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gcz/survey/core/template.go

104 lines
2.9 KiB

package core
import (
"bytes"
"os"
"sync"
"text/template"
"github.com/mgutz/ansi"
)
// DisableColor can be used to make testing reliable
var DisableColor = false
var TemplateFuncsWithColor = map[string]interface{}{
// Templates with Color formatting. See Documentation: https://github.com/mgutz/ansi#style-format
"color": ansi.ColorCode,
}
var TemplateFuncsNoColor = map[string]interface{}{
// Templates without Color formatting. For layout/ testing.
"color": func(color string) string {
return ""
},
}
// envColorDisabled returns if output colors are forbid by environment variables
func envColorDisabled() bool {
return os.Getenv("NO_COLOR") != "" || os.Getenv("CLICOLOR") == "0"
}
// envColorForced returns if output colors are forced from environment variables
func envColorForced() bool {
val, ok := os.LookupEnv("CLICOLOR_FORCE")
return ok && val != "0"
}
// RunTemplate returns two formatted strings given a template and
// the data it requires. The first string returned is generated for
// user-facing output and may or may not contain ANSI escape codes
// for colored output. The second string does not contain escape codes
// and can be used by the renderer for layout purposes.
func RunTemplate(tmpl string, data interface{}) (string, string, error) {
tPair, err := GetTemplatePair(tmpl)
if err != nil {
return "", "", err
}
userBuf := bytes.NewBufferString("")
err = tPair[0].Execute(userBuf, data)
if err != nil {
return "", "", err
}
layoutBuf := bytes.NewBufferString("")
err = tPair[1].Execute(layoutBuf, data)
if err != nil {
return userBuf.String(), "", err
}
return userBuf.String(), layoutBuf.String(), err
}
var (
memoizedGetTemplate = map[string][2]*template.Template{}
memoMutex = &sync.RWMutex{}
)
// GetTemplatePair returns a pair of compiled templates where the
// first template is generated for user-facing output and the
// second is generated for use by the renderer. The second
// template does not contain any color escape codes, whereas
// the first template may or may not depending on DisableColor.
func GetTemplatePair(tmpl string) ([2]*template.Template, error) {
memoMutex.RLock()
if t, ok := memoizedGetTemplate[tmpl]; ok {
memoMutex.RUnlock()
return t, nil
}
memoMutex.RUnlock()
templatePair := [2]*template.Template{nil, nil}
templateNoColor, err := template.New("prompt").Funcs(TemplateFuncsNoColor).Parse(tmpl)
if err != nil {
return [2]*template.Template{}, err
}
templatePair[1] = templateNoColor
envColorHide := envColorDisabled() && !envColorForced()
if DisableColor || envColorHide {
templatePair[0] = templatePair[1]
} else {
templateWithColor, err := template.New("prompt").Funcs(TemplateFuncsWithColor).Parse(tmpl)
templatePair[0] = templateWithColor
if err != nil {
return [2]*template.Template{}, err
}
}
memoMutex.Lock()
memoizedGetTemplate[tmpl] = templatePair
memoMutex.Unlock()
return templatePair, nil
}