terminal/command: add support for next [count] (#1629)

* terminal/command: add support for next [count]

* disallow negative counts.

* handle github comments, and regen docs.

* Fix the fact that we don't print the file info in the last step of the next count.

* Fix a typo, cleanup a few other observations.

Documentation/cli/README.md

@@ -296,6 +296,11 @@ If regex is specified only local variables with a name matching it will be retur
 ## next
 Step over to next source line.
 
+	 next [count]
+
+Optional [count] argument allows you to skip multiple lines.
+
+
 Aliases: n
 
 ## on

pkg/terminal/command.go

@@ -138,7 +138,12 @@ the arguments.  With -noargs, the process starts with an empty commandline.
 		{aliases: []string{"continue", "c"}, cmdFn: c.cont, helpMsg: "Run until breakpoint or program termination."},
 		{aliases: []string{"step", "s"}, cmdFn: c.step, helpMsg: "Single step through program."},
 		{aliases: []string{"step-instruction", "si"}, allowedPrefixes: revPrefix, cmdFn: c.stepInstruction, helpMsg: "Single step a single cpu instruction."},
-		{aliases: []string{"next", "n"}, cmdFn: c.next, helpMsg: "Step over to next source line."},
+		{aliases: []string{"next", "n"}, cmdFn: c.next, helpMsg: `Step over to next source line.
+
+	 next [count]
+
+Optional [count] argument allows you to skip multiple lines.
+`},
 		{aliases: []string{"stepout"}, cmdFn: c.stepout, helpMsg: "Step out of the current function."},
 		{aliases: []string{"call"}, cmdFn: c.call, helpMsg: `Resumes process, injecting a function call (EXPERIMENTAL!!!)
 	
@@ -864,6 +869,15 @@ func parseArgs(args string) ([]string, error) {
 	return v[0], nil
 }
 
+// parseOptionalCount parses an optional count argument.
+// If there are not arguments, a value of 1 is returned as the default.
+func parseOptionalCount(arg string) (int64, error) {
+	if len(arg) == 0 {
+		return 1, nil
+	}
+	return strconv.ParseInt(arg, 0, 64)
+}
+
 func restart(t *Term, ctx callContext, args string) error {
 	v, err := parseArgs(args)
 	if err != nil {
@@ -932,9 +946,11 @@ func (c *Commands) cont(t *Term, ctx callContext, args string) error {
 	return nil
 }
 
-func continueUntilCompleteNext(t *Term, state *api.DebuggerState, op string) error {
+func continueUntilCompleteNext(t *Term, state *api.DebuggerState, op string, shouldPrintFile bool) error {
 	if !state.NextInProgress {
-		printfile(t, state.CurrentThread.File, state.CurrentThread.Line, true)
+		if shouldPrintFile {
+			printfile(t, state.CurrentThread.File, state.CurrentThread.Line, true)
+		}
 		return nil
 	}
 	for {
@@ -983,7 +999,7 @@ func (c *Commands) step(t *Term, ctx callContext, args string) error {
 		return err
 	}
 	printcontext(t, state)
-	return continueUntilCompleteNext(t, state, "step")
+	return continueUntilCompleteNext(t, state, "step", true)
 }
 
 var notOnFrameZeroErr = errors.New("not on topmost frame")
@@ -1032,13 +1048,29 @@ func (c *Commands) next(t *Term, ctx callContext, args string) error {
 	if c.frame != 0 {
 		return notOnFrameZeroErr
 	}
-	state, err := exitedToError(t.client.Next())
-	if err != nil {
-		printcontextNoState(t)
+	var count int64
+	var err error
+	if count, err = parseOptionalCount(args); err != nil {
 		return err
+	} else if count <= 0 {
+		return errors.New("Invalid next count")
 	}
-	printcontext(t, state)
-	return continueUntilCompleteNext(t, state, "next")
+	for ; count > 0; count-- {
+		state, err := exitedToError(t.client.Next())
+		if err != nil {
+			printcontextNoState(t)
+			return err
+		}
+		// If we're about the exit the loop, print the context.
+		finishedNext := count == 1
+		if finishedNext {
+			printcontext(t, state)
+		}
+		if err := continueUntilCompleteNext(t, state, "next", finishedNext); err != nil {
+			return err
+		}
+	}
+	return nil
 }
 
 func (c *Commands) stepout(t *Term, ctx callContext, args string) error {
@@ -1054,7 +1086,7 @@ func (c *Commands) stepout(t *Term, ctx callContext, args string) error {
 		return err
 	}
 	printcontext(t, state)
-	return continueUntilCompleteNext(t, state, "stepout")
+	return continueUntilCompleteNext(t, state, "stepout", true)
 }
 
 func (c *Commands) call(t *Term, ctx callContext, args string) error {
@@ -1074,7 +1106,7 @@ func (c *Commands) call(t *Term, ctx callContext, args string) error {
 		return err
 	}
 	printcontext(t, state)
-	return continueUntilCompleteNext(t, state, "call")
+	return continueUntilCompleteNext(t, state, "call", true)
 }
 
 func clear(t *Term, ctx callContext, args string) error {

pkg/terminal/command_test.go

@@ -664,6 +664,15 @@ func TestCheckpoints(t *testing.T) {
 	})
 }
 
+func TestNextWithCount(t *testing.T) {
+	test.AllowRecording(t)
+	withTestTerminal("nextcond", t, func(term *FakeTerminal) {
+		term.MustExec("break main.main")
+		listIsAt(t, term, "continue", 8, -1, -1)
+		listIsAt(t, term, "next 2", 10, -1, -1)
+	})
+}
+
 func TestRestart(t *testing.T) {
 	withTestTerminal("restartargs", t, func(term *FakeTerminal) {
 		term.MustExec("break main.printArgs")