From a1a02bed3ccafb744d01ce24a9e9216a51023ddf Mon Sep 17 00:00:00 2001
From: Ingo Weinhold <ingo_weinhold@gmx.de>
Date: Sat, 11 Feb 2006 01:57:34 +0000
Subject: [PATCH] New feature: Now jam defines a variable JAM_TARGETS, which
 contains the targets given on the command line (respectively "all", if none
 has been given). The contents of the variable can be changed from within the
 Jamrules/Jamfiles. The targets that are in JAM_TARGETS after Jamfile parsing
 is done, are those that will be built (and their dependencies, of course).
 This allows for interesting build system features.

git-svn-id: file:///srv/svn/repos/haiku/buildtools/trunk@16345 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 jam/Jamfile |  6 +++++-
 jam/jam.c   | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/jam/Jamfile b/jam/Jamfile
index c5fb0cf586..f6492f85d8 100644
--- a/jam/Jamfile
+++ b/jam/Jamfile
@@ -52,10 +52,14 @@ if $(OS) = NT 			{ CCFLAGS += /DNT ; }
 
 ### LOCAL CHANGE
 # 
-# Include header caching.
+# Include:
+# * header caching
+# * jamfile caching
+# * definition of JAM_TARGETS variable
 #
 DEFINES += OPT_HEADER_CACHE_EXT ;
 DEFINES += OPT_JAMFILE_CACHE_EXT ;
+DEFINES += OPT_JAM_TARGETS_VARIABLE_EXT ;
 #
 ### LOCAL CHANGE
 
diff --git a/jam/jam.c b/jam/jam.c
index 7a69ccd791..5bf427ce4e 100644
--- a/jam/jam.c
+++ b/jam/jam.c
@@ -320,6 +320,26 @@ main( int argc, char **argv, char **arg_environ )
 
 	var_defines( (const char **)use_environ );
 
+#ifdef OPT_JAM_TARGETS_VARIABLE_EXT
+	/* define the variable JAM_TARGETS containing the targets specified on
+	   the command line */
+	{
+		LIST *l = L0;
+		int i;
+		char **targets = argv;
+		int targetCount = argc;
+		if (targetCount == 0) {
+			targets = (char**)&all;
+			targetCount = 1;
+		}
+
+		for (i = 0; i < targetCount; i++)
+			l = list_new( l, targets[i], 0 );
+
+		var_set( "JAM_TARGETS", l, VAR_SET );
+	}
+#endif
+
 	/* Load up variables set on command line. */
 
 	for( n = 0; s = getoptval( optv, 's', n ); n++ )
@@ -368,6 +388,35 @@ main( int argc, char **argv, char **arg_environ )
 	    globs.noexec++;
 	}
 
+#ifdef OPT_JAM_TARGETS_VARIABLE_EXT
+	/* get value of variable JAM_TARGETS and build the targets */
+	{
+		LIST *l = var_get( "JAM_TARGETS" );
+		int targetCount = list_length(l);
+		char **targets;
+		int i;
+
+		if (targetCount == 0) {
+			/* No targets. Nothing to do. */
+			exit( EXITOK );
+		}
+
+		targets = malloc(targetCount * sizeof(char*));
+		if (!targets) {
+			printf( "Memory allocation failed!\n" );
+			exit( EXITBAD );
+		}
+
+		for (i = 0; i < targetCount; i++) {
+			targets[i] = (char*)l->string;
+			l = l->next;
+		}
+
+		argv = targets;
+		argc = targetCount;
+	}
+#endif
+
 	/* Now make target */
 
 	if( !argc )