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<!--- Thank you for contributing to Boa! Please fill out the template below, and remove or add any information as you feel necessary. ---> This Pull Request implements the [`escape`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/escape) and [`unescape`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/unescape) functions. Both are technically deprecated, but they're also part of the [Additional ECMAScript Features for Web Browsers](https://tc39.es/ecma262/#sec-additional-ecmascript-features-for-web-browsers) section, so it is preferable to have them in place.pull/2780/head
José Julián Espina
2 years ago
8 changed files with 308 additions and 5 deletions
@ -0,0 +1,256 @@
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//! Boa's implementation of ECMAScript's string escaping functions.
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//!
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//! The `escape()` function replaces all characters with escape sequences, with the exception of ASCII
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//! word characters (A–Z, a–z, 0–9, _) and @*_+-./.
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//!
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//! The `unescape()` function replaces any escape sequence with the character that it represents.
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//!
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//! More information:
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//! - [ECMAScript reference][spec]
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//!
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//! [spec]: https://tc39.es/ecma262/#sec-additional-properties-of-the-global-object
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use crate::{ |
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context::intrinsics::Intrinsics, js_string, Context, JsArgs, JsObject, JsResult, JsValue, |
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}; |
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use super::{BuiltInBuilder, BuiltInObject, IntrinsicObject}; |
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/// The `escape` function
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#[derive(Debug, Clone, Copy)] |
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pub(crate) struct Escape; |
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impl IntrinsicObject for Escape { |
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fn init(intrinsics: &Intrinsics) { |
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BuiltInBuilder::with_intrinsic::<Self>(intrinsics) |
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.callable(escape) |
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.name(Self::NAME) |
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.length(1) |
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.build(); |
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} |
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fn get(intrinsics: &Intrinsics) -> JsObject { |
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intrinsics.objects().escape().into() |
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} |
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} |
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impl BuiltInObject for Escape { |
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const NAME: &'static str = "escape"; |
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} |
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/// Builtin JavaScript `escape ( string )` function.
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fn escape(_: &JsValue, args: &[JsValue], context: &mut Context<'_>) -> JsResult<JsValue> { |
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/// Returns `true` if the codepoint `cp` is part of the `unescapedSet`.
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fn is_unescaped(cp: u16) -> bool { |
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let Ok(cp) = TryInto::<u8>::try_into(cp) else { |
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return false; |
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}; |
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// 4. Let unescapedSet be the string-concatenation of the ASCII word characters and "@*+-./".
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cp.is_ascii_alphanumeric() || [b'_', b'@', b'*', b'+', b'-', b'.', b'/'].contains(&cp) |
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} |
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// 1. Set string to ? ToString(string).
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let string = args.get_or_undefined(0).to_string(context)?; |
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// 3. Let R be the empty String.
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let mut vec = Vec::with_capacity(string.len()); |
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// 2. Let len be the length of string.
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// 5. Let k be 0.
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// 6. Repeat, while k < len,
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// a. Let C be the code unit at index k within string.
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for &cp in &*string { |
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// b. If unescapedSet contains C, then
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if is_unescaped(cp) { |
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// i. Let S be C.
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vec.push(cp); |
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continue; |
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} |
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// c. Else,
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// i. Let n be the numeric value of C.
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// ii. If n < 256, then
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let c = if cp < 256 { |
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// 1. Let hex be the String representation of n, formatted as an uppercase hexadecimal number.
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// 2. Let S be the string-concatenation of "%" and ! StringPad(hex, 2𝔽, "0", start).
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format!("%{cp:02X}") |
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} |
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// iii. Else,
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else { |
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// 1. Let hex be the String representation of n, formatted as an uppercase hexadecimal number.
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// 2. Let S be the string-concatenation of "%u" and ! StringPad(hex, 4𝔽, "0", start).
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format!("%u{cp:04X}") |
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}; |
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// d. Set R to the string-concatenation of R and S.
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// e. Set k to k + 1.
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vec.extend(c.encode_utf16()); |
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} |
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// 7. Return R.
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Ok(js_string!(vec).into()) |
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} |
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/// The `unescape` function
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#[derive(Debug, Clone, Copy)] |
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pub(crate) struct Unescape; |
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impl IntrinsicObject for Unescape { |
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fn init(intrinsics: &Intrinsics) { |
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BuiltInBuilder::with_intrinsic::<Self>(intrinsics) |
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.callable(unescape) |
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.name(Self::NAME) |
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.length(1) |
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.build(); |
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} |
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fn get(intrinsics: &Intrinsics) -> JsObject { |
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intrinsics.objects().unescape().into() |
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} |
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} |
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impl BuiltInObject for Unescape { |
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const NAME: &'static str = "unescape"; |
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} |
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/// Builtin JavaScript `unescape ( string )` function.
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fn unescape(_: &JsValue, args: &[JsValue], context: &mut Context<'_>) -> JsResult<JsValue> { |
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/// Converts a char `cp` to its corresponding hex digit value.
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fn to_hex_digit(cp: u16) -> Option<u16> { |
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char::from_u32(u32::from(cp)) |
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.and_then(|c| c.to_digit(16)) |
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.and_then(|d| d.try_into().ok()) |
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} |
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// 1. Set string to ? ToString(string).
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let string = args.get_or_undefined(0).to_string(context)?; |
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// 3. Let R be the empty String.
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let mut vec = Vec::with_capacity(string.len()); |
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let mut codepoints = <PeekableN<_, 6>>::new(string.iter().copied()); |
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// 2. Let len be the length of string.
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// 4. Let k be 0.
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// 5. Repeat, while k < len,
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loop { |
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// a. Let C be the code unit at index k within string.
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let Some(cp) = codepoints.next() else { |
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break; |
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}; |
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// b. If C is the code unit 0x0025 (PERCENT SIGN), then
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if cp != u16::from(b'%') { |
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vec.push(cp); |
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continue; |
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} |
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// i. Let hexDigits be the empty String.
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// ii. Let optionalAdvance be 0.
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// TODO: Try blocks :(
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let Some(unescaped_cp) = (|| match *codepoints.peek_n(5) { |
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// iii. If k + 5 < len and the code unit at index k + 1 within string is the code unit
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// 0x0075 (LATIN SMALL LETTER U), then
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[u, n1, n2, n3, n4] if u == u16::from(b'u') => { |
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// 1. Set hexDigits to the substring of string from k + 2 to k + 6.
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// 2. Set optionalAdvance to 5.
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let n1 = to_hex_digit(n1)?; |
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let n2 = to_hex_digit(n2)?; |
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let n3 = to_hex_digit(n3)?; |
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let n4 = to_hex_digit(n4)?; |
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// TODO: https://github.com/rust-lang/rust/issues/77404
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for _ in 0..5 { |
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codepoints.next(); |
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} |
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Some((n1 << 12) + (n2 << 8) + (n3 << 4) + n4) |
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} |
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// iv. Else if k + 3 ≤ len, then
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[n1, n2, ..] => { |
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// 1. Set hexDigits to the substring of string from k + 1 to k + 3.
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// 2. Set optionalAdvance to 2.
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let n1 = to_hex_digit(n1)?; |
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let n2 = to_hex_digit(n2)?; |
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// TODO: https://github.com/rust-lang/rust/issues/77404
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for _ in 0..2 { |
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codepoints.next(); |
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} |
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Some((n1 << 4) + n2) |
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} |
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_ => None |
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})() else { |
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vec.push(u16::from(b'%')); |
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continue; |
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}; |
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// v. Let parseResult be ParseText(StringToCodePoints(hexDigits), HexDigits[~Sep]).
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// vi. If parseResult is a Parse Node, then
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// 1. Let n be the MV of parseResult.
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// 2. Set C to the code unit whose numeric value is n.
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// 3. Set k to k + optionalAdvance.
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// c. Set R to the string-concatenation of R and C.
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// d. Set k to k + 1.
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vec.push(unescaped_cp); |
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} |
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// 6. Return R.
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Ok(js_string!(vec).into()) |
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} |
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/// An iterator that can peek `N` items.
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struct PeekableN<I, const N: usize> |
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where |
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I: Iterator, |
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{ |
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iterator: I, |
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buffer: [I::Item; N], |
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buffered_end: usize, |
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} |
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impl<I, const N: usize> PeekableN<I, N> |
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where |
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I: Iterator, |
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I::Item: Default + Copy, |
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{ |
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/// Creates a new `PeekableN`.
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fn new(iterator: I) -> Self { |
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Self { |
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iterator, |
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buffer: [I::Item::default(); N], |
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buffered_end: 0, |
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} |
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} |
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/// Peeks `n` items from the iterator.
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fn peek_n(&mut self, count: usize) -> &[I::Item] { |
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if count <= self.buffered_end { |
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return &self.buffer[..count]; |
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} |
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for _ in 0..(count - self.buffered_end) { |
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let Some(next) = self.iterator.next() else { |
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return &self.buffer[..self.buffered_end]; |
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}; |
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self.buffer[self.buffered_end] = next; |
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self.buffered_end += 1; |
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} |
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&self.buffer[..count] |
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} |
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} |
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impl<I, const N: usize> Iterator for PeekableN<I, N> |
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where |
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I: Iterator, |
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I::Item: Copy, |
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{ |
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type Item = I::Item; |
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fn next(&mut self) -> Option<Self::Item> { |
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if self.buffered_end > 0 { |
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let item = self.buffer[0]; |
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self.buffer.rotate_left(1); |
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self.buffered_end -= 1; |
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return Some(item); |
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} |
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self.iterator.next() |
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} |
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} |
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