Improve include() function: only include files once, and allow including specific files instead of just directories

.hgcheck/hg-checklink-8ud9oN

@@ -0,0 +1 @@
+.

CHANGES.txt

@@ -4,6 +4,8 @@ Sony NGP  (in progress)
 
 * Added debugformat with C7 support for Visual Studio
 * The error message for invalid flags now includes the offending value
+* The include() function will now include each file only once
+* The include() function can now include specific files
 
 
 -------

src/base/globals.lua

@@ -114,11 +114,25 @@
 	
 	
 --
--- A shortcut for including another "premake4.lua" file, often used for projects.
+-- Load and run an external script file, with a bit of extra logic to make 
+-- including projects easier. if "path" is a directory, will look for 
+-- path/premake4.lua. And each file is tracked, and loaded only once.
 --
 
-	function include(fname)
-		return dofile(fname .. "/premake4.lua")
+	io._includedFiles = { }
+	
+	function include(filename)
+		-- if a directory, load the premake script inside it
+		if os.isdir(filename) then
+			filename = path.join(filename, "premake4.lua")
+		end
+				
+		-- but only load each file once
+		filename = path.getabsolute(filename)
+		if not io._includedFiles[filename] then
+			io._includedFiles[filename] = true
+			dofile(filename)
+		end
 	end
 
 

tests/base/test_include.lua

@@ -0,0 +1,49 @@
+--
+-- tests/base/test_include.lua
+-- Test the include() function, for including external scripts
+-- Copyright (c) 2011 Jason Perkins and the Premake project
+--
+
+
+	T.include = { }
+	local suite = T.include
+	
+
+--
+-- Setup and teardown
+--
+
+	function suite.teardown()
+		-- clear the list of included files after each run
+		io._includedFiles = { }
+	end
+	
+	
+--
+-- Tests
+--
+
+	function suite.include_findsPremakeFile_onFolderNameOnly()
+		include "folder"
+		test.isequal("ok\n", io.endcapture())
+	end
+
+
+	function suite.include_onExactFilename()
+		include "folder/premake4.lua"
+		test.isequal("ok\n", io.endcapture())
+	end
+
+
+	function suite.include_runsOnlyOnce_onMultipleIncludes()
+		include "folder/premake4.lua"
+		include "folder/premake4.lua"
+		test.isequal("ok\n", io.endcapture())
+	end
+
+
+	function suite.include_runsOnlyOnce_onMultipleIncludesWithDifferentPaths()
+		include "folder/premake4.lua"
+		include "../tests/folder/premake4.lua"
+		test.isequal("ok\n", io.endcapture())
+	end	

tests/folder/ok.lua.2

@@ -1 +0,0 @@
-return "ok"

tests/folder/premake4.lua

@@ -0,0 +1 @@
+io.printf("ok")

tests/premake4.lua

@@ -37,6 +37,7 @@
 -- The test suites
 --
 
+	-- Base API tests
 	dofile("test_dofile.lua")
 	dofile("test_string.lua")
 	dofile("test_premake.lua")
@@ -48,6 +49,7 @@
 	dofile("base/test_api.lua")
 	dofile("base/test_action.lua")
 	dofile("base/test_config.lua")
+	dofile("base/test_include.lua")
 	dofile("base/test_location.lua")
 	dofile("base/test_os.lua")
 	dofile("base/test_path.lua")

tests/testfx.lua

@@ -30,9 +30,11 @@
 	function test.capture(expected)
 		local actual = io.endcapture()
 		
+		-- create line-by-line iterators for both values
 		local ait = actual:gfind("(.-)" .. io.eol)
 		local eit = expected:gfind("(.-)\n")
 		
+		-- compare each value line by line
 		local linenum = 1
 		local atxt = ait()
 		local etxt = eit()