Initial pass for true and false conditionals for tasks

command.go

@@ -61,7 +61,7 @@ func findCmdDeps(params []string, conf *config) []string {
 	return nil
 }
 
-func processCmdMacro(macroName string, args []string, conf *config) error {
+func processCmdMacro(macroName string, args []string, interact bool, conf *config) error {
 	m, mn := findCmdMacro(macroName, conf)
 	if m == nil {
 		return fmt.Errorf("macro or variant not found: %s", macroName)
@@ -75,10 +75,10 @@ func processCmdMacro(macroName string, args []string, conf *config) error {
 		log.Printf("expanding macro: %s", mn)
 	}
 
-	return processCmd(margs, conf)
+	return processCmd(margs, interact, conf)
 }
 
-func processCmd(params []string, conf *config) error {
+func processCmd(params []string, interact bool, conf *config) error {
 	args := appendExpEnv(nil, params)
 	if len(args) == 0 {
 		return fmt.Errorf("invalid command statement")
@@ -91,19 +91,28 @@ func processCmd(params []string, conf *config) error {
 	}
 
 	if strings.HasPrefix(cmdName, "@") {
-		return processCmdMacro(cmdName, cmdArgs, conf)
+		return processCmdMacro(cmdName, cmdArgs, interact, conf)
 	}
 
 	if conf.flags&flagVerbose != 0 {
 		log.Printf("executing command: %s %s", cmdName, strings.Join(cmdArgs, " "))
 	}
 
-	return try(func() error {
+	exec := func() error {
 		cmd := exec.Command(cmdName, cmdArgs...)
 		cmd.Dir = conf.dstDir
+		if interact {
 			cmd.Stderr = os.Stderr
 			cmd.Stdout = os.Stdout
 			cmd.Stdin = os.Stdin
-		return cmd.Run()
-	})
+		}
+
+		return cmd.Run()
+	}
+
+	if interact {
+		return try(exec)
+	}
+
+	return exec()
 }

task.go

@@ -32,6 +32,8 @@ type task struct {
 	Links   [][]string
 	Cmds    [][]string
 	Envs    [][]string
+	IfTrue  [][]string
+	IfFalse [][]string
 }
 
 func (t *task) deps(conf *config) []string {
@@ -60,11 +62,28 @@ func (t *task) process(conf *config) error {
 	}
 
 	if conf.flags&flagNoCmds == 0 {
+	CmdLoop:
+		for {
+			for _, currCnd := range t.IfTrue {
+				if err := processCmd(currCnd, false, conf); err != nil {
+					break CmdLoop
+				}
+			}
+
+			for _, currCnd := range t.IfFalse {
+				if err := processCmd(currCnd, false, conf); err == nil {
+					break CmdLoop
+				}
+			}
+
 			for _, currCmd := range t.Cmds {
-			if err := processCmd(currCmd, conf); err != nil {
+				if err := processCmd(currCmd, true, conf); err != nil {
 					return err
 				}
 			}
+
+			break
+		}
 	}
 
 	if conf.flags&flagNoLinks == 0 {