arsd.shell

Support functions to build a custom unix-style shell.

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Members

Aliases

Globber alias Globber = string[] delegate(ShellLexeme[] str, ShellContext context)

Classes

Shell class Shell: Undocumented in source.
ShellCommand class ShellCommand: Undocumented in source.

Functions

constructLineGetter auto constructLineGetter(): Constructs an instance of arsd.terminal.LineGetter appropriate for use in a repl for this shell.
enableInteractiveShell void enableInteractiveShell(): Sets up signal handling and progress groups to become an interactive shell.
lexShellCommandLine ShellLexeme[] lexShellCommandLine(string commandLine): This function in pure in all but formal annotation; it does not interact with the outside world.
nextComponent ShellLexeme[] nextComponent(ShellLexeme[] lexemes): A shell component - which is likely an argument, but that is a semantic distinction we can't make until parsing - may be made up of several lexemes. Think foo'bar'. This will extract them from the given array up to and including the next unquoted space or newline char.
parseShellCommand ShellCommand[] parseShellCommand(ShellLexeme[] lexemes, ShellContext context, Globber globber): Parses a set of lexemes into set of command objects.

Structs

ShellContext struct ShellContext: Holds some context needed for shell expansions.
ShellLexeme struct ShellLexeme: Represents one component of a shell command line as a precursor to parsing.

Do NOT use this to try to sanitize, escape, or otherwise parse what another shell would do with a string! Every shell is different and this implements my rules which may differ in subtle ways from any other common shell.

If you want to use this to understand a command, also use it to execute that command so you get what you expect.

Some notes about this shell syntax:

An "execution batch" is a set of command submitted to be run. This is typically a single command line or shell script.
; means "execute the current command and wait for it to complete". If it returns a non-zero errorlevel, the current execution batch is aborted.
;; means the same as ;, except that if it returned a non-zero errorlevel, the current batch is allowed to proceed.
& means "execute current command in the background"
ASCII space, tab, and newline outside of quotes are all collapsed to a single space, html style. If you want multiple commands in a single execution, use ;. Interactively, pressing enter usually means a new execution, but in a script, you need to use ; (or &, &&, or ||), not just newline, to separate commands.

Bugs

a failure in a pipeline at any point should mark that command as failing, not just the first command.
sleep 1 && sleep 1 & only puts the second sleep in the background.
bash supports $'\e' which follows C escape rules inside the single quotes. want?
${name:use_if_unset} not implemented. might not bother.
glob expansion is minimal - * works, but no ?, no stuff. The * is all i personally care about.
substitution and $(...) is not implemented
variable expansion ${IDENT} is not implemented.
no !history recall. or history command in general
job control is rudimentary - no fg, bg, jobs, ctrl+z, etc.
i'd like it to automatically set -o ignoreeof in some circumstances
prompt could be cooler PS1 = normal prompt PS2 = continuation prompt Bash shell executes the content of the PROMPT_COMMAND just before displaying the PS1 variable.
bash does it with \u and stuff but i kinda think using $USER and such might make more sense.
i do alias thing args... instead of alias thing="args...". i kinda prefer it this way tho
the api is not very good
ulimit? sourcing things too. aliases.
deeshrc is pulled from cwd
tab complete of available commands not implemented - get it from path search.

Questionable ideas

be able to receive an external command, e.g. from vim hotkey
separate stdout and stderr more by default, allow stderr pipes.
custom completion scripts? prolly not bash compatible since the scripts would be more involved
some kind of scriptable cmdlet? a full on script language with shell stuff embeddable? see https://hush-shell.github.io/cmd/index.html for some ok ideas
do something fun with job control. idk what tho really.
can terminal emulators get notifications when the foreground process group changes? i don't think so but i could make a "poll again now" sequence since i control shell and possibly terminal emulator now.
change DISPLAY and such when attaching remote sessions

arsd.shell

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