aboutsummaryrefslogtreecommitdiffstats
path: root/util/charset/utf8.cpp
blob: efe3a52f61524ac74a26f549eb0a27c73e7bf2a1 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
#include "unidata.h"
#include "utf8.h"

namespace {
    enum class ECaseConversion {
        ToUpper,
        ToLower,
    };

    wchar32 ConvertChar(ECaseConversion conversion, wchar32 ch) {
        switch (conversion) {
            case ECaseConversion::ToUpper:
                return ToUpper(ch);
            case ECaseConversion::ToLower:
                return ToLower(ch);
        }
        Y_ASSERT(false); // NOTREACHED
        return 0;
    }

    bool ConvertCaseUTF8Impl(ECaseConversion conversion, const char* beg, size_t n,
                             TString& newString) {
        const unsigned char* p = (const unsigned char*)beg;
        const unsigned char* const end = p + n;

        // first loop searches for the first character, which is changed by ConvertChar
        // if there is no changed character, we don't need reallocation/copy
        wchar32 cNew = 0;
        size_t cLen = 0;
        while (p < end) {
            wchar32 c;
            if (RECODE_OK != SafeReadUTF8Char(c, cLen, p, end)) {
                ythrow yexception()
                    << "failed to decode UTF-8 string at pos " << ((const char*)p - beg);
            }
            cNew = ConvertChar(conversion, c);

            if (cNew != c)
                break;
            p += cLen;
        }
        if (p == end) {
            return false;
        }

        // some character changed after ToLower. Write new string to newString.
        newString.resize(n);

        size_t written = (char*)p - beg;
        char* writePtr = newString.begin();
        memcpy(writePtr, beg, written);
        writePtr += written;
        size_t destSpace = n - written;

        // before each iteration (including the first one) variable 'cNew' contains unwritten symbol
        while (true) {
            size_t cNewLen;
            Y_ASSERT((writePtr - newString.data()) + destSpace == newString.size());
            if (RECODE_EOOUTPUT ==
                SafeWriteUTF8Char(cNew, cNewLen, (unsigned char*)writePtr, destSpace)) {
                destSpace += newString.size();
                newString.resize(newString.size() * 2);
                writePtr = newString.begin() + (newString.size() - destSpace);
                continue;
            }
            destSpace -= cNewLen;
            writePtr += cNewLen;
            p += cLen;
            if (p == end) {
                newString.resize(newString.size() - destSpace);
                return true;
            }
            wchar32 c = 0;
            if (RECODE_OK != SafeReadUTF8Char(c, cLen, p, end)) {
                ythrow yexception()
                    << "failed to decode UTF-8 string at pos " << ((const char*)p - beg);
            }
            cNew = ConvertChar(conversion, c);
        }
        Y_ASSERT(false);
        return false;
    }
} // namespace

extern const wchar32 BROKEN_RUNE = 0xFFFD;

static const char* SkipUTF8Chars(const char* begin, const char* end, size_t numChars) {
    const unsigned char* uEnd = reinterpret_cast<const unsigned char*>(end);
    while (begin != end && numChars > 0) {
        const unsigned char* uBegin = reinterpret_cast<const unsigned char*>(begin);
        size_t runeLen;
        if (GetUTF8CharLen(runeLen, uBegin, uEnd) != RECODE_OK) {
            ythrow yexception() << "invalid UTF-8 char";
        }
        begin += runeLen;
        Y_ASSERT(begin <= end);
        --numChars;
    }
    return begin;
}

TStringBuf SubstrUTF8(const TStringBuf str, size_t pos, size_t len) {
    const char* start = SkipUTF8Chars(str.begin(), str.end(), pos);
    const char* end = SkipUTF8Chars(start, str.end(), len);
    return TStringBuf(start, end - start);
}

EUTF8Detect UTF8Detect(const char* s, size_t len) {
    const unsigned char* s0 = (const unsigned char*)s;
    const unsigned char* send = s0 + len;
    wchar32 rune;
    size_t rune_len;
    EUTF8Detect res = ASCII;

    while (s0 < send) {
        RECODE_RESULT rr = SafeReadUTF8Char(rune, rune_len, s0, send);

        if (rr != RECODE_OK) {
            return NotUTF8;
        }

        if (rune_len > 1) {
            res = UTF8;
        }

        s0 += rune_len;
    }

    return res;
}

bool ToLowerUTF8Impl(const char* beg, size_t n, TString& newString) {
    return ConvertCaseUTF8Impl(ECaseConversion::ToLower, beg, n, newString);
}

TString ToLowerUTF8(const TString& s) {
    TString newString;
    bool changed = ToLowerUTF8Impl(s.data(), s.size(), newString);
    return changed ? newString : s;
}

TString ToLowerUTF8(TStringBuf s) {
    TString newString;
    bool changed = ToLowerUTF8Impl(s.data(), s.size(), newString);
    return changed ? newString : TString(s.data(), s.size());
}

TString ToLowerUTF8(const char* s) {
    return ToLowerUTF8(TStringBuf(s));
}

bool ToUpperUTF8Impl(const char* beg, size_t n, TString& newString) {
    return ConvertCaseUTF8Impl(ECaseConversion::ToUpper, beg, n, newString);
}

TString ToUpperUTF8(const TString& s) {
    TString newString;
    bool changed = ToUpperUTF8Impl(s.data(), s.size(), newString);
    return changed ? newString : s;
}

TString ToUpperUTF8(TStringBuf s) {
    TString newString;
    bool changed = ToUpperUTF8Impl(s.data(), s.size(), newString);
    return changed ? newString : TString(s.data(), s.size());
}

TString ToUpperUTF8(const char* s) {
    return ToUpperUTF8(TStringBuf(s));
}