112 lines
2.9 KiB
Go
112 lines
2.9 KiB
Go
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/*
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Copyright 2014 SAP SE
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package unicode implements UTF-8 to CESU-8 and vice versa transformations.
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package unicode
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import (
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"errors"
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"unicode/utf8"
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"github.com/SAP/go-hdb/internal/unicode/cesu8"
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"golang.org/x/text/transform"
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)
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var (
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// Utf8ToCesu8Transformer implements the golang.org/x/text/transform/Transformer interface for UTF-8 to CESU-8 transformation.
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Utf8ToCesu8Transformer = new(utf8ToCesu8Transformer)
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// Cesu8ToUtf8Transformer implements the golang.org/x/text/transform/Transformer interface for CESU-8 to UTF-8 transformation.
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Cesu8ToUtf8Transformer = new(cesu8ToUtf8Transformer)
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// ErrInvalidUtf8 means that a transformer detected invalid UTF-8 data.
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ErrInvalidUtf8 = errors.New("Invalid UTF-8")
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// ErrInvalidCesu8 means that a transformer detected invalid CESU-8 data.
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ErrInvalidCesu8 = errors.New("Invalid CESU-8")
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)
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type utf8ToCesu8Transformer struct{ transform.NopResetter }
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func (t *utf8ToCesu8Transformer) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
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i, j := 0, 0
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for i < len(src) {
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if src[i] < utf8.RuneSelf {
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if j < len(dst) {
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dst[j] = src[i]
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i++
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j++
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} else {
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return j, i, transform.ErrShortDst
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}
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} else {
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if !utf8.FullRune(src[i:]) {
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return j, i, transform.ErrShortSrc
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}
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r, n := utf8.DecodeRune(src[i:])
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if r == utf8.RuneError {
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return j, i, ErrInvalidUtf8
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}
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m := cesu8.RuneLen(r)
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if m == -1 {
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panic("internal UTF-8 to CESU-8 transformation error")
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}
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if j+m <= len(dst) {
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cesu8.EncodeRune(dst[j:], r)
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i += n
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j += m
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} else {
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return j, i, transform.ErrShortDst
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}
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}
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}
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return j, i, nil
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}
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type cesu8ToUtf8Transformer struct{ transform.NopResetter }
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func (t *cesu8ToUtf8Transformer) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
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i, j := 0, 0
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for i < len(src) {
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if src[i] < utf8.RuneSelf {
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if j < len(dst) {
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dst[j] = src[i]
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i++
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j++
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} else {
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return j, i, transform.ErrShortDst
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}
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} else {
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if !cesu8.FullRune(src[i:]) {
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return j, i, transform.ErrShortSrc
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}
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r, n := cesu8.DecodeRune(src[i:])
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if r == utf8.RuneError {
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return j, i, ErrInvalidCesu8
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}
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m := utf8.RuneLen(r)
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if m == -1 {
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panic("internal CESU-8 to UTF-8 transformation error")
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}
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if j+m <= len(dst) {
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utf8.EncodeRune(dst[j:], r)
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i += n
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j += m
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} else {
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return j, i, transform.ErrShortDst
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}
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}
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}
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return j, i, nil
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}
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