text: // Copyright 2011 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 norm
  
  import "unicode/utf8"
  
  type input struct {
  	str   string
  	bytes []byte
  }
  
  func inputBytes(str []byte) input {
  	return input{bytes: str}
  }
  
  func inputString(str string) input {
  	return input{str: str}
  }
  
  func (in *input) setBytes(str []byte) {
  	in.str = ""
  	in.bytes = str
  }
  
  func (in *input) setString(str string) {
  	in.str = str
  	in.bytes = nil
  }
  
  func (in *input) _byte(p int) byte {
  	if in.bytes == nil {
  		return in.str[p]
  	}
  	return in.bytes[p]
  }
  
  func (in *input) skipASCII(p, max int) int {
  	if in.bytes == nil {
  		for ; p < max && in.str[p] < utf8.RuneSelf; p++ {
  		}
  	} else {
  		for ; p < max && in.bytes[p] < utf8.RuneSelf; p++ {
  		}
  	}
  	return p
  }
  
  func (in *input) skipContinuationBytes(p int) int {
  	if in.bytes == nil {
  		for ; p < len(in.str) && !utf8.RuneStart(in.str[p]); p++ {
  		}
  	} else {
  		for ; p < len(in.bytes) && !utf8.RuneStart(in.bytes[p]); p++ {
  		}
  	}
  	return p
  }
  
  func (in *input) appendSlice(buf []byte, b, e int) []byte {
  	if in.bytes != nil {
  		return append(buf, in.bytes[b:e]...)
  	}
  	for i := b; i < e; i++ {
  		buf = append(buf, in.str[i])
  	}
  	return buf
  }
  
  func (in *input) copySlice(buf []byte, b, e int) int {
  	if in.bytes == nil {
  		return copy(buf, in.str[b:e])
  	}
  	return copy(buf, in.bytes[b:e])
  }
  
  func (in *input) charinfoNFC(p int) (uint16, int) {
  	if in.bytes == nil {
  		return nfcData.lookupString(in.str[p:])
  	}
  	return nfcData.lookup(in.bytes[p:])
  }
  
  func (in *input) charinfoNFKC(p int) (uint16, int) {
  	if in.bytes == nil {
  		return nfkcData.lookupString(in.str[p:])
  	}
  	return nfkcData.lookup(in.bytes[p:])
  }
  
  func (in *input) hangul(p int) (r rune) {
  	var size int
  	if in.bytes == nil {
  		if !isHangulString(in.str[p:]) {
  			return 0
  		}
  		r, size = utf8.DecodeRuneInString(in.str[p:])
  	} else {
  		if !isHangul(in.bytes[p:]) {
  			return 0
  		}
  		r, size = utf8.DecodeRune(in.bytes[p:])
  	}
  	if size != hangulUTF8Size {
  		return 0
  	}
  	return r
  }
  