mirror of
https://github.com/ziglang/zig.git
synced 2024-11-27 07:32:44 +00:00
460 lines
18 KiB
Zig
460 lines
18 KiB
Zig
const std = @import("std.zig");
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const assert = std.debug.assert;
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const testing = std.testing;
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const mem = std.mem;
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pub const Error = error{
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InvalidCharacter,
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InvalidPadding,
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NoSpaceLeft,
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};
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const decoderWithIgnoreProto = *const fn (ignore: []const u8) Base64DecoderWithIgnore;
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/// Base64 codecs
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pub const Codecs = struct {
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alphabet_chars: [64]u8,
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pad_char: ?u8,
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decoderWithIgnore: decoderWithIgnoreProto,
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Encoder: Base64Encoder,
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Decoder: Base64Decoder,
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};
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pub const standard_alphabet_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".*;
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fn standardBase64DecoderWithIgnore(ignore: []const u8) Base64DecoderWithIgnore {
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return Base64DecoderWithIgnore.init(standard_alphabet_chars, '=', ignore);
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}
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/// Standard Base64 codecs, with padding
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pub const standard = Codecs{
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.alphabet_chars = standard_alphabet_chars,
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.pad_char = '=',
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.decoderWithIgnore = standardBase64DecoderWithIgnore,
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.Encoder = Base64Encoder.init(standard_alphabet_chars, '='),
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.Decoder = Base64Decoder.init(standard_alphabet_chars, '='),
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};
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/// Standard Base64 codecs, without padding
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pub const standard_no_pad = Codecs{
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.alphabet_chars = standard_alphabet_chars,
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.pad_char = null,
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.decoderWithIgnore = standardBase64DecoderWithIgnore,
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.Encoder = Base64Encoder.init(standard_alphabet_chars, null),
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.Decoder = Base64Decoder.init(standard_alphabet_chars, null),
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};
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pub const url_safe_alphabet_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_".*;
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fn urlSafeBase64DecoderWithIgnore(ignore: []const u8) Base64DecoderWithIgnore {
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return Base64DecoderWithIgnore.init(url_safe_alphabet_chars, null, ignore);
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}
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/// URL-safe Base64 codecs, with padding
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pub const url_safe = Codecs{
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.alphabet_chars = url_safe_alphabet_chars,
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.pad_char = '=',
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.decoderWithIgnore = urlSafeBase64DecoderWithIgnore,
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.Encoder = Base64Encoder.init(url_safe_alphabet_chars, '='),
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.Decoder = Base64Decoder.init(url_safe_alphabet_chars, '='),
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};
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/// URL-safe Base64 codecs, without padding
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pub const url_safe_no_pad = Codecs{
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.alphabet_chars = url_safe_alphabet_chars,
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.pad_char = null,
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.decoderWithIgnore = urlSafeBase64DecoderWithIgnore,
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.Encoder = Base64Encoder.init(url_safe_alphabet_chars, null),
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.Decoder = Base64Decoder.init(url_safe_alphabet_chars, null),
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};
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pub const Base64Encoder = struct {
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alphabet_chars: [64]u8,
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pad_char: ?u8,
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/// A bunch of assertions, then simply pass the data right through.
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pub fn init(alphabet_chars: [64]u8, pad_char: ?u8) Base64Encoder {
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assert(alphabet_chars.len == 64);
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var char_in_alphabet = [_]bool{false} ** 256;
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for (alphabet_chars) |c| {
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assert(!char_in_alphabet[c]);
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assert(pad_char == null or c != pad_char.?);
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char_in_alphabet[c] = true;
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}
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return Base64Encoder{
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.alphabet_chars = alphabet_chars,
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.pad_char = pad_char,
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};
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}
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/// Compute the encoded length
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pub fn calcSize(encoder: *const Base64Encoder, source_len: usize) usize {
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if (encoder.pad_char != null) {
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return @divTrunc(source_len + 2, 3) * 4;
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} else {
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const leftover = source_len % 3;
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return @divTrunc(source_len, 3) * 4 + @divTrunc(leftover * 4 + 2, 3);
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}
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}
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/// dest.len must at least be what you get from ::calcSize.
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pub fn encode(encoder: *const Base64Encoder, dest: []u8, source: []const u8) []const u8 {
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const out_len = encoder.calcSize(source.len);
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assert(dest.len >= out_len);
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var idx: usize = 0;
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var out_idx: usize = 0;
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while (idx + 2 < source.len) : (idx += 3) {
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dest[out_idx] = encoder.alphabet_chars[source[idx] >> 2];
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dest[out_idx + 1] = encoder.alphabet_chars[((source[idx] & 0x3) << 4) | (source[idx + 1] >> 4)];
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dest[out_idx + 2] = encoder.alphabet_chars[(source[idx + 1] & 0xf) << 2 | (source[idx + 2] >> 6)];
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dest[out_idx + 3] = encoder.alphabet_chars[source[idx + 2] & 0x3f];
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out_idx += 4;
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}
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if (idx + 1 < source.len) {
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dest[out_idx] = encoder.alphabet_chars[source[idx] >> 2];
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dest[out_idx + 1] = encoder.alphabet_chars[((source[idx] & 0x3) << 4) | (source[idx + 1] >> 4)];
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dest[out_idx + 2] = encoder.alphabet_chars[(source[idx + 1] & 0xf) << 2];
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out_idx += 3;
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} else if (idx < source.len) {
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dest[out_idx] = encoder.alphabet_chars[source[idx] >> 2];
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dest[out_idx + 1] = encoder.alphabet_chars[(source[idx] & 0x3) << 4];
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out_idx += 2;
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}
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if (encoder.pad_char) |pad_char| {
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for (dest[out_idx..out_len]) |*pad| {
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pad.* = pad_char;
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}
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}
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return dest[0..out_len];
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}
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};
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pub const Base64Decoder = struct {
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const invalid_char: u8 = 0xff;
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/// e.g. 'A' => 0.
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/// `invalid_char` for any value not in the 64 alphabet chars.
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char_to_index: [256]u8,
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pad_char: ?u8,
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pub fn init(alphabet_chars: [64]u8, pad_char: ?u8) Base64Decoder {
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var result = Base64Decoder{
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.char_to_index = [_]u8{invalid_char} ** 256,
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.pad_char = pad_char,
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};
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var char_in_alphabet = [_]bool{false} ** 256;
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for (alphabet_chars, 0..) |c, i| {
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assert(!char_in_alphabet[c]);
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assert(pad_char == null or c != pad_char.?);
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result.char_to_index[c] = @as(u8, @intCast(i));
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char_in_alphabet[c] = true;
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}
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return result;
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}
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/// Return the maximum possible decoded size for a given input length - The actual length may be less if the input includes padding.
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/// `InvalidPadding` is returned if the input length is not valid.
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pub fn calcSizeUpperBound(decoder: *const Base64Decoder, source_len: usize) Error!usize {
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var result = source_len / 4 * 3;
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const leftover = source_len % 4;
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if (decoder.pad_char != null) {
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if (leftover % 4 != 0) return error.InvalidPadding;
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} else {
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if (leftover % 4 == 1) return error.InvalidPadding;
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result += leftover * 3 / 4;
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}
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return result;
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}
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/// Return the exact decoded size for a slice.
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/// `InvalidPadding` is returned if the input length is not valid.
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pub fn calcSizeForSlice(decoder: *const Base64Decoder, source: []const u8) Error!usize {
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const source_len = source.len;
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var result = try decoder.calcSizeUpperBound(source_len);
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if (decoder.pad_char) |pad_char| {
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if (source_len >= 1 and source[source_len - 1] == pad_char) result -= 1;
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if (source_len >= 2 and source[source_len - 2] == pad_char) result -= 1;
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}
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return result;
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}
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/// dest.len must be what you get from ::calcSize.
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/// invalid characters result in error.InvalidCharacter.
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/// invalid padding results in error.InvalidPadding.
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pub fn decode(decoder: *const Base64Decoder, dest: []u8, source: []const u8) Error!void {
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if (decoder.pad_char != null and source.len % 4 != 0) return error.InvalidPadding;
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var acc: u12 = 0;
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var acc_len: u4 = 0;
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var dest_idx: usize = 0;
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var leftover_idx: ?usize = null;
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for (source, 0..) |c, src_idx| {
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const d = decoder.char_to_index[c];
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if (d == invalid_char) {
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if (decoder.pad_char == null or c != decoder.pad_char.?) return error.InvalidCharacter;
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leftover_idx = src_idx;
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break;
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}
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acc = (acc << 6) + d;
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acc_len += 6;
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if (acc_len >= 8) {
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acc_len -= 8;
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dest[dest_idx] = @as(u8, @truncate(acc >> acc_len));
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dest_idx += 1;
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}
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}
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if (acc_len > 4 or (acc & (@as(u12, 1) << acc_len) - 1) != 0) {
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return error.InvalidPadding;
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}
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if (leftover_idx == null) return;
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var leftover = source[leftover_idx.?..];
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if (decoder.pad_char) |pad_char| {
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const padding_len = acc_len / 2;
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var padding_chars: usize = 0;
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for (leftover) |c| {
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if (c != pad_char) {
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return if (c == Base64Decoder.invalid_char) error.InvalidCharacter else error.InvalidPadding;
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}
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padding_chars += 1;
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}
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if (padding_chars != padding_len) return error.InvalidPadding;
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}
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}
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};
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pub const Base64DecoderWithIgnore = struct {
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decoder: Base64Decoder,
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char_is_ignored: [256]bool,
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pub fn init(alphabet_chars: [64]u8, pad_char: ?u8, ignore_chars: []const u8) Base64DecoderWithIgnore {
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var result = Base64DecoderWithIgnore{
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.decoder = Base64Decoder.init(alphabet_chars, pad_char),
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.char_is_ignored = [_]bool{false} ** 256,
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};
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for (ignore_chars) |c| {
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assert(result.decoder.char_to_index[c] == Base64Decoder.invalid_char);
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assert(!result.char_is_ignored[c]);
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assert(result.decoder.pad_char != c);
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result.char_is_ignored[c] = true;
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}
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return result;
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}
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/// Return the maximum possible decoded size for a given input length - The actual length may be less if the input includes padding
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/// `InvalidPadding` is returned if the input length is not valid.
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pub fn calcSizeUpperBound(decoder_with_ignore: *const Base64DecoderWithIgnore, source_len: usize) Error!usize {
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var result = source_len / 4 * 3;
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if (decoder_with_ignore.decoder.pad_char == null) {
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const leftover = source_len % 4;
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result += leftover * 3 / 4;
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}
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return result;
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}
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/// Invalid characters that are not ignored result in error.InvalidCharacter.
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/// Invalid padding results in error.InvalidPadding.
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/// Decoding more data than can fit in dest results in error.NoSpaceLeft. See also ::calcSizeUpperBound.
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/// Returns the number of bytes written to dest.
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pub fn decode(decoder_with_ignore: *const Base64DecoderWithIgnore, dest: []u8, source: []const u8) Error!usize {
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const decoder = &decoder_with_ignore.decoder;
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var acc: u12 = 0;
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var acc_len: u4 = 0;
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var dest_idx: usize = 0;
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var leftover_idx: ?usize = null;
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for (source, 0..) |c, src_idx| {
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if (decoder_with_ignore.char_is_ignored[c]) continue;
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const d = decoder.char_to_index[c];
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if (d == Base64Decoder.invalid_char) {
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if (decoder.pad_char == null or c != decoder.pad_char.?) return error.InvalidCharacter;
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leftover_idx = src_idx;
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break;
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}
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acc = (acc << 6) + d;
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acc_len += 6;
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if (acc_len >= 8) {
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if (dest_idx == dest.len) return error.NoSpaceLeft;
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acc_len -= 8;
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dest[dest_idx] = @as(u8, @truncate(acc >> acc_len));
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dest_idx += 1;
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}
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}
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if (acc_len > 4 or (acc & (@as(u12, 1) << acc_len) - 1) != 0) {
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return error.InvalidPadding;
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}
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const padding_len = acc_len / 2;
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if (leftover_idx == null) {
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if (decoder.pad_char != null and padding_len != 0) return error.InvalidPadding;
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return dest_idx;
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}
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var leftover = source[leftover_idx.?..];
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if (decoder.pad_char) |pad_char| {
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var padding_chars: usize = 0;
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for (leftover) |c| {
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if (decoder_with_ignore.char_is_ignored[c]) continue;
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if (c != pad_char) {
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return if (c == Base64Decoder.invalid_char) error.InvalidCharacter else error.InvalidPadding;
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}
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padding_chars += 1;
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}
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if (padding_chars != padding_len) return error.InvalidPadding;
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}
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return dest_idx;
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}
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};
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test "base64" {
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@setEvalBranchQuota(8000);
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try testBase64();
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try comptime testAllApis(standard, "comptime", "Y29tcHRpbWU=");
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}
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test "base64 padding dest overflow" {
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const input = "foo";
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var expect: [128]u8 = undefined;
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@memset(&expect, 0);
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_ = url_safe.Encoder.encode(expect[0..url_safe.Encoder.calcSize(input.len)], input);
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var got: [128]u8 = undefined;
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@memset(&got, 0);
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_ = url_safe.Encoder.encode(&got, input);
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try std.testing.expectEqualSlices(u8, &expect, &got);
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}
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test "base64 url_safe_no_pad" {
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@setEvalBranchQuota(8000);
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try testBase64UrlSafeNoPad();
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try comptime testAllApis(url_safe_no_pad, "comptime", "Y29tcHRpbWU");
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}
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fn testBase64() !void {
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const codecs = standard;
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try testAllApis(codecs, "", "");
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try testAllApis(codecs, "f", "Zg==");
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try testAllApis(codecs, "fo", "Zm8=");
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try testAllApis(codecs, "foo", "Zm9v");
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try testAllApis(codecs, "foob", "Zm9vYg==");
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try testAllApis(codecs, "fooba", "Zm9vYmE=");
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try testAllApis(codecs, "foobar", "Zm9vYmFy");
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try testDecodeIgnoreSpace(codecs, "", " ");
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try testDecodeIgnoreSpace(codecs, "f", "Z g= =");
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try testDecodeIgnoreSpace(codecs, "fo", " Zm8=");
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try testDecodeIgnoreSpace(codecs, "foo", "Zm9v ");
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try testDecodeIgnoreSpace(codecs, "foob", "Zm9vYg = = ");
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try testDecodeIgnoreSpace(codecs, "fooba", "Zm9v YmE=");
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try testDecodeIgnoreSpace(codecs, "foobar", " Z m 9 v Y m F y ");
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// test getting some api errors
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try testError(codecs, "A", error.InvalidPadding);
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try testError(codecs, "AA", error.InvalidPadding);
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try testError(codecs, "AAA", error.InvalidPadding);
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try testError(codecs, "A..A", error.InvalidCharacter);
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try testError(codecs, "AA=A", error.InvalidPadding);
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try testError(codecs, "AA/=", error.InvalidPadding);
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try testError(codecs, "A/==", error.InvalidPadding);
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try testError(codecs, "A===", error.InvalidPadding);
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try testError(codecs, "====", error.InvalidPadding);
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try testNoSpaceLeftError(codecs, "AA==");
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try testNoSpaceLeftError(codecs, "AAA=");
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try testNoSpaceLeftError(codecs, "AAAA");
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try testNoSpaceLeftError(codecs, "AAAAAA==");
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}
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fn testBase64UrlSafeNoPad() !void {
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const codecs = url_safe_no_pad;
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try testAllApis(codecs, "", "");
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try testAllApis(codecs, "f", "Zg");
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try testAllApis(codecs, "fo", "Zm8");
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try testAllApis(codecs, "foo", "Zm9v");
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try testAllApis(codecs, "foob", "Zm9vYg");
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try testAllApis(codecs, "fooba", "Zm9vYmE");
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try testAllApis(codecs, "foobar", "Zm9vYmFy");
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try testDecodeIgnoreSpace(codecs, "", " ");
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try testDecodeIgnoreSpace(codecs, "f", "Z g ");
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try testDecodeIgnoreSpace(codecs, "fo", " Zm8");
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try testDecodeIgnoreSpace(codecs, "foo", "Zm9v ");
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try testDecodeIgnoreSpace(codecs, "foob", "Zm9vYg ");
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try testDecodeIgnoreSpace(codecs, "fooba", "Zm9v YmE");
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try testDecodeIgnoreSpace(codecs, "foobar", " Z m 9 v Y m F y ");
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// test getting some api errors
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try testError(codecs, "A", error.InvalidPadding);
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try testError(codecs, "AAA=", error.InvalidCharacter);
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try testError(codecs, "A..A", error.InvalidCharacter);
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try testError(codecs, "AA=A", error.InvalidCharacter);
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try testError(codecs, "AA/=", error.InvalidCharacter);
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try testError(codecs, "A/==", error.InvalidCharacter);
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try testError(codecs, "A===", error.InvalidCharacter);
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try testError(codecs, "====", error.InvalidCharacter);
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try testNoSpaceLeftError(codecs, "AA");
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try testNoSpaceLeftError(codecs, "AAA");
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try testNoSpaceLeftError(codecs, "AAAA");
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try testNoSpaceLeftError(codecs, "AAAAAA");
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}
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fn testAllApis(codecs: Codecs, expected_decoded: []const u8, expected_encoded: []const u8) !void {
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// Base64Encoder
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{
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var buffer: [0x100]u8 = undefined;
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const encoded = codecs.Encoder.encode(&buffer, expected_decoded);
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try testing.expectEqualSlices(u8, expected_encoded, encoded);
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}
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// Base64Decoder
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{
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var buffer: [0x100]u8 = undefined;
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var decoded = buffer[0..try codecs.Decoder.calcSizeForSlice(expected_encoded)];
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try codecs.Decoder.decode(decoded, expected_encoded);
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try testing.expectEqualSlices(u8, expected_decoded, decoded);
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}
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// Base64DecoderWithIgnore
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{
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const decoder_ignore_nothing = codecs.decoderWithIgnore("");
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var buffer: [0x100]u8 = undefined;
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var decoded = buffer[0..try decoder_ignore_nothing.calcSizeUpperBound(expected_encoded.len)];
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var written = try decoder_ignore_nothing.decode(decoded, expected_encoded);
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try testing.expect(written <= decoded.len);
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try testing.expectEqualSlices(u8, expected_decoded, decoded[0..written]);
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}
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}
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fn testDecodeIgnoreSpace(codecs: Codecs, expected_decoded: []const u8, encoded: []const u8) !void {
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const decoder_ignore_space = codecs.decoderWithIgnore(" ");
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var buffer: [0x100]u8 = undefined;
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var decoded = buffer[0..try decoder_ignore_space.calcSizeUpperBound(encoded.len)];
|
|
var written = try decoder_ignore_space.decode(decoded, encoded);
|
|
try testing.expectEqualSlices(u8, expected_decoded, decoded[0..written]);
|
|
}
|
|
|
|
fn testError(codecs: Codecs, encoded: []const u8, expected_err: anyerror) !void {
|
|
const decoder_ignore_space = codecs.decoderWithIgnore(" ");
|
|
var buffer: [0x100]u8 = undefined;
|
|
if (codecs.Decoder.calcSizeForSlice(encoded)) |decoded_size| {
|
|
var decoded = buffer[0..decoded_size];
|
|
if (codecs.Decoder.decode(decoded, encoded)) |_| {
|
|
return error.ExpectedError;
|
|
} else |err| if (err != expected_err) return err;
|
|
} else |err| if (err != expected_err) return err;
|
|
|
|
if (decoder_ignore_space.decode(buffer[0..], encoded)) |_| {
|
|
return error.ExpectedError;
|
|
} else |err| if (err != expected_err) return err;
|
|
}
|
|
|
|
fn testNoSpaceLeftError(codecs: Codecs, encoded: []const u8) !void {
|
|
const decoder_ignore_space = codecs.decoderWithIgnore(" ");
|
|
var buffer: [0x100]u8 = undefined;
|
|
var decoded = buffer[0 .. (try codecs.Decoder.calcSizeForSlice(encoded)) - 1];
|
|
if (decoder_ignore_space.decode(decoded, encoded)) |_| {
|
|
return error.ExpectedError;
|
|
} else |err| if (err != error.NoSpaceLeft) return err;
|
|
}
|