I would like to search through a file and find all instances where the last non-blank character is a comma and move the line below that up one. Essentially, undoing line continuations like
private static final double SOME_NUMBERS[][] = {
{1.0, -6.032174644509064E-23},
{-0.25, -0.25},
{-0.16624879837036133, -2.6033824355191673E-8}
};
and transforming that to
private static final double SOME_NUMBERS[][] = {
{1.0, -6.032174644509064E-23}, {-0.25, -0.25}, {-0.16624879837036133, -2.6033824355191673E-8}
};
Is there a good way to do this?
As mjswartz suggests in the comments, we need a sed substitution command like s/,\n/ /g. That, however, does not work by itself because, by default, sed reads in only one line at a time. We can fix that by reading in the whole file first and then doing the substitution:
$ sed 'H;1h;$!d;x; s/,[[:blank:]]*\n[[:blank:]]*/, /g;' file
private static final double SOME_NUMBERS[][] = {
{1.0, -6.032174644509064E-23}, {-0.25, -0.25}, {-0.16624879837036133, -2.6033824355191673E-8}
};
Because this reads in the whole file at once, this is not a good approach for huge files.
The above was tested with GNU sed.
H;1h;$!d;x;
This series of commands reads in the whole file. It is probably simplest to think of this as an idiom. If you really want to know the gory details:
H - Append current line to hold space 1h - If this is the first line, overwrite the hold space with it $!d - If this is not the last line, delete pattern space and jump to the next line. x - Exchange hold and pattern space to put whole file in pattern space s/,[[:blank:]]*\n[[:blank:]]*/, /g
This looks for lines that end with a comma, optionally followed by blanks, followed by a newline and replaces that, and any leading space on the following line, with a comma and a single space.