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glex.gleam
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glex.gleam
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import gleam/string
import gleam/list
import gleam/bit_array
import gleam/regex.{type Options, type Regex, Options}
import gleam/iterator.{type Iterator}
pub type Token {
Valid(name: String, value: String)
Ignored(name: String, value: String)
Invalid(value: String)
EndOfFile
}
pub type Position {
Position(Int)
}
pub opaque type Rule {
Rule(name: String, pattern: String, regex: Regex)
}
pub fn new_rule(name: String, pattern: String) -> Rule {
let options = Options(case_insensitive: False, multi_line: False)
let pattern = case pattern {
"^" <> _rest -> pattern
_ -> "^" <> pattern
}
let assert Ok(regex) = regex.compile(pattern, options)
Rule(name, pattern, regex)
}
pub opaque type Lexer {
Lexer(rules: List(Rule), ignore: List(Rule), source: String, position: Int)
}
pub fn new() -> Lexer {
Lexer([], [], "", 0)
}
pub fn add_rule(lexer: Lexer, name: String, pattern: String) -> Lexer {
let rule = new_rule(name, pattern)
Lexer(
list.concat([lexer.rules, [rule]]),
lexer.ignore,
lexer.source,
lexer.position,
)
}
pub fn add_ignore(lexer: Lexer, name: String, pattern: String) -> Lexer {
let rule = new_rule(name, pattern)
Lexer(
lexer.rules,
list.concat([lexer.ignore, [rule]]),
lexer.source,
lexer.position,
)
}
pub fn build(lexer: Lexer, source: String) -> Lexer {
Lexer(lexer.rules, lexer.ignore, source, 0)
}
pub fn lex(lexer: Lexer) -> List(#(Token, Position)) {
iterator(lexer)
|> iterator.to_list()
}
pub fn iterator(lexer: Lexer) -> Iterator(#(Token, Position)) {
use lexer <- iterator.unfold(from: lexer)
case next(lexer) {
#(_lexer, #(EndOfFile, _position)) -> iterator.Done
#(lexer, wraped_token) ->
iterator.Next(element: wraped_token, accumulator: lexer)
}
}
pub fn next(lexer: Lexer) -> #(Lexer, #(Token, Position)) {
let ignore = lex_rules(lexer.ignore, lexer.source)
case ignore {
Ok(#(name, value)) -> {
let rest =
lexer.source
|> string.drop_left(string.length(value))
#(
advance(lexer, rest, string.length(value)),
wrap_token(lexer, Ignored(name, value)),
)
}
Error(Nil) -> {
let rules = lex_rules(lexer.rules, lexer.source)
case rules {
Ok(#(name, value)) -> {
let rest =
lexer.source
|> string.drop_left(string.length(value))
#(
advance(lexer, rest, string.length(value)),
wrap_token(lexer, Valid(name, value)),
)
}
Error(Nil) -> {
case string.pop_grapheme(lexer.source) {
Error(Nil) -> #(lexer, #(EndOfFile, Position(lexer.position)))
Ok(#(grapheme, rest)) -> {
#(
advance(lexer, rest, byte_size(grapheme)),
wrap_token(lexer, Invalid(grapheme)),
)
}
}
}
}
}
}
}
pub fn ok(tokens: List(#(Token, Position))) -> Bool {
tokens
|> list.all(fn(token) {
case token {
#(Invalid(_), _) -> False
_ -> True
}
})
}
pub fn valid_only(tokens: List(#(Token, Position))) -> List(#(Token, Position)) {
tokens
|> list.filter(fn(token) {
case token {
#(Valid(_, _), _) -> True
_ -> False
}
})
}
pub fn ignored_only(
tokens: List(#(Token, Position)),
) -> List(#(Token, Position)) {
tokens
|> list.filter(fn(token) {
case token {
#(Ignored(_, _), _) -> True
_ -> False
}
})
}
pub fn invalid_only(
tokens: List(#(Token, Position)),
) -> List(#(Token, Position)) {
tokens
|> list.filter(fn(token) {
case token {
#(Invalid(_), _) -> True
_ -> False
}
})
}
fn advance(lexer: Lexer, source: String, offset: Int) -> Lexer {
Lexer(
rules: lexer.rules,
ignore: lexer.ignore,
source: source,
position: lexer.position + offset,
)
}
fn wrap_token(lexer: Lexer, token: Token) -> #(Token, Position) {
#(token, Position(lexer.position))
}
fn byte_size(string: String) -> Int {
bit_array.byte_size(<<string:utf8>>)
}
fn lex_rules(
rules: List(Rule),
source: String,
) -> Result(#(String, String), Nil) {
rules
|> list.flat_map(fn(rule) {
rule.regex
|> regex.scan(source)
|> list.map(fn(match) { #(rule.name, match.content) })
})
|> list.first()
}