source: code/trunk/vendor/gopkg.in/irc.v3/utils.go@ 822

package irc

import (
        "bytes"
        "regexp"
)

var maskTranslations = map[byte]string{
        '?': ".",
        '*': ".*",
}

// MaskToRegex converts an irc mask to a go Regexp for more convenient
// use. This should never return an error, but we have this here just
// in case.
func MaskToRegex(rawMask string) (*regexp.Regexp, error) {
        input := bytes.NewBufferString(rawMask)

        output := &bytes.Buffer{}
        output.WriteByte('^')

        for {
                c, err := input.ReadByte()
                if err != nil {
                        break
                }

                if c == '\\' {
                        c, err = input.ReadByte()
                        if err != nil {
                                output.WriteString(regexp.QuoteMeta("\\"))
                                break
                        }

                        if c == '?' || c == '*' || c == '\\' {
                                output.WriteString(regexp.QuoteMeta(string(c)))
                        } else {
                                output.WriteString(regexp.QuoteMeta("\\" + string(c)))
                        }
                } else if trans, ok := maskTranslations[c]; ok {
                        output.WriteString(trans)
                } else {
                        output.WriteString(regexp.QuoteMeta(string(c)))
                }
        }

        output.WriteByte('$')

        return regexp.Compile(output.String())
}