From 306ad185e8d8f50923316bdd1b68ef9a3b1e50e6 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 11 Apr 2023 14:47:42 +0200
Subject: Split package configuration into two passes in pkg-build

---
 bpkg/pkg-configure.hxx | 75 +++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 65 insertions(+), 10 deletions(-)

(limited to 'bpkg/pkg-configure.hxx')

diff --git a/bpkg/pkg-configure.hxx b/bpkg/pkg-configure.hxx
index 16ed96f..a7409b9 100644
--- a/bpkg/pkg-configure.hxx
+++ b/bpkg/pkg-configure.hxx
@@ -21,6 +21,14 @@ namespace bpkg
   int
   pkg_configure (const pkg_configure_options&, cli::scanner& args);
 
+  // Configure a system package and commit the transaction.
+  //
+  shared_ptr<selected_package>
+  pkg_configure_system (const package_name&,
+                        const version&,
+                        database&,
+                        transaction&);
+
   // The custom search function. If specified, it is called by pkg_configure()
   // to obtain the database to search for the prerequisite in, instead of
   // searching for it in the linked databases, recursively. If the function
@@ -31,7 +39,14 @@ namespace bpkg
                                             const package_name&,
                                             bool buildtime);
 
-  // Configure the package, update its state, and commit the transaction.
+  // Given dependencies of a package, return its prerequisite packages,
+  // configuration variables that resulted from selection of these
+  // prerequisites (import, reflection, etc), and sources of the configuration
+  // variables resulted from evaluating the reflect clauses. See
+  // pkg_configure() for the semantics of the dependency list. Fail if for
+  // some of the dependency alternative lists there is no satisfactory
+  // alternative (all its dependencies are configured, satisfy the respective
+  // constraints, etc).
   //
   // The package dependency constraints are expected to be complete.
   //
@@ -50,6 +65,54 @@ namespace bpkg
   // dependency decisions" mode). Failed that, select an alternative as if no
   // prerequisites are specified (the "make dependency decisions" mode).
   //
+  struct configure_prerequisites_result
+  {
+    package_prerequisites   prerequisites;
+    strings                 config_variables; // Note: name and value.
+
+    // Only contains sources of configuration variables collected using the
+    // package skeleton, excluding those user-specified variables which are
+    // not the project variables for the specified package (module
+    // configuration variables, etc). Thus, it is not parallel to the
+    // config_variables member.
+    //
+    vector<config_variable> config_sources; // Note: name and source.
+  };
+
+  // Return the "would be" state for packages that would be configured
+  // by this stage.
+  //
+  using find_package_state_function =
+    optional<pair<package_state, package_substate>> (
+      const shared_ptr<selected_package>&);
+
+  // Note: loads selected packages.
+  //
+  configure_prerequisites_result
+  pkg_configure_prerequisites (const common_options&,
+                               database&,
+                               transaction&,
+                               const dependencies&,
+                               const vector<size_t>* alternatives,
+                               package_skeleton&&,
+                               const vector<package_name>* prev_prerequisites,
+                               bool simulate,
+                               const function<find_database_function>&,
+                               const function<find_package_state_function>&);
+
+  // Configure the package, update its state, and commit the transaction.
+  //
+  void
+  pkg_configure (const common_options&,
+                 database&,
+                 transaction&,
+                 const shared_ptr<selected_package>&,
+                 configure_prerequisites_result&&,
+                 bool disfigured,
+                 bool simulate);
+
+  // Note: loads selected packages.
+  //
   void
   pkg_configure (const common_options&,
                  database&,
@@ -58,18 +121,10 @@ namespace bpkg
                  const dependencies&,
                  const vector<size_t>* alternatives,
                  package_skeleton&&,
-                 const vector<package_name>* prerequisites,
+                 const vector<package_name>* prev_prerequisites,
                  bool disfigured,
                  bool simulate,
                  const function<find_database_function>& = {});
-
-  // Configure a system package and commit the transaction.
-  //
-  shared_ptr<selected_package>
-  pkg_configure_system (const package_name&,
-                        const version&,
-                        database&,
-                        transaction&);
 }
 
 #endif // BPKG_PKG_CONFIGURE_HXX
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