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LibUnicode: Add Punycode::encode
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parent
299d35aadc
commit
cfd0a60863
Notes:
sideshowbarker
2024-07-16 22:16:50 +09:00
Author: https://github.com/skyrising Commit: https://github.com/SerenityOS/serenity/commit/cfd0a60863 Pull-request: https://github.com/SerenityOS/serenity/pull/19414 Reviewed-by: https://github.com/AtkinsSJ Reviewed-by: https://github.com/nico Reviewed-by: https://github.com/shannonbooth Reviewed-by: https://github.com/trflynn89
@ -47,4 +47,11 @@ TEST_CASE(decode)
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EXPECT(decode("Nåväl hej vänner"sv).is_error());
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}
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TEST_CASE(encode)
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{
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#define CASE(a, b) EXPECT_EQ(TRY_OR_FAIL(encode(a)), b);
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ENUMERATE_TEST_CASES
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#undef CASE
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}
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}
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@ -5,6 +5,7 @@
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*/
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#include <AK/Utf32View.h>
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#include <AK/Utf8View.h>
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#include <LibUnicode/Punycode.h>
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namespace Unicode::Punycode {
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@ -30,6 +31,14 @@ static Optional<u32> digit_value_of_code_point(u32 code_point)
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return {};
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}
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static u32 code_point_value_of_digit(u32 digit)
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{
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VERIFY(digit < 36);
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if (digit <= 25)
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return 'a' + digit;
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return '0' + digit - 26;
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}
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// https://www.rfc-editor.org/rfc/rfc3492.html#section-6.1
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static u32 adapt(u32 delta, u32 num_points, bool first_time)
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{
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@ -160,4 +169,118 @@ ErrorOr<String> decode(StringView input)
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return builder.to_string();
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}
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static Optional<u32> find_smallest_code_point_greater_than_or_equal(Utf32View code_points, u32 threshold)
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{
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Optional<u32> result;
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for (auto code_point : code_points) {
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if (code_point >= threshold && (!result.has_value() || code_point < result.value()))
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result = code_point;
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}
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return result;
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}
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ErrorOr<String> encode(StringView input)
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{
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Vector<u32> code_points;
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for (auto code_point : Utf8View(input))
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TRY(code_points.try_append(code_point));
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return encode(Utf32View(code_points.data(), code_points.size()));
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}
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// https://www.rfc-editor.org/rfc/rfc3492.html#section-6.3
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ErrorOr<String> encode(Utf32View input)
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{
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Vector<u32> output;
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// let n = initial_n
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Checked<size_t> n = INITIAL_N;
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// let delta = 0
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Checked<size_t> delta = 0;
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// let bias = initial_bias
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u32 bias = INITIAL_BIAS;
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// let h = b = the number of basic code points in the input
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// copy them to the output in order, followed by a delimiter if b > 0
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size_t b = 0;
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for (auto code_point : input) {
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if (is_ascii(code_point)) {
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TRY(output.try_append(code_point));
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b++;
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}
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}
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auto h = b;
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if (b > 0)
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TRY(output.try_append(DELIMITER));
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// while h < length(input) do begin
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while (h < input.length()) {
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// let m = the minimum {non-basic} code point >= n in the input
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auto m = find_smallest_code_point_greater_than_or_equal(input, n.value());
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VERIFY(m.has_value());
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// let delta = delta + (m - n) * (h + 1), fail on overflow
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delta = delta + (Checked(static_cast<size_t>(m.value())) - n) * Checked(h + 1);
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if (delta.has_overflow())
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return Error::from_string_literal("Numeric overflow");
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// let n = m
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n = m.value();
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// for each code point c in the input (in order) do begin
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for (auto c : input) {
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// if c < n {or c is basic} then increment delta, fail on overflow
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if (c < n.value()) {
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delta++;
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if (delta.has_overflow())
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return Error::from_string_literal("Numeric overflow");
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}
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// if c == n then begin
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if (c == n.value()) {
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// let q = delta
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auto q = delta.value();
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// for k = base to infinity in steps of base do begin
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for (size_t k = BASE;; k += BASE) {
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// let t = tmin if k <= bias {+ tmin}, or
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// tmax if k >= bias + tmax, or k - bias otherwise
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u32 t = k <= bias ? TMIN : (k >= bias + TMAX ? TMAX : k - bias);
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// if q < t then break
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if (q < t)
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break;
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// output the code point for digit t + ((q - t) mod (base - t))
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auto digit = t + ((q - t) % (BASE - t));
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TRY(output.try_append(code_point_value_of_digit(digit)));
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// let q = (q - t) div (base - t)
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q = (q - t) / (BASE - t);
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}
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// output the code point for digit q
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TRY(output.try_append(code_point_value_of_digit(q)));
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// let bias = adapt(delta, h + 1, test h equals b?)
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bias = adapt(delta.value(), h + 1, h == b);
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// let delta = 0
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delta = 0;
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// increment h
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h++;
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}
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}
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// increment delta and n
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delta++;
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n++;
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}
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StringBuilder builder;
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TRY(builder.try_append(Utf32View(output.data(), output.size())));
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return builder.to_string();
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}
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}
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@ -11,5 +11,7 @@
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namespace Unicode::Punycode {
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ErrorOr<String> decode(StringView);
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ErrorOr<String> encode(StringView);
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ErrorOr<String> encode(Utf32View);
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}
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