master
  1const std = @import("std");
  2const windows1252 = @import("windows1252.zig");
  3
  4/// https://learn.microsoft.com/en-us/windows/win32/intl/code-page-identifiers
  5pub const SupportedCodePage = enum(u16) {
  6    windows1252 = 1252, // windows-1252    ANSI Latin 1; Western European (Windows)
  7    utf8 = 65001, // utf-8    Unicode (UTF-8)
  8
  9    pub fn codepointAt(code_page: SupportedCodePage, index: usize, bytes: []const u8) ?Codepoint {
 10        if (index >= bytes.len) return null;
 11        switch (code_page) {
 12            .windows1252 => {
 13                // All byte values have a representation, so just convert the byte
 14                return Codepoint{
 15                    .value = windows1252.toCodepoint(bytes[index]),
 16                    .byte_len = 1,
 17                };
 18            },
 19            .utf8 => {
 20                return Utf8.WellFormedDecoder.decode(bytes[index..]);
 21            },
 22        }
 23    }
 24};
 25
 26/// https://learn.microsoft.com/en-us/windows/win32/intl/code-page-identifiers
 27pub const UnsupportedCodePage = enum(u16) {
 28    ibm037 = 37, // IBM037    IBM EBCDIC US-Canada
 29    ibm437 = 437, // IBM437    OEM United States
 30    ibm500 = 500, // IBM500    IBM EBCDIC International
 31    asmo708 = 708, // ASMO-708    Arabic (ASMO 708)
 32    asmo449plus = 709, // Arabic (ASMO-449+, BCON V4)
 33    transparent_arabic = 710, // Arabic - Transparent Arabic
 34    dos720 = 720, // DOS-720    Arabic (Transparent ASMO); Arabic (DOS)
 35    ibm737 = 737, // ibm737    OEM Greek (formerly 437G); Greek (DOS)
 36    ibm775 = 775, // ibm775    OEM Baltic; Baltic (DOS)
 37    ibm850 = 850, // ibm850    OEM Multilingual Latin 1; Western European (DOS)
 38    ibm852 = 852, // ibm852    OEM Latin 2; Central European (DOS)
 39    ibm855 = 855, // IBM855    OEM Cyrillic (primarily Russian)
 40    ibm857 = 857, // ibm857    OEM Turkish; Turkish (DOS)
 41    ibm00858 = 858, // IBM00858    OEM Multilingual Latin 1 + Euro symbol
 42    ibm860 = 860, // IBM860    OEM Portuguese; Portuguese (DOS)
 43    ibm861 = 861, // ibm861    OEM Icelandic; Icelandic (DOS)
 44    dos862 = 862, // DOS-862    OEM Hebrew; Hebrew (DOS)
 45    ibm863 = 863, // IBM863    OEM French Canadian; French Canadian (DOS)
 46    ibm864 = 864, // IBM864    OEM Arabic; Arabic (864)
 47    ibm865 = 865, // IBM865    OEM Nordic; Nordic (DOS)
 48    cp866 = 866, // cp866    OEM Russian; Cyrillic (DOS)
 49    ibm869 = 869, // ibm869    OEM Modern Greek; Greek, Modern (DOS)
 50    ibm870 = 870, // IBM870    IBM EBCDIC Multilingual/ROECE (Latin 2); IBM EBCDIC Multilingual Latin 2
 51    windows874 = 874, // windows-874    Thai (Windows)
 52    cp875 = 875, // cp875    IBM EBCDIC Greek Modern
 53    shift_jis = 932, // shift_jis    ANSI/OEM Japanese; Japanese (Shift-JIS)
 54    gb2312 = 936, // gb2312    ANSI/OEM Simplified Chinese (PRC, Singapore); Chinese Simplified (GB2312)
 55    ks_c_5601_1987 = 949, // ks_c_5601-1987    ANSI/OEM Korean (Unified Hangul Code)
 56    big5 = 950, // big5    ANSI/OEM Traditional Chinese (Taiwan; Hong Kong SAR, PRC); Chinese Traditional (Big5)
 57    ibm1026 = 1026, // IBM1026    IBM EBCDIC Turkish (Latin 5)
 58    ibm01047 = 1047, // IBM01047    IBM EBCDIC Latin 1/Open System
 59    ibm01140 = 1140, // IBM01140    IBM EBCDIC US-Canada (037 + Euro symbol); IBM EBCDIC (US-Canada-Euro)
 60    ibm01141 = 1141, // IBM01141    IBM EBCDIC Germany (20273 + Euro symbol); IBM EBCDIC (Germany-Euro)
 61    ibm01142 = 1142, // IBM01142    IBM EBCDIC Denmark-Norway (20277 + Euro symbol); IBM EBCDIC (Denmark-Norway-Euro)
 62    ibm01143 = 1143, // IBM01143    IBM EBCDIC Finland-Sweden (20278 + Euro symbol); IBM EBCDIC (Finland-Sweden-Euro)
 63    ibm01144 = 1144, // IBM01144    IBM EBCDIC Italy (20280 + Euro symbol); IBM EBCDIC (Italy-Euro)
 64    ibm01145 = 1145, // IBM01145    IBM EBCDIC Latin America-Spain (20284 + Euro symbol); IBM EBCDIC (Spain-Euro)
 65    ibm01146 = 1146, // IBM01146    IBM EBCDIC United Kingdom (20285 + Euro symbol); IBM EBCDIC (UK-Euro)
 66    ibm01147 = 1147, // IBM01147    IBM EBCDIC France (20297 + Euro symbol); IBM EBCDIC (France-Euro)
 67    ibm01148 = 1148, // IBM01148    IBM EBCDIC International (500 + Euro symbol); IBM EBCDIC (International-Euro)
 68    ibm01149 = 1149, // IBM01149    IBM EBCDIC Icelandic (20871 + Euro symbol); IBM EBCDIC (Icelandic-Euro)
 69    utf16 = 1200, // utf-16    Unicode UTF-16, little endian byte order (BMP of ISO 10646); available only to managed applications
 70    utf16_fffe = 1201, // unicodeFFFE    Unicode UTF-16, big endian byte order; available only to managed applications
 71    windows1250 = 1250, // windows-1250    ANSI Central European; Central European (Windows)
 72    windows1251 = 1251, // windows-1251    ANSI Cyrillic; Cyrillic (Windows)
 73    windows1253 = 1253, // windows-1253    ANSI Greek; Greek (Windows)
 74    windows1254 = 1254, // windows-1254    ANSI Turkish; Turkish (Windows)
 75    windows1255 = 1255, // windows-1255    ANSI Hebrew; Hebrew (Windows)
 76    windows1256 = 1256, // windows-1256    ANSI Arabic; Arabic (Windows)
 77    windows1257 = 1257, // windows-1257    ANSI Baltic; Baltic (Windows)
 78    windows1258 = 1258, // windows-1258    ANSI/OEM Vietnamese; Vietnamese (Windows)
 79    johab = 1361, // Johab    Korean (Johab)
 80    macintosh = 10000, // macintosh    MAC Roman; Western European (Mac)
 81    x_mac_japanese = 10001, // x-mac-japanese    Japanese (Mac)
 82    x_mac_chinesetrad = 10002, // x-mac-chinesetrad    MAC Traditional Chinese (Big5); Chinese Traditional (Mac)
 83    x_mac_korean = 10003, // x-mac-korean    Korean (Mac)
 84    x_mac_arabic = 10004, // x-mac-arabic    Arabic (Mac)
 85    x_mac_hebrew = 10005, // x-mac-hebrew    Hebrew (Mac)
 86    x_mac_greek = 10006, // x-mac-greek    Greek (Mac)
 87    x_mac_cyrillic = 10007, // x-mac-cyrillic    Cyrillic (Mac)
 88    x_mac_chinesesimp = 10008, // x-mac-chinesesimp    MAC Simplified Chinese (GB 2312); Chinese Simplified (Mac)
 89    x_mac_romanian = 10010, // x-mac-romanian    Romanian (Mac)
 90    x_mac_ukranian = 10017, // x-mac-ukrainian    Ukrainian (Mac)
 91    x_mac_thai = 10021, // x-mac-thai    Thai (Mac)
 92    x_mac_ce = 10029, // x-mac-ce    MAC Latin 2; Central European (Mac)
 93    x_mac_icelandic = 10079, // x-mac-icelandic    Icelandic (Mac)
 94    x_mac_turkish = 10081, // x-mac-turkish    Turkish (Mac)
 95    x_mac_croatian = 10082, // x-mac-croatian    Croatian (Mac)
 96    utf32 = 12000, // utf-32    Unicode UTF-32, little endian byte order; available only to managed applications
 97    utf32_be = 12001, // utf-32BE    Unicode UTF-32, big endian byte order; available only to managed applications
 98    x_chinese_cns = 20000, // x-Chinese_CNS    CNS Taiwan; Chinese Traditional (CNS)
 99    x_cp20001 = 20001, // x-cp20001    TCA Taiwan
100    x_chinese_eten = 20002, // x_Chinese-Eten    Eten Taiwan; Chinese Traditional (Eten)
101    x_cp20003 = 20003, // x-cp20003    IBM5550 Taiwan
102    x_cp20004 = 20004, // x-cp20004    TeleText Taiwan
103    x_cp20005 = 20005, // x-cp20005    Wang Taiwan
104    x_ia5 = 20105, // x-IA5    IA5 (IRV International Alphabet No. 5, 7-bit); Western European (IA5)
105    x_ia5_german = 20106, // x-IA5-German    IA5 German (7-bit)
106    x_ia5_swedish = 20107, // x-IA5-Swedish    IA5 Swedish (7-bit)
107    x_ia5_norwegian = 20108, // x-IA5-Norwegian    IA5 Norwegian (7-bit)
108    us_ascii = 20127, // us-ascii    US-ASCII (7-bit)
109    x_cp20261 = 20261, // x-cp20261    T.61
110    x_cp20269 = 20269, // x-cp20269    ISO 6937 Non-Spacing Accent
111    ibm273 = 20273, // IBM273    IBM EBCDIC Germany
112    ibm277 = 20277, // IBM277    IBM EBCDIC Denmark-Norway
113    ibm278 = 20278, // IBM278    IBM EBCDIC Finland-Sweden
114    ibm280 = 20280, // IBM280    IBM EBCDIC Italy
115    ibm284 = 20284, // IBM284    IBM EBCDIC Latin America-Spain
116    ibm285 = 20285, // IBM285    IBM EBCDIC United Kingdom
117    ibm290 = 20290, // IBM290    IBM EBCDIC Japanese Katakana Extended
118    ibm297 = 20297, // IBM297    IBM EBCDIC France
119    ibm420 = 20420, // IBM420    IBM EBCDIC Arabic
120    ibm423 = 20423, // IBM423    IBM EBCDIC Greek
121    ibm424 = 20424, // IBM424    IBM EBCDIC Hebrew
122    x_ebcdic_korean_extended = 20833, // x-EBCDIC-KoreanExtended    IBM EBCDIC Korean Extended
123    ibm_thai = 20838, // IBM-Thai    IBM EBCDIC Thai
124    koi8_r = 20866, // koi8-r    Russian (KOI8-R); Cyrillic (KOI8-R)
125    ibm871 = 20871, // IBM871    IBM EBCDIC Icelandic
126    ibm880 = 20880, // IBM880    IBM EBCDIC Cyrillic Russian
127    ibm905 = 20905, // IBM905    IBM EBCDIC Turkish
128    ibm00924 = 20924, // IBM00924    IBM EBCDIC Latin 1/Open System (1047 + Euro symbol)
129    euc_jp_jis = 20932, // EUC-JP    Japanese (JIS 0208-1990 and 0212-1990)
130    x_cp20936 = 20936, // x-cp20936    Simplified Chinese (GB2312); Chinese Simplified (GB2312-80)
131    x_cp20949 = 20949, // x-cp20949    Korean Wansung
132    cp1025 = 21025, // cp1025    IBM EBCDIC Cyrillic Serbian-Bulgarian
133    // = 21027, // (deprecated)
134    koi8_u = 21866, // koi8-u    Ukrainian (KOI8-U); Cyrillic (KOI8-U)
135    iso8859_1 = 28591, // iso-8859-1    ISO 8859-1 Latin 1; Western European (ISO)
136    iso8859_2 = 28592, // iso-8859-2    ISO 8859-2 Central European; Central European (ISO)
137    iso8859_3 = 28593, // iso-8859-3    ISO 8859-3 Latin 3
138    iso8859_4 = 28594, // iso-8859-4    ISO 8859-4 Baltic
139    iso8859_5 = 28595, // iso-8859-5    ISO 8859-5 Cyrillic
140    iso8859_6 = 28596, // iso-8859-6    ISO 8859-6 Arabic
141    iso8859_7 = 28597, // iso-8859-7    ISO 8859-7 Greek
142    iso8859_8 = 28598, // iso-8859-8    ISO 8859-8 Hebrew; Hebrew (ISO-Visual)
143    iso8859_9 = 28599, // iso-8859-9    ISO 8859-9 Turkish
144    iso8859_13 = 28603, // iso-8859-13    ISO 8859-13 Estonian
145    iso8859_15 = 28605, // iso-8859-15    ISO 8859-15 Latin 9
146    x_europa = 29001, // x-Europa    Europa 3
147    is8859_8_i = 38598, // iso-8859-8-i    ISO 8859-8 Hebrew; Hebrew (ISO-Logical)
148    iso2022_jp = 50220, // iso-2022-jp    ISO 2022 Japanese with no halfwidth Katakana; Japanese (JIS)
149    cs_iso2022_jp = 50221, // csISO2022JP    ISO 2022 Japanese with halfwidth Katakana; Japanese (JIS-Allow 1 byte Kana)
150    iso2022_jp_jis_x = 50222, // iso-2022-jp    ISO 2022 Japanese JIS X 0201-1989; Japanese (JIS-Allow 1 byte Kana - SO/SI)
151    iso2022_kr = 50225, // iso-2022-kr    ISO 2022 Korean
152    x_cp50227 = 50227, // x-cp50227    ISO 2022 Simplified Chinese; Chinese Simplified (ISO 2022)
153    iso2022_chinesetrad = 50229, // ISO 2022 Traditional Chinese
154    ebcdic_jp_katakana_extended = 50930, // EBCDIC Japanese (Katakana) Extended
155    ebcdic_us_ca_jp = 50931, // EBCDIC US-Canada and Japanese
156    ebcdic_kr_extended = 50933, // EBCDIC Korean Extended and Korean
157    ebcdic_chinesesimp_extended = 50935, // EBCDIC Simplified Chinese Extended and Simplified Chinese
158    ebcdic_chinesesimp = 50936, // EBCDIC Simplified Chinese
159    ebcdic_us_ca_chinesetrad = 50937, // EBCDIC US-Canada and Traditional Chinese
160    ebcdic_jp_latin_extended = 50939, // EBCDIC Japanese (Latin) Extended and Japanese
161    euc_jp = 51932, // euc-jp    EUC Japanese
162    euc_cn = 51936, // EUC-CN    EUC Simplified Chinese; Chinese Simplified (EUC)
163    euc_kr = 51949, // euc-kr    EUC Korean
164    euc_chinesetrad = 51950, // EUC Traditional Chinese
165    hz_gb2312 = 52936, // hz-gb-2312    HZ-GB2312 Simplified Chinese; Chinese Simplified (HZ)
166    gb18030 = 54936, // GB18030    Windows XP and later: GB18030 Simplified Chinese (4 byte); Chinese Simplified (GB18030)
167    x_iscii_de = 57002, // x-iscii-de    ISCII Devanagari
168    x_iscii_be = 57003, // x-iscii-be    ISCII Bangla
169    x_iscii_ta = 57004, // x-iscii-ta    ISCII Tamil
170    x_iscii_te = 57005, // x-iscii-te    ISCII Telugu
171    x_iscii_as = 57006, // x-iscii-as    ISCII Assamese
172    x_iscii_or = 57007, // x-iscii-or    ISCII Odia
173    x_iscii_ka = 57008, // x-iscii-ka    ISCII Kannada
174    x_iscii_ma = 57009, // x-iscii-ma    ISCII Malayalam
175    x_iscii_gu = 57010, // x-iscii-gu    ISCII Gujarati
176    x_iscii_pa = 57011, // x-iscii-pa    ISCII Punjabi
177    utf7 = 65000, // utf-7    Unicode (UTF-7)
178};
179
180pub const CodePage = blk: {
181    const fields = @typeInfo(SupportedCodePage).@"enum".fields ++ @typeInfo(UnsupportedCodePage).@"enum".fields;
182    var field_names: [fields.len][]const u8 = undefined;
183    var field_values: [fields.len]u16 = undefined;
184    for (fields, &field_names, &field_values) |field, *name, *val| {
185        name.* = field.name;
186        val.* = field.value;
187    }
188    break :blk @Enum(u16, .exhaustive, &field_names, &field_values);
189};
190
191pub fn isSupported(code_page: CodePage) bool {
192    inline for (@typeInfo(SupportedCodePage).@"enum".fields) |enumField| {
193        if (@intFromEnum(code_page) == @intFromEnum(@field(SupportedCodePage, enumField.name))) {
194            return true;
195        }
196    }
197    return false;
198}
199
200pub fn getByIdentifier(identifier: u16) !CodePage {
201    // There's probably a more efficient way to do this (e.g. ComptimeHashMap?) but
202    // this should be fine, especially since this function likely won't be called much.
203    inline for (@typeInfo(CodePage).@"enum".fields) |enumField| {
204        if (identifier == enumField.value) {
205            return @field(CodePage, enumField.name);
206        }
207    }
208    return error.InvalidCodePage;
209}
210
211pub fn getByIdentifierEnsureSupported(identifier: u16) !SupportedCodePage {
212    const code_page = try getByIdentifier(identifier);
213    return if (isSupported(code_page))
214        @enumFromInt(@intFromEnum(code_page))
215    else
216        error.UnsupportedCodePage;
217}
218
219pub const Utf8 = struct {
220    /// Implements decoding with rejection of ill-formed UTF-8 sequences based on section
221    /// D92 of Chapter 3 of the Unicode standard (Table 3-7 specifically).
222    ///
223    /// Note: This does not match "U+FFFD Substitution of Maximal Subparts", but instead
224    ///       matches the behavior of the Windows RC compiler.
225    pub const WellFormedDecoder = struct {
226        /// Like std.unicode.utf8ByteSequenceLength, but:
227        /// - Rejects non-well-formed first bytes, i.e. C0-C1, F5-FF
228        /// - Returns an optional value instead of an error union
229        pub fn sequenceLength(first_byte: u8) ?u3 {
230            return switch (first_byte) {
231                0x00...0x7F => 1,
232                0xC2...0xDF => 2,
233                0xE0...0xEF => 3,
234                0xF0...0xF4 => 4,
235                else => null,
236            };
237        }
238
239        fn isContinuationByte(byte: u8) bool {
240            return switch (byte) {
241                0x80...0xBF => true,
242                else => false,
243            };
244        }
245
246        pub fn decode(bytes: []const u8) Codepoint {
247            std.debug.assert(bytes.len > 0);
248            const first_byte = bytes[0];
249            const expected_len = sequenceLength(first_byte) orelse {
250                return .{ .value = Codepoint.invalid, .byte_len = 1 };
251            };
252            if (expected_len == 1) return .{ .value = first_byte, .byte_len = 1 };
253
254            var value: u21 = first_byte & 0b00011111;
255            var byte_index: u8 = 1;
256            while (byte_index < @min(bytes.len, expected_len)) : (byte_index += 1) {
257                const byte = bytes[byte_index];
258                // See Table 3-7 of D92 in Chapter 3 of the Unicode Standard
259                const valid: bool = switch (byte_index) {
260                    1 => switch (first_byte) {
261                        0xE0 => switch (byte) {
262                            0xA0...0xBF => true,
263                            else => false,
264                        },
265                        0xED => switch (byte) {
266                            0x80...0x9F => true,
267                            else => false,
268                        },
269                        0xF0 => switch (byte) {
270                            0x90...0xBF => true,
271                            else => false,
272                        },
273                        0xF4 => switch (byte) {
274                            0x80...0x8F => true,
275                            else => false,
276                        },
277                        else => switch (byte) {
278                            0x80...0xBF => true,
279                            else => false,
280                        },
281                    },
282                    else => switch (byte) {
283                        0x80...0xBF => true,
284                        else => false,
285                    },
286                };
287
288                if (!valid) {
289                    var len = byte_index;
290                    // Only include the byte in the invalid sequence if it's in the range
291                    // of a continuation byte. All other values should not be included in the
292                    // invalid sequence.
293                    if (isContinuationByte(byte)) len += 1;
294                    return .{ .value = Codepoint.invalid, .byte_len = len };
295                }
296
297                value <<= 6;
298                value |= byte & 0b00111111;
299            }
300            if (byte_index != expected_len) {
301                return .{ .value = Codepoint.invalid, .byte_len = byte_index };
302            }
303            return .{ .value = value, .byte_len = expected_len };
304        }
305    };
306};
307
308test "Utf8.WellFormedDecoder" {
309    const invalid_utf8 = "\xF0\x80";
310    const decoded = Utf8.WellFormedDecoder.decode(invalid_utf8);
311    try std.testing.expectEqual(Codepoint.invalid, decoded.value);
312    try std.testing.expectEqual(@as(usize, 2), decoded.byte_len);
313}
314
315test "codepointAt invalid utf8" {
316    {
317        const invalid_utf8 = "\xf0\xf0\x80\x80\x80";
318        try std.testing.expectEqual(Codepoint{
319            .value = Codepoint.invalid,
320            .byte_len = 1,
321        }, SupportedCodePage.utf8.codepointAt(0, invalid_utf8).?);
322        try std.testing.expectEqual(Codepoint{
323            .value = Codepoint.invalid,
324            .byte_len = 2,
325        }, SupportedCodePage.utf8.codepointAt(1, invalid_utf8).?);
326        try std.testing.expectEqual(Codepoint{
327            .value = Codepoint.invalid,
328            .byte_len = 1,
329        }, SupportedCodePage.utf8.codepointAt(3, invalid_utf8).?);
330        try std.testing.expectEqual(Codepoint{
331            .value = Codepoint.invalid,
332            .byte_len = 1,
333        }, SupportedCodePage.utf8.codepointAt(4, invalid_utf8).?);
334        try std.testing.expectEqual(@as(?Codepoint, null), SupportedCodePage.utf8.codepointAt(5, invalid_utf8));
335    }
336
337    {
338        const invalid_utf8 = "\xE1\xA0\xC0";
339        try std.testing.expectEqual(Codepoint{
340            .value = Codepoint.invalid,
341            .byte_len = 2,
342        }, SupportedCodePage.utf8.codepointAt(0, invalid_utf8).?);
343        try std.testing.expectEqual(Codepoint{
344            .value = Codepoint.invalid,
345            .byte_len = 1,
346        }, SupportedCodePage.utf8.codepointAt(2, invalid_utf8).?);
347        try std.testing.expectEqual(@as(?Codepoint, null), SupportedCodePage.utf8.codepointAt(3, invalid_utf8));
348    }
349
350    {
351        const invalid_utf8 = "\xD2";
352        try std.testing.expectEqual(Codepoint{
353            .value = Codepoint.invalid,
354            .byte_len = 1,
355        }, SupportedCodePage.utf8.codepointAt(0, invalid_utf8).?);
356        try std.testing.expectEqual(@as(?Codepoint, null), SupportedCodePage.utf8.codepointAt(1, invalid_utf8));
357    }
358
359    {
360        const invalid_utf8 = "\xE1\xA0";
361        try std.testing.expectEqual(Codepoint{
362            .value = Codepoint.invalid,
363            .byte_len = 2,
364        }, SupportedCodePage.utf8.codepointAt(0, invalid_utf8).?);
365        try std.testing.expectEqual(@as(?Codepoint, null), SupportedCodePage.utf8.codepointAt(2, invalid_utf8));
366    }
367
368    {
369        const invalid_utf8 = "\xC5\xFF";
370        try std.testing.expectEqual(Codepoint{
371            .value = Codepoint.invalid,
372            .byte_len = 1,
373        }, SupportedCodePage.utf8.codepointAt(0, invalid_utf8).?);
374        try std.testing.expectEqual(Codepoint{
375            .value = Codepoint.invalid,
376            .byte_len = 1,
377        }, SupportedCodePage.utf8.codepointAt(1, invalid_utf8).?);
378        try std.testing.expectEqual(@as(?Codepoint, null), SupportedCodePage.utf8.codepointAt(2, invalid_utf8));
379    }
380
381    {
382        // encoded high surrogate
383        const invalid_utf8 = "\xED\xA0\xBD";
384        try std.testing.expectEqual(Codepoint{
385            .value = Codepoint.invalid,
386            .byte_len = 2,
387        }, SupportedCodePage.utf8.codepointAt(0, invalid_utf8).?);
388        try std.testing.expectEqual(Codepoint{
389            .value = Codepoint.invalid,
390            .byte_len = 1,
391        }, SupportedCodePage.utf8.codepointAt(2, invalid_utf8).?);
392    }
393}
394
395test "codepointAt utf8 encoded" {
396    const utf8_encoded = "²";
397
398    // with code page utf8
399    try std.testing.expectEqual(Codepoint{
400        .value = '²',
401        .byte_len = 2,
402    }, SupportedCodePage.utf8.codepointAt(0, utf8_encoded).?);
403    try std.testing.expectEqual(@as(?Codepoint, null), SupportedCodePage.utf8.codepointAt(2, utf8_encoded));
404
405    // with code page windows1252
406    try std.testing.expectEqual(Codepoint{
407        .value = '\xC2',
408        .byte_len = 1,
409    }, SupportedCodePage.windows1252.codepointAt(0, utf8_encoded).?);
410    try std.testing.expectEqual(Codepoint{
411        .value = '\xB2',
412        .byte_len = 1,
413    }, SupportedCodePage.windows1252.codepointAt(1, utf8_encoded).?);
414    try std.testing.expectEqual(@as(?Codepoint, null), SupportedCodePage.windows1252.codepointAt(2, utf8_encoded));
415}
416
417test "codepointAt windows1252 encoded" {
418    const windows1252_encoded = "\xB2";
419
420    // with code page utf8
421    try std.testing.expectEqual(Codepoint{
422        .value = Codepoint.invalid,
423        .byte_len = 1,
424    }, SupportedCodePage.utf8.codepointAt(0, windows1252_encoded).?);
425    try std.testing.expectEqual(@as(?Codepoint, null), SupportedCodePage.utf8.codepointAt(2, windows1252_encoded));
426
427    // with code page windows1252
428    try std.testing.expectEqual(Codepoint{
429        .value = '\xB2',
430        .byte_len = 1,
431    }, SupportedCodePage.windows1252.codepointAt(0, windows1252_encoded).?);
432    try std.testing.expectEqual(@as(?Codepoint, null), SupportedCodePage.windows1252.codepointAt(1, windows1252_encoded));
433}
434
435pub const Codepoint = struct {
436    value: u21,
437    byte_len: usize,
438
439    pub const invalid: u21 = std.math.maxInt(u21);
440};