/* Copyright (C) 2004 J.F.Dockes
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the
* Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifndef _UTF8ITER_H_INCLUDED_
#define _UTF8ITER_H_INCLUDED_
#ifdef UTF8ITER_CHECK
#include "assert.h"
#endif
/**
* A small helper class to iterate over utf8 strings. This is not an
* STL iterator and does not much error checking. It is designed purely
* for recoll usage, where the utf-8 string comes out of iconv in most cases
* and is assumed legal. We just try to catch cases where there would be
* a risk of crash.
*/
class Utf8Iter {
public:
Utf8Iter(const string &in)
: m_s(in), m_cl(0), m_pos(0), m_charpos(0), m_error(false)
{
update_cl();
}
const string& buffer() const {return m_s;}
void rewind()
{
m_cl = 0;
m_pos = 0;
m_charpos = 0;
m_error = false;
update_cl();
}
/** "Direct" access. Awfully inefficient as we skip from start or current
* position at best. This can only be useful for a lookahead from the
* current position */
unsigned int operator[](unsigned int charpos) const
{
string::size_type mypos = 0;
unsigned int mycp = 0;
if (charpos >= m_charpos) {
mypos = m_pos;
mycp = m_charpos;
}
int l;
while (mypos < m_s.length() && mycp != charpos) {
l = get_cl(mypos);
if (l <= 0)
return (unsigned int)-1;
mypos += l;
++mycp;
}
if (mypos < m_s.length() && mycp == charpos) {
l = get_cl(mypos);
if (poslok(mypos, l))
return getvalueat(mypos, get_cl(mypos));
}
return (unsigned int)-1;
}
/** Increment current position to next utf-8 char */
string::size_type operator++(int)
{
// Note: m_cl may be zero at eof if user's test not right
// this shouldn't crash the program until actual data access
#ifdef UTF8ITER_CHECK
assert(m_cl != 0);
#endif
if (m_cl <= 0)
return string::npos;
m_pos += m_cl;
m_charpos++;
update_cl();
return m_pos;
}
/** operator* returns the ucs4 value as a machine integer*/
unsigned int operator*()
{
#ifdef UTF8ITER_CHECK
assert(m_cl != 0);
#endif
return getvalueat(m_pos, m_cl);
}
/** Append current utf-8 possibly multi-byte character to string param.
This needs to be fast. No error checking. */
unsigned int appendchartostring(string &out) {
#ifdef UTF8ITER_CHECK
assert(m_cl != 0);
#endif
out.append(&m_s[m_pos], m_cl);
return m_cl;
}
/** Return current character as string */
operator string() {
#ifdef UTF8ITER_CHECK
assert(m_cl != 0);
#endif
return m_s.substr(m_pos, m_cl);
}
bool eof() {
return m_pos == m_s.length();
}
bool error() {
return m_error;
}
/** Return current byte offset in input string */
string::size_type getBpos() const {
return m_pos;
}
/** Return current character length */
string::size_type getBlen() const {
return m_cl;
}
/** Return current unicode character offset in input string */
string::size_type getCpos() const {
return m_charpos;
}
private:
// String we're working with
const string& m_s;
// Character length at current position. A value of zero indicates
// an error.
unsigned int m_cl;
// Current byte offset in string.
string::size_type m_pos;
// Current character position
unsigned int m_charpos;
// Am I ok ?
mutable bool m_error;
// Check position and cl against string length
bool poslok(string::size_type p, int l) const {
#ifdef UTF8ITER_CHECK
assert(p != string::npos && l > 0 && p + l <= m_s.length());
#endif
return p != string::npos && l > 0 && p + l <= m_s.length();
}
// Update current char length in object state, minimum checking
// for errors
inline void update_cl()
{
m_cl = 0;
if (m_pos >= m_s.length())
return;
m_cl = get_cl(m_pos);
if (!poslok(m_pos, m_cl)) {
// Used to set eof here for safety, but this is bad because it
// basically prevents the caller to discriminate error and eof.
// m_pos = m_s.length();
m_cl = 0;
m_error = true;
}
}
// Get character byte length at specified position. Returns 0 for error.
inline int get_cl(string::size_type p) const
{
unsigned int z = (unsigned char)m_s[p];
if (z <= 127) {
return 1;
} else if ((z & 224) == 192) {
return 2;
} else if ((z & 240) == 224) {
return 3;
} else if ((z & 248) == 240) {
return 4;
}
#ifdef UTF8ITER_CHECK
assert(z <= 127 || (z & 224) == 192 || (z & 240) == 224 ||
(z & 248) == 240);
#endif
return 0;
}
// Compute value at given position. No error checking.
inline unsigned int getvalueat(string::size_type p, int l) const
{
switch (l) {
case 1:
#ifdef UTF8ITER_CHECK
assert((unsigned char)m_s[p] < 128);
#endif
return (unsigned char)m_s[p];
case 2:
#ifdef UTF8ITER_CHECK
assert(
((unsigned char)m_s[p] & 224) == 192
&& ((unsigned char)m_s[p+1] & 192) == 128
);
#endif
return ((unsigned char)m_s[p] - 192) * 64 +
(unsigned char)m_s[p+1] - 128 ;
case 3:
#ifdef UTF8ITER_CHECK
assert(
(((unsigned char)m_s[p]) & 240) == 224
&& (((unsigned char)m_s[p+1]) & 192) == 128
&& (((unsigned char)m_s[p+2]) & 192) == 128
);
#endif
return ((unsigned char)m_s[p] - 224) * 4096 +
((unsigned char)m_s[p+1] - 128) * 64 +
(unsigned char)m_s[p+2] - 128;
case 4:
#ifdef UTF8ITER_CHECK
assert(
(((unsigned char)m_s[p]) & 248) == 240
&& (((unsigned char)m_s[p+1]) & 192) == 128
&& (((unsigned char)m_s[p+2]) & 192) == 128
&& (((unsigned char)m_s[p+3]) & 192) == 128
);
#endif
return ((unsigned char)m_s[p]-240)*262144 +
((unsigned char)m_s[p+1]-128)*4096 +
((unsigned char)m_s[p+2]-128)*64 +
(unsigned char)m_s[p+3]-128;
default:
#ifdef UTF8ITER_CHECK
assert(l <= 4);
#endif
m_error = true;
return (unsigned int)-1;
}
}
};
#endif /* _UTF8ITER_H_INCLUDED_ */