Using only regexps

$_="...<value>...<value>...</value>...</value>...";
($re=$_)=~s#((<value>)|(</value>)|.)#${[')','']}[!$3]\Q$1\E${['(','']}
+[!$2]#gs;
print join "\n",eval{/$re/};
die $@ if $@=~/unmatched/i;
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