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116 lines
3.4 KiB
116 lines
3.4 KiB
// This package is a character-set conversion library for Go.
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//
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// (DEPRECATED: use code.google.com/p/go.text/encoding, perhaps along with
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// code.google.com/p/go.net/html/charset)
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package mahonia
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import (
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"bytes"
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"unicode"
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)
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// Status is the type for the status return value from a Decoder or Encoder.
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type Status int
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const (
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// SUCCESS means that the character was converted with no problems.
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SUCCESS = Status(iota)
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// INVALID_CHAR means that the source contained invalid bytes, or that the character
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// could not be represented in the destination encoding.
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// The Encoder or Decoder should have output a substitute character.
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INVALID_CHAR
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// NO_ROOM means there were not enough input bytes to form a complete character,
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// or there was not enough room in the output buffer to write a complete character.
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// No bytes were written, and no internal state was changed in the Encoder or Decoder.
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NO_ROOM
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// STATE_ONLY means that bytes were read or written indicating a state transition,
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// but no actual character was processed. (Examples: byte order marks, ISO-2022 escape sequences)
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STATE_ONLY
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)
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// A Decoder is a function that decodes a character set, one character at a time.
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// It works much like utf8.DecodeRune, but has an additional status return value.
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type Decoder func(p []byte) (c rune, size int, status Status)
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// An Encoder is a function that encodes a character set, one character at a time.
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// It works much like utf8.EncodeRune, but has an additional status return value.
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type Encoder func(p []byte, c rune) (size int, status Status)
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// A Charset represents a character set that can be converted, and contains functions
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// to create Converters to encode and decode strings in that character set.
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type Charset struct {
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// Name is the character set's canonical name.
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Name string
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// Aliases returns a list of alternate names.
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Aliases []string
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// NewDecoder returns a Decoder to convert from the charset to Unicode.
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NewDecoder func() Decoder
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// NewEncoder returns an Encoder to convert from Unicode to the charset.
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NewEncoder func() Encoder
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}
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// The charsets are stored in charsets under their canonical names.
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var charsets = make(map[string]*Charset)
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// aliases maps their aliases to their canonical names.
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var aliases = make(map[string]string)
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// simplifyName converts a name to lower case and removes non-alphanumeric characters.
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// This is how the names are used as keys to the maps.
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func simplifyName(name string) string {
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var buf bytes.Buffer
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for _, c := range name {
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switch {
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case unicode.IsDigit(c):
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buf.WriteRune(c)
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case unicode.IsLetter(c):
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buf.WriteRune(unicode.ToLower(c))
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default:
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}
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}
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return buf.String()
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}
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// RegisterCharset adds a charset to the charsetMap.
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func RegisterCharset(cs *Charset) {
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name := cs.Name
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charsets[name] = cs
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aliases[simplifyName(name)] = name
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for _, alias := range cs.Aliases {
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aliases[simplifyName(alias)] = name
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}
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}
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// GetCharset fetches a charset by name.
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// If the name is not found, it returns nil.
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func GetCharset(name string) *Charset {
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return charsets[aliases[simplifyName(name)]]
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}
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// NewDecoder returns a Decoder to decode the named charset.
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// If the name is not found, it returns nil.
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func NewDecoder(name string) Decoder {
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cs := GetCharset(name)
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if cs == nil {
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return nil
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}
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return cs.NewDecoder()
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}
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// NewEncoder returns an Encoder to encode the named charset.
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func NewEncoder(name string) Encoder {
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cs := GetCharset(name)
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if cs == nil {
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return nil
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}
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return cs.NewEncoder()
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}
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