* ls: add new optional arguments to --classify flag
The --classify flag in ls now takes an option when argument
that may have the values always, auto and none.
Modified clap argument to allow an optional parameter and
changed the classify flag value parsing logic to account for
this change.
* ls: add test for indicator-style, ind and classify with value none
* ls: require option paramter to --classify to use a = to specify flag value
* ls: account for all the undocumented possible values for the --classify flag
Added the other values for the --classify flag along with modifications to tests.
Also documented the inconsistency between GNU coreutils because we accept the
flag value even for the short version of the flag.
Replace `ByteSplitter` and `LineSplitter` with `ByteChunkWriter` and
`LineChunkWriter` respectively. This results in a more maintainable
design and an increase in the speed of splitting by lines.
Add the `ByteChunkWriter` and `LineChunkWriter` structs and
implementations, but don't use them yet. This structs offer an
alternative approach to writing chunks of output (contrasted with
`ByteSplitter` and `LineSplitter`). The main difference is that
control of which underlying file is being written is inside the writer
instead of outside.
Add some helper functions and adjust some error-handling to make the
`Output::dd_out()` method, containing the main loop of the `dd`
program, more concise. This commit also adds documentation and
comments describing the main loop procedure in more detail.
This lets us use fewer reallocations when parsing each line.
The current guess is set to the maximum fields in a line so far. This is
a free performance win in the common case where each line has the same
number of fields, but comes with some memory overhead in the case where
there is a line with lots of fields at the beginning of the file, and
fewer later, but each of these lines are typically not kept for very
long anyway.
Using indexes into the line instead of Vec<u8>s means we don't have to copy
the line to store the fields (indexes instead of slices because it avoids
self-referential structs). Using memchr also empirically saves a lot of
intermediate allocations.
Refactor the code for representing the `df` data table into `Header`
and `Row` structs. These structs live in a new module `table.rs`. When
combined with the `Options` struct, these structs can be
`Display`ed. Organizing the code this way makes it possible to test
the display settings independently of the machinery for getting the
filesystem data. New unit tests have been added to `table.rs` to
demonstrate this benefit.
Show a warning if the `skip=N` command-line argument would cause `dd`
to skip past the end of the input. For example:
$ printf "abcd" | dd bs=1 skip=5 count=0 status=noxfer
'standard input': cannot skip to specified offset
0+0 records in
0+0 records out
Add some structure to errors that can be created during parsing of
settings from command-line options. This commit creates
`StrategyError` and `SettingsError` enumerations to represent the
various parsing and other errors that can arise when transforming
`ArgMatches` into `Settings`.
