Ensure the oxide parser has feature parity with the stable RegEx parser (tailwindlabs#11389)

* WIP

* use `parse` instead of `defaultExtractor`

* skip `Vue` describe block

* add a few more dedicated arbitrary values/properties tests

* use parallel parsing

* splitup Vue tests

* add some Rust specific tests

* setup parse candidate strings test system

These tests will run against the `Regex` and `Rust` based parsers. We
have groups of classes of various shapes and forms + variants and
rendered in various template situation (plain, html, Vue, ...)

+ enable all skipped tests

* ensure we also validate the classes with variants

The classes with variants are built in the `templateTable` function, so
we get them out again by using the potional arguments of the `test.each`
cb function.

* cleanup test suite

* add "anti-test" tests

To make sure that we are _not_ parsing out certain values given a
certain input.

* Add ParseAction enum

* Restart parsing following an arbitrary parse failure

* Split variants off before validating the uility part

* Collapse candidate from the end when validation fails

* Support `<`, and `>` in variant position

* fix error

* format parser.rs

* Refactor

* Update editorconfig

* wip

* wip

* Refactor

* Refactor

* Simplify

* wip

* wip

* wip

* wip

* wip

* wip

* wip

* run `cargo clippy --fix`

* run `cargo fmt`

* implement `cargo clippy` suggestions

These were not applied using `cargo clippy --fix`

* only allow `.` in the candidate part when surrounded by 0-9

This is only in the candidate part, not the arbitrary part.

* % characters can only appear at the end after digits

* > and < should only be part of variants (start OR end)

It can technically be inside the candidate when we have stacked
variants:
```
dark:<sm:underline
dark:md>:underline
```

* handle parsing utilities within quotes, parans or brackets

* mark `pt-1.5` as an expected value sliced out from `["pt-1.5"]`

* Add cursor abstraction

* wip

* disable the oxideParser if using a custom `prefix` or `separator`

* update tests

* Use cursor abstraction

* Refactor more code toward use of global cursor

* wip

* simplify

* Simplify

* Simplify

* Simplify

* Cleanup

* wip

* Simplify

* wip

* Simplify

* Handle candidates ending with % sign

* Tweak code a bit

* fmt

* Simplify

* Add cursor details to trace

* cargo fmt

* use preferred `zoom-0.5` name instead of `zoom-.5`

* drop over-extracted utilities in oxide parser

The RegEx parser does extract `underline` from

```html
<div class="peer-aria-[labelledby='a_b']:underline"></div>
```
... but that's not needed and is not happening in the oxide parser

This means that we have to make the output check a little bit different
but they are explicit based on the feature flag.

* allow extracting variants+utilities inside `{}` for the oxide parser

* characters in candidates such as `group-${id}` should not be allowed

* do not extract any of the following candidate `w-[foo-bar]w-[bar-baz]`

* ensure we can consume the full candidate and discard it

* Add fast skipping of whitespace

* Use fast skipping whenever possible

* Add fast skipping to benchmark

* Hand-tune to generate more optimized assembly

* Move code around a bit

This makes sure all the fancy SIMD stuff is as early as possible. This results in an extremely minor perf increase.

* Undo tweak

no meaningful perf difference in real world scenarios

* Disable fast skipping for now

It needs to be done in a different spot so it doesn’t affect how things are returned

* Change test names

* Fix normalize config error

* cleanup a bit

* Cleanup

* Extract validation result enum

* Cleanup comments

* Simplify

* Fix formatting

* Run clippy

* wip

* add `md>` under the special characters test set

---------

Co-authored-by: Adam Wathan <4323180+adamwathan@users.noreply.github.com>
Co-authored-by: Jordan Pittman <jordan@cryptica.me>

Author: 3 people

.editorconfig

@@ -7,3 +7,11 @@ end_of_line = lf
 charset = utf-8
 trim_trailing_whitespace = true
 insert_final_newline = true
+
+[*.rs]
+indent_style = space
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true

oxide/crates/core/benches/parse_candidates.rs

@@ -31,6 +31,18 @@ pub fn criterion_benchmark(c: &mut Criterion) {
     c.bench_function("parse_candidate_strings (real world)", |b| {
         b.iter(|| parse(include_bytes!("./fixtures/template-499.html")))
     });
+
+    let mut group = c.benchmark_group("sample-size-example");
+    group.sample_size(10);
+
+    group.bench_function("parse_candidate_strings (fast space skipping)", |b| {
+        let count = 10_000;
+        let crazy1 = format!("{}underline", " ".repeat(count));
+        let crazy2 = crazy1.repeat(count);
+        let crazy3 = crazy2.as_bytes();
+
+        b.iter(|| parse(black_box(crazy3)))
+    });
 }
 
 criterion_group!(benches, criterion_benchmark);

oxide/crates/core/src/cursor.rs

@@ -0,0 +1,159 @@
+use std::{ascii::escape_default, fmt::Display};
+
+#[derive(Debug, Clone)]
+pub struct Cursor<'a> {
+    // The input we're scanning
+    pub input: &'a [u8],
+
+    // The location of the cursor in the input
+    pub pos: usize,
+
+    /// Is the cursor at the start of the input
+    pub at_start: bool,
+
+    /// Is the cursor at the end of the input
+    pub at_end: bool,
+
+    /// The previously consumed character
+    /// If `at_start` is true, this will be NUL
+    pub prev: u8,
+
+    /// The current character
+    pub curr: u8,
+
+    /// The upcoming character (if any)
+    /// If `at_end` is true, this will be NUL
+    pub next: u8,
+}
+
+impl<'a> Cursor<'a> {
+    pub fn new(input: &'a [u8]) -> Self {
+        let mut cursor = Self {
+            input,
+            pos: 0,
+            at_start: true,
+            at_end: false,
+            prev: 0x00,
+            curr: 0x00,
+            next: 0x00,
+        };
+        cursor.move_to(0);
+        cursor
+    }
+
+    pub fn rewind_by(&mut self, amount: usize) {
+        self.move_to(self.pos.saturating_sub(amount));
+    }
+
+    pub fn advance_by(&mut self, amount: usize) {
+        self.move_to(self.pos.saturating_add(amount));
+    }
+
+    pub fn move_to(&mut self, pos: usize) {
+        let len = self.input.len();
+        let pos = pos.clamp(0, len);
+
+        self.pos = pos;
+        self.at_start = pos == 0;
+        self.at_end = pos + 1 >= len;
+
+        self.prev = if pos > 0 { self.input[pos - 1] } else { 0x00 };
+        self.curr = if pos < len { self.input[pos] } else { 0x00 };
+        self.next = if pos + 1 < len {
+            self.input[pos + 1]
+        } else {
+            0x00
+        };
+    }
+}
+
+impl<'a> Display for Cursor<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let len = self.input.len().to_string();
+
+        let pos = format!("{: >len_count$}", self.pos, len_count = len.len());
+        write!(f, "{}/{} ", pos, len)?;
+
+        if self.at_start {
+            write!(f, "S ")?;
+        } else if self.at_end {
+            write!(f, "E ")?;
+        } else {
+            write!(f, "M ")?;
+        }
+
+        fn to_str(c: u8) -> String {
+            if c == 0x00 {
+                "NUL".into()
+            } else {
+                format!("{:?}", escape_default(c).to_string())
+            }
+        }
+
+        write!(
+            f,
+            "[{} {} {}]",
+            to_str(self.prev),
+            to_str(self.curr),
+            to_str(self.next)
+        )
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_cursor() {
+        let mut cursor = Cursor::new(b"hello world");
+        assert_eq!(cursor.pos, 0);
+        assert!(cursor.at_start);
+        assert!(!cursor.at_end);
+        assert_eq!(cursor.prev, 0x00);
+        assert_eq!(cursor.curr, b'h');
+        assert_eq!(cursor.next, b'e');
+
+        cursor.advance_by(1);
+        assert_eq!(cursor.pos, 1);
+        assert!(!cursor.at_start);
+        assert!(!cursor.at_end);
+        assert_eq!(cursor.prev, b'h');
+        assert_eq!(cursor.curr, b'e');
+        assert_eq!(cursor.next, b'l');
+
+        // Advancing too far should stop at the end
+        cursor.advance_by(10);
+        assert_eq!(cursor.pos, 11);
+        assert!(!cursor.at_start);
+        assert!(cursor.at_end);
+        assert_eq!(cursor.prev, b'd');
+        assert_eq!(cursor.curr, 0x00);
+        assert_eq!(cursor.next, 0x00);
+
+        // Can't advance past the end
+        cursor.advance_by(1);
+        assert_eq!(cursor.pos, 11);
+        assert!(!cursor.at_start);
+        assert!(cursor.at_end);
+        assert_eq!(cursor.prev, b'd');
+        assert_eq!(cursor.curr, 0x00);
+        assert_eq!(cursor.next, 0x00);
+
+        cursor.rewind_by(1);
+        assert_eq!(cursor.pos, 10);
+        assert!(!cursor.at_start);
+        assert!(cursor.at_end);
+        assert_eq!(cursor.prev, b'l');
+        assert_eq!(cursor.curr, b'd');
+        assert_eq!(cursor.next, 0x00);
+
+        cursor.rewind_by(10);
+        assert_eq!(cursor.pos, 0);
+        assert!(cursor.at_start);
+        assert!(!cursor.at_end);
+        assert_eq!(cursor.prev, 0x00);
+        assert_eq!(cursor.curr, b'h');
+        assert_eq!(cursor.next, b'e');
+    }
+}

oxide/crates/core/src/fast_skip.rs

@@ -0,0 +1,89 @@
+use crate::cursor::Cursor;
+
+const STRIDE: usize = 16;
+type Mask = [bool; STRIDE];
+
+#[inline(always)]
+pub fn fast_skip(cursor: &Cursor) -> Option<usize> {
+    // If we don't have enough bytes left to check then bail early
+    if cursor.pos + STRIDE >= cursor.input.len() {
+        return None;
+    }
+
+    if !cursor.curr.is_ascii_whitespace() {
+        return None;
+    }
+
+    let mut offset = 1;
+
+    // SAFETY: We've already checked (indirectly) that this index is valid
+    let remaining = unsafe { cursor.input.get_unchecked(cursor.pos..) };
+
+    // NOTE: This loop uses primitives designed to be auto-vectorized
+    // Do not change this loop without benchmarking the results
+    // And checking the generated assembly using godbolt.org
+    for (i, chunk) in remaining.chunks_exact(STRIDE).enumerate() {
+        let value = load(chunk);
+        let is_whitespace = is_ascii_whitespace(value);
+        let is_all_whitespace = all_true(is_whitespace);
+
+        if is_all_whitespace {
+            offset = (i + 1) * STRIDE;
+        } else {
+            break;
+        }
+    }
+
+    Some(cursor.pos + offset)
+}
+
+#[inline(always)]
+fn load(input: &[u8]) -> [u8; STRIDE] {
+    let mut value = [0u8; STRIDE];
+    value.copy_from_slice(input);
+    value
+}
+
+#[inline(always)]
+fn eq(input: [u8; STRIDE], val: u8) -> Mask {
+    let mut res = [false; STRIDE];
+    for n in 0..STRIDE {
+        res[n] = input[n] == val
+    }
+    res
+}
+
+#[inline(always)]
+fn or(a: [bool; STRIDE], b: [bool; STRIDE]) -> [bool; STRIDE] {
+    let mut res = [false; STRIDE];
+    for n in 0..STRIDE {
+        res[n] = a[n] | b[n];
+    }
+    res
+}
+
+#[inline(always)]
+fn all_true(a: [bool; STRIDE]) -> bool {
+    let mut res = true;
+    for item in a.iter().take(STRIDE) {
+        res &= item;
+    }
+    res
+}
+
+#[inline(always)]
+fn is_ascii_whitespace(value: [u8; STRIDE]) -> [bool; STRIDE] {
+    let whitespace_1 = eq(value, b'\t');
+    let whitespace_2 = eq(value, b'\n');
+    let whitespace_3 = eq(value, b'\x0C');
+    let whitespace_4 = eq(value, b'\r');
+    let whitespace_5 = eq(value, b' ');
+
+    or(
+        or(
+            or(or(whitespace_1, whitespace_2), whitespace_3),
+            whitespace_4,
+        ),
+        whitespace_5,
+    )
+}

oxide/crates/core/src/lib.rs

@@ -9,6 +9,8 @@ use tracing::event;
 use walkdir::WalkDir;
 
 pub mod candidate;
+pub mod cursor;
+pub mod fast_skip;
 pub mod glob;
 pub mod location;
 pub mod modifier;