# env is an alist of ((sym . val) (sym . val) ...)
fn evaluate _in: (addr handle cell), out: (addr handle cell), env: (addr cell), trace: (addr trace) {
trace-text trace, "eval", "evaluate"
trace-lower trace
var in/eax: (addr handle cell) <- copy _in
var in-addr/eax: (addr cell) <- lookup *in
{
var is-nil?/eax: boolean <- is-nil? in-addr
compare is-nil?, 0/false
break-if-=
# nil is a literal
copy-object _in, out
trace-higher trace
return
}
var in-type/ecx: (addr int) <- get in-addr, type
compare *in-type, 1/number
{
break-if-!=
# numbers are literals
copy-object _in, out
trace-higher trace
return
}
compare *in-type, 2/symbol
{
break-if-!=
lookup-symbol in-addr, out, env, trace
trace-higher trace
return
}
# TODO: pairs
copy-object _in, out
trace-higher trace
}
fn lookup-symbol sym: (addr cell), out: (addr handle cell), _env: (addr cell), trace: (addr trace) {
# trace sym
{
var stream-storage: (stream byte 0x40)
var stream/ecx: (addr stream byte) <- address stream-storage
write stream, "lookup "
var sym2/eax: (addr cell) <- copy sym
var sym-data-ah/eax: (addr handle stream byte) <- get sym2, text-data
var sym-data/eax: (addr stream byte) <- lookup *sym-data-ah
rewind-stream sym-data
write-stream stream, sym-data
trace trace, "eval", stream
}
trace-lower trace
var env/ebx: (addr cell) <- copy _env
# if env is not a list, abort
{
var env-type/ecx: (addr int) <- get env, type
compare *env-type, 0/pair
break-if-=
error trace, "eval found a non-list environment"
trace-higher trace
return
}
# if env is nil, abort
{
var env-is-nil?/eax: boolean <- is-nil? env
compare env-is-nil?, 0/false
break-if-=
# error "unbound symbol: ", sym
var stream-storage: (stream byte 0x40)
var stream/ecx: (addr stream byte) <- address stream-storage
write stream, "unbound symbol: "
var sym2/eax: (addr cell) <- copy sym
var sym-data-ah/eax: (addr handle stream byte) <- get sym2, text-data
var sym-data/eax: (addr stream byte) <- lookup *sym-data-ah
rewind-stream sym-data
write-stream stream, sym-data
trace trace, "error", stream
trace-higher trace
return
}
# check car
var env-head-storage: (handle cell)
var env-head-ah/eax: (addr handle cell) <- address env-head-storage
car env, env-head-ah, trace
var _env-head/eax: (addr cell) <- lookup *env-head-ah
var env-head/ecx: (addr cell) <- copy _env-head
# if car is not a list, abort
{
var env-head-type/eax: (addr int) <- get env-head, type
compare *env-head-type, 0/pair
break-if-=
error trace, "environment is not a list of (key . value) pairs"
trace-higher trace
return
}
# check key
var curr-key-storage: (handle cell)
var curr-key-ah/eax: (addr handle cell) <- address curr-key-storage
car env-head, curr-key-ah, trace
var curr-key/eax: (addr cell) <- lookup *curr-key-ah
# if key is not a symbol, abort
{
var curr-key-type/eax: (addr int) <- get curr-key, type
compare *curr-key-type, 2/symbol
break-if-=
error trace, "environment contains a binding for a non-symbol"
trace-higher trace
return
}
# if key matches sym, return val
var match?/eax: boolean <- cell-isomorphic? curr-key, sym, trace
compare match?, 0/false
{
break-if-=
cdr env-head, out, trace
trace-higher trace
return
}
# otherwise recurse
var env-tail-storage: (handle cell)
var env-tail-ah/eax: (addr handle cell) <- address env-tail-storage
cdr env, env-tail-ah, trace
var env-tail/eax: (addr cell) <- lookup *env-tail-ah
lookup-symbol sym, out, env-tail, trace
trace-higher trace
}
fn car _in: (addr cell), out: (addr handle cell), trace: (addr trace) {
trace-text trace, "eval", "car"
trace-lower trace
var in/eax: (addr cell) <- copy _in
# if in is not a list, abort
{
var in-type/ecx: (addr int) <- get in, type
compare *in-type, 0/pair
break-if-=
error trace, "car on a non-list"
trace-higher trace
return
}
# if in is nil, abort
{
var in-is-nil?/eax: boolean <- is-nil? in
compare in-is-nil?, 0/false
break-if-=
error trace, "car on nil"
trace-higher trace
return
}
var in-left/eax: (addr handle cell) <- get in, left
copy-object in-left, out
trace-higher trace
return
}
fn cdr _in: (addr cell), out: (addr handle cell), trace: (addr trace) {
trace-text trace, "eval", "cdr"
trace-lower trace
var in/eax: (addr cell) <- copy _in
# if in is not a list, abort
{
var in-type/ecx: (addr int) <- get in, type
compare *in-type, 0/pair
break-if-=
error trace, "car on a non-list"
trace-higher trace
return
}
# if in is nil, abort
{
var in-is-nil?/eax: boolean <- is-nil? in
compare in-is-nil?, 0/false
break-if-=
error trace, "car on nil"
trace-higher trace
return
}
var in-right/eax: (addr handle cell) <- get in, right
copy-object in-right, out
trace-higher trace
return
}
fn cell-isomorphic? _a: (addr cell), _b: (addr cell), trace: (addr trace) -> _/eax: boolean {
trace-text trace, "eval", "cell-isomorphic?"
trace-lower trace
var a/esi: (addr cell) <- copy _a
var b/edi: (addr cell) <- copy _b
# if types don't match, return false
var a-type-addr/eax: (addr int) <- get a, type
var b-type-addr/ecx: (addr int) <- get b, type
var b-type/ecx: int <- copy *b-type-addr
compare b-type, *a-type-addr
{
break-if-=
trace-text trace, "eval", "=> false (type)"
trace-higher trace
return 0/false
}
# if types are number, compare number-data
# TODO: exactly comparing floats is a bad idea
compare b-type, 1/number
{
break-if-!=
var a-val-addr/eax: (addr float) <- get a, number-data
var b-val-addr/ecx: (addr float) <- get b, number-data
var a-val/xmm0: float <- copy *a-val-addr
compare a-val, *b-val-addr
{
break-if-=
trace-text trace, "eval", "=> false (numbers)"
trace-higher trace
return 0/false
}
trace-text trace, "eval", "=> true (numbers)"
trace-higher trace
return 1/true
}
compare b-type, 2/symbol
{
break-if-!=
var b-val-ah/eax: (addr handle stream byte) <- get b, text-data
var _b-val/eax: (addr stream byte) <- lookup *b-val-ah
var b-val/ecx: (addr stream byte) <- copy _b-val
var a-val-ah/eax: (addr handle stream byte) <- get a, text-data
var a-val/eax: (addr stream byte) <- lookup *a-val-ah
var tmp-array: (handle array byte)
var tmp-ah/edx: (addr handle array byte) <- address tmp-array
stream-to-array a-val, tmp-ah
var tmp/eax: (addr array byte) <- lookup *tmp-ah
var match?/eax: boolean <- stream-data-equal? b-val, tmp
trace-text trace, "eval", "=> ? (symbols)"
trace-higher trace
return match?
}
# if a is nil, b should be nil
{
# (assumes is-nil? returns 0 or 1)
var _b-is-nil?/eax: boolean <- is-nil? b
var b-is-nil?/ecx: boolean <- copy _b-is-nil?
var a-is-nil?/eax: boolean <- is-nil? a
# a == nil and b == nil => return true
{
compare a-is-nil?, 0/false
break-if-=
compare b-is-nil?, 0/false
break-if-=
trace-text trace, "eval", "=> true (nils)"
trace-higher trace
return 1/true
}
# a == nil => return false
{
compare a-is-nil?, 0/false
break-if-=
trace-text trace, "eval", "=> false (b != nil)"
trace-higher trace
return 0/false
}
# b == nil => return false
{
compare b-is-nil?, 0/false
break-if-=
trace-text trace, "eval", "=> false (a != nil)"
trace-higher trace
return 0/false
}
}
# a and b are pairs
var a-tmp-storage: (handle cell)
var a-tmp-ah/edx: (addr handle cell) <- address a-tmp-storage
var b-tmp-storage: (handle cell)
var b-tmp-ah/ebx: (addr handle cell) <- address b-tmp-storage
# if cars aren't equal, return false
car a, a-tmp-ah, trace
car b, b-tmp-ah, trace
{
var _a-tmp/eax: (addr cell) <- lookup *a-tmp-ah
var a-tmp/ecx: (addr cell) <- copy _a-tmp
var b-tmp/eax: (addr cell) <- lookup *b-tmp-ah
var result/eax: boolean <- cell-isomorphic? a-tmp, b-tmp, trace
compare result, 0/false
break-if-!=
return 0/false
}
# recurse on cdrs
cdr a, a-tmp-ah, trace
cdr b, b-tmp-ah, trace
var _a-tmp/eax: (addr cell) <- lookup *a-tmp-ah
var a-tmp/ecx: (addr cell) <- copy _a-tmp
var b-tmp/eax: (addr cell) <- lookup *b-tmp-ah
var result/eax: boolean <- cell-isomorphic? a-tmp, b-tmp, trace
return result
}
fn test-evaluate-is-well-behaved {
var t-storage: trace
var t/esi: (addr trace) <- address t-storage
initialize-trace t, 0x10, 0/visible # we don't use trace UI
#
var tmp-storage: (handle cell)
var tmp-ah/edx: (addr handle cell) <- address tmp-storage
# eval sym(a), nil env
allocate-pair tmp-ah
var env/eax: (addr cell) <- lookup *tmp-ah
new-symbol tmp-ah, "a"
evaluate tmp-ah, tmp-ah, env, t
# doesn't die
check-trace-contains t, "error", "unbound symbol: a", "F - test-evaluate-is-well-behaved"
}
fn test-evaluate {
# tmp = (a . 3)
var val-storage: (handle cell)
var val-ah/ecx: (addr handle cell) <- address val-storage
new-integer val-ah, 3
var key-storage: (handle cell)
var key-ah/edx: (addr handle cell) <- address key-storage
new-symbol key-ah, "a"
var tmp-storage: (handle cell)
var tmp-ah/ebx: (addr handle cell) <- address tmp-storage
new-pair tmp-ah, *key-ah, *val-ah
# env = ((a . 3))
var nil-storage: (handle cell)
var nil-ah/ecx: (addr handle cell) <- address nil-storage
allocate-pair nil-ah
new-pair tmp-ah, *tmp-ah, *nil-ah
var env/eax: (addr cell) <- lookup *tmp-ah
# eval sym(a), env
new-symbol tmp-ah, "a"
evaluate tmp-ah, tmp-ah, env, 0/no-trace
var result/eax: (addr cell) <- lookup *tmp-ah
var result-type/edx: (addr int) <- get result, type
check-ints-equal *result-type, 1/number, "F - test-evaluate/0"
var result-value-addr/eax: (addr float) <- get result, number-data
var result-value/eax: int <- convert *result-value-addr
check-ints-equal result-value, 3, "F - test-evaluate/1"
}