| //! **heck** is a case conversion library. |
| //! |
| //! This library exists to provide case conversion between common cases like |
| //! CamelCase and snake_case. It is intended to be unicode aware, internally, |
| //! consistent, and reasonably well performing. |
| //! |
| //! ## Definition of a word boundary |
| //! |
| //! Word boundaries are defined as the "unicode words" defined in the |
| //! `unicode_segmentation` library, as well as within those words in this manner: |
| //! |
| //! 1. All underscore characters are considered word boundaries. |
| //! 2. If an uppercase character is followed by lowercase letters, a word boundary |
| //! is considered to be just prior to that uppercase character. |
| //! 3. If multiple uppercase characters are consecutive, they are considered to be |
| //! within a single word, except that the last will be part of the next word if it |
| //! is followed by lowercase characters (see rule 2). |
| //! |
| //! That is, "HelloWorld" is segmented `Hello|World` whereas "XMLHttpRequest" is |
| //! segmented `XML|Http|Request`. |
| //! |
| //! Characters not within words (such as spaces, punctuations, and underscores) |
| //! are not included in the output string except as they are a part of the case |
| //! being converted to. Multiple adjacent word boundaries (such as a series of |
| //! underscores) are folded into one. ("hello__world" in snake case is therefore |
| //! "hello_world", not the exact same string). Leading or trailing word boundary |
| //! indicators are dropped, except insofar as CamelCase capitalizes the first word. |
| //! |
| //! ### Cases contained in this library: |
| //! |
| //! 1. CamelCase |
| //! 2. snake_case |
| //! 3. kebab-case |
| //! 4. SHOUTY_SNAKE_CASE |
| //! 5. mixedCase |
| //! 6. Title Case |
| #![deny(missing_docs)] |
| extern crate unicode_segmentation; |
| |
| mod camel; |
| mod kebab; |
| mod mixed; |
| mod shouty_snake; |
| mod snake; |
| mod title; |
| |
| pub use camel::CamelCase; |
| pub use kebab::KebabCase; |
| pub use mixed::MixedCase; |
| pub use shouty_snake::{ShoutySnakeCase, ShoutySnekCase}; |
| pub use snake::{SnakeCase, SnekCase}; |
| pub use title::TitleCase; |
| |
| use unicode_segmentation::UnicodeSegmentation; |
| |
| fn transform<F, G>(s: &str, with_word: F, boundary: G) -> String |
| where |
| F: Fn(&str, &mut String), |
| G: Fn(&mut String) |
| { |
| |
| /// Tracks the current 'mode' of the transformation algorithm as it scans the input string. |
| /// |
| /// The mode is a tri-state which tracks the case of the last cased character of the current |
| /// word. If there is no cased character (either lowercase or uppercase) since the previous |
| /// word boundary, than the mode is `Boundary`. If the last cased character is lowercase, then |
| /// the mode is `Lowercase`. Othertherwise, the mode is `Uppercase`. |
| #[derive(Clone, Copy, PartialEq)] |
| enum WordMode { |
| /// There have been no lowercase or uppercase characters in the current word. |
| Boundary, |
| /// The previous cased character in the current word is lowercase. |
| Lowercase, |
| /// The previous cased character in the current word is uppercase. |
| Uppercase, |
| } |
| |
| let mut out = String::new(); |
| let mut first_word = true; |
| |
| for word in s.unicode_words() { |
| let mut char_indices = word.char_indices().peekable(); |
| let mut init = 0; |
| let mut mode = WordMode::Boundary; |
| |
| while let Some((i, c)) = char_indices.next() { |
| // Skip underscore characters |
| if c == '_' { |
| if init == i { init += 1; } |
| continue |
| } |
| |
| if let Some(&(next_i, next)) = char_indices.peek() { |
| |
| // The mode including the current character, assuming the current character does |
| // not result in a word boundary. |
| let next_mode = if c.is_lowercase() { |
| WordMode::Lowercase |
| } else if c.is_uppercase() { |
| WordMode::Uppercase |
| } else { |
| mode |
| }; |
| |
| // Word boundary after if next is underscore or current is |
| // not uppercase and next is uppercase |
| if next == '_' || (next_mode == WordMode::Lowercase && next.is_uppercase()) { |
| if !first_word { boundary(&mut out); } |
| with_word(&word[init..next_i], &mut out); |
| first_word = false; |
| init = next_i; |
| mode = WordMode::Boundary; |
| |
| // Otherwise if current and previous are uppercase and next |
| // is lowercase, word boundary before |
| } else if mode == WordMode::Uppercase && c.is_uppercase() && next.is_lowercase() { |
| if !first_word { boundary(&mut out); } |
| else { first_word = false; } |
| with_word(&word[init..i], &mut out); |
| init = i; |
| mode = WordMode::Boundary; |
| |
| // Otherwise no word boundary, just update the mode |
| } else { |
| mode = next_mode; |
| } |
| } else { |
| // Collect trailing characters as a word |
| if !first_word { boundary(&mut out); } |
| else { first_word = false; } |
| with_word(&word[init..], &mut out); |
| break; |
| } |
| } |
| } |
| |
| out |
| } |
| |
| fn lowercase(s: &str, out: &mut String) { |
| let mut chars = s.chars().peekable(); |
| while let Some(c) = chars.next() { |
| if c == 'Σ' && chars.peek().is_none() { |
| out.push('ς'); |
| } else { |
| out.extend(c.to_lowercase()); |
| } |
| } |
| } |
| |
| fn uppercase(s: &str, out: &mut String ) { |
| for c in s.chars() { |
| out.extend(c.to_uppercase()) |
| } |
| } |
| |
| fn capitalize(s: &str, out: &mut String) { |
| let mut char_indices = s.char_indices(); |
| if let Some((_, c)) = char_indices.next() { |
| out.extend(c.to_uppercase()); |
| if let Some((i, _)) = char_indices.next() { |
| lowercase(&s[i..], out); |
| } |
| } |
| } |