terminal: bugfix: tolerate spurious spaces after command prefixes

Expressions such as:

 frame 0    list
 frame   0   list
 on abreakpoint     print x
 goroutine    1    frame     0     list

should all execute correctly

Fixes #712

cmd/dlv/cmds/commands.go

@@ -333,7 +333,7 @@ func traceCmd(cmd *cobra.Command, args []string) {
 		cmds := terminal.DebugCommands(client)
 		t := terminal.New(client, nil)
 		defer t.Close()
-		err = cmds.Call("continue", "", t)
+		err = cmds.Call("continue", t)
 		if err != nil {
 			fmt.Fprintln(os.Stderr, err)
 			return 1

pkg/terminal/command.go

@@ -260,13 +260,19 @@ func (c *Commands) Find(cmdstr string, prefix cmdPrefix) cmdfunc {
 	return noCmdAvailable
 }
 
-func (c *Commands) CallWithContext(cmdstr, args string, t *Term, ctx callContext) error {
+func (c *Commands) CallWithContext(cmdstr string, t *Term, ctx callContext) error {
-	return c.Find(cmdstr, ctx.Prefix)(t, ctx, args)
+	vals := strings.SplitN(strings.TrimSpace(cmdstr), " ", 2)
+	cmdname := vals[0]
+	var args string
+	if len(vals) > 1 {
+		args = strings.TrimSpace(vals[1])
+	}
+	return c.Find(cmdname, ctx.Prefix)(t, ctx, args)
 }
 
-func (c *Commands) Call(cmdstr, args string, t *Term) error {
+func (c *Commands) Call(cmdstr string, t *Term) error {
 	ctx := callContext{Prefix: noPrefix, Scope: api.EvalScope{GoroutineID: -1, Frame: 0}}
-	return c.CallWithContext(cmdstr, args, t, ctx)
+	return c.CallWithContext(cmdstr, t, ctx)
 }
 
 // Merge takes aliases defined in the config struct and merges them with the default aliases.
@@ -433,7 +439,7 @@ func goroutines(t *Term, ctx callContext, argstr string) error {
 }
 
 func (c *Commands) goroutine(t *Term, ctx callContext, argstr string) error {
-	args := strings.SplitN(argstr, " ", 3)
+	args := strings.SplitN(argstr, " ", 2)
 
 	if ctx.Prefix == onPrefix {
 		if len(args) != 1 || args[0] != "" {
@@ -443,8 +449,7 @@ func (c *Commands) goroutine(t *Term, ctx callContext, argstr string) error {
 		return nil
 	}
 
-	switch len(args) {
+	if len(args) == 1 {
-	case 1:
 		if ctx.Prefix == scopePrefix {
 			return errors.New("no command passed to goroutine")
 		}
@@ -467,8 +472,6 @@ func (c *Commands) goroutine(t *Term, ctx callContext, argstr string) error {
 
 		fmt.Printf("Switched from %d to %d (thread %d)\n", oldState.SelectedGoroutine.ID, gid, newState.CurrentThread.ID)
 		return nil
-	case 2:
-		args = append(args, "")
 	}
 
 	var err error
@@ -477,17 +480,15 @@ func (c *Commands) goroutine(t *Term, ctx callContext, argstr string) error {
 	if err != nil {
 		return err
 	}
-	return c.CallWithContext(args[1], args[2], t, ctx)
+	return c.CallWithContext(args[1], t, ctx)
 }
 
 func (c *Commands) frame(t *Term, ctx callContext, args string) error {
-	v := strings.SplitN(args, " ", 3)
+	v := strings.SplitN(args, " ", 2)
 
 	switch len(v) {
 	case 0, 1:
 		return errors.New("not enough arguments")
-	case 2:
-		v = append(v, "")
 	}
 
 	var err error
@@ -496,7 +497,7 @@ func (c *Commands) frame(t *Term, ctx callContext, args string) error {
 	if err != nil {
 		return err
 	}
-	return c.CallWithContext(v[1], v[2], t, ctx)
+	return c.CallWithContext(v[1], t, ctx)
 }
 
 func printscope(t *Term) error {
@@ -1328,16 +1329,12 @@ func getBreakpointByIDOrName(t *Term, arg string) (*api.Breakpoint, error) {
 }
 
 func (c *Commands) onCmd(t *Term, ctx callContext, argstr string) error {
-	args := strings.SplitN(argstr, " ", 3)
+	args := strings.SplitN(argstr, " ", 2)
 
 	if len(args) < 2 {
 		return errors.New("not enough arguments")
 	}
 
-	if len(args) < 3 {
-		args = append(args, "")
-	}
-
 	bp, err := getBreakpointByIDOrName(t, args[0])
 	if err != nil {
 		return err
@@ -1345,7 +1342,7 @@ func (c *Commands) onCmd(t *Term, ctx callContext, argstr string) error {
 
 	ctx.Prefix = onPrefix
 	ctx.Breakpoint = bp
-	err = c.CallWithContext(args[1], args[2], t, ctx)
+	err = c.CallWithContext(args[1], t, ctx)
 	if err != nil {
 		return err
 	}
@@ -1392,9 +1389,7 @@ func (c *Commands) executeFile(t *Term, name string) error {
 			continue
 		}
 
-		cmdstr, args := parseCommand(line)
+		if err := c.Call(line, t); err != nil {
-
-		if err := c.Call(cmdstr, args, t); err != nil {
 			fmt.Printf("%s:%d: %v\n", name, lineno, err)
 		}
 	}

pkg/terminal/command_test.go

@@ -38,8 +38,6 @@ type FakeTerminal struct {
 }
 
 func (ft *FakeTerminal) Exec(cmdstr string) (outstr string, err error) {
-	cmdstr, args := parseCommand(cmdstr)
-
 	outfh, err := ioutil.TempFile("", "cmdtestout")
 	if err != nil {
 		ft.t.Fatalf("could not create temporary file: %v", err)
@@ -57,7 +55,7 @@ func (ft *FakeTerminal) Exec(cmdstr string) (outstr string, err error) {
 		outstr = string(outbs)
 		os.Remove(outfh.Name())
 	}()
-	err = ft.cmds.Call(cmdstr, args, ft.Term)
+	err = ft.cmds.Call(cmdstr, ft.Term)
 	return
 }
 
@@ -305,7 +303,7 @@ func TestScopePrefix(t *testing.T) {
 			if fid < 0 {
 				t.Fatalf("Could not find frame for goroutine %d: %v", gid, stackOut)
 			}
-			term.AssertExec(fmt.Sprintf("goroutine %d frame %d locals", gid, fid), "(no locals)\n")
+			term.AssertExec(fmt.Sprintf("goroutine     %d    frame     %d     locals", gid, fid), "(no locals)\n")
 			argsOut := strings.Split(term.MustExec(fmt.Sprintf("goroutine %d frame %d args", gid, fid)), "\n")
 			if len(argsOut) != 4 || argsOut[3] != "" {
 				t.Fatalf("Wrong number of arguments in goroutine %d frame %d: %v", gid, fid, argsOut)

pkg/terminal/terminal.go

@@ -128,8 +128,7 @@ func (t *Term) Run() (int, error) {
 			return 1, fmt.Errorf("Prompt for input failed.\n")
 		}
 
-		cmdstr, args := parseCommand(strings.TrimSpace(cmdstr))
+		if err := t.cmds.Call(cmdstr, t); err != nil {
-		if err := t.cmds.Call(cmdstr, args, t); err != nil {
 			if _, ok := err.(ExitRequestError); ok {
 				return t.handleExit()
 			}
@@ -241,11 +240,3 @@ func (t *Term) handleExit() (int, error) {
 	}
 	return 0, nil
 }
-
-func parseCommand(cmdstr string) (string, string) {
-	vals := strings.SplitN(cmdstr, " ", 2)
-	if len(vals) == 1 {
-		return vals[0], ""
-	}
-	return vals[0], strings.TrimSpace(vals[1])
-}