aoc_parse/

lib.rs

//! A parser library designed for Advent of Code.
//!
//! This library mainly provides a macro, `parser!`, that lets you write
//! a custom parser for your [AoC] puzzle input in seconds.
//!
//! For example, my puzzle input for [December 2, 2015][example] looked like this:
//!
//! ```text
//! 4x23x21
//! 22x29x19
//! 11x4x11
//! 8x10x5
//! 24x18x16
//! ...
//! ```
//!
//! The parser for this format is a one-liner: `parser!(lines(u64 "x" u64 "x" u64))`.
//!
//! # How to use aoc-parse
//!
//! It's pretty easy.
//!
//! ```
//! use aoc_parse::{parser, prelude::*};
//!
//! let p = parser!(lines(u64 "x" u64 "x" u64));
//! assert_eq!(
//!     p.parse("4x23x21\n22x29x19\n").unwrap(),
//!     vec![(4, 23, 21), (22, 29, 19)]
//! );
//! ```
//!
//! If you're using [aoc-runner], it might look like this:
//!
//! ```
//! use aoc_runner_derive::*;
//! use aoc_parse::{parser, prelude::*};
//!
//! #[aoc_generator(day2)]
//! fn parse_input(text: &str) -> Vec<(u64, u64, u64)> {
//!     let p = parser!(lines(u64 "x" u64 "x" u64));
//!     p.parse(text).unwrap()
//! }
//! ```
//!
//! # Patterns
//!
//! The argument you need to pass to the `parser!` macro is a *pattern*; all aoc-parse does is
//! **match** strings against your chosen pattern and **convert** them into Rust values.
//!
//! Here are some examples of patterns:
//!
//! ```
//! # use aoc_parse::{parser, prelude::*};
//! # let _p1 = parser!(
//! lines(i32)      // matches a list of integers, one per line
//!                 // converts them to a Vec<i32>
//! # );
//!
//! # let _p2 = parser!(
//! line(lower+)    // matches a single line of one or more lowercase letters
//!                 // converts them to a Vec<char>
//! # );
//!
//! # let _p3 = parser!(
//! lines({         // matches lines made up of the characters < = >
//!     "<" => -1,  // converts them to a Vec<Vec<i32>> filled with -1, 0, and 1
//!     "=" => 0,
//!     ">" => 1
//! }+)
//! # );
//! ```
//!
//! Here are the pieces that you can use in a pattern:
//!
//! ## Basic patterns
//!
//! `i8`, `i16`, `i32`, `i64`, `i128`, `isize`, `big_int` - These match an integer, written out
//! using decimal digits, with an optional `+` or `-` sign at the start, like `0` or `-11474`.
//!
//! It's an error if the string contains a number too big to fit in the type you chose. For
//! example, `parser!(i8).parse("1000")` is an error. (It matches the string, but fails during the
//! "convert" phase.)
//!
//! `big_int` parses a [`num_bigint::BigInt`].
//!
//! `u8`, `u16`, `u32`, `u64`, `u128`, `usize`, `big_uint` - The same, but without the sign.
//!
//! `i8_bin`, `i16_bin`, `i32_bin`, `i64_bin`, `i128_bin`, `isize_bin`, `big_int_bin`,
//! `u8_bin`, `u16_bin`, `u32_bin`, `u64_bin`, `u128_bin`, `usize_bin`, `big_uint_bin`,
//! `i8_hex`, `i16_hex`, `i32_hex`, `i64_hex`, `i128_hex`, `isize_hex`, `big_int_hex`,
//! `u8_hex`, `u16_hex`, `u32_hex`, `u64_hex`, `u128_hex`, `usize_hex`, `big_uint_hex` -
//! Match an integer in base 2 or base 16. The `_hex` parsers allow both uppercase and lowercase
//! digits `A`-`F`.
//!
//! `f32` ,`f64` - These match a floating-point number written out using decimal digits, in [this
//! format](https://doc.rust-lang.org/std/primitive.f64.html#impl-FromStr-for-f64). (No Advent of
//! Code puzzle has ever hinged on floating-point numbers, but it doesn't hurt to be prepared.)
//!
//! `bool` - Matches either `true` or `false` and converts it to the corresponding `bool` value.
//!
//! `'x'` or `"hello"` - A Rust character or string, in quotes, is a pattern that matches that
//! exact text only.
//!
//! Exact patterns don't produce a value.
//!
//! <code><var>pattern1 pattern2 pattern3</var>...</code> - Patterns can be concatenated to form
//! larger patterns. This is how `parser!(u64 "x" u64 "x" u64)` matches the string `4x23x21`. It
//! simply matches each subpattern in order. It converts the match to a tuple if there are two or
//! more subpatterns that produce values.
//!
//! <code><var>parser_var</var></code> - You can use previously defined parsers that you've stored
//! in local variables.
//!
//! For example, the `amount` parser below makes use of the `fraction` parser defined on the
//! previous line.
//!
//! ```
//! # use aoc_parse::{parser, prelude::*};
//! let fraction = parser!(i64 "/" u64);
//! let amount = parser!(fraction " tsp");
//!
//! assert_eq!(amount.parse("1/4 tsp").unwrap(), (1, 4));
//! ```
//!
//! An identifier can also refer to a string or character constant.
//!
//! ## Repeating patterns
//!
//! <code><var>pattern</var>*</code> - Any pattern followed by an asterisk matches that pattern
//! zero or more times. It converts the results to a `Vec`. For example, `parser!("A"*)` matches
//! the strings `A`, `AA`, `AAAAAAAAAAAAAA`, and so on, as well as the empty string.
//!
//! <code><var>pattern</var>+</code> - Matches the pattern one or more times, producing a `Vec`.
//! `parser!("A"+)` matches `A`, `AA`, etc., but not the empty string.
//!
//! <code><var>pattern</var>?</code> - Optional pattern, producing a Rust `Option`. For example,
//! `parser!("x=" i32?)` matches `x=123`, producing `Some(123)`; it also matches `x=`, producing
//! the value `None`.
//!
//! These behave just like the `*`, `+`, and `?` special characters in regular expressions.
//!
//! <code>repeat_sep(<var>pattern</var>, <var>separator</var>)</code> - Match the given *pattern*
//! any number of times, separated by the *separator*. This converts only the bits that match
//! *pattern* to Rust values, producing a `Vec`. Any parts of the string matched by *separator* are
//! not converted.
//!
//! ## Matching single characters
//!
//! `alpha`, `alnum`, `upper`, `lower` - Match single characters of various categories. (These use
//! the Unicode categories, even though Advent of Code historically sticks to ASCII.)
//!
//! `digit`, `digit_bin`, `digit_hex` - Match a single ASCII character that's a digit in base 10,
//! base 2, or base 16, respectively. The digit is converted to its numeric value, as a `usize`.
//!
//! `any_char` - Match the next character, no matter what it is (like `.` in a regular expression,
//! except that `any_char` matches newline characters too).
//!
//! <code>char_of(<var>str</var>)</code> - Match the next character if it's one of the characters
//! in *str*. For example, `char_of(">^<v")` matches exactly one character, either `>`, `^`, `<`,
//! or `v`. Returns the index of the character within the list of options (in this case, `0`, `1`,
//! `2`, or `3`).
//!
//! ## Matching multiple characters
//!
//! <code>string(<var>pattern</var>)</code> - Matches the given *pattern*, but instead of
//! converting it to some value, simply return the matched characters as a `String`.
//!
//! By default, `alpha+` returns a `Vec<char>`, and sometimes that is handy in AoC, but often it's
//! better to have it return a `String`.
//!
//! ## Custom conversion
//!
//! <code>... <var>name1</var>:<var>pattern1</var> ... => <var>expr</var></code> - On successfully
//! matching the patterns to the left of `=>`, evaluate the Rust expression *expr* to convert the
//! results to a single Rust value.
//!
//! Use this to convert input to structs. For instance, suppose your puzzle input contains each
//! elf's name and height:
//!
//! ```text
//! Holly=33
//! Ivy=7
//! DouglasFir=1093
//! ```
//!
//! and you'd like to turn this into a vector of `struct Elf` values. The code you need is:
//!
//! ```
//! # use aoc_parse::{parser, prelude::*};
//! struct Elf {
//!     name: String,
//!     height: u32,
//! }
//!
//! let p = parser!(lines(
//!     elf:string(alpha+) '=' ht:u32 => Elf { name: elf, height: ht }
//! ));
//! ```
//!
//! The name `elf` applies to the pattern `string(alpha+)` and the name `ht` applies to the pattern
//! `i32`. The bit after the `=>` is plain old Rust code.
//!
//! The *name*s are in scope only for the following *expr* in the same set of matching parentheses
//! or braces.
//!
//! ## Alternatives
//!
//! <code>{<var>pattern1</var>, <var>pattern2</var>, ...}</code> - Matches any one of the
//! *patterns*. First try matching *pattern1*; if it matches, stop. If not, try *pattern2*, and so
//! on. All the patterns must produce the same type of Rust value.
//!
//! This is sort of like a Rust `match` expression.
//!
//! For example, `parser!({"<" => -1, ">" => 1})` either matches `<`, returning the value `-1`, or
//! matches `>`, returing `1`.
//!
//! Alternatives are handy when you want to convert the input into an enum. For example, my puzzle
//! input for December 23, 2015 was a list of instructions that looked (in part) like this:
//!
//! ```text
//! jie a, +4
//! tpl a
//! inc a
//! jmp +2
//! hlf a
//! jmp -7
//! ```
//!
//! This can be easily parsed into a vector of beautiful enums, like so:
//!
//! ```
//! # use aoc_parse::{parser, prelude::*};
//! enum Reg {
//!     A,
//!     B,
//! }
//!
//! enum Insn {
//!     Hlf(Reg),
//!     Tpl(Reg),
//!     Inc(Reg),
//!     Jmp(isize),
//!     Jie(Reg, isize),
//!     Jio(Reg, isize),
//! }
//!
//! use Reg::*;
//! use Insn::*;
//!
//! let reg = parser!({"a" => A, "b" => B});
//! let p = parser!(lines({
//!     "hlf " r:reg => Hlf(r),
//!     "tpl " r:reg => Tpl(r),
//!     "inc " r:reg => Inc(r),
//!     "jmp " offset:isize => Jmp(offset),
//!     "jie " r:reg ", " offset:isize => Jie(r, offset),
//!     "jio " r:reg ", " offset:isize => Jio(r, offset),
//! }));
//! ```
//!
//! ## Rule sets
//!
//! <code>rule <var>name1</var>: <var>type1</var> = <var>pattern1</var>;</code> - Introduce a
//! "rule", a named subparser.
//!
//! This supports parsing text with nesting parentheses or brackets.
//!
//! ```
//! # use aoc_parse::{parser, prelude::*};
//! enum Formation {
//!     Elf(char),
//!     Stack(Vec<Formation>),
//! }
//!
//! let p = parser!(
//!     // First rule: A "formation" has return type Formation and is either
//!     // a letter or a stack.
//!     rule formation: Formation = {
//!         s:alpha => Formation::Elf(s),
//!         v:stack => Formation::Stack(v),
//!     };
//!
//!     // Second rule: A "stack" is one or more formations, wrapped in
//!     // matching parentheses.
//!     rule stack: Vec<Formation> = '(' v:formation+ ')' => v;
//!
//!     // After all rules, the pattern that .parse() will actually match.
//!     lines(formation+)
//! );
//!
//! assert!(p.parse("px(fo(i)(RR(c)))j(Q)zww\n").is_ok());
//!
//! assert!(p.parse("x(fo))\n").is_err());  // parens not balanced
//! ```
//!
//! Ordinarily `let` suffices for parsers used by other parsers; but `rule` is needed for parsers
//! that refer to themselves or to each other, cyclically, like `formation` and `stack` above.
//! Rust's `let` doesn't support that.
//!
//! Note: Left-recursive grammars don't work, as usual for PEG parsers.
//!
//! ## Lines and sections
//!
//! <code>line(<var>pattern</var>)</code> - Matches a single line of text that matches *pattern*,
//! and the newline at the end of the line.
//!
//! This is like <code>^<var>pattern</var>\n</code> in regular expressions, with two minor
//! differences:
//!
//! -   <code>line(<var>pattern</var>)</code> will only ever match exactly one line of text, even
//!     if *pattern* could match more newlines.
//!
//! -   If your input does not end with a newline, <code>line(<var<pattern</var>)</code> can still
//!     match the non-newline-terminated "line" at the end.
//!
//! `line(string(any_char+))` matches a line of text, strips off the newline character, and returns
//! the rest as a `String`. `line("")` matches a blank line.
//!
//! <code>lines(<var>pattern</var>)</code> - Matches any number of lines of text matching
//! *pattern*. Equivalent to <code>line(<var>pattern</var>)*</code>.
//!
//! ```
//! # use aoc_parse::{parser, prelude::*};
//! let p = parser!(lines(repeat_sep(digit, " ")));
//! assert_eq!(
//!     p.parse("1 2 3\n4 5 6\n").unwrap(),
//!     vec![vec![1, 2, 3], vec![4, 5, 6]],
//! );
//! ```
//!
//! <code>section(<var>pattern</var>)</code> - Matches zero or more nonblank lines, followed by
//! either a blank line or the end of input. The nonblank lines must match *pattern*. For example,
//! `section(lines(u64))` matches a section that's a list of numbers, one per line.
//!
//! It's common for an AoC puzzle input to have several lines of data, then a blank line, and then
//! a different kind of data. You can parse this with
//! <code>section(<var>p1</var>) section(<var>p2</var>)</code>.
//!
//! <code>sections(<var>pattern</var>)</code> - Matches any number of sections matching *pattern*.
//! Equivalent to <code>section(<var>pattern</var>)*</code>.
//!
//! ## Collections
//!
//! <code>hash_set(<var>pattern</var>)</code>, <code>hash_map(<var>pattern</var>)</code>,
//! <code>btree_set(<var>pattern</var>)</code>, <code>btree_map(<var>pattern</var>)</code>,
//! <code>vec_deque(<var>pattern</var>)</code> - These match some text using *pattern*, then put
//! the resulting values in a `HashSet` or other collection.
//!
//! The *pattern* must produce an [iterable](std::iter::IntoIterator) type. These functions work by
//! calling `.into_iter()` on whatever *pattern* produces, then using `.collect()` to produce the
//! new collection.
//!
//! The *pattern* itself needs a `*` or `+`, or something else that makes it match multiple values:
//!
//! ```
//! # use std::collections::HashSet;
//! # use aoc_parse::{parser, prelude::*};
//! let p = parser!(hash_set(digit+));  // <-- note the `+`
//! assert_eq!(p.parse("3127").unwrap(), HashSet::from([1, 2, 3, 7]));
//! ```
//!
//! A map is built from a sequence of pairs:
//!
//! ```
//! # use std::collections::HashMap;
//! # use aoc_parse::{parser, prelude::*};
//! let p = parser!(hash_map(
//!     lines(string(alpha+) ": " any_char)   // <-- this produces a vector of (String, char) pairs
//! ));
//!
//! assert_eq!(
//!     p.parse("Midge: @\nToyler: #\nKnitley: &\n").unwrap(),
//!     HashMap::from([
//!         ("Midge".to_string(), '@'),
//!         ("Toyler".to_string(), '#'),
//!         ("Knitley".to_string(), '&'),
//!     ]),
//! );
//! ```
//!
//! ----
//!
//! Bringing it all together to parse a complex example:
//!
//! ```
//! # use aoc_parse::{parser, prelude::*};
//! let example = "\
//! Wiring Diagram #1:
//! a->q->E->z->J
//! D->f->D
//!
//! Wiring Diagram #2:
//! g->r->f
//! g->B
//! ";
//!
//! let p = parser!(sections(
//!     line("Wiring Diagram #" usize ":")
//!     lines(repeat_sep(alpha, "->"))
//! ));
//! assert_eq!(
//!     p.parse(example).unwrap(),
//!     vec![
//!         (1, vec![vec!['a', 'q', 'E', 'z', 'J'], vec!['D', 'f', 'D']]),
//!         (2, vec![vec!['g', 'r', 'f'], vec!['g', 'B']]),
//!     ],
//! );
//! ```
//!
//! [AoC]: https://adventofcode.com/
//! [example]: https://adventofcode.com/2015/day/2
//! [aoc-runner]: https://lib.rs/crates/aoc-runner

#![deny(missing_docs)]

mod context;
mod error;
#[doc(hidden)]
pub mod macros;
mod parsers;
#[cfg(test)]
mod testing;
mod traits;
mod types;
mod util;

pub use context::{ParseContext, Reported};
pub use error::ParseError;
use error::Result;
pub use traits::{ParseIter, Parser};

/// A giant sack of toys and goodies to import along with `parser!`.
///
/// The `parser!()` macro will work fine without this, so you can explicitly
/// import the names you want to use instead of doing `use aoc_parse::{parser,
/// prelude::*};`.
///
/// This includes some constants that have the same name as a built-in Rust
/// type: `i32`, `usize`, `bool`, and so on. There's no conflict because Rust
/// types and constants live in separate namespaces.
pub mod prelude {
    pub use crate::traits::Parser;

    pub use crate::util::aoc_parse;

    pub use crate::parsers::{
        alnum, alpha, any_char, big_int, big_int_bin, big_int_hex, big_uint, big_uint_bin,
        big_uint_hex, bool, btree_map, btree_set, char_of, digit, digit_bin, digit_hex, f32, f64,
        hash_map, hash_set, i128, i128_bin, i128_hex, i16, i16_bin, i16_hex, i32, i32_bin, i32_hex,
        i64, i64_bin, i64_hex, i8, i8_bin, i8_hex, isize, isize_bin, isize_hex, lower, u128,
        u128_bin, u128_hex, u16, u16_bin, u16_hex, u32, u32_bin, u32_hex, u64, u64_bin, u64_hex,
        u8, u8_bin, u8_hex, upper, usize, usize_bin, usize_hex, vec_deque,
    };

    pub use crate::parsers::{line, lines, repeat_sep, section, sections};

    /// Parse using `parser`, but instead of converting the matched text to a
    /// Rust value, simply return it as a `String`.
    ///
    /// By default, `parser!(alpha+)` returns a `Vec<char>`, and sometimes that
    /// is handy in AoC, but often it's better to have it return a `String`.
    /// That can be done with `parser!(string(alpha+))`.
    pub fn string<P: Parser>(parser: P) -> crate::parsers::StringParser<P> {
        crate::parsers::StringParser { parser }
    }
}