frp/vendor/github.com/rodaine/table/table.go

268 lines
7.7 KiB
Go

// Package table provides a convenient way to generate tabular output of any
// data, primarily useful for CLI tools.
//
// Columns are left-aligned and padded to accomodate the largest cell in that
// column.
//
// Source: https://github.com/rodaine/table
//
// table.DefaultHeaderFormatter = func(format string, vals ...interface{}) string {
// return strings.ToUpper(fmt.Sprintf(format, vals...))
// }
//
// tbl := table.New("ID", "Name", "Cost ($)")
//
// for _, widget := range Widgets {
// tbl.AddRow(widget.ID, widget.Name, widget.Cost)
// }
//
// tbl.Print()
//
// // Output:
// // ID NAME COST ($)
// // 1 Foobar 1.23
// // 2 Fizzbuzz 4.56
// // 3 Gizmo 78.90
package table
import (
"fmt"
"io"
"os"
"strings"
"unicode/utf8"
)
// These are the default properties for all Tables created from this package
// and can be modified.
var (
// DefaultPadding specifies the number of spaces between columns in a table.
DefaultPadding = 2
// DefaultWriter specifies the output io.Writer for the Table.Print method.
DefaultWriter io.Writer = os.Stdout
// DefaultHeaderFormatter specifies the default Formatter for the table header.
DefaultHeaderFormatter Formatter
// DefaultFirstColumnFormatter specifies the default Formatter for the first column cells.
DefaultFirstColumnFormatter Formatter
// DefaultWidthFunc specifies the default WidthFunc for calculating column widths
DefaultWidthFunc WidthFunc = utf8.RuneCountInString
)
// Formatter functions expose a fmt.Sprintf signature that can be used to modify
// the display of the text in either the header or first column of a Table.
// The formatter should not change the width of original text as printed since
// column widths are calculated pre-formatting (though this issue can be mitigated
// with increased padding).
//
// tbl.WithHeaderFormatter(func(format string, vals ...interface{}) string {
// return strings.ToUpper(fmt.Sprintf(format, vals...))
// })
//
// A good use case for formatters is to use ANSI escape codes to color the cells
// for a nicer interface. The package color (https://github.com/fatih/color) makes
// it easy to generate these automatically: http://godoc.org/github.com/fatih/color#Color.SprintfFunc
type Formatter func(string, ...interface{}) string
// A WidthFunc calculates the width of a string. By default, the number of runes
// is used but this may not be appropriate for certain character sets. The
// package runewidth (https://github.com/mattn/go-runewidth) could be used to
// accomodate multi-cell characters (such as emoji or CJK characters).
type WidthFunc func(string) int
// Table describes the interface for building up a tabular representation of data.
// It exposes fluent/chainable methods for convenient table building.
//
// WithHeaderFormatter and WithFirstColumnFormatter sets the Formatter for the
// header and first column, respectively. If nil is passed in (the default), no
// formatting will be applied.
//
// New("foo", "bar").WithFirstColumnFormatter(func(f string, v ...interface{}) string {
// return strings.ToUpper(fmt.Sprintf(f, v...))
// })
//
// WithPadding specifies the minimum padding between cells in a row and defaults
// to DefaultPadding. Padding values less than or equal to zero apply no extra
// padding between the columns.
//
// New("foo", "bar").WithPadding(3)
//
// WithWriter modifies the writer which Print outputs to, defaulting to DefaultWriter
// when instantiated. If nil is passed, os.Stdout will be used.
//
// New("foo", "bar").WithWriter(os.Stderr)
//
// WithWidthFunc sets the function used to calculate the width of the string in
// a column. By default, the number of utf8 runes in the string is used.
//
// AddRow adds another row of data to the table. Any values can be passed in and
// will be output as its string representation as described in the fmt standard
// package. Rows can have less cells than the total number of columns in the table;
// subsequent cells will be rendered empty. Rows with more cells than the total
// number of columns will be truncated. References to the data are not held, so
// the passed in values can be modified without affecting the table's output.
//
// New("foo", "bar").AddRow("fizz", "buzz").AddRow(time.Now()).AddRow(1, 2, 3).Print()
// // Output:
// // foo bar
// // fizz buzz
// // 2006-01-02 15:04:05.0 -0700 MST
// // 1 2
//
// Print writes the string representation of the table to the provided writer.
// Print can be called multiple times, even after subsequent mutations of the
// provided data. The output is always preceded and followed by a new line.
type Table interface {
WithHeaderFormatter(f Formatter) Table
WithFirstColumnFormatter(f Formatter) Table
WithPadding(p int) Table
WithWriter(w io.Writer) Table
WithWidthFunc(f WidthFunc) Table
AddRow(vals ...interface{}) Table
Print()
}
// New creates a Table instance with the specified header(s) provided. The number
// of columns is fixed at this point to len(columnHeaders) and the defined defaults
// are set on the instance.
func New(columnHeaders ...interface{}) Table {
t := table{header: make([]string, len(columnHeaders))}
t.WithPadding(DefaultPadding)
t.WithWriter(DefaultWriter)
t.WithHeaderFormatter(DefaultHeaderFormatter)
t.WithFirstColumnFormatter(DefaultFirstColumnFormatter)
t.WithWidthFunc(DefaultWidthFunc)
for i, col := range columnHeaders {
t.header[i] = fmt.Sprint(col)
}
return &t
}
type table struct {
FirstColumnFormatter Formatter
HeaderFormatter Formatter
Padding int
Writer io.Writer
Width WidthFunc
header []string
rows [][]string
widths []int
}
func (t *table) WithHeaderFormatter(f Formatter) Table {
t.HeaderFormatter = f
return t
}
func (t *table) WithFirstColumnFormatter(f Formatter) Table {
t.FirstColumnFormatter = f
return t
}
func (t *table) WithPadding(p int) Table {
if p < 0 {
p = 0
}
t.Padding = p
return t
}
func (t *table) WithWriter(w io.Writer) Table {
if w == nil {
w = os.Stdout
}
t.Writer = w
return t
}
func (t *table) WithWidthFunc(f WidthFunc) Table {
t.Width = f
return t
}
func (t *table) AddRow(vals ...interface{}) Table {
row := make([]string, len(t.header))
for i, val := range vals {
if i >= len(t.header) {
break
}
row[i] = fmt.Sprint(val)
}
t.rows = append(t.rows, row)
return t
}
func (t *table) Print() {
format := strings.Repeat("%s", len(t.header)) + "\n"
t.calculateWidths()
fmt.Fprintln(t.Writer)
t.printHeader(format)
for _, row := range t.rows {
t.printRow(format, row)
}
}
func (t *table) printHeader(format string) {
vals := t.applyWidths(t.header, t.widths)
if t.HeaderFormatter != nil {
txt := t.HeaderFormatter(format, vals...)
fmt.Fprint(t.Writer, txt)
} else {
fmt.Fprintf(t.Writer, format, vals...)
}
}
func (t *table) printRow(format string, row []string) {
vals := t.applyWidths(row, t.widths)
if t.FirstColumnFormatter != nil {
vals[0] = t.FirstColumnFormatter("%s", vals[0])
}
fmt.Fprintf(t.Writer, format, vals...)
}
func (t *table) calculateWidths() {
t.widths = make([]int, len(t.header))
for _, row := range t.rows {
for i, v := range row {
if w := t.Width(v) + t.Padding; w > t.widths[i] {
t.widths[i] = w
}
}
}
for i, v := range t.header {
if w := t.Width(v) + t.Padding; w > t.widths[i] {
t.widths[i] = w
}
}
}
func (t *table) applyWidths(row []string, widths []int) []interface{} {
out := make([]interface{}, len(row))
for i, s := range row {
out[i] = s + t.lenOffset(s, widths[i])
}
return out
}
func (t *table) lenOffset(s string, w int) string {
l := w - t.Width(s)
if l <= 0 {
return ""
}
return strings.Repeat(" ", l)
}