day 19 part 1 (bash)

day19/Makefile

@@ -0,0 +1,30 @@
+INPUT := INPUT.txt
+SHELL := /bin/bash
+CFLAGS := -w -g
+#CFLAGS := -w -g -pg
+#CFLAGS := -w -O3
+TIME := \time -f "\ttime: %E real, %U user, %S sys\n\tcontext-switch:\t%c+%w, page-faults: %F+%R\n"
+export PATH := .:$(PATH)
+
+.PHONY: clean all compile deploy ex1 ex2
+
+all: ex1 ex2
+
+output:
+	@$(MAKE) --no-print-directory all 2>&1 > OUTPUT
+
+compile: ex1-c ex2-c
+
+ex1:
+	@$(TIME) ex1.bash < $(INPUT) 2>&1
+	@#$(TIME) ex1-c 2020 < $(INPUT) 2>&1
+
+ex2:
+	@$(TIME) ex2.bash < $(INPUT) 2>&1
+	@#$(TIME) ex1-c 30000000 < $(INPUT) 2>&1
+
+clean:
+	@rm -f ex1-c ex2-c core
+
+deploy:
+	@$(MAKE) -C .. deploy

day19/ex1.bash

@@ -0,0 +1,63 @@
+#!/bin/bash
+#
+# ex1.bash: Advent2020 game, day 19/game 1.
+
+CMD=${0##*/}
+set -o noglob
+shopt -s extglob
+
+declare -a RULE=() MATCH=() STRING=()
+# shellcheck disable=SC2034
+declare var_0
+declare -i res=0
+
+# build a regexp use-able by bash =~ operator.
+# Recursively replace rules, until we get final text values.
+# To avoid running subshell, we must create local variables w/ different
+# names at each recursion level (to avoid "circular name reference" error).
+function buildtree {
+    local -i prof="$1"                            # to allow ≠ local names
+    local -n upname="$2"                          # caller variable name
+    local name="var_$prof"                        # local var name, w/ depth
+    eval "local $name"                            # ... declared here
+    shift 2
+    local args=$* res="" arg
+
+    for arg in $args; do
+        if [[ -z "${arg/[|ab]}" ]]; then
+            res+="$arg"
+        else
+            if [[ ! -v MATCH[$arg] ]]; then
+                buildtree "$((prof+1))" "$name" "${RULE[$arg]}"
+                MATCH[$arg]="(${!name})"
+            fi
+            res+=${MATCH[$arg]}
+        fi
+    done
+    # shellcheck disable=SC2034
+    upname="$res"
+}
+
+while read -r line; do
+    case ${line:0:1} in
+        [0-9]*)                                   # rule
+            rule=${line%:*}
+            val=${line#*: }
+            RULE[$rule]="${val//\"}"
+            ;;
+        [a-z]*)                                   # string
+            STRING+=("$line")
+            ;;
+    esac
+done
+
+buildtree 1 var_0 0
+#printf "RULE ZERO = %s\n" "${MATCH[0]}"
+
+for str in "${STRING[@]}"; do
+    [[ "$str" =~ ^${MATCH[0]}$ ]] && ((res++))
+done
+
+printf "%s : res=%d\n" "$CMD" "$res"
+
+exit 0