1 files changed, 167 insertions, 2 deletions

diff --git a/build/file.cxx b/build/file.cxx
index 0b0220d..70a5ed8 100644
--- a/build/file.cxx
+++ b/build/file.cxx
@@ -15,6 +15,19 @@ using namespace std;
 
 namespace build
 {
+  bool
+  is_src_root (const path& d)
+  {
+    return file_exists (d / path ("build/bootstrap.build")) ||
+      file_exists (d / path ("build/root.build"));
+  }
+
+  bool
+  is_out_root (const path& d)
+  {
+    return file_exists (d / path ("build/bootstrap/src-root.build"));
+  }
+
   void
   source (const path& bf, scope& root, scope& base)
   {
@@ -146,18 +159,170 @@ namespace build
   }
 
   void
-  root_pre (scope& root)
+  create_bootstrap_outer (scope& root)
+  {
+    auto v (root.ro_variables ()["amalgamation"]);
+
+    if (!v)
+      return;
+
+    const path& d (v.as<const path&> ());
+    path out_root (root.path () / d);
+    path src_root (root.src_path () / d);
+    out_root.normalize ();
+    src_root.normalize ();
+
+    scope& rs (create_root (out_root, src_root));
+
+    bootstrap_out (rs);
+
+    // Check if the bootstrap process changed src_root.
+    //
+    const path& p (rs.variables["src_root"].as<const path&> ());
+
+    if (src_root != p)
+      fail << "bootstrapped src_root " << p << " does not match "
+           << "amalgamated " << src_root;
+
+    rs.src_path_ = &p;
+
+    bootstrap_src (rs);
+    create_bootstrap_outer (rs);
+  }
+
+  scope&
+  create_bootstrap_inner (scope& root, const path& out_base)
+  {
+    if (auto v = root.ro_variables ()["subprojects"])
+    {
+      for (const name& n: v.as<const list_value&> ())
+      {
+        // Should be a list of directories.
+        //
+        if (!n.type.empty () || !n.value.empty () || n.dir.empty ())
+          fail << "expected directory in subprojects variable "
+               << "instead of " << n;
+
+        path out_root (root.path () / n.dir);
+
+        if (!out_base.sub (out_root))
+          continue;
+
+        path src_root (root.src_path () / n.dir);
+        scope& rs (create_root (out_root, src_root));
+
+        bootstrap_out (rs);
+
+        // Check if the bootstrap process changed src_root.
+        //
+        const path& p (rs.variables["src_root"].as<const path&> ());
+
+        if (src_root != p)
+          fail << "bootstrapped src_root " << p << " does not match "
+               << "subproject " << src_root;
+
+        rs.src_path_ = &p;
+
+        bootstrap_src (rs);
+
+        // See if there are more inner roots.
+        //
+        return create_bootstrap_inner (rs, out_base);
+      }
+    }
+
+    return root;
+  }
+
+  void
+  load_root_pre (scope& root)
   {
     tracer trace ("root_pre");
 
     // First load outer roots, if any.
     //
     if (scope* rs = root.parent_scope ()->root_scope ())
-      root_pre (*rs);
+      load_root_pre (*rs);
 
     path bf (root.src_path () / path ("build/root.build"));
 
     if (file_exists (bf))
       source_once (bf, root, root);
   }
+
+  void
+  import (scope& ibase, const name& n, const location& l)
+  {
+    scope& iroot (*ibase.root_scope ());
+
+    // Figure out this project's out_root.
+    //
+    const variable& var (variable_pool.find ("config." + n.value));
+    auto val (iroot[var]);
+
+    if (val)
+    {
+      if (val.scope == global_scope)
+        iroot.variables[var] = val; // Copy into root scope.
+    }
+    else
+      fail (l) << "unable to find out_root for imported " << n <<
+        info << "consider explicitly configuring its out_root via the "
+               << var.name << " command line variable";
+
+    const path& out_root (val.as<const path&> ());
+
+    // Bootstrap the imported root scope. This is pretty similar to
+    // what we do in main() except that here we don't try to guess
+    // src_root.
+    //
+    path src_root (is_src_root (out_root) ? out_root : path ());
+    scope& root (create_root (out_root, src_root));
+
+    bootstrap_out (root);
+
+    // Check that the bootstrap process set src_root.
+    //
+    if (auto v = root.ro_variables ()["src_root"])
+    {
+      const path& p (v.as<const path&> ());
+
+      if (!src_root.empty () && p != src_root)
+        fail << "bootstrapped src_root " << p << " does not match "
+             << "discovered " << src_root;
+
+      root.src_path_ = &p;
+    }
+    else
+      fail (l) << "unable to determine src_root for imported " << n <<
+        info << "consider configuring " << out_root;
+
+    bootstrap_src (root);
+
+    // Bootstrap outer roots if any. Loading will be done by
+    // load_root_pre() below.
+    //
+    create_bootstrap_outer (root);
+
+    // Load the imported root scope.
+    //
+    load_root_pre (root);
+
+    // Create a temporary scope so that the export stub does not mess
+    // up any of our variables.
+    //
+    temp_scope ts (ibase);
+
+    // "Pass" the imported project's roots to the stub.
+    //
+    ts.variables["out_root"] = out_root;
+    ts.variables["src_root"] = src_root;
+
+    // Load the export stub. Note that it is loaded in the context
+    // of the importing project, not the imported one. The export
+    // stub will normally switch to the imported root scope at some
+    // point.
+    //
+    source (root.src_path () / path ("build/export.build"), iroot, ts);
+  }
 }