AoikBatchCmdLineArgsParser

Batch command line arguments parser:

Tested working with:

Inspired by: this post

Features

Supported to define a normal option or a flag option.
Supported to define an option key to contain %, ^, ! and space.
Supported to define an option default value to contain %, ^, ! and space.
Supported to supply an option actual value to contain %, ^, ! and space.
Supported to supply an option actual value that is empty.
Prevented ^ and ! in an option definition from being treated specially so no escaping or quoting is needed.
Prevented -key supplied from matching --key defined.
Provided both DisableDelayedExpansion and EnableDelayedExpansion versions.
Added extensive comments to explain how the parsing works.

The OPT_DEFS variable contains a list of option definitions, delimited by unquoted space.
An option definition is an _OPT_KEY_:_OPT_DFT_ pair. The option key and option default value are delimited by : colon. E.g. --title:test defines a normal option taking a value. E.g. --version defines a flag option taking no value.
" double quote should not be used either in an option definition, or in the middle of a command line argument, because it would cause quote mismatch which interferes with Batch's execution.
' single quote is used to quote option default values. It is not allowed to be part of an option default value, but is ok to be part of an option actual value.
Command line argument --key=val is automatically converted to two arguments --key and val by CMD. The parser does not handle the --key=val style directly. If the Batch script is not run by CMD, e.g. by a Cygwin program instead, only the --key val style works, the --key=val style not works.
If the execution failed with the error The syntax of the command is incorrect or The system cannot find the batch label specified, it might be caused by a bug of Batch that has something to do with the number of characters in the code. To let the error go away, try adding some comment lines to the middle of the code.

To get result --flag=1, define option --flag, supply argument --flag.
To get result --key=val, define option --key:val, supply argument --key val or --key=val.
To get result --key=, define option --key:'', supply argument --key "" or --key="".
To get result --%=%, define option --%%:%%, supply argument --% % or --%=%.
To get result --^=^, define option --^:^, supply argument "--^" "^" or "--^"="^".
To get result --!=!, define option --!:!, supply argument --! ! or --!=!.
To get result --key with spaces=val with spaces, define option '--key with spaces':'val with spaces', supply argument "--key with spaces" "val with spaces" or "--key with spaces"="val with spaces".