Based on users/5283: Implement xargs-like segmenting of argument list, with

a command called on each segment.

1 files changed, 199 insertions, 0 deletions

diff --git a/Functions/Misc/zargs b/Functions/Misc/zargs
new file mode 100644
index 000000000..b52c80af5
--- /dev/null
+++ b/Functions/Misc/zargs
@@ -0,0 +1,199 @@
+# function zargs {
+#
+# This function works like GNU xargs, except that instead of reading lines
+# of arguments from the standard input, it takes them from the command
+# line.  This is possible/useful because, especially with recursive glob
+# operators, zsh often can construct a command line for a shell function
+# that is longer than can be accepted by an external command.
+#
+# Like xargs, zargs exits with the following status:
+#   0 if it succeeds
+#   123 if any invocation of the command exited with status 1-125
+#   124 if the command exited with status 255
+#   125 if the command is killed by a signal
+#   126 if the command cannot be run
+#   127 if the command is not found
+#   1 if some other error occurred.
+#
+# However, "killed by a signal" is determined by the usual shell rule
+# that $? is the signal number plus 128, so zargs can be fooled by a
+# command that explicitly exits with 129+.  Also, zsh prior to 4.1.x
+# returns 1 rather than 127 for "command not found" so this function
+# incorrectly returns 123 in that case if used with zsh 4.0.x.
+#
+# The full set of GNU xargs options is supported (see help text below);
+# although --eof and --max-lines therefore have odd names, they have
+# analogous meanings to their xargs counterparts.  Also zargs --help is
+# a lot more helpful than xargs --help, at least as of xargs 4.1.
+#
+# Note that "--" is used both to end the options and to begin the command,
+# so to specify some options along with an empty set of input-args, one
+# must repeat the "--" as TWO consecutive arguments, e.g.:
+#   zargs --verbose -- -- print There are no input-args
+# If there is at least one input-arg, the first "--" may be omitted:
+#   zargs -p -i one -- print There is just {} input-arg
+# Obviously, if there is no command, the second "--" may be omitted:
+#   zargs -n2 These words will be echoed in five lines of two
+#
+
+emulate -L zsh || return 1
+local -a opts eof n s l P i
+
+local ZARGS_VERSION="1.0"
+
+if zparseopts -a opts -D -- \
+	-eof::=eof e::=eof \
+	-exit x \
+	-help \
+	-interactive p \
+	-max-args:=n n:=n \
+	-max-chars:=s s:=s \
+	-max-lines::=l l::=l \
+	-max-procs:=P P:=P \
+	-no-run-if-empty r \
+	-null 0 \
+	-replace::=i i::=i \
+	-verbose t \
+	-version
+then
+    if (( $opts[(I)--version] ))
+    then
+	print -u2 zargs version $ZARGS_VERSION zsh $ZSH_VERSION
+    fi
+    if (( $opts[(I)--help] ))
+    then
+	>&2 <<-\HELP
+	Usage: zargs [options --] [input-args] [-- command [initial-args]]
+
+	If command and initial-args are omitted, "print -r --" is used.
+
+	Options:
+	--eof[=eof-str], -e[eof-str]
+	    Change the end-of-input-args string from "--" to eof-str.  If
+	    given as --eof=, an empty argument is the end; as --eof or -e,
+	    with no (or an empty) eof-str, all arguments are input-args.
+	--exit, -x
+	    Exit if the size (see --max-chars) is exceeded.
+	--help
+	    Print this summary and exit.
+	--interactive, -p
+	    Prompt before executing each command line.
+	--max-args=max-args, -n max-args
+	    Use at most max-args arguments per command line.
+	--max-chars=max-chars, -s max-chars
+	    Use at most max-chars characters per command line.
+	--max-lines[=max-lines], -l[max-lines]
+	    Use at most max-lines of the input-args per command line.
+	    This option is misnamed for xargs compatibility.
+	--max-procs=max-procs, -P max-procs
+	    Run up to max-procs command lines in the background at once.
+	--no-run-if-empty, -r
+	    Do nothing if there are no input arguments before the eof-str.
+	--null, -0
+	    Split each input-arg at null bytes, for xargs compatibility.
+	--replace[=replace-str], -i[replace-str]
+	    Substitute replace-str in the initial-args by each initial-arg.
+	    Implies --exit --max-lines=1.
+	--verbose, -t
+	    Print each command line to stderr before executing it.
+	--version
+	    Print the version number of zargs and exit.
+HELP
+	return 0
+    fi
+    if (( $opts[(I)--version] ))
+    then
+	return 0
+    fi
+    if (( $#i ))
+    then
+	l=1
+	i=${${i##-(i|-replace(=|))}:-\{\}}
+	opts[(r)-x]=-x
+	# The following is not how xargs is documented,
+	# but GNU xargs does behave as if -i implies -r.
+	opts[(r)-r]=-r
+    fi
+else
+    return 1
+fi
+
+local -i end c=0
+if [[ $eof == -(e|-eof) ]]; then ((end=ARGC+1))
+elif (( $#eof )); then end=$argv[(i)${eof##-(e|-eof=)}]
+else end=$argv[(i)--]
+fi
+local -a args call command; command=( ${argv[end+1,-1]} )
+
+if (( $opts[(I)-(null|0)] ))
+then set -- ${(ps:\000:)argv[1,end-1]}
+else set -- $argv[1,end-1]
+fi
+
+if [[ -n $command ]]
+then (( c = $#command - 1 ))
+else command=( print -r -- )
+fi
+
+local last='return $ret' execute='
+    if (( $opts[(I)-(-interactive|p)] ))
+    then read -q "?$call?..." || eval "$last"
+    elif (( $opts[(I)-(-verbose|t)] ))
+    then print -u2 -r -- "$call"
+    fi
+    $call
+    case $? in
+    (0) ;;
+    (<1-125>|128)  ret=123;;
+    (255)       return 124;;
+    (<129-254>) return 125;;
+    (126)       return 126;;
+    (127)       return 127;;
+    (*)         return 1;;
+    esac
+    eval "$last"'
+
+if (( ARGC == 0 ))
+then
+    if (( $opts[(I)-(-no-run-if-empty|r)] ))
+    then return 0
+    else call=($command); eval "$execute"
+    fi
+fi
+
+n=${${n##-(n|-max-args(=|))}:-$[ARGC+c]}
+s=${${s##-(s|-max-chars(=|))}:-20480}
+l=${${l##-(l|-max-lines(=|))}:-${${l[1]:+1}:-$ARGC}}
+P=${${P##-(P|-max-procs(=|))}:-1}
+
+if (( n > c ))
+then (( n -= c ))
+else
+    print -u2 zargs: argument list too long
+    return 1
+fi
+
+last='shift $((end > ARGC ? ARGC : end)); continue'
+while ((ARGC))
+do
+    for (( end=l; end && ${(c)#argv[1,end]} > s; end/=2 )) :
+    (( end > n && ( end = n ) ))
+    args=( $argv[1,end] )
+    if (( $#i ))
+    then call=( ${command/$i/$args} )
+    else call=( $command $args )
+    fi
+    if (( ${(c)#call} > s ))
+    then
+	print -u2 zargs: cannot fit single argument within size limit
+	# GNU xargs exits here whether or not -x,
+	# but that just makes the option useless.
+	(( $opts[(I)-(-exit|x)] )) && return 1
+	eval "$last"
+    else
+	eval "$execute"
+    fi
+done
+return $ret
+
+# }