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//! Code to convert the Rust-styled field/variant (e.g. `my_field`, `MyType`) to the
//! case of the source (e.g. `my-field`, `MY_FIELD`).
use self::RenameRule::*;
use std::fmt::{self, Debug, Display};
/// The different possible ways to change case of fields in a struct, or variants in an enum.
#[derive(Copy, Clone, PartialEq)]
pub enum RenameRule {
/// Don't apply a default rename rule.
None,
/// Rename direct children to "lowercase" style.
LowerCase,
/// Rename direct children to "UPPERCASE" style.
UpperCase,
/// Rename direct children to "PascalCase" style, as typically used for
/// enum variants.
PascalCase,
/// Rename direct children to "camelCase" style.
CamelCase,
/// Rename direct children to "snake_case" style, as commonly used for
/// fields.
SnakeCase,
/// Rename direct children to "SCREAMING_SNAKE_CASE" style, as commonly
/// used for constants.
ScreamingSnakeCase,
/// Rename direct children to "kebab-case" style.
KebabCase,
/// Rename direct children to "SCREAMING-KEBAB-CASE" style.
ScreamingKebabCase,
}
static RENAME_RULES: &[(&str, RenameRule)] = &[
("lowercase", LowerCase),
("UPPERCASE", UpperCase),
("PascalCase", PascalCase),
("camelCase", CamelCase),
("snake_case", SnakeCase),
("SCREAMING_SNAKE_CASE", ScreamingSnakeCase),
("kebab-case", KebabCase),
("SCREAMING-KEBAB-CASE", ScreamingKebabCase),
];
impl RenameRule {
pub fn from_str(rename_all_str: &str) -> Result<Self, ParseError> {
for (name, rule) in RENAME_RULES {
if rename_all_str == *name {
return Ok(*rule);
}
}
Err(ParseError {
unknown: rename_all_str,
})
}
/// Apply a renaming rule to an enum variant, returning the version expected in the source.
pub fn apply_to_variant(self, variant: &str) -> String {
match self {
None | PascalCase => variant.to_owned(),
LowerCase => variant.to_ascii_lowercase(),
UpperCase => variant.to_ascii_uppercase(),
CamelCase => variant[..1].to_ascii_lowercase() + &variant[1..],
SnakeCase => {
let mut snake = String::new();
for (i, ch) in variant.char_indices() {
if i > 0 && ch.is_uppercase() {
snake.push('_');
}
snake.push(ch.to_ascii_lowercase());
}
snake
}
ScreamingSnakeCase => SnakeCase.apply_to_variant(variant).to_ascii_uppercase(),
KebabCase => SnakeCase.apply_to_variant(variant).replace('_', "-"),
ScreamingKebabCase => ScreamingSnakeCase
.apply_to_variant(variant)
.replace('_', "-"),
}
}
/// Apply a renaming rule to a struct field, returning the version expected in the source.
pub fn apply_to_field(self, field: &str) -> String {
match self {
None | LowerCase | SnakeCase => field.to_owned(),
UpperCase => field.to_ascii_uppercase(),
PascalCase => {
let mut pascal = String::new();
let mut capitalize = true;
for ch in field.chars() {
if ch == '_' {
capitalize = true;
} else if capitalize {
pascal.push(ch.to_ascii_uppercase());
capitalize = false;
} else {
pascal.push(ch);
}
}
pascal
}
CamelCase => {
let pascal = PascalCase.apply_to_field(field);
pascal[..1].to_ascii_lowercase() + &pascal[1..]
}
ScreamingSnakeCase => field.to_ascii_uppercase(),
KebabCase => field.replace('_', "-"),
ScreamingKebabCase => ScreamingSnakeCase.apply_to_field(field).replace('_', "-"),
}
}
/// Returns the `RenameRule` if it is not `None`, `rule_b` otherwise.
pub fn or(self, rule_b: Self) -> Self {
match self {
None => rule_b,
_ => self,
}
}
}
pub struct ParseError<'a> {
unknown: &'a str,
}
impl<'a> Display for ParseError<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("unknown rename rule `rename_all = ")?;
Debug::fmt(self.unknown, f)?;
f.write_str("`, expected one of ")?;
for (i, (name, _rule)) in RENAME_RULES.iter().enumerate() {
if i > 0 {
f.write_str(", ")?;
}
Debug::fmt(name, f)?;
}
Ok(())
}
}
#[test]
fn rename_variants() {
for &(original, lower, upper, camel, snake, screaming, kebab, screaming_kebab) in &[
(
"Outcome", "outcome", "OUTCOME", "outcome", "outcome", "OUTCOME", "outcome", "OUTCOME",
),
(
"VeryTasty",
"verytasty",
"VERYTASTY",
"veryTasty",
"very_tasty",
"VERY_TASTY",
"very-tasty",
"VERY-TASTY",
),
("A", "a", "A", "a", "a", "A", "a", "A"),
("Z42", "z42", "Z42", "z42", "z42", "Z42", "z42", "Z42"),
] {
assert_eq!(None.apply_to_variant(original), original);
assert_eq!(LowerCase.apply_to_variant(original), lower);
assert_eq!(UpperCase.apply_to_variant(original), upper);
assert_eq!(PascalCase.apply_to_variant(original), original);
assert_eq!(CamelCase.apply_to_variant(original), camel);
assert_eq!(SnakeCase.apply_to_variant(original), snake);
assert_eq!(ScreamingSnakeCase.apply_to_variant(original), screaming);
assert_eq!(KebabCase.apply_to_variant(original), kebab);
assert_eq!(
ScreamingKebabCase.apply_to_variant(original),
screaming_kebab
);
}
}
#[test]
fn rename_fields() {
for &(original, upper, pascal, camel, screaming, kebab, screaming_kebab) in &[
(
"outcome", "OUTCOME", "Outcome", "outcome", "OUTCOME", "outcome", "OUTCOME",
),
(
"very_tasty",
"VERY_TASTY",
"VeryTasty",
"veryTasty",
"VERY_TASTY",
"very-tasty",
"VERY-TASTY",
),
("a", "A", "A", "a", "A", "a", "A"),
("z42", "Z42", "Z42", "z42", "Z42", "z42", "Z42"),
] {
assert_eq!(None.apply_to_field(original), original);
assert_eq!(UpperCase.apply_to_field(original), upper);
assert_eq!(PascalCase.apply_to_field(original), pascal);
assert_eq!(CamelCase.apply_to_field(original), camel);
assert_eq!(SnakeCase.apply_to_field(original), original);
assert_eq!(ScreamingSnakeCase.apply_to_field(original), screaming);
assert_eq!(KebabCase.apply_to_field(original), kebab);
assert_eq!(ScreamingKebabCase.apply_to_field(original), screaming_kebab);
}
}