DockerCLI/command/formatter/formatter.go

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package formatter
import (
"bytes"
"fmt"
"io"
"strings"
"text/tabwriter"
"text/template"
"github.com/docker/docker/pkg/templates"
)
// Format keys used to specify certain kinds of output formats
const (
TableFormatKey = "table"
RawFormatKey = "raw"
PrettyFormatKey = "pretty"
defaultQuietFormat = "{{.ID}}"
)
// Format is the format string rendered using the Context
type Format string
// IsTable returns true if the format is a table-type format
func (f Format) IsTable() bool {
return strings.HasPrefix(string(f), TableFormatKey)
}
// Contains returns true if the format contains the substring
func (f Format) Contains(sub string) bool {
return strings.Contains(string(f), sub)
}
// Context contains information required by the formatter to print the output as desired.
type Context struct {
// Output is the output stream to which the formatted string is written.
Output io.Writer
// Format is used to choose raw, table or custom format for the output.
Format Format
// Trunc when set to true will truncate the output of certain fields such as Container ID.
Trunc bool
// internal element
finalFormat string
header interface{}
buffer *bytes.Buffer
}
func (c *Context) preFormat() {
c.finalFormat = string(c.Format)
// TODO: handle this in the Format type
if c.Format.IsTable() {
c.finalFormat = c.finalFormat[len(TableFormatKey):]
}
c.finalFormat = strings.Trim(c.finalFormat, " ")
r := strings.NewReplacer(`\t`, "\t", `\n`, "\n")
c.finalFormat = r.Replace(c.finalFormat)
}
func (c *Context) parseFormat() (*template.Template, error) {
tmpl, err := templates.Parse(c.finalFormat)
if err != nil {
return tmpl, fmt.Errorf("Template parsing error: %v\n", err)
}
return tmpl, err
}
func (c *Context) postFormat(tmpl *template.Template, subContext subContext) {
if c.Format.IsTable() {
t := tabwriter.NewWriter(c.Output, 20, 1, 3, ' ', 0)
buffer := bytes.NewBufferString("")
tmpl.Funcs(templates.HeaderFunctions).Execute(buffer, subContext.FullHeader())
buffer.WriteTo(t)
t.Write([]byte("\n"))
c.buffer.WriteTo(t)
t.Flush()
} else {
c.buffer.WriteTo(c.Output)
}
}
func (c *Context) contextFormat(tmpl *template.Template, subContext subContext) error {
if err := tmpl.Execute(c.buffer, subContext); err != nil {
return fmt.Errorf("Template parsing error: %v\n", err)
}
if c.Format.IsTable() && c.header != nil {
c.header = subContext.FullHeader()
}
c.buffer.WriteString("\n")
return nil
}
// SubFormat is a function type accepted by Write()
type SubFormat func(func(subContext) error) error
// Write the template to the buffer using this Context
func (c *Context) Write(sub subContext, f SubFormat) error {
c.buffer = bytes.NewBufferString("")
c.preFormat()
tmpl, err := c.parseFormat()
if err != nil {
return err
}
subFormat := func(subContext subContext) error {
return c.contextFormat(tmpl, subContext)
}
if err := f(subFormat); err != nil {
return err
}
c.postFormat(tmpl, sub)
return nil
}