287 lines
9.1 KiB
Rust
287 lines
9.1 KiB
Rust
// Copyright 2016 The Servo Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! A crate to create static string caches at compiletime.
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//!
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//! # Examples
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//!
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//! With static atoms:
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//!
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//! In `Cargo.toml`:
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//!
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//! ```toml
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//! [package]
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//! build = "build.rs"
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//!
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//! [dependencies]
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//! string_cache = "0.8"
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//!
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//! [build-dependencies]
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//! string_cache_codegen = "0.5"
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//! ```
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//!
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//! In `build.rs`:
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//!
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//! ```no_run
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//! extern crate string_cache_codegen;
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//!
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//! use std::env;
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//! use std::path::Path;
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//!
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//! fn main() {
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//! string_cache_codegen::AtomType::new("foo::FooAtom", "foo_atom!")
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//! .atoms(&["foo", "bar"])
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//! .write_to_file(&Path::new(&env::var("OUT_DIR").unwrap()).join("foo_atom.rs"))
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//! .unwrap()
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//! }
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//! ```
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//!
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//! In `lib.rs`:
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//!
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//! ```ignore
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//! extern crate string_cache;
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//!
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//! mod foo {
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//! include!(concat!(env!("OUT_DIR"), "/foo_atom.rs"));
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//! }
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//! ```
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//!
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//! The generated code will define a `FooAtom` type and a `foo_atom!` macro.
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//! The macro can be used in expression or patterns, with strings listed in `build.rs`.
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//! For example:
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//!
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//! ```ignore
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//! fn compute_something(input: &foo::FooAtom) -> u32 {
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//! match *input {
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//! foo_atom!("foo") => 1,
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//! foo_atom!("bar") => 2,
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//! _ => 3,
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//! }
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//! }
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//! ```
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//!
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#![recursion_limit = "128"]
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use quote::quote;
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use std::collections::HashSet;
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use std::fs::File;
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use std::io::{self, BufWriter, Write};
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use std::path::Path;
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/// A builder for a static atom set and relevant macros
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pub struct AtomType {
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path: String,
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atom_doc: Option<String>,
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static_set_doc: Option<String>,
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macro_name: String,
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macro_doc: Option<String>,
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atoms: HashSet<String>,
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}
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impl AtomType {
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/// Constructs a new static atom set builder
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///
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/// `path` is a path within a crate of the atom type that will be created.
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/// e.g. `"FooAtom"` at the crate root or `"foo::Atom"` if the generated code
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/// is included in a `foo` module.
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///
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/// `macro_name` must end with `!`.
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///
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/// For example, `AtomType::new("foo::FooAtom", "foo_atom!")` will generate:
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///
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/// ```ignore
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/// pub type FooAtom = ::string_cache::Atom<FooAtomStaticSet>;
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/// pub struct FooAtomStaticSet;
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/// impl ::string_cache::StaticAtomSet for FooAtomStaticSet {
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/// // ...
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/// }
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/// #[macro_export]
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/// macro_rules foo_atom {
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/// // Expands to: $crate::foo::FooAtom { … }
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/// }
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/// ```
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pub fn new(path: &str, macro_name: &str) -> Self {
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assert!(macro_name.ends_with("!"), "`macro_name` must end with '!'");
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AtomType {
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path: path.to_owned(),
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macro_name: macro_name[..macro_name.len() - "!".len()].to_owned(),
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atom_doc: None,
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static_set_doc: None,
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macro_doc: None,
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atoms: HashSet::new(),
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}
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}
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/// Add some documentation to the generated Atom type alias.
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///
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/// This can help the user know that the type uses interned strings.
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///
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/// Note that `docs` should not contain the `///` at the front of normal docs.
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pub fn with_atom_doc(&mut self, docs: &str) -> &mut Self {
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self.atom_doc = Some(docs.to_owned());
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self
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}
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/// Add some documentation to the generated static set.
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///
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/// This can help the user know that this type is zero-sized and just references a static
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/// lookup table, or point them to the `Atom` type alias for more info.
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///
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/// Note that `docs` should not contain the `///` at the front of normal docs.
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pub fn with_static_set_doc(&mut self, docs: &str) -> &mut Self {
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self.static_set_doc = Some(docs.to_owned());
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self
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}
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/// Add some documentation to the generated macro.
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///
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/// Note that `docs` should not contain the `///` at the front of normal docs.
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pub fn with_macro_doc(&mut self, docs: &str) -> &mut Self {
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self.macro_doc = Some(docs.to_owned());
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self
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}
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/// Adds an atom to the builder
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pub fn atom(&mut self, s: &str) -> &mut Self {
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self.atoms.insert(s.to_owned());
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self
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}
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/// Adds multiple atoms to the builder
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pub fn atoms<I>(&mut self, iter: I) -> &mut Self
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where
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I: IntoIterator,
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I::Item: AsRef<str>,
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{
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self.atoms
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.extend(iter.into_iter().map(|s| s.as_ref().to_owned()));
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self
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}
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/// Write generated code to `destination`.
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pub fn write_to<W>(&mut self, mut destination: W) -> io::Result<()>
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where
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W: Write,
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{
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destination.write_all(
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self.to_tokens()
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.to_string()
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// Insert some newlines to make the generated code slightly easier to read.
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.replace(" [ \"", "[\n\"")
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.replace("\" , ", "\",\n")
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.replace(" ( \"", "\n( \"")
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.replace("; ", ";\n")
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.as_bytes(),
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)
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}
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fn to_tokens(&mut self) -> proc_macro2::TokenStream {
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// `impl Default for Atom` requires the empty string to be in the static set.
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// This also makes sure the set in non-empty,
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// which would cause divisions by zero in rust-phf.
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self.atoms.insert(String::new());
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let atoms: Vec<&str> = self.atoms.iter().map(|s| &**s).collect();
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let hash_state = phf_generator::generate_hash(&atoms);
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let phf_generator::HashState { key, disps, map } = hash_state;
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let (disps0, disps1): (Vec<_>, Vec<_>) = disps.into_iter().unzip();
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let atoms: Vec<&str> = map.iter().map(|&idx| atoms[idx]).collect();
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let empty_string_index = atoms.iter().position(|s| s.is_empty()).unwrap() as u32;
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let indices = 0..atoms.len() as u32;
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let hashes: Vec<u32> = atoms
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.iter()
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.map(|string| {
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let hash = phf_shared::hash(string, &key);
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(hash.g ^ hash.f1) as u32
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})
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.collect();
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let mut path_parts = self.path.rsplitn(2, "::");
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let type_name = path_parts.next().unwrap();
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let module = match path_parts.next() {
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Some(m) => format!("$crate::{}", m),
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None => format!("$crate"),
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};
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let atom_doc = match self.atom_doc {
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Some(ref doc) => quote!(#[doc = #doc]),
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None => quote!(),
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};
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let static_set_doc = match self.static_set_doc {
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Some(ref doc) => quote!(#[doc = #doc]),
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None => quote!(),
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};
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let macro_doc = match self.macro_doc {
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Some(ref doc) => quote!(#[doc = #doc]),
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None => quote!(),
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};
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let new_term =
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|string: &str| proc_macro2::Ident::new(string, proc_macro2::Span::call_site());
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let static_set_name = new_term(&format!("{}StaticSet", type_name));
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let type_name = new_term(type_name);
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let macro_name = new_term(&*self.macro_name);
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let module = module.parse::<proc_macro2::TokenStream>().unwrap();
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let atom_prefix = format!("ATOM_{}_", type_name.to_string().to_uppercase());
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let const_names: Vec<_> = atoms
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.iter()
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.map(|atom| {
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let mut name = atom_prefix.clone();
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for c in atom.chars() {
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name.push_str(&format!("_{:02X}", c as u32))
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}
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new_term(&name)
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})
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.collect();
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quote! {
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#atom_doc
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pub type #type_name = ::string_cache::Atom<#static_set_name>;
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#static_set_doc
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#[derive(PartialEq, Eq, PartialOrd, Ord)]
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pub struct #static_set_name;
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impl ::string_cache::StaticAtomSet for #static_set_name {
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fn get() -> &'static ::string_cache::PhfStrSet {
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static SET: ::string_cache::PhfStrSet = ::string_cache::PhfStrSet {
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key: #key,
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disps: &[#((#disps0, #disps1)),*],
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atoms: &[#(#atoms),*],
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hashes: &[#(#hashes),*]
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};
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&SET
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}
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fn empty_string_index() -> u32 {
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#empty_string_index
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}
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}
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#(
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pub const #const_names: #type_name = #type_name::pack_static(#indices);
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)*
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#macro_doc
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#[macro_export]
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macro_rules! #macro_name {
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#(
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(#atoms) => { #module::#const_names };
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)*
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}
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}
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}
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/// Create a new file at `path` and write generated code there.
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///
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/// Typical usage:
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/// `.write_to_file(&Path::new(&env::var("OUT_DIR").unwrap()).join("foo_atom.rs"))`
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pub fn write_to_file(&mut self, path: &Path) -> io::Result<()> {
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self.write_to(BufWriter::new(File::create(path)?))
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}
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}
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