73 lines
1.8 KiB
Bash
Executable File
73 lines
1.8 KiB
Bash
Executable File
#!/bin/bash
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#
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# ex1.bash: Advent2020 game, day 19/game 1.
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CMD=${0##*/}
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set -o noglob
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shopt -s extglob
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declare -a RULE=() MATCH=() STRING=()
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# shellcheck disable=SC2034
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declare var_0
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declare -i res=0
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# build a regexp use-able by bash =~ operator.
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# Recursively replace rules, until we get final text values.
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# To avoid running subshell, we must create local variables w/ different
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# names at each recursion level (to avoid "circular name reference" error).
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function buildtree {
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local -i prof="$1" # to allow ≠ local names
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local -n upname="$2" # caller variable name
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local name="var_$prof" # local var name, w/ depth
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eval "local $name" # ... declared here
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shift 2
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local args=$* res="" arg
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for arg in $args; do
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if [[ -z "${arg/[|ab]}" ]]; then
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res+="$arg"
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else
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if [[ ! -v MATCH[$arg] ]]; then
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buildtree "$((prof+1))" "$name" "${RULE[$arg]}"
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MATCH[$arg]="(${!name})"
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fi
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res+=${MATCH[$arg]}
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fi
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done
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# shellcheck disable=SC2034
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upname="$res"
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}
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while read -r line; do
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case ${line:0:1} in
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[0-9]*) # rule
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rule=${line%:*}
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val=${line#*: }
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RULE[$rule]="${val//\"}"
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;;
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[a-z]*) # string
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STRING+=("$line")
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;;
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esac
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done
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# Old rules:
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# 8: 42
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# 11: 42 31
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# New rules:
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# 8: 42 | 42 8
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# 11: 42 31 | 42 11 31
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buildtree 1 var_0 42
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printf "RULE 42 = %s\n" "${MATCH[42]}"
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buildtree 1 var_0 31
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printf "RULE 31 = %s\n" "${MATCH[11]}"
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for str in "${STRING[@]}"; do
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[[ "$str" =~ ^${MATCH[0]}$ ]] && ((res++))
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done
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printf "%s : res=%d\n" "$CMD" "$res"
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exit 0
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