* Use the cursor position for the span when between locations.
This fixes a bug where completing
ls <TAB>
would result in replacing the entire line.
* Revert to the default update implementation.
Replacing the length of the elected value was intended to do replacement when
one moves inside a quote. The problem is that a long elected suggestion could
replace bits of a pipeline that are after the cursor. For example:
ls <TAB> | get name | str collect
Previously, lite parse would stack up opening delimiters in vec, and if we
didn't close everything off, it would simply return an error with a partial form
that didn't include the missing closing delimiters. This commits adds those
delimiters so that `classify_block` can parse correctly.
The parser sees this as a positional argument, but when requesting completions
this could be either a filename that starts with a hyphen, or it could be a
flag. This expands the completion engine's interface to return a vec of possible
completion locations instead of an optional one, because we want to show all
possibilities instead of assuming one or the either.
The completion engine maps completion locations to spans on a line, which
indicate whther to complete a command name, flag name, argument, and so on.
Initial implementation is simplistic, with some rough edges, since it relies
heavily on the parser's interpretation. For example
du -
if asking for completions, `-` is considered a positional argument by the
parser, but the user is likely looking for a flag. These scenarios will be
addressed in a series of progressive enhancements to the engine.
