We can't know how many bytes fgets() read when we reach EOF and fgets()
didn't see a newline; we can only assume that at least strlen(buf) bytes
were read. This is quite obnoxious if one wants to use NULs in raw
input, but at least we can make reading "a\0b\0c\0" with no newline
yield "a\0b\0c", losing only the final sequence of NULs.
We can't use getline() either, since it will want to allocate a buffer
big enough for an entire line, and we might not have any newlines in our
input. A complete fix will have to use getc() or read(), preferably the
latter.
Streaming means that outputs are produced as soon as possible. With the
`foreach` syntax one can write programs which reduce portions of the
streaming parse of a large input (reduce into proper JSON values, for
example), and discard the rest, processing incrementally.
This:
$ jq -c --stream .
should produce the same output as this:
$ jq -c '. as $dot | path(..) as $p | $dot | getpath($p) | [$p,.]'
The output of `jq --stream .` should be a sequence of`[[<path>],<leaf>]`
and `[[<path>]]` values. The latter indicate that the array/object at
that path ended.
Scalars and empty arrays and objects are leaf values for this purpose.
For example, a truncated input produces a path as soon as possible, then
later the error:
$ printf '[0,\n'|./jq -c --stream .
[[0],0]
parse error: Unfinished JSON term at EOF at line 3, column 0
$
The search path listed in an import directive can now be an array. The
top-level search path is appended. Null and empty strings in the path
terminate any search. The "." in "." and "./*" is replaced with the
directory containing the file doing the import (for command-line
programs this is the current directory, though that may be a bad idea).
No version numbers or anything of the sort are gratuitously added to the
search paths.
All this makes external package managers possible by allowing
dependencies to be installed local to dependents.
Nicolas Williams