diff options
Diffstat (limited to 'vendor/logos-codegen/src/generator/fork.rs')
| -rw-r--r-- | vendor/logos-codegen/src/generator/fork.rs | 216 |
1 files changed, 0 insertions, 216 deletions
diff --git a/vendor/logos-codegen/src/generator/fork.rs b/vendor/logos-codegen/src/generator/fork.rs deleted file mode 100644 index 11d4eab2..00000000 --- a/vendor/logos-codegen/src/generator/fork.rs +++ /dev/null @@ -1,216 +0,0 @@ -use std::cmp::max; - -use fnv::FnvHashMap as Map; -use proc_macro2::TokenStream; -use quote::quote; - -use crate::generator::{Context, Generator}; -use crate::graph::{Fork, NodeId, Range}; -use crate::util::ToIdent; - -type Targets = Map<NodeId, Vec<Range>>; - -impl Generator<'_> { - pub fn generate_fork(&mut self, this: NodeId, fork: &Fork, mut ctx: Context) -> TokenStream { - let mut targets: Targets = Map::default(); - - for (range, then) in fork.branches() { - targets.entry(then).or_default().push(range); - } - let loops_to_self = self.meta[this].loop_entry_from.contains(&this); - - match targets.len() { - 1 if loops_to_self => return self.generate_fast_loop(fork, ctx), - 0..=2 => (), - _ => return self.generate_fork_jump_table(this, fork, targets, ctx), - } - let miss = ctx.miss(fork.miss, self); - let end = self.fork_end(this, &miss); - let (byte, read) = self.fork_read(this, end, &mut ctx); - let branches = targets.into_iter().map(|(id, ranges)| { - let next = self.goto(id, ctx.advance(1)); - - match *ranges { - [range] => { - quote!(#range => #next,) - } - [a, b] if a.is_byte() && b.is_byte() => { - quote!(#a | #b => #next,) - } - _ => { - let test = self.generate_test(ranges).clone(); - let next = self.goto(id, ctx.advance(1)); - - quote!(byte if #test(byte) => #next,) - } - } - }); - - quote! { - #read - - match #byte { - #(#branches)* - _ => #miss, - } - } - } - - fn generate_fork_jump_table( - &mut self, - this: NodeId, - fork: &Fork, - targets: Targets, - mut ctx: Context, - ) -> TokenStream { - let miss = ctx.miss(fork.miss, self); - let end = self.fork_end(this, &miss); - let (byte, read) = self.fork_read(this, end, &mut ctx); - - let mut table: [u8; 256] = [0; 256]; - let mut jumps = vec!["__".to_ident()]; - - let branches = targets - .into_iter() - .enumerate() - .map(|(idx, (id, ranges))| { - let idx = (idx as u8) + 1; - let next = self.goto(id, ctx.advance(1)); - jumps.push(format!("J{}", id).to_ident()); - - for byte in ranges.into_iter().flatten() { - table[byte as usize] = idx; - } - let jump = jumps.last().unwrap(); - - quote!(Jump::#jump => #next,) - }) - .collect::<TokenStream>(); - - let may_error = table.iter().any(|&idx| idx == 0); - - let jumps = jumps.as_slice(); - let table = table.iter().copied().map(|idx| &jumps[idx as usize]); - - let jumps = if may_error { jumps } else { &jumps[1..] }; - let error_branch = if may_error { - Some(quote!(Jump::__ => #miss)) - } else { - None - }; - - quote! { - enum Jump { - #(#jumps,)* - } - - const LUT: [Jump; 256] = { - use Jump::*; - - [#(#table),*] - }; - - #read - - match LUT[#byte as usize] { - #branches - #error_branch - } - } - } - - fn fork_end(&self, this: NodeId, miss: &TokenStream) -> TokenStream { - if this == self.root { - quote!(_end(lex)) - } else { - miss.clone() - } - } - - fn fork_read( - &self, - this: NodeId, - end: TokenStream, - ctx: &mut Context, - ) -> (TokenStream, TokenStream) { - let min_read = self.meta[this].min_read; - - if ctx.remainder() >= max(min_read, 1) { - let read = ctx.read_byte(); - - return (quote!(byte), quote!(let byte = #read;)); - } - - match min_read { - 0 | 1 => { - let read = ctx.read(0); - - ( - quote!(byte), - quote! { - let byte = match #read { - Some(byte) => byte, - None => return #end, - }; - }, - ) - } - len => { - let read = ctx.read(len); - - ( - quote!(arr[0]), - quote! { - let arr = match #read { - Some(arr) => arr, - None => return #end, - }; - }, - ) - } - } - } - - fn generate_fast_loop(&mut self, fork: &Fork, ctx: Context) -> TokenStream { - let miss = ctx.miss(fork.miss, self); - let ranges = fork.branches().map(|(range, _)| range).collect::<Vec<_>>(); - let test = self.generate_test(ranges); - - quote! { - _fast_loop!(lex, #test, #miss); - } - } - - pub fn fast_loop_macro() -> TokenStream { - quote! { - macro_rules! _fast_loop { - ($lex:ident, $test:ident, $miss:expr) => { - // Do one bounds check for multiple bytes till EOF - while let Some(arr) = $lex.read::<&[u8; 16]>() { - if $test(arr[0]) { if $test(arr[1]) { if $test(arr[2]) { if $test(arr[3]) { - if $test(arr[4]) { if $test(arr[5]) { if $test(arr[6]) { if $test(arr[7]) { - if $test(arr[8]) { if $test(arr[9]) { if $test(arr[10]) { if $test(arr[11]) { - if $test(arr[12]) { if $test(arr[13]) { if $test(arr[14]) { if $test(arr[15]) { - - $lex.bump_unchecked(16); continue; } $lex.bump_unchecked(15); return $miss; } - $lex.bump_unchecked(14); return $miss; } $lex.bump_unchecked(13); return $miss; } - $lex.bump_unchecked(12); return $miss; } $lex.bump_unchecked(11); return $miss; } - $lex.bump_unchecked(10); return $miss; } $lex.bump_unchecked(9); return $miss; } - $lex.bump_unchecked(8); return $miss; } $lex.bump_unchecked(7); return $miss; } - $lex.bump_unchecked(6); return $miss; } $lex.bump_unchecked(5); return $miss; } - $lex.bump_unchecked(4); return $miss; } $lex.bump_unchecked(3); return $miss; } - $lex.bump_unchecked(2); return $miss; } $lex.bump_unchecked(1); return $miss; } - - return $miss; - } - - while $lex.test($test) { - $lex.bump_unchecked(1); - } - - $miss - }; - } - } - } -} |