feat: add command.preexec hook

it provides 2 arguments: what the user typed, and the command hilbish
will execute.

golibs/bait/bait.go

@@ -30,6 +30,6 @@ func (b *Bait) throw(name string, args ...interface{}) {
 	b.Em.Emit(name, args...)
 }
 
-func (b *Bait) catch(name string, catcher func(interface{})) {
+func (b *Bait) catch(name string, catcher func(...interface{})) {
 	b.Em.On(name, catcher)
 }

main.go

@@ -184,7 +184,10 @@ input:
 		}
 
 		input = strings.TrimSpace(input)
-		if len(input) == 0 { continue }
+		if len(input) == 0 {
+			hooks.Em.Emit("command.exit", 0)
+			continue
+		}
 
 		if strings.HasSuffix(input, "\\") {
 			for {

rl.go

@@ -22,6 +22,7 @@ func NewLineReader(prompt string) *LineReader {
 }
 
 func (lr *LineReader) Read() (string, error) {
+	hooks.Em.Emit("command.precmd", nil)
 	return readline.String(lr.Prompt)
 }
 

shell.go

@@ -31,6 +31,7 @@ func RunInput(input string) {
 			continue
 		}
 	}
+	hooks.Em.Emit("command.preexec", input, cmdString)
 
 	// First try to load input, essentially compiling to bytecode
 	fn, err := l.LoadString(cmdString)