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//! This module provides functionality for generating variable names and type names so that they
//! adhere to the Rust naming conventions.
const KEYWORDS: &[&str] = &[
"abstract", "as", "async", "await", "become", "box", "break", "const", "continue", "crate",
"do", "dyn", "else", "enum", "extern", "false", "final", "fn", "for", "gen", "if", "impl",
"in", "let", "loop", "macro", "match", "mod", "move", "mut", "override", "priv", "pub", "ref",
"return", "Self", "self", "static", "struct", "super", "trait", "true", "try", "type",
"typeof", "union", "unsafe", "unsized", "use", "virtual", "where", "while", "yield",
];
/// Struct used as namespace only
pub struct NamingHelper;
impl NamingHelper {
/// Checks whether the given name is a reserved Rust keyword
/// ```
/// use parol::generators::NamingHelper as NmHlp;
/// assert!(!NmHlp::is_rust_keyword("Type"));
/// assert!(NmHlp::is_rust_keyword("type"));
/// ```
pub fn is_rust_keyword(name: &str) -> bool {
KEYWORDS.iter().any(|kw| kw == &name)
}
/// Checks whether the symbol starts with "r#"
///
/// ```
/// use parol::generators::naming_helper::NamingHelper;
///
/// assert!(NamingHelper::is_raw_identifier("r#let"));
/// assert!(!NamingHelper::is_raw_identifier("_let"));
/// ```
pub fn is_raw_identifier(name: &str) -> bool {
name.starts_with("r#")
}
/// If the given name is a reserved Rust keyword it is converted into a raw identifier
/// ```
/// use parol::generators::NamingHelper as NmHlp;
/// assert_eq!("Type".to_string(), NmHlp::escape_rust_keyword("Type".to_string()));
/// assert_eq!("r#type".to_string(), NmHlp::escape_rust_keyword("type".to_string()));
/// ```
pub fn escape_rust_keyword(name: String) -> String {
if Self::is_rust_keyword(&name) {
format!("r#{name}")
} else {
name
}
}
/// Returns an underscore string if the item is not used.
pub fn item_unused_indicator(used: bool) -> &'static str {
if used { "" } else { "_" }
}
/// Returns an underscore string if the item is not used.
///
/// ```
/// use parol::generators::naming_helper::NamingHelper;
///
/// assert_eq!(NamingHelper::add_unused_indicator(false, "r#let"), "_let");
/// assert_eq!(NamingHelper::add_unused_indicator(false, "x"), "_x");
/// assert_eq!(NamingHelper::add_unused_indicator(true, "x"), "x");
/// ```
pub fn add_unused_indicator(used: bool, name: &str) -> String {
if !used && !Self::is_raw_identifier(name) {
format!("_{name}")
} else if !used {
name.to_string().replace("r#", "_")
} else {
name.to_string()
}
}
///
/// Produces a lower snake case version of the given name.
/// Since these names are supposed to be used as identifiers a clash with rust keywords is
/// detected and prevented.
///
/// ```
/// use parol::generators::NamingHelper as NmHlp;
/// assert_eq!("prolog0", NmHlp::to_lower_snake_case("Prolog0"));
/// assert_eq!("_prolog_0_", NmHlp::to_lower_snake_case("_prolog_0_"));
/// assert_eq!("_prolog_0_1_3", NmHlp::to_lower_snake_case("_prolog_0_1__3"));
/// assert_eq!("_", NmHlp::to_lower_snake_case("_____"));
/// assert_eq!("calc_lst1_1", NmHlp::to_lower_snake_case("calc_lst1_1"));
/// assert_eq!("nor_op_23", NmHlp::to_lower_snake_case("nor_op_23"));
/// assert_eq!("r#type", NmHlp::to_lower_snake_case("type"));
/// assert_eq!("r#type", NmHlp::to_lower_snake_case("r#type"));
/// assert_eq!("_0", NmHlp::to_lower_snake_case("0"));
/// assert_eq!("_123_a_b_c", NmHlp::to_lower_snake_case("123ABC"));
/// ```
pub fn to_lower_snake_case(name: &str) -> String {
let mut last_char = '.';
let result = name.chars().fold(String::new(), |mut acc, c| {
if acc.is_empty() {
acc.push(c.to_lowercase().next().unwrap())
} else if c == '_' {
if !acc.ends_with('_') {
acc.push('_');
}
} else if c.is_ascii_digit() && last_char.is_ascii_alphabetic() {
acc.push(c.to_lowercase().next().unwrap())
} else if c.is_ascii_uppercase() {
if !acc.ends_with('_') {
acc.push('_');
}
acc.push(c.to_lowercase().next().unwrap())
} else {
acc.push(c);
}
last_char = c;
acc
});
let result = if result.starts_with(|c: char| c.is_ascii_digit()) {
format!("_{result}")
} else {
result
};
Self::escape_rust_keyword(result)
}
///
/// Produces an upper camel case version of the given name.
/// Separated numbers are kept separated.
/// Camel case compliant input should be preserved.
///
/// ```
/// use parol::generators::NamingHelper as NmHlp;
/// assert_eq!("Prolog0", NmHlp::to_upper_camel_case("_prolog_0"));
/// assert_eq!("Prolog0", NmHlp::to_upper_camel_case("_prolog_0_"));
/// assert_eq!("Prolog0", NmHlp::to_upper_camel_case("_prolog_0__"));
/// assert_eq!("Prolog0_1", NmHlp::to_upper_camel_case("_prolog_0__1"));
/// assert_eq!("Prolog0_1_10_20", NmHlp::to_upper_camel_case("_prolog_0__1_10___20__"));
/// assert_eq!("Prolog0A", NmHlp::to_upper_camel_case("_prolog_0__a"));
/// assert_eq!("PrologAA", NmHlp::to_upper_camel_case("_prolog_a_a"));
/// assert_eq!("PrologItem", NmHlp::to_upper_camel_case("prolog_item"));
/// assert_eq!("PrologItem", NmHlp::to_upper_camel_case("PrologItem"));
/// assert_eq!("AA", NmHlp::to_upper_camel_case("_a_a_"));
/// assert_eq!("If", NmHlp::to_upper_camel_case("r#if"));
/// assert_eq!("_0", NmHlp::to_upper_camel_case("0"));
/// assert_eq!("_0", NmHlp::to_upper_camel_case("_0"));
/// ```
pub fn to_upper_camel_case(name: &str) -> String {
// Handle raw identifiers are not allowed
let is_raw = name.starts_with("r#");
let mut up = true;
let mut last_char = '.';
let result =
name.chars()
.skip(if is_raw { 2 } else { 0 })
.fold(String::new(), |mut acc, c| {
if c == '_' {
up = true;
} else if up {
if last_char.is_ascii_digit() && c.is_ascii_digit() {
acc.push('_');
}
last_char = c.to_uppercase().next().unwrap();
acc.push(last_char);
up = false;
} else {
last_char = c;
acc.push(last_char);
}
acc
});
if result.starts_with(|c: char| c.is_ascii_digit()) {
format!("_{result}")
} else {
result
}
// Currently rust identifiers only start with a lowercase letter, thus we do not need to
// check for rust keywords
// if Self::is_rust_keyword(&result) {
// format!("r#{}", result)
// } else {
// result
// }
}
/// This is a very restrictive definition of allowed characters in identifiers `parol` allows.
/// Invalid characters in terminal names, non-terminal names and module names are typically
/// replaced by the underscore character and can later be removed during name generations using
/// special casing rules like UpperCamelCase.
///
/// ```
/// use parol::generators::naming_helper::NamingHelper;
///
/// assert!(NamingHelper::is_valid_name_character('a'));
/// assert!(NamingHelper::is_valid_name_character('A'));
/// assert!(NamingHelper::is_valid_name_character('1'));
/// assert!(NamingHelper::is_valid_name_character('_'));
///
/// assert!(!NamingHelper::is_valid_name_character('-'));
/// assert!(!NamingHelper::is_valid_name_character(':'));
/// assert!(!NamingHelper::is_valid_name_character('/'));
/// ```
pub fn is_valid_name_character(c: char) -> bool {
c.is_alphanumeric() || c == '_'
}
/// Replaces all invalid characters from the given name with underscores. It is used to process
/// user given names which are for instance given as command arguments.
///
/// # Examples
///
/// ```
/// use parol::generators::naming_helper::NamingHelper;
///
/// assert_eq!(NamingHelper::purge_name("test-module"), "test_module");
/// ```
pub fn purge_name(name: &str) -> String {
let mut result = String::with_capacity(name.len());
for c in name.chars() {
result.push(if Self::is_valid_name_character(c) {
c
} else {
'_'
});
}
result
}
}