Struct LexemeDescriptor

pub struct LexemeDescriptor<LexemeType> {
    pub lexeme_type: LexemeType,
    pub pattern: Regex,
}

Describes a category of lexemes with similar syntactic meanings.

This is used as part of a lexical-analyzer’s specification, as it is built to recognize different types of lexemes.

Fields

lexeme_type: LexemeType

The type of lexemes being described.

pattern: Regex

A regular-expression pattern that matches the lexemes of the specified type.

Implementations

impl<LexemeType> LexemeDescriptor<LexemeType>

pub fn new(lexeme_type: LexemeType, pattern: Regex) -> Self

Creates a LexemeDescriptor describing the specified lexeme_type with the specified pattern.

pub fn keyword(lexeme_type: LexemeType, name: &str) -> Self

Creates a new LexemeDescriptor that describes a keyword.

A keyword is a type of lexeme that only matches some hard-coded string (such as if or int). This function can be used to efficiently describe such keywords.

Example

enum MyLexemeType { If, While }
let my_lexeme_descriptors = vec![
    LexemeDescriptor::keyword(MyLexemeType::If, "if"),
    LexemeDescriptor::keyword(MyLexemeType::While, "while"),
];

pub fn special_char(lexeme_type: LexemeType, value: char) -> Self

Creates a new LexemeDescriptor that describes a special character.

A special character is a type of lexeme that only matches some hard-coded character (such as operators: +, *). This function can be used to efficiently describe such characters.

Example

enum MyLexemeType { Addition, Subtraction }
let my_lexeme_descriptors = vec![
    LexemeDescriptor::special_char(MyLexemeType::Addition, '+'),
    LexemeDescriptor::special_char(MyLexemeType::Subtraction, '-'),
];