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Awk-like table data processing in J (jsoftware)
#!/bin/sh
#0 :0
trap '' PIPE
exec /usr/lib/j8/bin/jconsole "$0" "$@"
# vim:ft=j
)
NB.SUMMARY: awk-like table data processing
NB.USAGE: $ ./$0 [-b 'beg-exprs'..] [-e 'end-exprs'..] ['line-exprs'...]
NB. TODO: gather all files (and stdin by '-') into single list of boxes with data
NB. => process each file in loop
NB. => use file name/number matchers to apply different exprs to different data
errhandle=: 9!:27
errexit=: 9!:29]1
onfail=:3 :0
smoutput 1}.ARGV NB. print actual cmdline (in boxes)
stderr]dberm'' NB. print error message and line number
exit>:dberr'' NB. exit with immex error code
)
errhandle 'onfail 1'
errexit
NB. BET:USE: {getenv'RS'} with fallback to LF
RS =: LF
FS =: ' '
print=: [
NB. print=: echo
NB.NOTE: parse cmdline options
verb define ''
prolog =: i.0
eachln =: i.0
epilog =: i.0
i=.1
while. (i=.>:i) < #ARGV do.
o=. >i{ARGV
if. '-' = {.o do.
if. 2 > #o do.
k=. 2}.o
o=. 1{o
else.
i=. >:i
k=. i{ARGV
o=. 1{o
end.
else.
k=. i{ARGV
o=. ' '
end.
NB. if. '-n' do. print=: [ end.
if. 'b' = o do.
prolog =: prolog,k
elseif. 'e' = o do.
epilog =: epilog,k
elseif. do.
eachln =: eachln,k
end.
end.
)
NB.DEBUG:
NB. echo 'B:';prolog
NB. echo 'X:';eachln
NB. echo 'E:';epilog
NB.NOTE: prolog expressions (e.g. read and manually parse header)
print".>prolog
verb define ''
if. (0 = isatty 0) do.
NB. read whole text from /dev/stdin (line-by-line is impossible it seems...)
S=: input=: stdin''
else.
input=: ''
NB. stderr 'Err: requires stdin input or [-f file..] specified on cmdline'
NB. exit 2
end.
)
NB.NOTE: table-as-whole
lines =: RS splitstring input NB. split text into lines
R=: lines =: }:lines NB. remove last empty line (proper UNIX must end with '\n')
NB. lines =: -.&a: lines NB. remove all empty lines (only on demand)
cells =: (FS splitstring>) "0 lines NB. split lines into columns
T=: cells =: -.&a:"1 cells NB. remove empty columns (created after splitting)
NB. echo cells
NB. [_] READ: https://code.jsoftware.com/wiki/User:Devon_McCormick/Code/WorkOnLargeFiles
NB. BAD:(still whole file at once): readln =: [: (1!:01) 1: | while (s:'`.') ~: s:<L=:readln''
NB.INFO: split on space; strip isolated spaces (0x20); OR:( TAB | LF | 10{a. )
NB. [ (#~ a: ~: ]) <;._1 ' ' , 'hello world test abc 123'
NB.INFO: prepend space (,); split on first char (' '), enbox; strip empty boxes (-.&a:)
NB. [ -.&a: <;._1 ' ' , 'hello world test abc 123'
NB.INFO: adaptable to arbitrary white space
NB. [ WHITE =. ' ',TAB,CRLF
NB. [ (</.~ (* +/\@({. , 2&(</\)))@(-.@(e.&WHITE)))&.(' '&, :. }.) 'a b cc dd'
NB. NOTE: line-by-line
NB.ALT:REF: https://code.jsoftware.com/wiki/Interfaces/Text
verb define ''
NR=: -1
while. (NR=:>:NR) < #cells do.
L=: > NR{ lines
NB. BAD: fixed max number of cols in each row
F=: NR{ cells
V=: 0".& >F
print".>eachln
end.
)
NB.NOTE: epilog expressions (e.g. apply once for whole table)
print".>epilog
exit 0
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