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Diffstat (limited to 'third_party/rust/serde_derive/src/internals/case.rs')
| -rw-r--r-- | third_party/rust/serde_derive/src/internals/case.rs | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/third_party/rust/serde_derive/src/internals/case.rs b/third_party/rust/serde_derive/src/internals/case.rs new file mode 100644 index 0000000000..8c8c02e757 --- /dev/null +++ b/third_party/rust/serde_derive/src/internals/case.rs @@ -0,0 +1,200 @@ +//! 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); + } +} |