include/xapian/unicode.h

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/* Copyright (C) 2006,2007,2008,2009,2010,2011 Olly Betts
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#ifndef XAPIAN_INCLUDED_UNICODE_H
#define XAPIAN_INCLUDED_UNICODE_H

#include <xapian/visibility.h>

#include <string>

namespace Xapian {

class XAPIAN_VISIBILITY_DEFAULT Utf8Iterator {
    const unsigned char *p;
    const unsigned char *end;
    mutable unsigned seqlen;

    void calculate_sequence_length() const;

    unsigned get_char() const;

    Utf8Iterator(const unsigned char *p_, const unsigned char *end_, unsigned seqlen_)
        : p(p_), end(end_), seqlen(seqlen_) { }

  public:
    const char * raw() const {
        return reinterpret_cast<const char *>(p ? p : end);
    }

    size_t left() const { return p ? end - p : 0; }

    void assign(const char *p_, size_t len) {
        if (len) {
            p = reinterpret_cast<const unsigned char*>(p_);
            end = p + len;
            seqlen = 0;
        } else {
            p = NULL;
        }
    }

    void assign(const std::string &s) { assign(s.data(), s.size()); }

    explicit Utf8Iterator(const char *p_);

    Utf8Iterator(const char *p_, size_t len) { assign(p_, len); }

    Utf8Iterator(const std::string &s) { assign(s.data(), s.size()); }

    Utf8Iterator() : p(NULL), end(0), seqlen(0) { }

    unsigned operator*() const;

    Utf8Iterator operator++(int) {
        // If we've not calculated seqlen yet, do so.
        if (seqlen == 0) calculate_sequence_length();
        const unsigned char *old_p = p;
        unsigned old_seqlen = seqlen;
        p += seqlen;
        if (p == end) p = NULL;
        seqlen = 0;
        return Utf8Iterator(old_p, end, old_seqlen);
    }

    Utf8Iterator & operator++() {
        if (seqlen == 0) calculate_sequence_length();
        p += seqlen;
        if (p == end) p = NULL;
        seqlen = 0;
        return *this;
    }

    bool operator==(const Utf8Iterator &other) const { return p == other.p; }

    bool operator!=(const Utf8Iterator &other) const { return p != other.p; }


    typedef std::input_iterator_tag iterator_category;
    typedef unsigned value_type;
    typedef size_t difference_type;
    typedef const unsigned * pointer;
    typedef const unsigned & reference;
};

namespace Unicode {

typedef enum {
    UNASSIGNED,
    UPPERCASE_LETTER,
    LOWERCASE_LETTER,
    TITLECASE_LETTER,
    MODIFIER_LETTER,
    OTHER_LETTER,
    NON_SPACING_MARK,
    ENCLOSING_MARK,
    COMBINING_SPACING_MARK,
    DECIMAL_DIGIT_NUMBER,
    LETTER_NUMBER,
    OTHER_NUMBER,
    SPACE_SEPARATOR,
    LINE_SEPARATOR,
    PARAGRAPH_SEPARATOR,
    CONTROL,
    FORMAT,
    PRIVATE_USE,
    SURROGATE,
    CONNECTOR_PUNCTUATION,
    DASH_PUNCTUATION,
    OPEN_PUNCTUATION,
    CLOSE_PUNCTUATION,
    INITIAL_QUOTE_PUNCTUATION,
    FINAL_QUOTE_PUNCTUATION,
    OTHER_PUNCTUATION,
    MATH_SYMBOL,
    CURRENCY_SYMBOL,
    MODIFIER_SYMBOL,
    OTHER_SYMBOL
} category;

namespace Internal {
    XAPIAN_VISIBILITY_DEFAULT
    int get_character_info(unsigned ch);

    inline int get_case_type(int info) { return ((info & 0xe0) >> 5); }

    inline category get_category(int info) { return static_cast<category>(info & 0x1f); }

    inline int get_delta(int info) {
        /* It's implementation defined if sign extension happens on right shift
         * of a signed int, hence the conditional (hopefully the compiler will
         * spot this and optimise it to a sign-extending shift on architectures
         * with a suitable instruction).
         */
#ifdef __GNUC__
        // GCC 4.7.1 doesn't optimise the more complex expression down
        // (reported as http://gcc.gnu.org/PR55299), but the documented
        // behaviour for GCC is that right shift of a signed integer performs
        // sign extension:
        // http://gcc.gnu.org/onlinedocs/gcc-4.7.2/gcc/Integers-implementation.html
        return info >> 15;
#else
        return (info >= 0) ? (info >> 15) : (~(~info >> 15));
#endif
    }
}

XAPIAN_VISIBILITY_DEFAULT
unsigned nonascii_to_utf8(unsigned ch, char * buf);

inline unsigned to_utf8(unsigned ch, char *buf) {
    if (ch < 128) {
        *buf = static_cast<unsigned char>(ch);
        return 1;
    }
    return Xapian::Unicode::nonascii_to_utf8(ch, buf);
}

inline void append_utf8(std::string &s, unsigned ch) {
    char buf[4];
    s.append(buf, to_utf8(ch, buf));
}

inline category get_category(unsigned ch) {
    // Categorise non-Unicode values as UNASSIGNED.
    if (ch >= 0x110000) return Xapian::Unicode::UNASSIGNED;
    return Internal::get_category(Internal::get_character_info(ch));
}

inline bool is_wordchar(unsigned ch) {
    const unsigned int WORDCHAR_MASK =
            (1 << Xapian::Unicode::UPPERCASE_LETTER) |
            (1 << Xapian::Unicode::LOWERCASE_LETTER) |
            (1 << Xapian::Unicode::TITLECASE_LETTER) |
            (1 << Xapian::Unicode::MODIFIER_LETTER) |
            (1 << Xapian::Unicode::OTHER_LETTER) |
            (1 << Xapian::Unicode::NON_SPACING_MARK) |
            (1 << Xapian::Unicode::ENCLOSING_MARK) |
            (1 << Xapian::Unicode::COMBINING_SPACING_MARK) |
            (1 << Xapian::Unicode::DECIMAL_DIGIT_NUMBER) |
            (1 << Xapian::Unicode::LETTER_NUMBER) |
            (1 << Xapian::Unicode::OTHER_NUMBER) |
            (1 << Xapian::Unicode::CONNECTOR_PUNCTUATION);
    return ((WORDCHAR_MASK >> get_category(ch)) & 1);
}

inline bool is_whitespace(unsigned ch) {
    const unsigned int WHITESPACE_MASK =
            (1 << Xapian::Unicode::CONTROL) | // For TAB, CR, LF, FF.
            (1 << Xapian::Unicode::SPACE_SEPARATOR) |
            (1 << Xapian::Unicode::LINE_SEPARATOR) |
            (1 << Xapian::Unicode::PARAGRAPH_SEPARATOR);
    return ((WHITESPACE_MASK >> get_category(ch)) & 1);
}

inline bool is_currency(unsigned ch) {
    return (get_category(ch) == Xapian::Unicode::CURRENCY_SYMBOL);
}

inline unsigned tolower(unsigned ch) {
    int info;
    // Leave non-Unicode values unchanged.
    if (ch >= 0x110000 || !(Internal::get_case_type((info = Xapian::Unicode::Internal::get_character_info(ch))) & 2))
        return ch;
    return ch + Internal::get_delta(info);
}

inline unsigned toupper(unsigned ch) {
    int info;
    // Leave non-Unicode values unchanged.
    if (ch >= 0x110000 || !(Internal::get_case_type((info = Xapian::Unicode::Internal::get_character_info(ch))) & 4))
        return ch;
    return ch - Internal::get_delta(info);
}

inline std::string
tolower(const std::string &term)
{
    std::string result;
    result.reserve(term.size());
    for (Utf8Iterator i(term); i != Utf8Iterator(); ++i) {
        append_utf8(result, tolower(*i));
    }
    return result;
}

inline std::string
toupper(const std::string &term)
{
    std::string result;
    result.reserve(term.size());
    for (Utf8Iterator i(term); i != Utf8Iterator(); ++i) {
        append_utf8(result, toupper(*i));
    }
    return result;
}

}

}

#endif // XAPIAN_INCLUDED_UNICODE_H

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