## TODO:
### priority
- [ ] **Phase 1** - implement essential bash compatibility
- [ ] **Phase 2** - implement essential rsh features
- [ ] **Phase 3** - implement QoL performance and UX refinements (testing, async, syntax highlighting)

### rsh features
- [ ] macros and custom builtins
	- [ ] macro definition syntax
	- [ ] macro execution syntax
	- [ ] macros with args
	- [ ] builtin macros for very common tasks
		- [ ] string replacement
		- [ ] pattern searching
		- [ ] field extraction
- [ ] handling for JSON and modern data structures
- [ ] modern error handling such as stack tracing and try/except (logging macros as well?)
	- [ ] includes line/col numbers
	- [ ] shows the line where the error occured like python/rust
	- [ ] points to the exact location of the error like python/rust
- [ ] typing system - typing builtins like int, string, float, etc along with the usual weak bash types
	- [ ] support for default bash typing
	- [ ] support for strongly typing function arguments like function(int:arg1,string:arg2)
- [ ] improved bash control structures?
- [ ] support for explicitly declaring expected arguments
	- [ ] do this in the shebang `#!/usr/bin/env rsh arg1 arg2`
	- [ ] do this in functions `function(arg1,arg2)`
	- [ ] allow for extra arguments `#!/usr/bin/env rsh arg1 arg2 ...`, `function(arg1, arg2, ...)`
	- [ ] allow for default values `arg1=default`, `string:arg1="hello"`
- [ ] syntax highlighting in shell prompt
- [ ] language server?
- [ ] better support for asynchronous scripting
- [ ] portability features
	- [ ] detection of missing commands at script runtime
	- [ ] detection of unset environment variables at script runtime
- [ ] builtin testing framework for scripts using asserts

### bash features
- [x] unquoted string suppport. (space character taken care of) (that one may still be a bit buggy)
- [x] "quoted" string support. (space character taken care of)
- [x] 'quoted' string support. (space character taken care of)
- [ ] \`backticked\` string support. (space character taken care of)
- [ ] binary numbers support (uint only for now ?). 0b mark. (i64 by default)
- [ ] octal numbers support (uint only for now ?). 0 mark. (i64 by default)
- [ ] hexadecimal numbers support (uint only for now ?). 0x mark. (i64 by default)
- [ ] (signed) int support (i64 by default).
- [ ] (signed) float support (f64 by default). exponent correctly parsed.
- [x] variable assignment. (type is autodetected)
- [ ] array assignment. (type is autodetected)
- [ ] shebang (#!) and comments are correctly parsed.
- [ ] : syntax
- [ ] compgen builtin.
- [ ] complete builtin.
- [ ] compopt builtin.
- [ ] fc builtin.
- [ ] history builtin.
- [ ] local builtin.
- [ ] mapfile builtin.
- [ ] readarray builtin.
- [ ] return builtin.
- [ ] shift builtin.
- [ ] test builtin.
- [ ] trap builtin.
- [ ] ulimit builtin.
- [ ] umask builtin.
- [ ] unalias builtin.
- [ ] arrays support (single dimension, can be both associative and indexed, and store int, float or string.
- [x] $variable, ${variable} and parameter ($1 etc).
- [ ] ${parameter-default} ${parameter:-default} If parameter not set, use default.
- [ ] ${parameter=default}, ${parameter:=default} If parameter not set, set it to default.
- [ ] ${parameter+alt_value}, ${parameter:+alt_value} If parameter set, use alt_value, else use null string.
- [ ] ${parameter?err_msg}, ${parameter:?err_msg} If parameter set, use it, else print err_msg and abort the script with an exit status of 1.
- [ ] variable builtin ${#string} (var length).
- [ ] variable builtin ${string:pos} (extract substring at pos).
- [ ] variable builtin ${string:pos:len} (extract len substring at pos).
- [ ] variable builtin ${string#substr} (deletes shortest match of $substr from front of $string).
- [ ] variable builtin ${string##substr} (deletes longest match of $substr from front of $string).
- [ ] variable builtin ${string%substr} (deletes shortest match of $substr from back of $string).
- [ ] variable builtin ${string%%substr} (deletes longest match of $substr from back of $string).
- [ ] variable builtin ${string/substr/repl} (Replace first match of $substr with $repl).
- [ ] variable builtin ${string//substr/repl} (Replace all matches of $substr with $repl).
- [ ] variable builtin ${string/#substr/repl} (If $substr matches front end of $string, substitute $repl for $substr.).
- [ ] variable builtin ${string/%substr/repl} (If $substr matches back end of $string, substitute $repl for $substr.).
- [ ] variable builtin ${!varprefix*}, ${!varprefix@} (Matches names of all previously declared variables beginning with varprefix.).
- [ ] alias substitution and builtin.
- [ ] $(command) substitution (kind of similar to backtick).
- [ ] ~ expansion.
- [ ] !! expansion (history).
- [ ] {} expansion.
- [ ] $(( )) arithmetic expansion.
- [ ] [[ ]] expansion.
- [ ] [ ] expansion.
- [ ] * ? etc expansion.
- [ ] regexp support =~
- [ ] POSIX characters classes [:alnum:] matches alphabetic or numeric characters. This is equivalent to A-Za-z0-9.
- [ ] POSIX characters classes [:alpha:] matches alphabetic characters. This is equivalent to A-Za-z.
- [ ] POSIX characters classes [:blank:] matches a space or a tab.
- [ ] POSIX characters classes [:cntrl:] matches control characters.
- [ ] POSIX characters classes [:digit:] matches (decimal) digits. This is equivalent to 0-9.
- [ ] POSIX characters classes [:graph:] (graphic printable characters). Matches characters in the range of ASCII 33 - 126. This is the same as [:print:], below, but excluding the space character.
- [ ] POSIX characters classes [:lower:] matches lowercase alphabetic characters. This is equivalent to a-z.
- [ ] POSIX characters classes [:print:] (printable characters). Matches characters in the range of ASCII 32 - 126. This is the same as [:graph:], above, but adding the space character.
- [ ] POSIX characters classes [:space:] matches whitespace characters (space and horizontal tab).
- [ ] POSIX characters classes [:upper:] matches uppercase alphabetic characters. This is equivalent to A-Z.
- [ ] POSIX characters classes [:xdigit:] matches hexadecimal digits. This is equivalent to 0-9A-Fa-f.
- [x] if elif else fi.
- [ ] case "$var" in "value") command ;; "value2") command ;; esac
- [ ] for n in list do done { } may be used instead of do done
- [ ] for ((a=1; a<bla; a++)) do done { } may be used instead of do done
- [ ] while [condition] do done (optional brackets)
- [ ] while (( condition )) do done
- [ ] until [condition] do done
- [ ] do done
- [ ] break
- [ ] continue
- [ ] function function_name() { } and function() { }
- [ ] select variable in list (optional in list) do command break done
- [ ] command execution
- [x] pipes
- [x] > < >> << 2>&1 etc redirections. don’t forget <<EOF kind.
- [ ] <(command list) >(command list) process substitution.
- [x] || && operators
- [ ] echo (complete support)
- [ ] printf
- [ ] read
- [ ] cd
- [ ] pwd
- [ ] popd
- [ ] pushd
- [ ] dirs
- [ ] let += -= /= \*= %=
- [ ] eval
- [ ] set
- [ ] unset
- [ ] export
- [ ] declare
- [ ] typeset
- [ ] readonly
- [ ] getopts
- [ ] source .
- [ ] exit
- [ ] exec
- [ ] shopt
- [ ] caller
- [ ] true
- [ ] false
- [ ] type
- [ ] hash
- [ ] bind
- [ ] help
- [ ] jobs
- [ ] disown
- [ ] bg
- [ ] fg
- [ ] wait
- [ ] suspend
- [ ] logout
- [ ] times
- [ ] kill
- [ ] killall
- [ ] command
- [ ] builtin
- [ ] enable
- [ ] autoload
- [ ] .pest files will need a complete overhaul to be cleaner and better structured.

### core
- [x] Variables management (simple variables, aliases and single dimension arrays).
- [x] Variables assignment.
- [ ] Arrays assignment.
- [x] $variable, ${variable} and parameter ($1 etc) expansion.
- [ ] ${parameter-default} ${parameter:-default} expansion.
- [ ] ${parameter=default}, ${parameter:=default} expansion.
- [ ] ${parameter+alt_value}, ${parameter:+alt_value} expansion.
- [ ] ${parameter?err_msg}, ${parameter:?err_msg} expansion.
- [ ] variable builtin ${#string} expansion.
- [ ] variable builtin ${string:pos} expansion.
- [ ] variable builtin ${string:pos:len} expansion.
- [ ] variable builtin ${string#substr} expansion.
- [ ] variable builtin ${string##substr} expansion.
- [ ] variable builtin ${string%substr} expansion.
- [ ] variable builtin ${string%%substr} expansion.
- [ ] variable builtin ${string/substr/repl} expansion.
- [ ] variable builtin ${string//substr/repl} expansion.
- [ ] variable builtin ${string/#substr/repl} expansion.
- [ ] variable builtin ${string/%substr/repl}  expansion.
- [ ] variable builtin ${!varprefix*}, ${!varprefix@} expansion.
- [ ] Write everything linked to builtins, pipes etc (yeah, that will be *very* long).
- [ ] Have a 100% code coverage when it comes to documentation *and* testing.
- [ ] Multi-lingual support (i18n ? l20n.rs ?).
- [ ] Proper color management (using [term](https://crates.io/crates/term) crate maybe ?).
- [ ] Think of ways to get speed with rsh (read: be faster than Bash). JIT ? Some kind of « parsed script ready to be executed » ?
- [ ] Support float processing. (kind of done, see variable management above).
- [ ] Deprecate several bashy thing (older versions compatibility etc, bash is so much of a noodles plate now due to history that I won’t be able to cover every point so I’ll have to focus).
- [ ] Use [hashbrown](https://github.com/Amanieu/hashbrown) instead of [seahash](https://crates.io/crates/seahash). It will be used by [default](https://github.com/rust-lang/rust/pull/58623) in std once rust 1.36 is out.
- [x] Use of cargo clippy.
- [x] Use of cargo fmt.
- [ ] Use of tarpaulin.
- [ ] Use of criterion for benchmarking.
- [ ] Put tests and benches in their own directories.
- [ ] Use of error-chain, some fuzzer ?
- [ ] So many other things. multidimensionnal arrays ?