Description
The dumper code (in chooseScalarStyle) checks in a couple places to see if any characters in the string to be written are non-printable, and if so only allows double-quoted output. This is mostly fine, except tabs are explicitly excluded from the "printable" set (there's a comment implying it's intentional). That means that any block quote with tabs is unconditionally rendered as a single-line double-quoted string.
For example, loading+dumping this:
value: |-
a
bresults in this:
value: "a\n\tb"obviously this example is trivial and no big deal, but with a very large string that has embedded tabs (for example, an example program embedded in a value of a yaml block), you can imagine it gets pretty ugly.
For my needs it'd be enough to change the isPrintable checks in chooseScalarStyle to also accept tabs (0x09), but I think there's a pretty reasonable case to be made for carriage returns and non-breaking spaces too. It turns out I also need carriage returns and newlines, so I've patched that as well in my PR.