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#![warn(missing_docs)]
#![feature(trait_alias)]
use proc_macro2::TokenStream;
use proc_macro2::TokenTree;
use quote::quote;
use std::iter::FromIterator;
use syn::visit::Visit;
use syn::WhereClause;
use syn::WherePredicate;
pub trait Str = Into<String> + AsRef<str>;
pub fn map_tokens<F:Fn(TokenTree) -> TokenTree>
(input:TokenStream, f:F) -> TokenStream {
let ret_iter = input.into_iter().map(f);
ret_iter.collect()
}
pub fn rewrite_stream
<F:Fn(TokenTree) -> TokenStream + Copy>
(input:TokenStream, f:F) -> TokenStream {
let mut ret = TokenStream::new();
for token in input.into_iter() {
match token {
proc_macro2::TokenTree::Group(group) => {
let delim = group.delimiter();
let span = group.span();
let rewritten = rewrite_stream(group.stream(), f);
let mut new_group = proc_macro2::Group::new(delim,rewritten);
new_group.set_span(span);
let new_group = vec![TokenTree::from(new_group)];
ret.extend(new_group.into_iter())
}
_ => ret.extend(f(token)),
}
}
ret
}
pub fn matching_ident(token:&TokenTree, name:&str) -> bool {
match token {
TokenTree::Ident(ident) => *ident == name,
_ => false,
}
}
pub fn repr<T: quote::ToTokens>(t:&T) -> String {
quote!(#t).to_string()
}
pub fn fields_list(fields:&syn::Fields) -> Vec<&syn::Field> {
match fields {
syn::Fields::Named (ref f) => f.named .iter().collect(),
syn::Fields::Unnamed(ref f) => f.unnamed.iter().collect(),
syn::Fields::Unit => Default::default(),
}
}
pub fn field_ident_token(field:&syn::Field, index:syn::Index) -> TokenStream {
match &field.ident {
Some(ident) => quote!(#ident),
None => quote!(#index),
}
}
pub fn field_names(fields:&syn::FieldsNamed) -> Vec<&syn::Ident> {
fields.named.iter().map(|field| {
field.ident.as_ref().expect("Impossible: no name on a named field.")
}).collect()
}
pub fn path_matching_ident(path:&syn::Path, str:impl Str) -> bool {
path.get_ident().map_or(false, |ident| ident == str.as_ref())
}
pub fn index_sequence(len:usize) -> Vec<syn::Index> {
(0..len).map(syn::Index::from).collect()
}
pub fn identifier_sequence(len:usize) -> Vec<syn::Ident> {
let format_field = |ix| quote::format_ident!("field{}",ix);
(0..len).map(format_field).collect()
}
pub fn path_segment_generic_args
(segment:&syn::PathSegment) -> Vec<&syn::GenericArgument> {
match segment.arguments {
syn::PathArguments::AngleBracketed(ref args) =>
args.args.iter().collect(),
_ =>
Vec::new(),
}
}
pub fn ty_path_generic_args
(ty_path:&syn::TypePath) -> Vec<&syn::GenericArgument> {
ty_path.path.segments.last().map_or(Vec::new(), path_segment_generic_args)
}
pub fn ty_path_type_args
(ty_path:&syn::TypePath) -> Vec<&syn::Type> {
ty_path_generic_args(ty_path).iter().filter_map( |generic_arg| {
match generic_arg {
syn::GenericArgument::Type(t) => Some(t),
_ => None,
}
}).collect()
}
pub fn last_type_arg(ty_path:&syn::TypePath) -> Option<&syn::GenericArgument> {
ty_path_generic_args(ty_path).last().copied()
}
#[derive(Default)]
pub struct TypeGatherer<'ast> {
pub types: Vec<&'ast syn::TypePath>
}
impl<'ast> Visit<'ast> for TypeGatherer<'ast> {
fn visit_type_path(&mut self, node:&'ast syn::TypePath) {
self.types.push(node);
syn::visit::visit_type_path(self, node);
}
}
pub fn gather_all_types(node:&syn::Type) -> Vec<&syn::TypePath> {
let mut type_gather = TypeGatherer::default();
type_gather.visit_type(node);
type_gather.types
}
pub fn gather_all_type_reprs(node:&syn::Type) -> Vec<String> {
gather_all_types(node).iter().map(|t| repr(t)).collect()
}
pub fn type_matches_repr(ty:&syn::Type, target_repr:&str) -> bool {
repr(ty) == target_repr
}
pub fn type_matches(ty:&syn::Type, target_param:&syn::GenericParam) -> bool {
type_matches_repr(ty, &repr(target_param))
}
pub fn type_depends_on(ty:&syn::Type, target_param:&syn::GenericParam) -> bool {
let target_param = repr(target_param);
let relevant_types = gather_all_types(ty);
relevant_types.iter().any(|ty| repr(ty) == target_param)
}
pub fn variant_depends_on
(var:&syn::Variant, target_param:&syn::GenericParam) -> bool {
var.fields.iter().any(|field| type_depends_on(&field.ty, target_param))
}
pub fn new_where_clause(predicates:impl IntoIterator<Item=WherePredicate>) -> WhereClause {
let predicates = syn::punctuated::Punctuated::from_iter(predicates);
WhereClause {where_token:Default::default(),predicates}
}
#[cfg(test)]
mod tests {
use super::*;
use proc_macro2::TokenStream;
fn parse<T:syn::parse::Parse>(code:&str) -> T {
syn::parse_str(code).unwrap()
}
#[test]
fn repr_round_trips() {
let program = "pub fn repr<T: quote::ToTokens>(t: &T) -> String {}";
let tokens = parse::<TokenStream>(program);
let quoted_program = repr(&tokens);
let tokens2 = parse::<TokenStream>("ed_program);
assert_eq!(repr(&tokens), repr(&tokens2));
}
#[test]
fn fields_list_test() {
let tuple_like = "struct Unnamed(i32, String, T);";
let proper_struct = "struct Named{i: i32, s: String, t: T}";
let expected_types = vec!["i32", "String", "T"];
fn assert_field_types(program:&str, expected_types:&[&str]) {
let tokens = parse::<syn::ItemStruct>(program);
let fields = fields_list(&tokens.fields);
let types = fields.iter().map(|f| repr(&f.ty));
assert_eq!(Vec::from_iter(types), expected_types);
}
assert_field_types(tuple_like, &expected_types);
assert_field_types(proper_struct, &expected_types);
}
#[test]
fn type_dependency() {
let param:syn::GenericParam = parse("T");
let depends = |code| {
let ty:syn::Type = parse(code);
type_depends_on(&ty, ¶m)
};
let dependents = vec!{
"T",
"Option<T>",
"Pair<T, U>",
"Pair<U, T>",
"Pair<U, (T,)>",
"&T",
"&'t mut T",
};
let independents = vec!{
"Tt",
"Option<Tt>",
"Pair<Tt, U>",
"Pair<U, Tt>",
"Pair<U, Tt>",
"i32",
"&str",
};
for dependent in dependents {
assert!(depends(dependent), "{} must depend on {}"
, repr(&dependent), repr(¶m));
}
for independent in independents {
assert!(!depends(independent), "{} must not depend on {}"
, repr(&independent), repr(¶m));
}
}
#[test]
fn collecting_type_path_args() {
fn check(expected_type_args:Vec<&str>, ty_path:&str) {
let ty_path = parse(ty_path);
let args = super::ty_path_type_args(&ty_path);
assert_eq!(expected_type_args.len(), args.len());
let zipped = expected_type_args.iter().zip(args.iter());
for (expected,got) in zipped {
assert_eq!(expected, &repr(got));
}
}
check(vec!["T"] , "std::Option<T>");
check(vec!["U"] , "std::Option<U>");
check(vec!["A", "B"], "Either<A,B>");
assert_eq!(super::last_type_arg(&parse("i32")), None);
assert_eq!(repr(&super::last_type_arg(&parse("Foo<C>"))), "C");
}
}