#parsec

#Features

• Parse any Array[T], including characters, bytes, integers, or domain tokens.
• Compose parsers with map, flat_map, then, then_left, and then_right.
• Match tokens with item, satisfy, and equality-based token.
• Build alternatives with or_else, choice, attempt, and cut.
• Repeat parsers with optional, option, many, many1, count, repeat_0_to_n, sep_by, and sep_by1 without zero-consumption infinite loops.
• Compose homogeneous and heterogeneous sequences with sequence, lift2, and apply; use ParserRef for staged recursive grammars.
• Build delimited, recursive, and lookahead grammars with between, delay, look_ahead, and not_followed_by.
• Add user-facing expectations with label and nested grammar context with context.
• Use optional feature packages for character-oriented factories and persistent pull-stream input without changing the root parser's array state.
• Parse strict RFC 8259 documents with duplicate-key detection and resource limits through the optional json package.

#Install

moon add Nanaloveyuki/parsec

import {
  "Nanaloveyuki/parsec",
}

import {
  "Nanaloveyuki/parsec" @parsec,
  "Nanaloveyuki/parsec/char" @char,
  "Nanaloveyuki/parsec/lazy" @lazy,
  "Nanaloveyuki/parsec/lexer" @lexer,
  "Nanaloveyuki/parsec/json" @json,
}

• @char creates character parsers for the root package's Array[Char] input model.
• @lazy provides an independent Stream[T] parser for persistent pull streams. Its parsers cannot be mixed with root parsers.
• @lexer maps character offsets to source positions and spans for tokenizers and parse diagnostics. It does not own parser state.
• @json is a strict JSON parser built from the root package and lexer. It is independent from JSON5, JSON-RPC, JSONPath, and JSONL libraries.

#Use

let parser = @parsec.Parser::between(
  @parsec.Parser::token('(', expected="opening parenthesis"),
  @parsec.Parser::token('x', expected="x"),
  @parsec.Parser::token(')', expected="closing parenthesis"),
)

match parser.parse_all(['(', 'x', ')']) {
  Ok(value) => println(value)
  Err(error) => println("parse failed at \{error.offset()}")
}

#Documentation

• Usage guide
• Development guide
• Contributing
• Release guide

#Nanaloveyuki/parsec

#Token parsers

///|
test "parse a delimited token" {
  let parser = @parsec.Parser::between(
    @parsec.Parser::token('(', expected="opening parenthesis"),
    @parsec.Parser::token('x', expected="x"),
    @parsec.Parser::token(')', expected="closing parenthesis"),
  )
  match parser.parse_all(['(', 'x', ')']) {
    Ok(value) => inspect(value, content="x")
    Err(_) => fail("expected a complete parse")
  }
}

#Composition