From 4fae733892d6fd64d67fa0b2e6223779a219bb86 Mon Sep 17 00:00:00 2001
From: Dave Abrahams <dave@boostpro.com>
Date: Thu, 10 Apr 2003 11:33:13 +0000
Subject: [PATCH] optimized insertion-sort

[SVN r18225]
---
 src/util/sequence.jam | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/src/util/sequence.jam b/src/util/sequence.jam
index 50ab5c0aa..c3f86965b 100644
--- a/src/util/sequence.jam
+++ b/src/util/sequence.jam
@@ -59,17 +59,36 @@ rule insertion-sort ( s * : ordered * )
     local caller = [ CALLER_MODULE ] ;
     ordered ?= sequence.less ;
     local result = $(s[1]) ;
-    for local x in $(s[2-])
+    if $(ordered) = sequence.less
     {
         local head tail ;
-        tail = $(result) ;
-        while $(tail) && [ modules.call-in $(caller) : $(ordered) $(tail[1]) $(x) ]
+        for local x in $(s[2-])
         {
-            head += $(tail[1]) ;
-            tail = $(tail[2-]) ;
+            head = ;
+            tail = $(result) ;
+            while $(tail) && ( $(tail[1]) < $(x) )
+            {
+                head += $(tail[1]) ;
+                tail = $(tail[2-]) ;
+            }
+            result = $(head) $(x) $(tail) ;
         }
-        result = $(head) $(x) $(tail) ;
     }
+    else
+    {
+        for local x in $(s[2-])
+        {
+            local head tail ;
+            tail = $(result) ;
+            while $(tail) && [ modules.call-in $(caller) : $(ordered) $(tail[1]) $(x) ]
+            {
+                head += $(tail[1]) ;
+                tail = $(tail[2-]) ;
+            }
+            result = $(head) $(x) $(tail) ;
+        }
+    }
+    
     return $(result) ;
 }