Add a new perlrun option "-j" which allows JSON parsing in line

With this option we basically extend the already existing "-n" and "-p"
flags to handle JSON using the inbuilt "JSON::PP" module. Basically we
decode the STDIN from "$_" with decode_json into $_ again so you can run
something like:

sudo journalctl -f -o json | ./perl -njle 'if ( $_->{"_GID"} == 0 ) {print $_->{"MESSAGE"}}'

To quickly filter out all root processes, this would make adhoc log
analysis of most modern applications a more convenient.

Author: catouc

AUTHORS

@@ -1142,6 +1142,7 @@ Philip Guenther                <[email protected]>
 Philip Hazel                   <[email protected]>
 Philip M. Gollucci             <[email protected]>
 Philip Newton                  <[email protected]>
+Philipp Böschen                <[email protected]>
 Philippe Bruhat (BooK)         <[email protected]>
 Philippe M. Chiasson           <[email protected]>
 Pierre Bogossian               <[email protected]>

embedvar.h

@@ -510,6 +510,7 @@ PERLVAR(I, minus_n,	bool)
 PERLVAR(I, minus_p,	bool)
 PERLVAR(I, minus_l,	bool)
 PERLVAR(I, minus_a,	bool)
+PERLVAR(I, minus_j,	bool)
 PERLVAR(I, minus_F,	bool)
 PERLVAR(I, doswitches,	bool)
 PERLVAR(I, minus_E,	bool)

intrpvar.h

@@ -1016,6 +1016,7 @@ perl_destruct(pTHXx)
     PL_minus_p      = FALSE;
     PL_minus_l      = FALSE;
     PL_minus_a      = FALSE;
+    PL_minus_j      = FALSE;
     PL_minus_F      = FALSE;
     PL_doswitches   = FALSE;
     PL_dowarn       = G_WARN_OFF;
@@ -2245,6 +2246,7 @@ S_parse_body(pTHX_ char **env, XSINIT_t xsinit)
         case 'h':
         case 'i':
         case 'l':
+        case 'j':
         case 'n':
         case 'p':
         case 's':
@@ -3552,6 +3554,7 @@ S_usage(pTHX)		/* XXX move this out into a module ? */
 "  -l[octnum]            enable line ending processing, specifies line terminator\n"
 "  -[mM][-]module        execute \"use/no module...\" before executing program\n"
 "  -n                    assume \"while (<>) { ... }\" loop around program\n"
+"  -j                    auto decode_json with -n or -p into $data"
 "  -p                    assume loop like -n but print line also, like sed\n"
 "  -s                    enable rudimentary parsing for switches after programfile\n"
 "  -S                    look for programfile using PATH environment variable\n",
@@ -3859,6 +3862,10 @@ Perl_moreswitches(pTHX_ const char *s)
         else
             Perl_croak(aTHX_ "No directory specified for -I");
         return s;
+    case 'j':
+        PL_minus_j = TRUE;
+        s++;
+        return s;
     case 'l':
         PL_minus_l = TRUE;
         s++;

perl.c

@@ -7,7 +7,7 @@ perlrun - how to execute the Perl interpreter
 B<perl>	S<[ B<-gsTtuUWX> ]>
 	S<[ B<-h?v> ] [ B<-V>[:I<configvar>] ]>
 	S<[ B<-cw> ] [ B<-d>[B<t>][:I<debugger>] ] [ B<-D>[I<number/list>] ]>
-	S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal/hexadecimal>] ]>
+	S<[ B<-pnaj> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal/hexadecimal>] ]>
 	S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ] [ B<-f> ]>
 	S<[ B<-C [I<number/list>] >]>
 	S<[ B<-S> ]>
@@ -662,6 +662,16 @@ X<-I> X<@INC>
 Directories specified by B<-I> are prepended to the search path for
 modules (C<@INC>).
 
+=item B<-j>
+
+enables automatic JSON decoding when used with L</-n> and decode plus
+printing when used with L</-p>. It basically automatically transforms
+C<$_> into a hashref that has been parsed from the current input using
+JSON::PP::decode_json.
+When used with L</-p> it overwrites the final print statement to first
+call JSON::PP::encode_json so whatever is in C<$_> will be JSON encoded
+before printing.
+
 =item B<-l>[I<octnum>]
 X<-l> X<$/> X<$\>
 

pod/perlrun.pod

@@ -1,4 +1,4 @@
-#!/usr/bin/perl -w
+#!/usr/bin/perl -W
 #
 # Regenerate (overwriting only if changed):
 #

regen/embed.pl

@@ -15813,6 +15813,7 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     PL_minus_p		= proto_perl->Iminus_p;
     PL_minus_l		= proto_perl->Iminus_l;
     PL_minus_a		= proto_perl->Iminus_a;
+    PL_minus_j		= proto_perl->Iminus_j;
     PL_minus_E		= proto_perl->Iminus_E;
     PL_minus_F		= proto_perl->Iminus_F;
     PL_doswitches	= proto_perl->Idoswitches;

sv.c

@@ -1564,8 +1564,13 @@ Perl_lex_next_chunk(pTHX_ U32 flags)
         PL_parser->rsfp = NULL;
         PL_parser->in_pod = PL_parser->filtered = 0;
         if (!PL_in_eval && PL_minus_p) {
-            sv_catpvs(linestr,
-                /*{*/";}continue{print or die qq(-p destination: $!\\n);}");
+            if (PL_minus_j) {
+                sv_catpvs(linestr,
+                    /*{*/";}continue{print JSON::PP::encode_json($_) or die qq(-p destination: $!\\n);}");
+            } else {
+                sv_catpvs(linestr,
+                    /*{*/";}continue{print or die qq(-p destination: $!\\n);}");
+            };
             PL_minus_n = PL_minus_p = 0;
         } else if (!PL_in_eval && PL_minus_n) {
             sv_catpvs(linestr, /*{*/";}");
@@ -9195,6 +9200,10 @@ yyl_try(pTHX_ char *s)
                 sv_catpvs(PL_linestr, "LINE: while (<>) {"/*}*/);
                 if (PL_minus_l)
                     sv_catpvs(PL_linestr,"chomp;");
+                if (PL_minus_j) {
+                    sv_catpvs(PL_linestr,"use JSON::PP ();");
+                    sv_catpvs(PL_linestr,"$_ = JSON::PP::decode_json($_);");
+                }
                 if (PL_minus_a) {
                     if (PL_minus_F) {
                         if (   (   *PL_splitstr == '/'