Added strings-with-deps, a set of functions that are intended to

build a minimal text which includes given strings and satisfies
'dependencies' of type A requires B to go before it. Just like
global variable intialization must occur before using them. Supposed
to be used for constructing builder.sh .

svn path=/nixpkgs/trunk/; revision=9196

pkgs/lib/strings-with-deps.nix

@@ -0,0 +1,48 @@
+args: 
+	with args;
+	with lib;
+	let 
+		inherit (builtins)	
+			head tail isList;
+rec {
+
+/*
+	let  shelllib = rec {
+		a= {
+			text = "aaaa";
+			deps = [b c];
+		};
+		b = {
+			text = "b";
+		};
+		c = {
+			text = "c";
+			deps = [];
+		};
+	};
+	in
+	
+	[textClosure [shelllib.a]
+		textclosure shelllib.a];
+
+	
+*/
+	
+	textClosureDupList = arg:
+	(
+		if isList arg then 
+			textClosureDupList {text = ""; deps = arg;} 
+		else
+			(if (arg ? deps) then 
+				map textClosureDupList arg.deps 
+			else []) 
+		++ [arg]
+	);
+
+	textClosureList = arg: uniqList (textClosureDupList arg);
+	textClosure = arg: concatStringsSep "
+" (textClosureList arg);
+	
+	noDepEntry = text : {inherit text;};
+	FullDepEntry = text : deps: {inherit text args;};
+}