, const scope&, A...>;
+
+      insert (move (name),
+              function_overload (
+                nullptr,
+                args::min,
+                args::max,
+                function_overload::types (args::types, args::max),
+                thunk,
+                typename cast::data {&cast::thunk, impl}));
+    }
+
     // Support for assigning a (capture-less) lambda.
     //
     // GCC up until version 6 has a bug (#62052) that is triggered by calling
@@ -625,6 +794,23 @@ namespace build2
                 thunk,
                 typename cast::data {&cast::thunk, op}));
     }
+
+    template <typename L, typename R, typename... A>
+    void
+    coerce_lambda (R (L::*op) (const scope&, A...) const) &&
+    {
+      using args = function_args<A...>;
+      using cast = function_cast_lamb<L, R, const scope&, A...>;
+
+      insert (move (name),
+              function_overload (
+                nullptr,
+                args::min,
+                args::max,
+                function_overload::types (args::types, args::max),
+                thunk,
+                typename cast::data {&cast::thunk, op}));
+    }
 #else
     template <typename L>
     void
diff --git a/build2/functions-path.cxx b/build2/functions-path.cxx
index 4542858..45ec8ed 100644
--- a/build2/functions-path.cxx
+++ b/build2/functions-path.cxx
@@ -10,10 +10,12 @@ using namespace std;
 namespace build2
 {
   static value
-  path_thunk (vector_view<value> args, const function_overload& f)
+  path_thunk (const scope& base,
+              vector_view<value> args,
+              const function_overload& f)
   try
   {
-    return function_family::default_thunk (move (args), f);
+    return function_family::default_thunk (base, move (args), f);
   }
   catch (const invalid_path& e)
   {
diff --git a/build2/install/functions.cxx b/build2/install/functions.cxx
new file mode 100644
index 0000000..b9298b2
--- /dev/null
+++ b/build2/install/functions.cxx
@@ -0,0 +1,27 @@
+// file      : build2/install/functions.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <build2/function.hxx>
+#include <build2/variable.hxx>
+
+#include <build2/install/utility.hxx>
+
+using namespace std;
+
+namespace build2
+{
+  namespace install
+  {
+    void
+    functions ()
+    {
+      function_family f ("install");
+
+      // Resolve potentially relative install.* value to an absolute directory
+      // based on (other) install.* values visible from the calling scope.
+      //
+      f["resolve"] = &resolve_dir;
+    }
+  }
+}
diff --git a/build2/install/init.cxx b/build2/install/init.cxx
index 757d4ef..b5fd007 100644
--- a/build2/install/init.cxx
+++ b/build2/install/init.cxx
@@ -7,6 +7,7 @@
 #include <build2/scope.hxx>
 #include <build2/target.hxx>
 #include <build2/rule.hxx>
+#include <build2/function.hxx>
 #include <build2/operation.hxx>
 #include <build2/diagnostics.hxx>
 
@@ -125,12 +126,20 @@ namespace build2
     }
 
     void
+    functions (); // functions.cxx
+
+    void
     boot (scope& r, const location&, unique_ptr<module_base>&)
     {
       tracer trace ("install::boot");
-
       l5 ([&]{trace << "for " << r.out_path ();});
 
+      // Register install function family if this is the first instance of the
+      // install modules.
+      //
+      if (!function_family::defined ("install"))
+        functions ();
+
       // Register the install and uninstall operations.
       //
       r.operations.insert (install_id, install);
diff --git a/build2/parser.cxx b/build2/parser.cxx
index 66af0a5..3782230 100644
--- a/build2/parser.cxx
+++ b/build2/parser.cxx
@@ -2893,7 +2893,7 @@ namespace build2
               }));
 
           p = functions.try_call (
-            "builtin.concat", vector_view<value> (a), loc);
+            *scope_, "builtin.concat", vector_view<value> (a), loc);
         }
 
         if (!p.second)
@@ -3398,7 +3398,7 @@ namespace build2
 
             // Note that we "move" args to call().
             //
-            result_data = functions.call (name, args, loc);
+            result_data = functions.call (*scope_, name, args, loc);
             what = "function call";
           }
           else
@@ -3506,7 +3506,7 @@ namespace build2
                   }));
 
               p = functions.try_call (
-                "string", vector_view<value> (&result_data, 1), loc);
+                *scope_, "string", vector_view<value> (&result_data, 1), loc);
             }
 
             if (!p.second)
diff --git a/build2/version/rule.cxx b/build2/version/rule.cxx
index a9d62ba..ceeb003 100644
--- a/build2/version/rule.cxx
+++ b/build2/version/rule.cxx
@@ -281,7 +281,7 @@ namespace build2
       // Perform substitutions for the project itself (normally the version.*
       // variables but we allow anything set on the root scope).
       //
-      auto subst_self = [&rs] (const location& l, const string& s)
+      auto subst_self = [&rs, &t] (const location& l, const string& s)
       {
         if (lookup x = rs.vars[s])
         {
@@ -291,7 +291,7 @@ namespace build2
 
           return convert<string> (
             functions.call (
-              "string", vector_view<value> (&v, 1), l));
+              t.base_scope (), "string", vector_view<value> (&v, 1), l));
         }
         else
           fail (l) << "undefined project variable '" << s << "'" << endf;
diff --git a/tests/function/install/buildfile b/tests/function/install/buildfile
new file mode 100644
index 0000000..356ca77
--- /dev/null
+++ b/tests/function/install/buildfile
@@ -0,0 +1,5 @@
+# file      : tests/function/install/buildfile
+# copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+# license   : MIT; see accompanying LICENSE file
+
+./: test{testscript} $b
diff --git a/tests/function/install/testscript b/tests/function/install/testscript
new file mode 100644
index 0000000..b0a0172
--- /dev/null
+++ b/tests/function/install/testscript
@@ -0,0 +1,33 @@
+# file      : tests/function/install/testscript
+# copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+# license   : MIT; see accompanying LICENSE file
+
+.include ../../common.test
+
++cat <<EOI >+build/bootstrap.build
+using config
+using install
+EOI
+
+root = ($cxx.target.class != 'windows' ? '/usr/' : 'C:\')
+
++cat <<"EOI" >=build/config.build
+config.version = 1
+config.install.root = $root
+EOI
+
+: realize
+:
+{
+  : existing
+  :
+  a = ($cxx.target.class != 'windows' ? '/usr/lib/a/' : 'C:\lib\a\');
+  $* <'print $install.resolve([dir_path] lib/a)' >$a
+
+  : non-existing
+  :
+  $* <'print $install.resolve([dir_path] foo/a)' 2>>EOE != 0
+  error: unknown installation directory name 'foo'
+    info: did you forget to specify config.install.foo?
+  EOE
+}
diff --git a/unit-tests/function/driver.cxx b/unit-tests/function/driver.cxx
index 4650a18..9286a48 100644
--- a/unit-tests/function/driver.cxx
+++ b/unit-tests/function/driver.cxx
@@ -22,6 +22,17 @@ namespace build2
     &value_traits<bool>::value_type
   };
 
+  static dir_path
+  scoped (const scope&, dir_path d)
+  {
+    return d;
+  }
+
+  static void
+  scoped_void (const scope&, dir_path)
+  {
+  }
+
   int
   main (int, char* argv[])
   {
@@ -43,6 +54,11 @@ namespace build2
     f["ambig"] = [](names a, optional<string>)   {return a;};
     f["ambig"] = [](names a, optional<uint64_t>) {return a;};
 
+    f["scoped"]      = [](const scope&, names a) {return a;};
+    f["scoped_void"] = [](const scope&, names) {};
+    f["scoped"] = &scoped;
+    f["scoped_void"] = &scoped_void;
+
     f[".qual"] = []() {return "abc";};
 
     f[".length"] = &path::size; // Member function.
@@ -60,7 +76,7 @@ namespace build2
         1,
         function_overload::arg_variadic,
         function_overload::types (arg_bool, 1),
-        [] (vector_view<value> args, const function_overload&)
+        [] (const scope&, vector_view<value> args, const function_overload&)
         {
           return value (static_cast<uint64_t> (args.size ()));
         }));
@@ -74,7 +90,7 @@ namespace build2
         0,
         function_overload::arg_variadic,
         function_overload::types (),
-        [] (vector_view<value> args, const function_overload&)
+        [] (const scope&, vector_view<value> args, const function_overload&)
         {
           for (value& a: args)
           {
-- 
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