$ cat file
100-105
107
108-112

$ awk '{print "NR--> "NR,$0 OFS}END{print "\n"}' ORS="" OFS="\t" file
NR--> 1    100-105    NR--> 2    107    NR--> 3    108-112

$ awk -F"-" '{a=$1; b=$2;} b{for(i=0;i<=NR;i++) {print  "looping--> "i" ";for(;a<=b;a++) print a" ";} print"\n"} !b {print  a"\n"}' ORS="" file
looping--> 0 100 101 102 103 104 105 looping--> 1 
107
looping--> 0 108 109 110 111 112 looping--> 1 looping--> 2 looping--> 3

$ awk -F"-" '{a=$1; b=$2;} b{for(;a<=b;a++) print a" ";print"\n"} !b {print a"\n"}' ORS="" file
100 101 102 103 104 105 
107
108 109 110 111 112