troubleshoot/pkg/convert/templates.go

package convert

import (
	"bytes"
	"strconv"
	"sync"
	"text/template"
)

var (
	funcMap   = template.FuncMap{}
	funcMapMu sync.Mutex
)

func String(text string, data interface{}) (string, error) {
	return Execute(text, data)
}

func Bool(text string, data interface{}) (bool, error) {
	str, err := Execute(text, data)
	if err != nil {
		return false, err
	}
	return strconv.ParseBool(str)
}

func Execute(text string, data interface{}) (string, error) {
	tmpl, err := template.New(text).
		Delims("{{repl", "}}").
		Funcs(funcMap).
		Parse(text)
	if err != nil {
		return "", err
	}
	var buf bytes.Buffer
	err = func() (err error) {
		defer errRecover(&err)
		err = tmpl.Execute(&buf, data)
		return
	}()
	return buf.String(), err
}

func RegisterFunc(key string, fn interface{}) {
	funcMapMu.Lock()
	funcMap[key] = fn
	funcMapMu.Unlock()
}

// errRecover is the handler that turns panics into returns from FuncMaps.
func errRecover(errp *error) {
	e := recover()
	if e != nil {
		switch err := e.(type) {
		case FuncError:
			*errp = err // Keep the wrapper.
		case error:
			*errp = err // Catch panics from template functions
		default:
			panic(e)
		}
	}
}