Switch parser to multi-byte processing

This patch overhauls the `Parser::advance` API to operate on byte slices
instead of individual bytes, which allows for additional performance
optimizations.

VTE does not support C1 escapes and C0 escapes always start with an
escape character. This makes it possible to simplify processing if a
byte stream is determined to not contain any escapes. The `memchr` crate
provides a battle-tested implementation for SIMD-accelerated byte
searches, which is why this implementation makes use of it.

VTE also only supports UTF8 characters in the ground state, which means
that the new non-escape parsing path is able to rely completely on STD's
`str::from_utf8` since `memchr` gives us the full length of the plain
text character buffer. This allows us to completely remove `utf8parse`
and all related code.

We also make use of `memchr` in the synchronized escape handling in
`ansi.rs`, since it relies heavily on scanning large amounts of text for
the extension/termination escape sequences.

1 files changed, 0 insertions, 132 deletions

diff --git a/utf8parse/src/lib.rs b/utf8parse/src/lib.rs
deleted file mode 100644
index 093de81..0000000
--- a/utf8parse/src/lib.rs
+++ /dev/null
@@ -1,132 +0,0 @@
-//! A table-driven UTF-8 Parser
-//!
-//! This module implements a table-driven UTF-8 parser which should
-//! theoretically contain the minimal number of branches (1). The only branch is
-//! on the `Action` returned from unpacking a transition.
-#![deny(clippy::all, clippy::if_not_else, clippy::enum_glob_use)]
-#![cfg_attr(all(feature = "nightly", test), feature(test))]
-#![no_std]
-
-use core::char;
-
-mod types;
-
-use types::{Action, State};
-
-/// Handles codepoint and invalid sequence events from the parser.
-pub trait Receiver {
-    /// Called whenever a codepoint is parsed successfully
-    fn codepoint(&mut self, _: char);
-
-    /// Called when an invalid_sequence is detected
-    fn invalid_sequence(&mut self);
-}
-
-/// A parser for Utf8 Characters
-///
-/// Repeatedly call `advance` with bytes to emit Utf8 characters
-#[derive(Clone, Default, PartialEq, Eq, Debug)]
-pub struct Parser {
-    point: u32,
-    state: State,
-}
-
-/// Continuation bytes are masked with this value.
-const CONTINUATION_MASK: u8 = 0b0011_1111;
-
-impl Parser {
-    /// Create a new Parser
-    pub fn new() -> Parser {
-        Parser { point: 0, state: State::Ground }
-    }
-
-    /// Advance the parser
-    ///
-    /// The provider receiver will be called whenever a codepoint is completed or an invalid
-    /// sequence is detected.
-    pub fn advance<R>(&mut self, receiver: &mut R, byte: u8)
-    where
-        R: Receiver,
-    {
-        let (state, action) = self.state.advance(byte);
-        self.perform_action(receiver, byte, action);
-        self.state = state;
-    }
-
-    fn perform_action<R>(&mut self, receiver: &mut R, byte: u8, action: Action)
-    where
-        R: Receiver,
-    {
-        match action {
-            Action::InvalidSequence => {
-                self.point = 0;
-                receiver.invalid_sequence();
-            },
-            Action::EmitByte => {
-                receiver.codepoint(byte as char);
-            },
-            Action::SetByte1 => {
-                let point = self.point | ((byte & CONTINUATION_MASK) as u32);
-                let c = unsafe { char::from_u32_unchecked(point) };
-                self.point = 0;
-
-                receiver.codepoint(c);
-            },
-            Action::SetByte2 => {
-                self.point |= ((byte & CONTINUATION_MASK) as u32) << 6;
-            },
-            Action::SetByte2Top => {
-                self.point |= ((byte & 0b0001_1111) as u32) << 6;
-            },
-            Action::SetByte3 => {
-                self.point |= ((byte & CONTINUATION_MASK) as u32) << 12;
-            },
-            Action::SetByte3Top => {
-                self.point |= ((byte & 0b0000_1111) as u32) << 12;
-            },
-            Action::SetByte4 => {
-                self.point |= ((byte & 0b0000_0111) as u32) << 18;
-            },
-        }
-    }
-}
-
-#[cfg(all(feature = "nightly", test))]
-mod benches {
-    extern crate std;
-    extern crate test;
-
-    use super::{Parser, Receiver};
-
-    use self::test::{black_box, Bencher};
-
-    static UTF8_DEMO: &[u8] = include_bytes!("../tests/UTF-8-demo.txt");
-
-    impl Receiver for () {
-        fn codepoint(&mut self, c: char) {
-            black_box(c);
-        }
-
-        fn invalid_sequence(&mut self) {}
-    }
-
-    #[bench]
-    fn parse_bench_utf8_demo(b: &mut Bencher) {
-        let mut parser = Parser::new();
-
-        b.iter(|| {
-            for byte in UTF8_DEMO {
-                parser.advance(&mut (), *byte);
-            }
-        })
-    }
-
-    #[bench]
-    fn std_string_parse_utf8(b: &mut Bencher) {
-        b.iter(|| {
-            for c in std::str::from_utf8(UTF8_DEMO).unwrap().chars() {
-                black_box(c);
-            }
-        });
-    }
-}