strum_macros/helpers/
case_style.rs

1use heck::{
2    ToKebabCase, ToLowerCamelCase, ToShoutySnakeCase, ToSnakeCase, ToTitleCase, ToUpperCamelCase, ToTrainCase,
3};
4use std::str::FromStr;
5use syn::{
6    parse::{Parse, ParseStream},
7    Ident, LitStr,
8};
9
10#[allow(clippy::enum_variant_names)]
11#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
12pub enum CaseStyle {
13    CamelCase,
14    KebabCase,
15    MixedCase,
16    ShoutySnakeCase,
17    SnakeCase,
18    TitleCase,
19    UpperCase,
20    LowerCase,
21    ScreamingKebabCase,
22    PascalCase,
23    TrainCase,
24}
25
26const VALID_CASE_STYLES: &[&str] = &[
27    "camelCase",
28    "PascalCase",
29    "kebab-case",
30    "snake_case",
31    "SCREAMING_SNAKE_CASE",
32    "SCREAMING-KEBAB-CASE",
33    "lowercase",
34    "UPPERCASE",
35    "title_case",
36    "mixed_case",
37    "Train-Case",
38];
39
40impl Parse for CaseStyle {
41    fn parse(input: ParseStream) -> syn::Result<Self> {
42        let text = input.parse::<LitStr>()?;
43        let val = text.value();
44
45        val.as_str().parse().map_err(|_| {
46            syn::Error::new_spanned(
47                &text,
48                format!(
49                    "Unexpected case style for serialize_all: `{}`. Valid values are: `{:?}`",
50                    val, VALID_CASE_STYLES
51                ),
52            )
53        })
54    }
55}
56
57impl FromStr for CaseStyle {
58    type Err = ();
59
60    fn from_str(text: &str) -> Result<Self, ()> {
61        Ok(match text {
62            // "camel_case" is a soft-deprecated case-style left for backward compatibility.
63            // <https://github.com/Peternator7/strum/pull/250#issuecomment-1374682221>
64            "PascalCase" | "camel_case" => CaseStyle::PascalCase,
65            "camelCase" => CaseStyle::CamelCase,
66            "snake_case" | "snek_case" => CaseStyle::SnakeCase,
67            "kebab-case" | "kebab_case" => CaseStyle::KebabCase,
68            "SCREAMING-KEBAB-CASE" => CaseStyle::ScreamingKebabCase,
69            "SCREAMING_SNAKE_CASE" | "shouty_snake_case" | "shouty_snek_case" => {
70                CaseStyle::ShoutySnakeCase
71            }
72            "title_case" => CaseStyle::TitleCase,
73            "mixed_case" => CaseStyle::MixedCase,
74            "lowercase" => CaseStyle::LowerCase,
75            "UPPERCASE" => CaseStyle::UpperCase,
76            "Train-Case" => CaseStyle::TrainCase,
77            _ => return Err(()),
78        })
79    }
80}
81
82pub trait CaseStyleHelpers {
83    fn convert_case(&self, case_style: Option<CaseStyle>) -> String;
84}
85
86impl CaseStyleHelpers for Ident {
87    fn convert_case(&self, case_style: Option<CaseStyle>) -> String {
88        let ident_string = self.to_string();
89        if let Some(case_style) = case_style {
90            match case_style {
91                CaseStyle::PascalCase => ident_string.to_upper_camel_case(),
92                CaseStyle::KebabCase => ident_string.to_kebab_case(),
93                CaseStyle::MixedCase => ident_string.to_lower_camel_case(),
94                CaseStyle::ShoutySnakeCase => ident_string.to_shouty_snake_case(),
95                CaseStyle::SnakeCase => ident_string.to_snake_case(),
96                CaseStyle::TitleCase => ident_string.to_title_case(),
97                CaseStyle::UpperCase => ident_string.to_uppercase(),
98                CaseStyle::LowerCase => ident_string.to_lowercase(),
99                CaseStyle::ScreamingKebabCase => ident_string.to_kebab_case().to_uppercase(),
100                CaseStyle::TrainCase => ident_string.to_train_case(),
101                CaseStyle::CamelCase => {
102                    let camel_case = ident_string.to_upper_camel_case();
103                    let mut pascal = String::with_capacity(camel_case.len());
104                    let mut it = camel_case.chars();
105                    if let Some(ch) = it.next() {
106                        pascal.extend(ch.to_lowercase());
107                    }
108                    pascal.extend(it);
109                    pascal
110                }
111            }
112        } else {
113            ident_string
114        }
115    }
116}
117
118#[cfg(test)]
119mod tests {
120    use super::*;
121
122    #[test]
123    fn test_convert_case() {
124        let id = Ident::new("test_me", proc_macro2::Span::call_site());
125        assert_eq!("testMe", id.convert_case(Some(CaseStyle::CamelCase)));
126        assert_eq!("TestMe", id.convert_case(Some(CaseStyle::PascalCase)));
127        assert_eq!("Test-Me", id.convert_case(Some(CaseStyle::TrainCase)));
128    }
129
130    #[test]
131    fn test_impl_from_str_for_case_style_pascal_case() {
132        use CaseStyle::*;
133        let f = CaseStyle::from_str;
134
135        assert_eq!(PascalCase, f("PascalCase").unwrap());
136        assert_eq!(PascalCase, f("camel_case").unwrap());
137
138        assert_eq!(CamelCase, f("camelCase").unwrap());
139
140        assert_eq!(SnakeCase, f("snake_case").unwrap());
141        assert_eq!(SnakeCase, f("snek_case").unwrap());
142
143        assert_eq!(KebabCase, f("kebab-case").unwrap());
144        assert_eq!(KebabCase, f("kebab_case").unwrap());
145
146        assert_eq!(ScreamingKebabCase, f("SCREAMING-KEBAB-CASE").unwrap());
147
148        assert_eq!(ShoutySnakeCase, f("SCREAMING_SNAKE_CASE").unwrap());
149        assert_eq!(ShoutySnakeCase, f("shouty_snake_case").unwrap());
150        assert_eq!(ShoutySnakeCase, f("shouty_snek_case").unwrap());
151
152        assert_eq!(LowerCase, f("lowercase").unwrap());
153
154        assert_eq!(UpperCase, f("UPPERCASE").unwrap());
155
156        assert_eq!(TitleCase, f("title_case").unwrap());
157
158        assert_eq!(MixedCase, f("mixed_case").unwrap());
159    }
160}
161
162/// heck doesn't treat numbers as new words, but this function does.
163/// E.g. for input `Hello2You`, heck would output `hello2_you`, and snakify would output `hello_2_you`.
164pub fn snakify(s: &str) -> String {
165    let mut output: Vec<char> = s.to_string().to_snake_case().chars().collect();
166    let mut num_starts = vec![];
167    for (pos, c) in output.iter().enumerate() {
168        if c.is_digit(10) && pos != 0 && !output[pos - 1].is_digit(10) {
169            num_starts.push(pos);
170        }
171    }
172    // need to do in reverse, because after inserting, all chars after the point of insertion are off
173    for i in num_starts.into_iter().rev() {
174        output.insert(i, '_')
175    }
176    output.into_iter().collect()
177}
strum_macros/helpers/case_style.rs

strum_macros/helpers/
case_style.rs
