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How to use multi-dimensional associative arrays in BASH

As promised, a solution in < 10 lines. Using grep with PCRE RegEx.

Introducing BAAM - [B]ASH [A]ssociative [A]rrarys in [M]ulti-dimensions

BAAM (){ # BAAM - [B]ASH [A]ssociative [A]rrarys in [M]ulti-dimensions
	REGEX_STR='(^|[^\t])\t{1}'$2'((?=\t{2}[^\t])|:)\K.*?'
	LEVEL=1
	for PROP_NAME in "${@:3}"; do
		REGEX_STR+='\t{'$((LEVEL++))'}'$PROP_NAME'((?=\t{'$(($LEVEL+1))'}[^\t])|:)\K.*?'
	done
	REGEX_STR+='[^\t](?=$|\t{1,'$LEVEL'}[^\t])'
	echo $(echo "$1" | grep -oPe "$REGEX_STR")
}

Example of use:

#!/usr/bin/env bash

# BAAM uses BAAML, a TAB deliminated multidimensional markup

# Option 1. Inline: Pass arbitrary text containing BAAML markup into a variable
{ MY_DATA=$(</dev/stdin); } <<\EOF
	SpaceX
		headquarters
			address:Rocket Road
			city:Hawthorne
			state:California
		links
			website:https://www.spacex.com/
			flickr:https://www.flickr.com/photos/spacex/
			twitter:https://twitter.com/SpaceX
			elon_twitter:https://twitter.com/elonmusk
		name:SpaceX
		founder:Elon Musk
		founded:2002
		employees:8000
EOF

# Option 2. Load: cat BAAML markup into a variable
# MY_DATA="`cat ./my_baaml.txt`"

MY_DATA=${MY_DATA//$'\n'/} # Remove newlines so grep can search it in one go

# Define search function
BAAM (){ # BAAM - [B]ASH [A]ssociative [A]rrarys in [M]ulti-dimensions
	REGEX_STR='(^|[^\t])\t{1}'$2'((?=\t{2}[^\t])|:)\K.*?'
	LEVEL=1
	for PROP_NAME in "${@:3}"; do
		REGEX_STR+='\t{'$((LEVEL++))'}'$PROP_NAME'((?=\t{'$(($LEVEL+1))'}[^\t])|:)\K.*?'
	done
	REGEX_STR+='[^\t](?=$|\t{1,'$LEVEL'}[^\t])'
	echo $(echo "$1" | grep -oPe "$REGEX_STR")
}

# Call BAAM wtih MY_DATA and each array property to reach the desired value
echo $(BAAM "$MY_DATA" SpaceX links website)

#Output: https://www.spacex.com/

If you’d like to see the process of me creating BAAM and BAAML:

Best way to simulate multidimensional arrays "objects" in BASH? - #27 by Ulfnic

This is ground floor for the project and I intend to take it a lot further. Time allowing i’ll be adding lots of features, documentation and testing.

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