Allow specifying an option terminator ("--" on POSIX) #101
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Add an option terminator to option styles. If not empty, this changes the parsing in the following ways: - Initially, arguments are not allowed to start with an option prefix; - unknown options will trigger a parse error; - after the specified terminator is encountered, all remaining tokens will be plain arguments; - the parser still tolerates "--" prefixes as option values. It has this in common with Python's argparse, but POSIX parsers tend to also error out with a "no option value provided" error. Other change: - Unnamed arguments must be separated from a group of short options: the "abc" token in "-vabc" cannot be interpreted as an unnamed argument, unless -a, -b and -c options are defined this will now result in an error. Having this terminator is not entirely backwards compatible, in particular it becomes cumbersome to pass in negative numbers as arguments. This is a known problem for POSIX style parsers. This commit therefore defines a new style for POSIX with terminator.
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Add an option terminator to option styles. If not empty, this changes the parsing in the following ways:
Having this terminator is not entirely backwards compatible, in particular it becomes cumbersome to pass in negative numbers as arguments. This is a known problem for POSIX style parsers. This commit therefore defines a new style for POSIX with terminator.
The detection of the "--" token is implemented in the token iterator, after encountering this token it will no longer return valid tokens from its option() function.