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mod trie;
use std::collections::BTreeMap;
use std::io;
use quote::{quote, ToTokens};
use proc_macro2::{Literal, Ident, TokenStream, Span};
#[derive(Clone)]
pub struct StrMapFunc {
atoms: Forest<TokenStream>,
func_name: Ident,
ret_ty: TokenStream,
case: Case,
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Case {
Sensitive,
Insensitive,
}
impl StrMapFunc {
pub fn new(func_name: &str, ret_ty: &str) -> Self {
StrMapFunc {
atoms: Default::default(),
func_name: Ident::new(func_name, Span::call_site()),
ret_ty: ret_ty.parse().unwrap(),
case: Case::Sensitive,
}
}
pub fn case(&mut self, case: Case) -> &mut Self {
self.case = case;
self
}
pub fn entry(&mut self, k: &str, v: impl ToTokens) -> &mut Self {
self.atoms.insert(k.as_bytes(), v.into_token_stream());
self
}
pub fn entries<'a, V: 'a>(&mut self, entries: impl IntoIterator<Item = (&'a str, V)>) -> &mut Self
where V: ToTokens,
{
for (s, v) in entries.into_iter() {
self.entry(s, v);
}
self
}
pub fn compile(&self, mut w: impl io::Write) -> io::Result<()> {
let tokens = self.into_token_stream();
w.write_all(format!("{}", tokens).as_bytes())
}
}
impl ToTokens for StrMapFunc {
fn to_tokens(&self, tokens: &mut TokenStream) {
let StrMapFunc { func_name, ret_ty, atoms, case } = self;
let match_arms = atoms.0.iter()
.map(|(&len, trie)| {
let branch = Forest::branch_tokens(trie, *case == Case::Insensitive);
let len = Literal::usize_unsuffixed(len);
quote!(#len => #branch)
});
let body = quote! {
match s.len() {
#( #match_arms, )*
_ => {}
}
None
};
tokens.extend(quote! {
fn #func_name(s: &[u8]) -> Option<#ret_ty> {
#body
}
});
}
}
#[derive(Debug, Clone)]
pub struct Forest<T>(BTreeMap<usize, trie::Node<T>>);
impl<T> Default for Forest<T> {
fn default() -> Self {
Forest(Default::default())
}
}
impl<T> Forest<T> {
pub fn get(&mut self, bytes: &[u8]) -> Option<&T> {
self.0.get(&bytes.len())
.and_then(|n| n.get(bytes))
}
pub fn insert(&mut self, bytes: &[u8], value: T) -> Option<T> {
let node = self.0.entry(bytes.len()).or_default();
node.insert(bytes, value)
}
}
fn byte_literal(b: u8) -> TokenStream {
if b < 128 {
let c: String = char::from(b).escape_default().collect();
format!("b'{}'", c).parse().unwrap()
} else {
Literal::u8_unsuffixed(b).into_token_stream()
}
}
impl<T> Forest<T>
where T: ToTokens
{
fn branch_tokens(node: &trie::Node<T>, ignore_case: bool) -> TokenStream {
use trie::TraversalOrder::*;
let mut tok = vec![TokenStream::new()];
let mut depth = 0;
let mut is_first_child = true;
let mut dfs = node.dfs();
while let Some((order, node)) = dfs.next() {
if node.bytes.is_empty() {
continue;
}
match order {
Pre => {
if !is_first_child {
tok.last_mut().unwrap().extend(quote!(else));
is_first_child = true;
}
let i = (depth..depth+node.bytes.len()).map(Literal::usize_unsuffixed);
let b = node.bytes.iter().cloned().map(byte_literal);
if !ignore_case {
tok.last_mut().unwrap().extend(quote!(if #( s[#i] == #b )&&*));
} else {
tok.last_mut().unwrap().extend(quote!(if #( s[#i].eq_ignore_ascii_case(&#b) )&&*));
}
tok.push(TokenStream::new());
depth += node.bytes.len();
if let Some(v) = node.value {
tok.last_mut().unwrap().extend(quote!(return Some(#v);));
}
}
Post => {
let body = tok.pop().unwrap();
tok.last_mut().unwrap().extend(quote!({ #body }));
depth -= node.bytes.len();
is_first_child = false;
}
}
}
let ret = tok.pop().unwrap();
assert!(tok.is_empty());
ret
}
}