ParselMouth

A combinatory parser library

This is my attempt at creating a combinatory parser library that feels easy to use and allows for easy usage. It attempts to maximize DX (Developer exprience) while staying coherent to its style.

$3

Simply import the module and call its main function, creating a new parselMouth instance:

``ts
import parselMouth from "parselMouth";

const pm = parselMouth();
`

You can add parsers through the `pm.addParser` method. All parsers are methods of the parselMouth instance, which can be used alone to create more complex parsers or used inside `pm.addParser` to finally be parser when you run the parselMouth instance with `pm.run`. To retrieve results or errors, you can use `pm.getResults` and `pm.getErrors`.

$3

Here an example of some parsers:
- `pm.char`: Validates, that the parsed char is the same as the char given as argument.
- `pm.string`: Validates, that the parsed string equals the string given as argument.
- `pm.digit`: Validates, that the parsed char is a digit.
- `pm.letter`: Validates, that the parsed char is a letter. There is also `pm.upperCaseLetter` and `pm.lowerCaseLetter` for easier use.
- `pm.not`: Validates, that the parsed char or string does not valiate the parser given as argument.
- `pm.many`: Validates the parsed string with a given parser as many times as it can.
- `pm.and`: Validates the current position of the code with each given parser. It does not travel along the code
- `pm.chain`: Validates the parsed code with each of the parsers applied one after another, moving on in the parsed code.
- `pm.same`: Validates, that the parsed position in the code is the same as the captured results of another given parser.
- `pm.ahead`: Validates, that the position in front of the current one fits the given parser.
- `pm.back`: Validates, that the position behind the current one fits the given parser.

Many more, feel free to explore!

With this, you could build something like that:
`ts
import parselMouth from "parselMouth";

const pm = parselMouth();

const usedQuote = pm.choice(pm.char("'"), pm.char("\""), pm.char("´"));
const endQuote = pm.same(usedQuote);
const stringInsides = pm.many(pm.not(endQuote));

const parsedString = pm.chain(usedQuote, stringInsides, endQuote);

pm.addParser(parsedString);
pm.run("'Hello world'");

console.log(pm.getResults);
`

$3

Parsers also have their own methods, such as:
- `parser.join`: Joins the captured group into an array with a single concatenated string. Returns the parser for chaining.
- `parser.map`: Allows you to set a mapping function that will be run on the result of the next parsed code. Returns the parser for chaining.
- `parser.error`: Sets the error message of a parser. Returns the parser for chaining.
- `parser.getError`: Returns the errormessage set for the partser.
- `parser.getResult`: Returns the result from the last parsed code.

Let's revisit our code!
`ts
import parselMouth from "parselMouth";

const pm = parselMouth();

const usedQuote = pm.choice(pm.char("'"), pm.char("\""), pm.char("´"));
const endQuote = pm.same(usedQuote).error("Error: Did not find matching quotes at end of string.");
const stringInsides = pm.many(pm.not(endQuote));

const parsedString = pm.chain(usedQuote, stringInsides, endQuote).join();

pm.addParser(parsedString);
pm.run("'Hello world'");

console.log(pm.getResults);
``