From 2a0f9e035f673f1ee387924501a31990de37f18d Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 24 Apr 2015 12:29:20 +0200
Subject: Implement lib/liba/libso{} target group, shared/static library build

---
 build/algorithm.txx | 139 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 135 insertions(+), 4 deletions(-)

(limited to 'build/algorithm.txx')

diff --git a/build/algorithm.txx b/build/algorithm.txx
index 2592b5e..4f5f9f3 100644
--- a/build/algorithm.txx
+++ b/build/algorithm.txx
@@ -2,11 +2,110 @@
 // copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
 // license   : MIT; see accompanying LICENSE file
 
+#include <build/context>
+#include <build/utility> // reverse_iterate
+
 namespace build
 {
-  template <typename T>
+  template <executor_function* E>
+  target_state
+  execute_prerequisites (action a, target& t)
+  {
+    target_state ts (target_state::unchanged);
+
+    if (t.group != nullptr)
+      ts = execute_prerequisites<E> (a, *t.group);
+
+    for (target* pt: t.prerequisites)
+    {
+      if (pt == nullptr) // Skip ignored.
+        continue;
+
+      if (E (a, *pt) == target_state::changed)
+        ts = target_state::changed;
+    }
+
+    return ts;
+  }
+
+  template <executor_function* E>
+  target_state
+  reverse_execute_prerequisites (action a, target& t)
+  {
+    target_state ts (target_state::unchanged);
+
+    for (target* pt: reverse_iterate (t.prerequisites))
+    {
+      if (pt == nullptr) // Skip ignored.
+        continue;
+
+      if (E (a, *pt) == target_state::changed)
+        ts = target_state::changed;
+    }
+
+    if (t.group != nullptr)
+    {
+      if (reverse_execute_prerequisites<E> (a, *t.group) ==
+            target_state::changed)
+        ts = target_state::changed;
+    }
+
+    return ts;
+  }
+
+  template <executor_function* E>
+  bool
+  execute_prerequisites (action a, target& t, const timestamp& mt)
+  {
+    bool e (mt == timestamp_nonexistent);
+
+    if (t.group != nullptr)
+    {
+      if (execute_prerequisites<E> (a, *t.group, mt))
+        e = true;
+    }
+
+    for (target* pt: t.prerequisites)
+    {
+      if (pt == nullptr) // Skip ignored.
+        continue;
+
+      target_state ts (E (a, *pt));
+
+      if (!e)
+      {
+        // If this is an mtime-based target, then compare timestamps.
+        //
+        if (auto mpt = dynamic_cast<const mtime_target*> (pt))
+        {
+          timestamp mp (mpt->mtime ());
+
+          // What do we do if timestamps are equal? This can happen, for
+          // example, on filesystems that don't have subsecond resolution.
+          // There is not much we can do here except detect the case where
+          // the prerequisite was changed in this run which means the
+          // action must be executed on the target as well.
+          //
+          if (mt < mp || (mt == mp && ts == target_state::changed))
+            e = true;
+        }
+        else
+        {
+          // Otherwise we assume the prerequisite is newer if it was changed.
+          //
+          if (ts == target_state::changed)
+            e = true;
+        }
+      }
+    }
+
+    return e;
+  }
+
+  template <typename T, executor_function* E>
   T*
-  execute_prerequisites (action a, target& t, const timestamp& mt, bool& e)
+  execute_find_prerequisites (
+    action a, target& t, const timestamp& mt, bool& e)
   {
     //@@ Can factor the bulk of it into a non-template code. Can
     // either do a function template that will do dynamic_cast check
@@ -15,14 +114,14 @@ namespace build
     T* r (nullptr);
 
     if (t.group != nullptr)
-      r = execute_prerequisites<T> (a, *t.group, mt, e);
+      r = execute_find_prerequisites<T, E> (a, *t.group, mt, e);
 
     for (target* pt: t.prerequisites)
     {
       if (pt == nullptr) // Skip ignored.
         continue;
 
-      target_state ts (execute (a, *pt));
+      target_state ts (E (a, *pt));
 
       if (!e)
       {
@@ -56,4 +155,36 @@ namespace build
 
     return r;
   }
+
+  template <executor_function* E = execute>
+  target_state
+  default_action (action a, target& t)
+  {
+    return current_mode == execution_mode::first
+      ? execute_prerequisites<E> (a, t)
+      : reverse_execute_prerequisites<E> (a, t);
+  }
+
+  template <executor_function* E>
+  target_state
+  perform_clean (action a, target& t)
+  {
+    // The reverse order of update: first delete the file, then clean
+    // prerequisites.
+    //
+    file& ft (dynamic_cast<file&> (t));
+
+    bool r (rmfile (ft.path (), ft));
+
+    // Update timestamp in case there are operations after us that
+    // could use the information.
+    //
+    ft.mtime (timestamp_nonexistent);
+
+    // Clean prerequisites.
+    //
+    target_state ts (reverse_execute_prerequisites<E> (a, t));
+
+    return r ? target_state::changed : ts;
+  }
 }
-- 
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