impl_tools_lib/
lib.rs

1// Licensed under the Apache License, Version 2.0 (the "License");
2// you may not use this file except in compliance with the License.
3// You may obtain a copy of the License in the LICENSE-APACHE file or at:
4//     https://www.apache.org/licenses/LICENSE-2.0
5
6//! # Impl-tools-lib
7//!
8//! To implement the proc-macros, copy and modify the
9//! [`impl-tools`](https://github.com/kas-gui/impl-tools/) crate, which is
10//! merely documentation plus wrappers around this crate.
11
12#![deny(missing_docs)]
13// Lint advocates use of bool::then_some, stabilized in rustc 1.62.0
14#![allow(clippy::unnecessary_lazy_evaluations)]
15#![allow(clippy::style)]
16
17pub mod anon;
18pub mod autoimpl;
19mod default;
20pub mod fields;
21pub mod generics;
22pub mod scope;
23mod split_impl;
24mod utils;
25
26pub use default::ImplDefault;
27pub use split_impl::SplitImpl;
28
29use proc_macro2::Span;
30use syn::Ident;
31
32/// Tool to make a formatted [`Ident`](struct@Ident)
33pub struct IdentFormatter(String);
34impl IdentFormatter {
35    /// Construct a formatter
36    pub fn new() -> Self {
37        IdentFormatter(String::with_capacity(32))
38    }
39
40    /// Construct a new [`Ident`](struct@Ident)
41    pub fn make(&mut self, args: std::fmt::Arguments, span: Span) -> Ident {
42        use std::fmt::Write;
43
44        self.0.clear();
45        self.0.write_fmt(args).unwrap();
46        Ident::new(&self.0, span)
47    }
48
49    /// Construct a new [`Ident`](struct@Ident), using [`Span::call_site`]
50    ///
51    /// # Example
52    ///
53    /// ```
54    /// # use impl_tools_lib::IdentFormatter;
55    /// let mut idfmt = IdentFormatter::new();
56    /// let ident = idfmt.make_call_site(format_args!("x{}", 6));
57    /// assert_eq!(ident, "x6");
58    /// ```
59    #[inline]
60    pub fn make_call_site(&mut self, args: std::fmt::Arguments) -> Ident {
61        self.make(args, Span::call_site())
62    }
63}
64
65/// Simple, allocation-free path representation
66#[derive(PartialEq, Eq)]
67pub struct SimplePath(&'static [&'static str]);
68
69impl std::fmt::Display for SimplePath {
70    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
71        if !self.0.is_empty() {
72            write!(f, "{}", self.0[0])?;
73            for component in &self.0[1..] {
74                write!(f, "::{}", component)?;
75            }
76        }
77
78        Ok(())
79    }
80}
81
82impl SimplePath {
83    /// Construct, verifying validity
84    ///
85    /// If the first component is an empty string, this is treated as a leading
86    /// colon (e.g. `["", "abc", "Def"] == `::abc::Def`). No other component may
87    /// be empty. At least one non-empty component is required.
88    ///
89    /// Panics if requirements are not met.
90    pub fn new(path: &'static [&'static str]) -> Self {
91        let mut is_empty = false;
92        for (i, s) in path.iter().enumerate() {
93            is_empty = is_empty && s.is_empty();
94            if i > 0 && s.is_empty() {
95                panic!("empty component");
96            }
97        }
98        if is_empty {
99            panic!("empty path");
100        }
101        SimplePath(path)
102    }
103
104    /// True if this matches a [`syn::Path`]
105    ///
106    /// This must match the path exactly, with two exceptions:
107    ///
108    /// -   if `path` has no leading colon but `self` does (empty first
109    ///     component), the paths may still match
110    /// -   if the first component of `self` is `core` or `alloc` but the first
111    ///     component of `path` is `std`, the paths may still match
112    pub fn matches(&self, path: &syn::Path) -> bool {
113        let mut q = self.0;
114        assert!(!q.is_empty());
115        if path.leading_colon.is_some() && !q[0].is_empty() {
116            return false;
117        }
118        if q[0].is_empty() {
119            q = &q[1..];
120        }
121
122        if path.segments.len() != q.len() {
123            return false;
124        }
125
126        let mut first = true;
127        for (x, y) in path.segments.iter().zip(q.iter()) {
128            if !x.arguments.is_empty() {
129                return false;
130            }
131
132            #[allow(clippy::if_same_then_else)]
133            if x.ident == y {
134            } else if first && (*y == "core" || *y == "alloc") && x.ident == "std" {
135            } else {
136                return false;
137            }
138
139            first = false;
140        }
141
142        true
143    }
144
145    /// True if the last component matches a [`syn::Ident`](struct@syn::Ident)
146    pub fn matches_ident(&self, ident: &syn::Ident) -> bool {
147        assert!(!self.0.is_empty());
148        self.0.iter().last().map(|s| ident == s).unwrap_or(false)
149    }
150
151    /// If input `path` has a single component with no leading colon, then
152    /// match via [`Self::matches_ident`]; otherwise match via
153    /// [`Self::matches`].
154    pub fn matches_ident_or_path(&self, path: &syn::Path) -> bool {
155        if path.leading_colon.is_none() && path.segments.len() == 1 {
156            let seg = &path.segments[0];
157            seg.arguments.is_empty() && self.matches_ident(&seg.ident)
158        } else {
159            self.matches(path)
160        }
161    }
162}
163
164// Attributes are supported in additional positions in syn v3.0.
165// For now we reject attributes in these positions.
166fn error_on_attrs(attrs: &[syn::Attribute]) {
167    use proc_macro_error3::emit_error;
168    for attr in attrs.iter() {
169        emit_error!(attr, "attributes are not (yet) supported in this context");
170    }
171}
impl_tools_lib/lib.rs

impl_tools_lib/
lib.rs
