;
; @ANO_SCRIPT_NAME		expression
; @ANO_SCRIPT_VERSION		0.0.1
; @ANO_SCRIPT_DESCRIPTION	LISP-style expression evaluation example
;
; @ANO_FLAGS_USE_PROTOS		[ ]
; @ANO_FLAGS_VAR_NAME_SUBS	[ ]
; @ANO_FLAGS_VAR_WARN_UNUSED	[ ]
;
; Copyright (c) 2016-2026, Jani Salonen <salojan@goto10.co>
; All rights reserved.
;
; An example of executing LISP-style expressions and examining their results.
; Individual expressions can be executed in the same environment, allowing the
; state from one expression to persist for the next. This enables, for example,
; the use of definitions such as 'define'.
;

main [exit: 0] {
	print "\nExpression example 1:\n\n"

	; Send greeting to expr_func function, let it add three parameters
	; together, and add 10 to it.
	;
	mov _exp ("\
		(add 10 (expr_func [int] 20 (add 30 (sub 40 5)) 50 \
		 \"Hello, \\\"world!\\\"\")) \
	")

	; We want new environment for expression, hence handle is invalid.
	;
	expr_eval (\
		expr_handle: INVALID, \
		expr: _exp)

	; Save expression handle needed to fetch the result.
	;
	mov _env (rc)

	; Fetch the result...
	;
	expr_ret (expr_handle: _env)

	print " 1.1. Expression result should be 145: " . rc . ".\n"

	; ...and close expression handle.
	;
	expr_free (expr_handle: _env)

	; Another round, reuse the environment.
	;
	print "\nExpression example 2:\n\n"

	mov _exp_a ("(define pi 3.14159265358979323846)")
	mov _exp_b ("(define radius 123)")
	mov _exp_c ("(mul pi radius radius)")

	; If x is between 30 and 50, say 'Yes'.
	;
	mov _exp_d ("(define x 42)")
	mov _exp_e ("(if (> x 50) 100 0)")
	mov _exp_f ("(if (and (> x 30) (< x 50)) \"Yes\" \"No\")")

	; Multiply 100 by two and then by x. Variable must be in global scope
	; when used in expression.
	;
	mov hundred (100)
	mov _exp_g ("(mul $hundred 2 x)")

	; Define z based on y.
	;
	mov _exp_h ("(define y (add 10 (sub 20 5)))")
	mov _exp_i ("(define z (if (and (> y 20) (< y 30)) \
		\"y is between 20 and 30\" \"y is something else\")")

	; We want new environment for first expression, hence handle is
	; invalid.
	;
	expr_eval (INVALID, _exp_a)

	mov _env (rc)

	; Pass the environment handle to the following expressions.
	;
	expr_eval (_env, _exp_b)
	expr_eval (_env, _exp_c)

	expr_ret (_env)

	print " 2.1. Circle area is: " . rc . "\n"

	;
	expr_eval (_env, _exp_d)
	expr_eval (_env, _exp_e)
	expr_eval (_env, _exp_f)

	expr_ret (_env)

	print " 2.2. Is x between 30 and 50? " . rc . "\n"

	;
	expr_eval (_env, _exp_g)

	expr_ret (_env)

	print " 2.3. Multiply 100 by two and then by x: " . rc . "\n"

	;
	expr_eval (_env, _exp_h)
	expr_eval (_env, _exp_i)

	expr_ret (_env)

	print " 2.4. Is y between 20 and 30? " . rc . "\n\n"

	; ...and close handle.
	;
	expr_free (_env)
}

function expr_func (_first, _second, _third, _greeting) {
	print	"Expression say: " . _greeting . "\n"
	print	"We return the sum of " . _first . ", " . _second . \
		" and " . _third . " to the caller.\n\n"

	ret	_first + _second + _third
}