Parser

[JacobNickerson]

Implement a more robust parser than just splitting on white space

[cbloodsworth]

The current lexer is a single function with a signature String -> ArrayList<String>. We can think of it as an intelligent string splitter. Here are some pieces I'd like to add before merging into main:

• [x] Do not split mid-quotation (' or " characters)
  • For string literals or formatted strings
• [x] Do not split mid-parentheses (( or ) characters)
  • For sub-expressions
  • [x] Also have it so that $(xxx) is grabbed as a single string.
• [x] Do not split mid-curly brackets ({ or } characters)
  • For ranges
  • [x] Also have it so ${xxx} is grabbed as a single string.
  • For shell variables

[cbloodsworth]

Before I begin the work here, I may have to modify the signature of the lexer -- rather than returning an ArrayList<String>, it'd be nice to return ArrayList<Token> -- these tokens would likely be just a record like Token(String lexeme, TokenType type), just so we have more information once we parse the tokens into some kind of tree.

This change would likely be committed directly to main, since it's a breaking change that I'd like to ensure we all have ASAP.

[cbloodsworth]

The parser is a lot more robust, but there are certain basic design decisions that is going to make POSIX-compliancy near impossible (i.e., order of operations on string evaluation.) Read here for more information on this. I am going to begin writing tests that ensure we stick as close to the standard as possible (we may deviate later, but as a starting point, we should keep as compliant as possible.)

[cbloodsworth]

Closing issue for now, too broad a scope. Will reopen with a narrower scope and more details.