errors.go

package v8go

import (
	"fmt"
	"io"
)

// JSError is an error that is returned if there is are any
// JavaScript exceptions handled in the context. When used with the fmt
// verb `%+v`, will output the JavaScript stack trace, if available.
type JSError struct {
	Message    string
	Location   string
	StackTrace string
}

func (e *JSError) Error() string {
	return e.Message
}

// Format implements the fmt.Formatter interface to provide a custom formatter
// primarily to output the javascript stack trace with %+v
func (e *JSError) Format(s fmt.State, verb rune) {
	switch verb {
	case 'v':
		if s.Flag('+') && e.StackTrace != "" {
			io.WriteString(s, e.StackTrace)
			return
		}
		fallthrough
	case 's':
		io.WriteString(s, e.Message)
	case 'q':
		fmt.Fprintf(s, "%q", e.Message)
	}
}