233 lines
3.1 KiB
Bash
Executable File
233 lines
3.1 KiB
Bash
Executable File
#!/bin/sh
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# Weird shell stack based forth "lookalike"
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# recursion can be done by repeating the
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# word. Words cannot have multiple defs
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# in a dictionary.
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# todo:
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# implement conditionals in _execword :^)
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ignore() :
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alias :=_newword
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alias ']=_execbody'
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_stack="" # top is
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_builtin_dictionary="swap dup rot over drop add sub div mod mul put not or and xor eq lt gt ne" # + - / * .
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_newword() {
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name="$1"
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shift
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[ "$_debug" ] && {
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printf '_newword %s: %s\n' "$name" "$*"
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read
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}
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eval "${name}_definition=\"$*\""
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}
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_execword() {
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[ "$_debug" ] && {
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printf '_execword %s\n' "$1"
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read
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}
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eval "def=\"\$$1_definition\""
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[ "$def" ] || {
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printf '%s\n' "Error: no word $1"
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return
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}
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_execbody $def
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}
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_execbody() {
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while [ "$1" ]; do
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word="$1"
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[ "$_debug" ] && {
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printf 'word %s\nstack %s\n' "$word" "$_stack"
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read
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}
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case "$_builtin_dictionary" in
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*"$word"*) "_$word" $_stack ;;
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*) case "$word" in
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then) ignore ;;
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if)
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[ "${_stack%% *}" = 0 ] && {
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[ "$_debug" ] && {
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printf 'failed if, jumping ahead\n'
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read
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}
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_ifcnt=1
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_thencnt=0
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while [ "$_ifcnt" != "$_thencnt" ]; do
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[ "$_debug" ] && {
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printf '$1 %s\n' "$1"
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printf '$* %s\n' "$*"
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printf 'ifcnt: %s thencnt: %s\n' "$_ifcnt" "$_thencnt"
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read
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}
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shift
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case "$1" in
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if) ignore $(( _ifcnt += 1 )) ;;
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then) ignore $(( _thencnt += 1 )) ;;
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"") printf 'Unmatched if\n'; return ;;
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esac
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done
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}
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_drop $_stack
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shift
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continue
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;;
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*[0-9]*) _stack="$word $_stack" ;;
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*) _execword "$word" ;;
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esac
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;;
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esac
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shift
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done
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}
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_swap() {
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one="$1"
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two="$2"
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shift 2
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_stack="$two $one $*"
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}
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_dup() {
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_stack="$1 $*"
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}
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_rot() {
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one="$1"
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two="$2"
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thr="$3"
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shift 3
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_stack="$thr $one $two $*"
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}
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_over() {
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_stack="$2 $*"
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}
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_drop() {
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shift
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_stack="$*"
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}
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_add() {
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one="$1"
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two="$2"
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shift 2
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_stack="$(( one + two )) $*"
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}
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_sub() {
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one="$1"
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two="$2"
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shift 2
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_stack="$(( two - one )) $*"
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}
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_div() {
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one="$1"
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two="$2"
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shift 2
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_stack="$(( two / one )) $*"
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}
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_mod() {
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one="$1"
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two="$2"
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shift 2
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_stack="$(( two % one )) $*"
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}
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_mul() {
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one="$1"
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two="$2"
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shift 2
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_stack="$(( one * two )) $*"
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}
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_put() {
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one="$1"
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shift
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printf '%s \n' "$one"
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_stack="$*"
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}
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_not() {
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one="$1"
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shift
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_stack="$(( ~ one )) $*"
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}
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_or() {
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one="$1"
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two="$2"
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shift 2
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_stack="$(( one | two )) $*"
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}
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_and() {
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one="$1"
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two="$2"
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shift 2
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_stack="$(( one & two )) $*"
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}
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_xor() {
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one="$1"
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two="$2"
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shift 2
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_stack="$(( one ^ two )) $*"
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}
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_eq() {
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one="$1"
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two="$2"
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shift 2
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if [ "$one" -eq "$two" ]; then
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_stack="$(( ~ 0 )) $*"
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else
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_stack="$(( 0 )) $*"
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fi
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}
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_lt() {
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one="$1"
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two="$2"
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shift 2
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if [ "$two" -lt "$one" ]; then
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_stack="$(( ~ 0 )) $*"
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else
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_stack="$(( 0 )) $*"
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fi
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}
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_gt() {
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one="$1"
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two="$2"
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shift 2
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if [ "$two" -gt "$one" ]; then
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_stack="$(( ~ 0 )) $*"
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else
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_stack="$(( 0 )) $*"
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fi
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}
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_ne() {
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one="$1"
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two="$2"
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shift 2
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if [ "$two" -ne "$one" ]; then
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_stack="$(( ~ 0 )) $*"
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else
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_stack="$(( 0 )) $*"
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fi
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}
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# definitions in forsh
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: true not false ;
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: false 0 ;
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