feat: newline when empty flag (#49)

* no large gaps between prompts on empty input due to NewlineBefore and NewlineAfter

* removed lastLine placeholder

* don't print lastLine

* check firstRead in newlineAfter

* set lastLine every iteration

Author: pygrum

console.go

@@ -33,6 +33,17 @@ type Console struct {
 	// know how to handle it in all situations.
 	NewlineAfter bool
 
+	// Leave empty lines with NewlineBefore and NewlineAfter, even if the provided input was empty.
+	// Empty characters are defined as any number of spaces and tabs. The 'empty' character set
+	// can be changed by modifying Console.EmptyChars
+	// This field is false by default.
+	NewlineWhenEmpty bool
+
+	// Characters that are used to determine whether an input line was empty. If a line is not entirely
+	// made up by any of these characters, then it is not considered empty. The default characters
+	// are ' ' and '\t'.
+	EmptyChars []rune
+
 	// PreReadlineHooks - All the functions in this list will be executed,
 	// in their respective orders, before the console starts reading
 	// any user input (ie, before redrawing the prompt).
@@ -89,6 +100,8 @@ func New(app string) *Console {
 	console.shell.Completer = console.complete
 	console.defaultStyleConfig()
 
+	// Defaults
+	console.EmptyChars = []rune{' ', '\t'}
 	return console
 }
 

line.go

@@ -267,3 +267,14 @@ func trimSpacesMatch(remain []string) (trimmed []string) {
 
 	return
 }
+
+func (c *Console) lineEmpty(line string) bool {
+	empty := true
+	for _, r := range line {
+		if !strings.ContainsRune(string(c.EmptyChars), r) {
+			empty = false
+			break
+		}
+	}
+	return empty
+}

run.go

@@ -23,11 +23,24 @@ func (c *Console) Start() error {
 		c.printLogo(c)
 	}
 
-	for {
+	lastLine := "" // used to check if last read line is empty.
+
+	for i := 0; ; i++ {
 		// Identical to printing it at the end of the loop, and
 		// leaves some space between the logo and the first prompt.
+
+		// If NewlineAfter is set but NewlineWhenEmpty is not set, we do a check to see
+		// if the last line was empty. If it wasn't, then we can print.
+		//fmt.Println(lastLine, len(lastLine))
 		if c.NewlineAfter {
-			fmt.Println()
+			if !c.NewlineWhenEmpty && i != 0 {
+				// Print on the condition that the last input wasn't empty.
+				if !c.lineEmpty(lastLine) {
+					fmt.Println()
+				}
+			} else {
+				fmt.Println()
+			}
 		}
 
 		// Always ensure we work with the active menu, with freshly
@@ -44,13 +57,19 @@ func (c *Console) Start() error {
 
 		// Block and read user input.
 		line, err := c.shell.Readline()
-
 		if c.NewlineBefore {
-			fmt.Println()
+			if !c.NewlineWhenEmpty {
+				if !c.lineEmpty(line) {
+					fmt.Println()
+				}
+			} else {
+				fmt.Println()
+			}
 		}
 
 		if err != nil {
 			menu.handleInterrupt(err)
+			lastLine = line
 			continue
 		}
 
@@ -63,10 +82,12 @@ func (c *Console) Start() error {
 		args, err := c.parse(line)
 		if err != nil {
 			fmt.Printf("Parsing error: %s\n", err.Error())
+			lastLine = line
 			continue
 		}
 
 		if len(args) == 0 {
+			lastLine = line
 			continue
 		}
 
@@ -75,6 +96,7 @@ func (c *Console) Start() error {
 		args, err = c.runLineHooks(args)
 		if err != nil {
 			fmt.Printf("Line error: %s\n", err.Error())
+			lastLine = line
 			continue
 		}
 
@@ -83,9 +105,10 @@ func (c *Console) Start() error {
 		// the library user is responsible for setting
 		// the cobra behavior.
 		// If it's an interrupt, we take care of it.
-		if err := c.execute(menu, args, false); err != nil {
+		if err = c.execute(menu, args, false); err != nil {
 			fmt.Println(err)
 		}
+		lastLine = line
 	}
 }