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Remove duplicated code to detect Rust keywords/identifiers #24

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Jun 23, 2024
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Remove duplicated code to detect Rust keywords/identifiers #24

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91 changes: 6 additions & 85 deletions rinja_derive/src/generator.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2285,84 +2285,6 @@ struct WritePartsBuffers {
expr: Option<Buffer>,
}

const MAX_KW_LEN: usize = 8;
const MAX_REPL_LEN: usize = MAX_KW_LEN + 2;
const KWS: &[&[[u8; MAX_REPL_LEN]]] = {
// FIXME: Replace `u8` with `[core:ascii::Char; MAX_REPL_LEN]` once
// <https://github.com/rust-lang/rust/issues/110998> is stable.

const KW0: &[[u8; MAX_REPL_LEN]] = &[];
const KW1: &[[u8; MAX_REPL_LEN]] = &[];
const KW2: &[[u8; MAX_REPL_LEN]] = &[
*b"r#as______",
*b"r#do______",
*b"r#fn______",
*b"r#if______",
*b"r#in______",
];
const KW3: &[[u8; MAX_REPL_LEN]] = &[
*b"r#box_____",
*b"r#dyn_____",
*b"r#for_____",
*b"r#let_____",
*b"r#mod_____",
*b"r#mut_____",
*b"r#pub_____",
*b"r#ref_____",
*b"r#try_____",
*b"r#use_____",
];
const KW4: &[[u8; MAX_REPL_LEN]] = &[
*b"r#else____",
*b"r#enum____",
*b"r#impl____",
*b"r#move____",
*b"r#priv____",
*b"r#true____",
*b"r#type____",
];
const KW5: &[[u8; MAX_REPL_LEN]] = &[
*b"r#async___",
*b"r#await___",
*b"r#break___",
*b"r#const___",
*b"r#crate___",
*b"r#false___",
*b"r#final___",
*b"r#macro___",
*b"r#match___",
*b"r#trait___",
*b"r#where___",
*b"r#while___",
*b"r#yield___",
];
const KW6: &[[u8; MAX_REPL_LEN]] = &[
*b"r#become__",
*b"r#extern__",
*b"r#return__",
*b"r#static__",
*b"r#struct__",
*b"r#typeof__",
*b"r#unsafe__",
];
const KW7: &[[u8; MAX_REPL_LEN]] = &[*b"r#unsized_", *b"r#virtual_"];
const KW8: &[[u8; MAX_REPL_LEN]] = &[*b"r#abstract", *b"r#continue", *b"r#override"];

&[KW0, KW1, KW2, KW3, KW4, KW5, KW6, KW7, KW8]
};

/// Ensure that all strings are UTF-8, because we use `from_utf8_unchecked()` further down.
#[test]
fn ensure_utf8() {
for kws in KWS {
for kw in *kws {
if std::str::from_utf8(kw).is_err() {
panic!("not UTF-8: {:?}", kw);
}
}
}
}

/// Identifiers to be replaced with raw identifiers, so as to avoid
/// collisions between template syntax and Rust's syntax. In particular
/// [Rust keywords](https://doc.rust-lang.org/reference/keywords.html)
Expand All @@ -2380,19 +2302,18 @@ fn normalize_identifier(ident: &str) -> &str {
// While the code does not need it, please keep the list sorted when adding new
// keywords.

if ident.len() > MAX_KW_LEN {
if ident.len() > parser::node::MAX_KW_LEN {
return ident;
}
let kws = KWS[ident.len()];
let kws = parser::node::KWS[ident.len()];

let mut padded_ident = [b'_'; MAX_KW_LEN];
let mut padded_ident = [b'_'; parser::node::MAX_KW_LEN];
padded_ident[..ident.len()].copy_from_slice(ident.as_bytes());

// Since the individual buckets are quite short, a linear search is faster than a binary search.
let replacement = match kws
.iter()
.find(|probe| padded_ident == <[u8; MAX_KW_LEN]>::try_from(&probe[2..]).unwrap())
{
let replacement = match kws.iter().find(|probe| {
padded_ident == <[u8; parser::node::MAX_KW_LEN]>::try_from(&probe[2..]).unwrap()
}) {
Some(replacement) => replacement,
None => return ident,
};
Expand Down
179 changes: 106 additions & 73 deletions rinja_parser/src/node.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1203,97 +1203,130 @@ impl<'a> Comment<'a> {
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Ws(pub Option<Whitespace>, pub Option<Whitespace>);

const MAX_KW_LEN: usize = 8;
const KWS: &[&[[u8; MAX_KW_LEN]]] = {
#[doc(hidden)]
pub const MAX_KW_LEN: usize = 8;
const MAX_REPL_LEN: usize = MAX_KW_LEN + 2;
#[doc(hidden)]
pub const KWS: &[&[[u8; MAX_REPL_LEN]]] = {
// FIXME: Replace `u8` with `[core:ascii::Char; MAX_REPL_LEN]` once
// <https://github.com/rust-lang/rust/issues/110998> is stable.

const KW0: &[[u8; MAX_KW_LEN]] = &[];
const KW1: &[[u8; MAX_KW_LEN]] = &[];
const KW2: &[[u8; MAX_KW_LEN]] = &[
*b"as______",
*b"do______",
*b"fn______",
*b"if______",
*b"in______",
const KW2: &[[u8; MAX_REPL_LEN]] = &[
*b"r#as______",
*b"r#do______",
*b"r#fn______",
*b"r#if______",
*b"r#in______",
];
const KW3: &[[u8; MAX_KW_LEN]] = &[
*b"box_____",
*b"dyn_____",
*b"for_____",
*b"let_____",
*b"mod_____",
*b"mut_____",
*b"pub_____",
*b"ref_____",
*b"try_____",
*b"use_____",
const KW3: &[[u8; MAX_REPL_LEN]] = &[
*b"r#box_____",
*b"r#dyn_____",
*b"r#for_____",
*b"r#let_____",
*b"r#mod_____",
*b"r#mut_____",
*b"r#pub_____",
*b"r#ref_____",
*b"r#try_____",
*b"r#use_____",
];
const KW4: &[[u8; MAX_KW_LEN]] = &[
*b"else____",
*b"enum____",
*b"impl____",
*b"loop____",
*b"move____",
*b"priv____",
*b"self____",
*b"Self____",
*b"true____",
*b"type____",
const KW4: &[[u8; MAX_REPL_LEN]] = &[
*b"r#else____",
*b"r#enum____",
*b"r#impl____",
*b"r#move____",
*b"r#priv____",
*b"r#true____",
*b"r#type____",
];
const KW5: &[[u8; MAX_KW_LEN]] = &[
*b"async___",
*b"await___",
*b"break___",
*b"const___",
*b"crate___",
*b"false___",
*b"final___",
*b"macro___",
*b"match___",
*b"super___",
*b"trait___",
*b"union___",
*b"where___",
*b"while___",
*b"yield___",
const KW5: &[[u8; MAX_REPL_LEN]] = &[
*b"r#async___",
*b"r#await___",
*b"r#break___",
*b"r#const___",
*b"r#crate___",
*b"r#false___",
*b"r#final___",
*b"r#macro___",
*b"r#match___",
*b"r#trait___",
*b"r#where___",
*b"r#while___",
*b"r#yield___",
];
const KW6: &[[u8; MAX_KW_LEN]] = &[
*b"become__",
*b"extern__",
*b"return__",
*b"static__",
*b"struct__",
*b"typeof__",
*b"unsafe__",
const KW6: &[[u8; MAX_REPL_LEN]] = &[
*b"r#become__",
*b"r#extern__",
*b"r#return__",
*b"r#static__",
*b"r#struct__",
*b"r#typeof__",
*b"r#unsafe__",
];
const KW7: &[[u8; MAX_KW_LEN]] = &[*b"unsized_", *b"virtual_"];
const KW8: &[[u8; MAX_KW_LEN]] = &[*b"abstract", *b"continue", *b"override"];
const KW7: &[[u8; MAX_REPL_LEN]] = &[*b"r#unsized_", *b"r#virtual_"];
const KW8: &[[u8; MAX_REPL_LEN]] = &[*b"r#abstract", *b"r#continue", *b"r#override"];

&[KW0, KW1, KW2, KW3, KW4, KW5, KW6, KW7, KW8]
&[&[], &[], KW2, KW3, KW4, KW5, KW6, KW7, KW8]
};

/// Ensure that all strings are UTF-8, because we use `from_utf8_unchecked()` further down.
#[test]
fn ensure_utf8() {
for kws in KWS {
for kw in *kws {
if std::str::from_utf8(kw).is_err() {
panic!("not UTF-8: {:?}", kw);
}
}
}
}
// These ones are only used in the parser, hence why they're private.
const KWS_EXTRA: &[&[[u8; MAX_REPL_LEN]]] = {
const KW4: &[[u8; MAX_REPL_LEN]] = &[*b"r#loop____", *b"r#self____", *b"r#Self____"];
const KW5: &[[u8; MAX_REPL_LEN]] = &[*b"r#super___", *b"r#union___"];

&[&[], &[], &[], &[], KW4, KW5, &[], &[], &[]]
};

fn is_rust_keyword(ident: &str) -> bool {
fn is_rust_keyword_inner(
kws: &[&[[u8; MAX_REPL_LEN]]],
padded_ident: &[u8; MAX_KW_LEN],
ident_len: usize,
) -> bool {
// Since the individual buckets are quite short, a linear search is faster than a binary search.
kws[ident_len]
.iter()
.any(|&probe| padded_ident == &probe[2..])
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Collaborator

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Interesting! You are right, the

padded_ident == <[u8; parser::node::MAX_KW_LEN]>::try_from(&probe[2..]).unwrap()

"optimization" is not needed anymore, and now the same code generated with and without it. When I first wrote the search, it was still needed because otherwise the assembly would needlessly contain length checks.

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Oh interesting. I checked and couldn't find out why it was needed. I suppose rustc/LLVM got better.

}
if ident.len() > MAX_KW_LEN {
return false;
}
let kws = KWS[ident.len()];
let ident_len = ident.len();

let mut padded_ident = [b'_'; MAX_KW_LEN];
padded_ident[..ident.len()].copy_from_slice(ident.as_bytes());

// Since the individual buckets are quite short, a linear search is faster than a binary search.
kws.iter().any(|&probe| padded_ident == probe)
is_rust_keyword_inner(KWS, &padded_ident, ident_len)
|| is_rust_keyword_inner(KWS_EXTRA, &padded_ident, ident_len)
}

#[cfg(test)]
mod kws_tests {
use super::{is_rust_keyword, KWS, KWS_EXTRA, MAX_REPL_LEN};

fn ensure_utf8_inner(entry: &[&[[u8; MAX_REPL_LEN]]]) {
for kws in entry {
for kw in *kws {
if std::str::from_utf8(kw).is_err() {
panic!("not UTF-8: {:?}", kw);
}
}
}
}

// Ensure that all strings are UTF-8, because we use `from_utf8_unchecked()` further down.
#[test]
fn ensure_utf8() {
assert_eq!(KWS.len(), KWS_EXTRA.len());
ensure_utf8_inner(KWS);
ensure_utf8_inner(KWS_EXTRA);
}

#[test]
fn test_is_rust_keyword() {
assert!(is_rust_keyword("super"));
assert!(is_rust_keyword("become"));
assert!(!is_rust_keyword("supeeeer"));
assert!(!is_rust_keyword("sur"));
}
}
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