Introduces the Map pseudodatastructure

The Map uses the Set for its list of keys, then hijacks the shell
variable namespace to store the mappings for each key.

Keys must be, therefore, valid variable names. This might change
in the future when we introduce hashing.

Changes were made to exp, dump and toenv to also work with it.

idiom/data.sh

@@ -6,7 +6,7 @@
 # Variables in this file are intentionally short because
 # it is eval heavy and it matters for some shells.
 
-_T=0 _L=0 _S=0 _A=0 # Some counters for Txt, Lst, Set and Arr
+_T=0 _L=0 _S=0 _A=0 _M=0 # Some counters for Txt, Lst, Set, Arr and Map
 
 # Evaluates an expression within brackets
 exp () {
@@ -35,13 +35,14 @@ exp () {
 				_e="${1:-}${1:+ }$_R"
 				shift
 				;;
-			_[TLSA][0-9]*)
+			\:*)
 				_e="${_e:-}${_e:+ }$_t"
 				;;
-			[A-Z][a-z]*)
-				test -z "$_e" &&
-					_e="${_e:-}${_e:+ }$_t" ||
-					eval "_e=\"\${_e:-}\${_e:+ }\$$_t\""
+			_[TLSAM][0-9]*)
+				_e="${_e:-}${_e:+ }$_t"
+				;;
+			Txt|Lst|Set|Arr|Map)
+				_e="${_e:-}${_e:+ }$_t"
 				;;
 			*)
 				_write "bad expression: '$_t'"
@@ -50,8 +51,8 @@ exp () {
 		esac
 	done
 	case $_e in
-		_[TLSA][0-9]*) _R=$_e ;;
-		            *) eval $_e ;;
+		_[TLSAM][0-9]*) _R=$_e ;;
+		             *) eval $_e ;;
 	esac
 }
 
@@ -94,6 +95,16 @@ dump () {
 			done
 			dump="$dump]"
 			;;
+		_M[0-9]*)
+			eval "REPLY=\"\$$1\""
+			dump="[ Map "
+			for item in $REPLY
+			do
+				eval "dump \$$1i$item"
+				dump="$dump:$item $REPLY "
+			done
+			dump="$dump]"
+			;;
 		*)
 			_write "bad data: '$1'"
 			exit 1
@@ -127,6 +138,15 @@ toenv () {
 				count=$((count + 1))
 			done
 			;;
+		_M[0-9]*)
+			eval "REPLY=\"\$$1\""
+			eval dump=\"$1=\'\$$1\'\${__EOL__}\"
+			for item in $REPLY
+			do
+				eval "toenv \$$1i$item"
+				eval "dump=\"\${dump}$1i$item=\$$1i$item\"\${__EOL__}"
+			done
+			;;
 		*)
 			_write "bad data: '$1'"
 			exit 1
@@ -195,3 +215,22 @@ Arr_add () {
 	do shift ; eval "${_R}i$(($_R - $#))=\$1"
 	done
 }
+
+# The Map pseudotype constructor
+Map () {
+	_M=$((_M + 1))
+	_R=_M$_M
+	eval "$_R="
+	Map_add $_R "$@"
+}
+
+Map_add () {
+	_R=$1
+	shift
+	while test $# -gt 0
+	do
+		Set_add $_R ${1#\:}
+		eval "${_R}i${1#\:}=\${2:-}"
+	 	shift 2
+	done
+}

test/_idiom/006-Map.sh

@@ -0,0 +1,41 @@
+# Copyright (c) Alexandre Gomes Gaigalas <[email protected]>
+# SPDX-License-Identifier: ISC
+
+test_Map_noargs () {
+	Map
+	eval deref=\$$_R
+	tap_assert "" "$deref"
+}
+
+test_Map_simple () {
+	Map :mykey myvalue
+	eval deref=\$$_R
+	tap_assert "mykey" "$deref"
+	eval deref=\$${_R}imykey
+	tap_assert "myvalue" "$deref"
+}
+
+test_Map_multiple_keys () {
+	Map :mykey myvalue :mysecond anothervalue
+	eval deref=\$$_R
+	tap_assert "mykey${__EOL__}mysecond" "$deref"
+	eval deref=\$${_R}imysecond
+	tap_assert "anothervalue" "$deref"
+}
+
+test_Map_add_to_existing () {
+	Map :mykey myvalue
+	Map_add $_R :mysecond anothervalue
+	eval deref=\$$_R
+	tap_assert "mykey${__EOL__}mysecond" "$deref"
+	eval deref=\$${_R}imysecond
+	tap_assert "anothervalue" "$deref"
+}
+
+test_Map_key_uniqueness_retains_last_value () {
+	Map :mykey myvalue :mykey whichvalue
+	eval deref=\$$_R
+	tap_assert "mykey" "$deref"
+	eval deref=\$${_R}imykey
+	tap_assert "whichvalue" "$deref"
+}

test/_idiom/007-dump.sh → test/_idiom/008-dump.sh

@@ -22,6 +22,15 @@ test_dump_Lst () {
 	tap_assert "[ Lst 'Lorem' 'Ipsum' ]" "$REPLY"
 }
 
+test_dump_nested_Lst () {
+	val first_name = "Lorem"
+	val last_name = "Ipsum"
+	val name_parts = [ Lst $first_name $last_name ]
+	val person = [ Arr $name_parts ]
+	dump $person
+	tap_assert "[ Arr [ Lst 'Lorem' 'Ipsum' ] ]" "$REPLY"
+}
+
 test_toenv_Lst () {
 	val first_name = "Lorem"
 	local r1=$_R
@@ -71,11 +80,21 @@ test_toenv_Arr () {
 	tap_assert "$r3='2'${__EOL__}${r3}i0=$r1${__EOL__}$r1='Lorem'${__EOL__}${r3}i1=$r2${__EOL__}$r2='Ipsum'${__EOL__}" "$REPLY"
 }
 
-test_dump_nested_Lst () {
+test_dump_Map () {
 	val first_name = "Lorem"
 	val last_name = "Ipsum"
-	val name_parts = [ Lst $first_name $last_name ]
-	val person = [ Arr $name_parts ]
-	dump $person
-	tap_assert "[ Arr [ Lst 'Lorem' 'Ipsum' ] ]" "$REPLY"
+	val profile = [ Map :fname $first_name :lname $last_name ]
+	dump $profile
+	tap_assert "[ Map :fname 'Lorem' :lname 'Ipsum' ]" "$REPLY"
+}
+
+test_toenv_Map () {
+	val first_name = "Lorem"
+	local r1=$_R
+	val last_name = "Ipsum"
+	local r2=$_R
+	val profile = [ Map :fname $first_name :lname $last_name ]
+	local r3=$_R
+	toenv $profile
+	tap_assert "$r3='fname${__EOL__}lname'${__EOL__}${r3}ifname=$r1${__EOL__}${r3}ilname=$r2${__EOL__}" "$REPLY"
 }