Support nested quoting

[remkop]

As an enhancement to #594, we can support nested quotes.

For example, when splitting on the "," split regex, with a Map option whose keys have embedded '=' characters, we want to be able to parse input like this:

<cmd> --option "'keyprefix=keypostfix'=value","'key2=key2'=value2"

Giving a map with key-value pairs like this:

keyprefix=keypostfix : value
key2=key2 : value2

[pubudu91]

I tried to pass multiple -e options like the following:

$ <cmd> -e \"a=b\"=foo -e \"a b\"=bar <file-name>

Is this the same scenario as the one you've described above?

[pubudu91]

Ah sorry. My bad. Should escape the space as well.

[remkop]

@pubudu91 Was there any problem with your example, or did it behave as expected?

To explain what I had in mind with nested quotes, assume we have a positional parameter defined like this:

@Parameters(split = ",")
Map<String, String> map;

the parameter values will first be split by the specified regular expression ("," in this case), and after that each substring is parsed as a KEY=VALUE map entry. For example:

"'aaa=bbb'=ccc","'xxx yyy'='zz zz zz'"

Given the above input, if CommandLine::setTrimQuotes() is set to true, first the parameter is split on the regex, and quotes are trimmed from each value, so we get these values:

'aaa=bbb'=ccc
'xxx yyy'='zz zz zz'

After that, each value is parsed as a KEY=VALUE pair and put into the map. We want the parser to recognize 'aaa=bbb' as a single token so we can have = characters embedded in the key, like you requested in #594.

For this to work, the current quote-parsing logic needs to be extended to recognize single quotes as well as double quotes, and recognize nested quoted sections. That is what this ticket is about.

[remkop]

@pubudu91 in your example, why do you need to escape the double quotes? Don't you want to do this instead?

$ <cmd> -e "a=b"=foo -e "a b"=bar <file-name>

[pubudu91]

If not escaped, the quotes seem to get trimmed. Checked the args array in main() and the quotes weren't there unless it was escaped. Similar story with the space I guess. Not an issue with picocli.

[remkop]

You can control quote trimming with CommandLine.setTrimQuotes. By default, picocli leaves the quotes in place. Could it be the shell (bash) that is trimming the quotes?

[pubudu91]

Yes, probably. As I said, it's not an issue with picocli.

[remkop]

Adding this ticket to the 4.0 roadmap:

As part of the work for #738, picocli 4.0 will fully support nested backslash-escaped double quotes. Single quotes will not have any special meaning.