Add number-lines processor (#65)

* Add numberlines processor

numberlines prepends non-empty lines with consecutive numbers

* Update README.md with number-lines

* Remove full name from a list of aliases

* Simplify creation of string from slice

* Remove unnecessary error variable, use ++ instead of +=1

* Re-generate processor

* Fix alias test for number-lines

* Pad line numbers with spaces, right-aligned

Author: kamchy

README.md

@@ -237,6 +237,7 @@ echo "Hello World" | sttr base64-encode | sttr md5
 - [x] **shuffle-lines** - Shuffle lines randomly
 - [x] **sort-lines** - Sort lines alphabetically
 - [x] **unique-lines** - Get unique lines from list
+- [x] **number-lines** -  Prepend consecutive number to each line
 
 #### Spaces
 

cmd/processor_number-lines.go

@@ -0,0 +1,62 @@
+package processors
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// / Prepends consecutive number to each line of input
+type LineNumberer struct{}
+
+func (p LineNumberer) Name() string {
+	return "number-lines"
+}
+
+func (p LineNumberer) Alias() []string {
+	return []string{"nl"}
+}
+
+func nonEmptyCount(strs []string) int {
+	var count = 0
+	for _, s := range strs {
+		if s != "" {
+			count++
+		}
+	}
+	return count
+}
+func (p LineNumberer) Transform(data []byte, _ ...Flag) (string, error) {
+	var s = string(data)
+	var counter = 1
+	var result = ""
+	var lines = strings.Split(s, "\n")
+	var nec = nonEmptyCount(lines)
+	var maxDigits = len(strconv.Itoa(nec))
+	for _, line := range lines {
+		if line != "" {
+			line = fmt.Sprintf("%*d. %s", maxDigits, counter, line)
+			counter++
+		}
+		result += line + "\n"
+
+	}
+	result = strings.TrimSuffix(result, "\n")
+	return result, nil
+}
+
+func (p LineNumberer) Flags() []Flag {
+	return nil
+}
+
+func (p LineNumberer) Title() string {
+	return "Line numberer"
+}
+
+func (p LineNumberer) Description() string {
+	return "Prepends consecutive number to each input line"
+}
+
+func (p LineNumberer) FilterValue() string {
+	return p.Title()
+}

processors/numberlines.go

@@ -0,0 +1,115 @@
+package processors
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestLineNumberer_Command(t *testing.T) {
+	test := struct {
+		alias       []string
+		description string
+		filterValue string
+		flags       []Flag
+		name        string
+		title       string
+	}{
+		alias:       []string{"nl"},
+		description: "Prepends consecutive number to each input line",
+		filterValue: "Line numberer",
+		flags:       nil,
+		name:        "number-lines",
+		title:       "Line numberer",
+	}
+	p := LineNumberer{}
+	if got := p.Alias(); !reflect.DeepEqual(got, test.alias) {
+		t.Errorf("Alias() = %v, want %v", got, test.alias)
+	}
+	if got := p.Description(); got != test.description {
+		t.Errorf("Description() = %v, want %v", got, test.description)
+	}
+	if got := p.FilterValue(); got != test.filterValue {
+		t.Errorf("FilterValue() = %v, want %v", got, test.filterValue)
+	}
+	if got := p.Flags(); !reflect.DeepEqual(got, test.flags) {
+		t.Errorf("Flags() = %v, want %v", got, test.flags)
+	}
+	if got := p.Name(); got != test.name {
+		t.Errorf("Name() = %v, want %v", got, test.name)
+	}
+	if got := p.Title(); got != test.title {
+		t.Errorf("Title() = %v, want %v", got, test.title)
+	}
+}
+
+func TestLineNumberer_Transform(t *testing.T) {
+	type args struct {
+		data []byte
+		in1  []Flag
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr bool
+	}{
+		{
+			name: "Test empty string",
+			args: args{data: []byte("")},
+			want: "",
+		},
+		{
+			name: "String",
+			args: args{data: []byte("this is string")},
+			want: "1. this is string",
+		}, {
+			name: "Emoji",
+			args: args{data: []byte("😃😇🙃🙂😉😌😙😗🇮🇳")},
+			want: "1. 😃😇🙃🙂😉😌😙😗🇮🇳",
+		}, {
+			name: "Multi line string",
+			args: args{data: []byte("Hello\nfoo\nbar\nfoo\nf00\n%*&^*&^&\n***")},
+			want: "1. Hello\n2. foo\n3. bar\n4. foo\n5. f00\n6. %*&^*&^&\n7. ***",
+		}, {
+			name: "Multi line string ending with \\n",
+			args: args{data: []byte("Hello\nfoo\nbar\n")},
+			want: "1. Hello\n2. foo\n3. bar\n",
+		}, {
+			name: "Multi line string with padding",
+			args: args{data: []byte("Hello\nfoo\nbar\nfoo\nf00\n%*&^*&^&\n***\neight\nnine\nten")},
+			want: " 1. Hello\n 2. foo\n 3. bar\n 4. foo\n 5. f00\n 6. %*&^*&^&\n 7. ***\n 8. eight\n 9. nine\n10. ten",
+		}, {
+			name: "Test multi lingual character",
+			args: args{data: []byte("नमस्ते")},
+			want: "1. नमस्ते",
+		},
+		{
+			name: "Lines with empty lines between",
+			args: args{data: []byte("this is string\n\nfollowed by empty line and another")},
+			want: "1. this is string\n\n2. followed by empty line and another",
+		},
+		{
+			name: "Lines with first empty line",
+			args: args{data: []byte("\nthis is string after newline\n\nfollowed by empty line and another")},
+			want: "\n1. this is string after newline\n\n2. followed by empty line and another",
+		},
+		{
+			name: "Lines with space-only lines between",
+			args: args{data: []byte("this is string\n   \nfollowed by three-space line and another")},
+			want: "1. this is string\n2.    \n3. followed by three-space line and another",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			p := LineNumberer{}
+			got, err := p.Transform(tt.args.data, tt.args.in1...)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Transform() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("Transform() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

processors/numberlines_test.go

@@ -43,6 +43,7 @@ var List = []list.Item{
 	MorseCodeDecode{},
 	MD5{},
 	MSGPACKToJSON{},
+	LineNumberer{},
 	Pascal{},
 	RemoveNewLines{},
 	RemoveSpaces{},