path: root/vendor/golang.org/x/text/encoding/korean/euckr.go

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package korean

import (
    "errors"
    "unicode/utf8"

    "golang.org/x/text/encoding"
    "golang.org/x/text/encoding/internal"
    "golang.org/x/text/encoding/internal/identifier"
    "golang.org/x/text/transform"
)

// All is a list of all defined encodings in this package.
var All = []encoding.Encoding{EUCKR}

// EUCKR is the EUC-KR encoding, also known as Code Page 949.
var EUCKR encoding.Encoding = &eucKR

var eucKR = internal.Encoding{
    &internal.SimpleEncoding{eucKRDecoder{}, eucKREncoder{}},
    "EUC-KR",
    identifier.EUCKR,
}

var errInvalidEUCKR = errors.New("korean: invalid EUC-KR encoding")

type eucKRDecoder struct{ transform.NopResetter }

func (eucKRDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
    r, size := rune(0), 0
loop:
    for ; nSrc < len(src); nSrc += size {
        switch c0 := src[nSrc]; {
        case c0 < utf8.RuneSelf:
            r, size = rune(c0), 1

        case 0x81 <= c0 && c0 < 0xff:
            if nSrc+1 >= len(src) {
                err = transform.ErrShortSrc
                break loop
            }
            c1 := src[nSrc+1]
            if c0 < 0xc7 {
                r = 178 * rune(c0-0x81)
                switch {
                case 0x41 <= c1 && c1 < 0x5b:
                    r += rune(c1) - (0x41 - 0*26)
                case 0x61 <= c1 && c1 < 0x7b:
                    r += rune(c1) - (0x61 - 1*26)
                case 0x81 <= c1 && c1 < 0xff:
                    r += rune(c1) - (0x81 - 2*26)
                default:
                    err = errInvalidEUCKR
                    break loop
                }
            } else if 0xa1 <= c1 && c1 < 0xff {
                r = 178*(0xc7-0x81) + rune(c0-0xc7)*94 + rune(c1-0xa1)
            } else {
                err = errInvalidEUCKR
                break loop
            }
            if int(r) < len(decode) {
                r = rune(decode[r])
                if r == 0 {
                    r = '\ufffd'
                }
            } else {
                r = '\ufffd'
            }
            size = 2

        default:
            err = errInvalidEUCKR
            break loop
        }

        if nDst+utf8.RuneLen(r) > len(dst) {
            err = transform.ErrShortDst
            break loop
        }
        nDst += utf8.EncodeRune(dst[nDst:], r)
    }
    if atEOF && err == transform.ErrShortSrc {
        err = errInvalidEUCKR
    }
    return nDst, nSrc, err
}

type eucKREncoder struct{ transform.NopResetter }

func (eucKREncoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
    r, size := rune(0), 0
    for ; nSrc < len(src); nSrc += size {
        r = rune(src[nSrc])

        // Decode a 1-byte rune.
        if r < utf8.RuneSelf {
            size = 1

            if nDst >= len(dst) {
                err = transform.ErrShortDst
                break
            }
            dst[nDst] = uint8(r)
            nDst++
            continue

        } else {
            // Decode a multi-byte rune.
            r, size = utf8.DecodeRune(src[nSrc:])
            if size == 1 {
                // All valid runes of size 1 (those below utf8.RuneSelf) were
                // handled above. We have invalid UTF-8 or we haven't seen the
                // full character yet.
                if !atEOF && !utf8.FullRune(src[nSrc:]) {
                    err = transform.ErrShortSrc
                    break
                }
            }

            // func init checks that the switch covers all tables.
            switch {
            case encode0Low <= r && r < encode0High:
                if r = rune(encode0[r-encode0Low]); r != 0 {
                    goto write2
                }
            case encode1Low <= r && r < encode1High:
                if r = rune(encode1[r-encode1Low]); r != 0 {
                    goto write2
                }
            case encode2Low <= r && r < encode2High:
                if r = rune(encode2[r-encode2Low]); r != 0 {
                    goto write2
                }
            case encode3Low <= r && r < encode3High:
                if r = rune(encode3[r-encode3Low]); r != 0 {
                    goto write2
                }
            case encode4Low <= r && r < encode4High:
                if r = rune(encode4[r-encode4Low]); r != 0 {
                    goto write2
                }
            case encode5Low <= r && r < encode5High:
                if r = rune(encode5[r-encode5Low]); r != 0 {
                    goto write2
                }
            case encode6Low <= r && r < encode6High:
                if r = rune(encode6[r-encode6Low]); r != 0 {
                    goto write2
                }
            }
            err = internal.ErrASCIIReplacement
            break
        }

    write2:
        if nDst+2 > len(dst) {
            err = transform.ErrShortDst
            break
        }
        dst[nDst+0] = uint8(r >> 8)
        dst[nDst+1] = uint8(r)
        nDst += 2
        continue
    }
    return nDst, nSrc, err
}

func init() {
    // Check that the hard-coded encode switch covers all tables.
    if numEncodeTables != 7 {
        panic("bad numEncodeTables")
    }
}