Integrating SWEET parser

[lavafroth]

Google Summer of Code Final Submission

• Student name: Himadri Bhattacharjee
• Devlogs: https://lavafroth.is-a.dev/tags/google-summer-of-code

Overview

• Keysym and modifier structs are replaced with respective structs from the crates
• evdev keys are automatically parsed in a single pass of the parser
• Commands
  • Command chunks inside shorthands must be escaped as and when needed. For example {a-program, b-program} is invalid since the dash will be considered a range. The only correct syntax is {a\-program, b\-program} when using shorthands with commands.
  • Commands sprinked with &&-mode instructions extract the instructions as an attribute of the Definition struct during parsing
• Removed manual implementation of logical errors (handled by new parser) grammar errors (handled by pest.rs)
• Added small match block to translate sweet::Modifier variants to local Modifier variants
• Unified shorthand syntax: there's at most one way to do shorthands correct
  • A shorthand must contain at least two variants. One should not use shorthands otherwise
  • Any literal like a comma or a curly brace inside a shorthand must be escaped
  • Literals do not need to be escaped outside shorthand contexts.
  • Shorthands with omissions (underscore elements) must always have a concatenator appended to each non-empty element. For example, unlike {control, super} + a, in {_, super + } a adding a plus to super inside the shorthand is the only valid syntax. This can be compared to expansions in bash
• There's a 50 MiB filesize cap for the config file as a precaution against accidental actions on the user end. This filesize cap can be changed by passing an environment variable or modifying the build.rs.
• The parser only accepts regular files so that the user does accidentally feed in block devices like their entire drives
• All of the tests for the daemon are ported to use the grammar and are moved to the grammar crate. See tests/tests.rs
  • Some tests are stricter than the previous iteration due to the strict nature of the EBNF grammar itself. For example: commented out binding definitions with dangling commands are no longer valid
  • Temporary files for tests are handled using the temporary file architecture for the respective platform

[Shinyzenith]

Minor issue, we need the sweet stuff in tree. After that this pr is good to go r🚀🚢🚢🚢🚢🚢⚓