tiny_cli/
lib.rs

1#![warn(clippy::pedantic)]
2#![cfg_attr(test, allow(clippy::struct_field_names))]
3mod derive_struct;
4mod subcommand;
5
6extern crate proc_macro;
7
8use proc_macro::{Group, Ident, Literal, TokenStream, TokenTree};
9use std::fmt::Display;
10
11#[proc_macro_derive(ArgParse, attributes(cli))]
12pub fn derive_arg_parse(struct_candidate: TokenStream) -> TokenStream {
13    derive_struct::do_derive(struct_candidate)
14}
15
16#[proc_macro_derive(Subcommand, attributes(cli))]
17pub fn derive_sc_parse(struct_candidate: TokenStream) -> TokenStream {
18    subcommand::do_derive(struct_candidate)
19}
20
21fn pop_expect_punct<I: Iterator<Item = TokenTree>, D: Display>(
22    stream: &mut I,
23    expect: char,
24    err_msg: D,
25) {
26    let punct = stream
27        .next()
28        .unwrap_or_else(|| panic!("[ArgParse derive] {err_msg}"));
29    if let TokenTree::Punct(p) = punct {
30        assert_eq!(p.as_char(), expect, "{err_msg}");
31    } else {
32        panic!(
33            "[ArgParse derive] Expected punctuation with {expect}, found: {punct:?}, ctx: {err_msg}"
34        );
35    }
36}
37
38fn pop_expect_ident<I: Iterator<Item = TokenTree>, D: Display>(
39    stream: &mut I,
40    expect: &str,
41    err_msg: D,
42) {
43    let ident = pop_ident(stream, &err_msg);
44    assert_eq!(
45        expect,
46        ident.to_string().trim(),
47        "[ArgParse derive] Ident {ident} didn't match expected {expect}, ctx: {err_msg}"
48    );
49}
50
51fn pop_ident<I: Iterator<Item = TokenTree>, D: Display>(stream: &mut I, err_msg: D) -> Ident {
52    let ident = stream
53        .next()
54        .unwrap_or_else(|| panic!("[ArgParse derive] {err_msg}"));
55    if let TokenTree::Ident(ident) = ident {
56        ident
57    } else {
58        panic!("[ArgParse derive] Expected ident, found '{ident:?}', ctx: {err_msg}");
59    }
60}
61
62fn pop_lit<I: Iterator<Item = TokenTree>, D: Display>(stream: &mut I, err_msg: D) -> Literal {
63    let lit = stream
64        .next()
65        .unwrap_or_else(|| panic!("[ArgParse derive] {err_msg}"));
66    if let TokenTree::Literal(l) = lit {
67        l
68    } else {
69        panic!("[ArgParse derive] Expected literal found: {lit:?}, ctx: {err_msg}");
70    }
71}
72
73fn pop_group<I: Iterator<Item = TokenTree>, D: Display>(stream: &mut I, err_msg: D) -> Group {
74    let group = stream
75        .next()
76        .unwrap_or_else(|| panic!("[ArgParse derive] {err_msg}"));
77    if let TokenTree::Group(g) = group {
78        g
79    } else {
80        panic!("[ArgParse derive] Expected group, found: {group:?}, ctx: {err_msg}");
81    }
82}
83
84pub(crate) fn try_extract_doc_comment(g: &Group) -> Option<String> {
85    let mut stream = g.stream().into_iter();
86    if let Some(TokenTree::Ident(id)) = stream.next() {
87        if id.to_string().trim() == "doc" {
88            pop_expect_punct(&mut stream, '=', "Expected a '=' after #[doc");
89            let ident = pop_lit(&mut stream, "Expected #[doc = <literal>...");
90            let id_str = ident.to_string();
91            let id_trimmed = id_str.trim().trim_matches('"').trim().to_string();
92            return Some(id_trimmed);
93        }
94    }
95    None
96}
97
98pub(crate) fn pascal_to_snake(prev: &str) -> String {
99    let mut new = String::new();
100    let mut chars = prev.chars();
101    if let Some(next) = chars.next() {
102        for lc in next.to_lowercase() {
103            new.push(lc);
104        }
105    } else {
106        return new;
107    }
108    for char in chars {
109        if char.is_uppercase() {
110            new.push('-');
111        }
112        for lc in char.to_lowercase() {
113            new.push(lc);
114        }
115    }
116    new
117}
118
119#[inline]
120pub(crate) fn snake_to_scream(prev: &str) -> String {
121    prev.replace('-', "_").to_uppercase()
122}
123
124#[cfg(test)]
125mod tests {
126    use super::*;
127
128    #[test]
129    fn switch_case() {
130        let orig = "MyStructDecl";
131        assert_eq!("my-struct-decl", pascal_to_snake(orig));
132        let orig = "M";
133        assert_eq!("m", pascal_to_snake(orig));
134        assert_eq!("", pascal_to_snake(""));
135        assert_eq!("m-m", pascal_to_snake("MM"));
136    }
137}
tiny_cli/lib.rs

tiny_cli/
lib.rs
