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restic/internal/ui/table/table.go

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package table
import (
"bytes"
"io"
"strings"
"text/template"
)
// Table contains data for a table to be printed.
type Table struct {
columns []string
templates []*template.Template
data []interface{}
footer []string
CellSeparator string
PrintHeader func(io.Writer, string) error
PrintSeparator func(io.Writer, string) error
PrintData func(io.Writer, int, string) error
PrintFooter func(io.Writer, string) error
}
var funcmap = template.FuncMap{
"join": strings.Join,
}
// New initializes a new Table
func New() *Table {
p := func(w io.Writer, s string) error {
_, err := w.Write(append([]byte(s), '\n'))
return err
}
return &Table{
CellSeparator: " ",
PrintHeader: p,
PrintSeparator: p,
PrintData: func(w io.Writer, _ int, s string) error {
return p(w, s)
},
PrintFooter: p,
}
}
// AddColumn adds a new header field with the header and format, which is
// expected to be template string compatible with text/template. When compiling
// the format fails, AddColumn panics.
func (t *Table) AddColumn(header, format string) {
t.columns = append(t.columns, header)
tmpl, err := template.New("template for " + header).Funcs(funcmap).Parse(format)
if err != nil {
panic(err)
}
t.templates = append(t.templates, tmpl)
}
// AddRow adds a new row to the table, which is filled with data.
func (t *Table) AddRow(data interface{}) {
t.data = append(t.data, data)
}
// AddFooter prints line after the table
func (t *Table) AddFooter(line string) {
t.footer = append(t.footer, line)
}
func printLine(w io.Writer, print func(io.Writer, string) error, sep string, data []string, widths []int) error {
var fields [][]string
maxLines := 1
for _, d := range data {
lines := strings.Split(d, "\n")
if len(lines) > maxLines {
maxLines = len(lines)
}
fields = append(fields, lines)
}
for i := 0; i < maxLines; i++ {
var s string
for fieldNum, lines := range fields {
var v string
if i < len(lines) {
v += lines[i]
}
// apply padding
pad := widths[fieldNum] - len(v)
if pad > 0 {
v += strings.Repeat(" ", pad)
}
if fieldNum > 0 {
v = sep + v
}
s += v
}
err := print(w, strings.TrimRight(s, " "))
if err != nil {
return err
}
}
return nil
}
// Write prints the table to w.
func (t *Table) Write(w io.Writer) error {
columns := len(t.templates)
if columns == 0 {
return nil
}
// collect all data fields from all columns
lines := make([][]string, 0, len(t.data))
buf := bytes.NewBuffer(nil)
for _, data := range t.data {
row := make([]string, 0, len(t.templates))
for _, tmpl := range t.templates {
err := tmpl.Execute(buf, data)
if err != nil {
return err
}
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row = append(row, buf.String())
buf.Reset()
}
lines = append(lines, row)
}
// find max width for each cell
columnWidths := make([]int, columns)
for i, desc := range t.columns {
for _, line := range strings.Split(desc, "\n") {
if columnWidths[i] < len(line) {
columnWidths[i] = len(desc)
}
}
}
for _, line := range lines {
for i, content := range line {
for _, l := range strings.Split(content, "\n") {
if columnWidths[i] < len(l) {
columnWidths[i] = len(l)
}
}
}
}
// calculate the total width of the table
totalWidth := 0
for _, width := range columnWidths {
totalWidth += width
}
totalWidth += (columns - 1) * len(t.CellSeparator)
// write header
if len(t.columns) > 0 {
err := printLine(w, t.PrintHeader, t.CellSeparator, t.columns, columnWidths)
if err != nil {
return err
}
// draw separation line
err = t.PrintSeparator(w, strings.Repeat("-", totalWidth))
if err != nil {
return err
}
}
// write all the lines
for i, line := range lines {
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printer := func(w io.Writer, s string) error {
return t.PrintData(w, i, s)
}
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err := printLine(w, printer, t.CellSeparator, line, columnWidths)
if err != nil {
return err
}
}
// draw separation line
err := t.PrintSeparator(w, strings.Repeat("-", totalWidth))
if err != nil {
return err
}
if len(t.footer) > 0 {
// write the footer
for _, line := range t.footer {
err := t.PrintFooter(w, line)
if err != nil {
return err
}
}
}
return nil
}