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ludic/runtime/native/value.ludic
Orkuncakilkaya 4499cedcb8 runtime: Json.write_file, and Json.encode through a kept buffer 
The encoder appends into RtJsonState's buffer (grown only past the biggest document yet): ints and
Q16.16 fixeds written as digits in place, floats through string() and freed. Json.encode copies the
answer out once; Json.write_file hands the buffer to Fs.write_text (.tmp + rename) and keeps nothing.
json_saves.ludic: exact text, the file equals encode, parse round-trips, 1000 saves grow 0; clean
under MallocScribble. json_quote (the + builder) is gone.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-09-28 15:32:36 +03:00

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# ============================================================================
# value.ludic — a generic value tree (`Value.*`) and its JSON bridge (`Json.*`),
# in Ludic. The value tree is the tagged, self-describing node the reflection
# serializer (runtime/native/reflect_io.ludic) walks an entity into, and the
# shape a JSON save round-trips through. A node is one of:
#
# kind 0 null kind 1 int kind 2 fixed kind 3 bool
# kind 4 str kind 5 list kind 6 object kind 7 float
#
# ludicc splices this file when it sees Value.* / Json.* / Reflect.serialize /
# Reflect.apply (parse.ludic). Everything is plain Ludic over heap records — no
# new runtime primitive — so the whole tree is deterministic and allocation is
# the only cost.
# ============================================================================
# one node of the tree. A list uses `kids`; an object uses `keys` + `kids` in
# parallel (keys[i] labels kids[i]). Scalars use `num` (int/bool/fixed-raw) or
# `txt` (str).
property Val {
tag: int = 0
num: int = 0
txt: pointer = null
keys: []pointer
kids: []Val
}
# a number, a string or a null is one record; only a list or an object carries lists (made when first
# filled) - three allocations for every scalar was most of what a UI frame made and never gave back
function value_new(tag: int) -> Val {
let v = new Val
v.tag = tag
if tag == 5 or tag == 6 { value_lists(v) }
return v
}
function value_lists(v: Val) -> void {
if v.kids != null { return }
v.keys = new []pointer
v.kids = new []Val
}
function value_n(v: Val) -> int {
if v.kids == null { return 0 }
return len(v.kids)
}
# --- constructors -----------------------------------------------------------
function value_null() -> Val { return value_new(0) }
function value_int(n: int) -> Val { let v = value_new(1); v.num = n; return v }
function value_fixed(f: int) -> Val { let v = value_new(2); v.num = f; return v } # f = raw Q16.16
function value_bool(b: int) -> Val { let v = value_new(3); if b != 0 { v.num = 1 }; return v }
function value_str(s: pointer) -> Val { let v = value_new(4); v.txt = s; return v }
function value_list() -> Val { return value_new(5) }
function value_float(x: float) -> Val { let v = value_new(7); v.num = float_bits(x); return v } # num = the IEEE bits
function value_object() -> Val { return value_new(6) }
# --- builders (return the container, so calls chain) ------------------------
function value_add(list: Val, item: Val) -> Val {
value_lists(list)
push(list.kids, item)
return list
}
function value_put(obj: Val, key: pointer, item: Val) -> Val {
value_lists(obj)
var i = 0
while i < len(obj.keys) { if obj.keys[i] == key { obj.kids[i] = item; return obj }; i += 1 }
push(obj.keys, key); push(obj.kids, item)
return obj
}
# --- accessors --------------------------------------------------------------
function value_kind(v: Val) -> int { return v.tag }
function value_count(v: Val) -> int { return value_n(v) }
# a scalar field of an object set in place: the Value under `key` is changed when it is already that
# kind, and made only the first time (a component's model, filled into the same object every frame)
function value_slot(o: Val, key: pointer, tag: int) -> Val {
value_lists(o)
var i = 0
while i < len(o.keys) {
if o.keys[i] == key {
if o.kids[i].tag == tag { return o.kids[i] }
let v = value_new(tag)
o.kids[i] = v
return v
}
i += 1
}
let v = value_new(tag)
push(o.keys, key)
push(o.kids, v)
return v
}
function value_set_int(o: Val, key: pointer, n: int) -> void {
let v = value_slot(o, key, 1)
value_num_set(v, n)
}
function value_set_float(o: Val, key: pointer, x: float) -> void {
let v = value_slot(o, key, 7)
value_num_set(v, float_bits(x))
}
function value_set_str(o: Val, key: pointer, s: pointer) -> void {
let v = value_slot(o, key, 4)
v.txt = s
}
function value_set_bool(o: Val, key: pointer, b: bool) -> void {
let v = value_slot(o, key, 3)
value_num_set(v, 0)
if b { value_num_set(v, 1) }
}
# a list field of an object set in place: the list under `key` is kept, and item i keeps its Value when it
# is already that kind (a component's model, filled into the same object every frame)
function value_list_fit(o: Val, key: pointer, n: int) -> Val {
let l = value_slot(o, key, 5)
value_lists(l)
while len(l.kids) > n { List.pop(l.kids) }
return l
}
function value_item(l: Val, i: int, tag: int) -> Val {
if i < len(l.kids) {
if l.kids[i].tag == tag { return l.kids[i] }
let v = value_new(tag)
l.kids[i] = v
return v
}
let v = value_new(tag)
push(l.kids, v)
return v
}
function value_set_ints(o: Val, key: pointer, xs: []int) -> void {
let l = value_list_fit(o, key, len(xs))
for i in 0 .. len(xs) {
let v = value_item(l, i, 1)
value_num_set(v, xs[i])
}
}
function value_set_floats(o: Val, key: pointer, xs: []float) -> void {
let l = value_list_fit(o, key, len(xs))
for i in 0 .. len(xs) {
let v = value_item(l, i, 7)
value_num_set(v, float_bits(xs[i]))
}
}
function value_set_strs(o: Val, key: pointer, xs: []string) -> void {
let l = value_list_fit(o, key, len(xs))
for i in 0 .. len(xs) {
let v = value_item(l, i, 4)
v.txt = xs[i]
}
}
function value_set_bools(o: Val, key: pointer, xs: []bool) -> void {
let l = value_list_fit(o, key, len(xs))
for i in 0 .. len(xs) {
let v = value_item(l, i, 3)
value_num_set(v, 0)
if xs[i] { value_num_set(v, 1) }
}
}
# a Value turned into a blank one of kind `tag`, its own lists (if it has them) kept and emptied - for
# a pool that hands the same records out again (ludic.ui's, frame after frame)
function value_become(v: Val, tag: int) -> Val {
v.tag = tag
value_num_set(v, 0)
v.txt = null
if tag == 5 or tag == 6 { value_lists(v) }
if v.kids != null { value_clear(v) }
return v
}
function value_be_int(v: Val, n: int) -> Val {
value_become(v, 1)
value_num_set(v, n)
return v
}
function value_be_float(v: Val, x: float) -> Val {
value_become(v, 7)
value_num_set(v, float_bits(x))
return v
}
function value_be_str(v: Val, s: pointer) -> Val {
value_become(v, 4)
v.txt = s
return v
}
# a result written into `into` when one is given (a record ludic.ui keeps and hands out again), made
# as ever when it is null - what a component's call() answers a template with
function value_into(into: Val, tag: int) -> Val {
if into == null { return value_new(tag) }
return value_become(into, tag)
}
function value_into_null(into: Val) -> Val { return value_into(into, 0) }
function value_into_int(into: Val, n: int) -> Val {
let v = value_into(into, 1)
value_num_set(v, n)
return v
}
function value_into_float(into: Val, x: float) -> Val {
let v = value_into(into, 7)
value_num_set(v, float_bits(x))
return v
}
function value_into_str(into: Val, s: pointer) -> Val {
let v = value_into(into, 4)
v.txt = s
return v
}
function value_into_bool(into: Val, b: bool) -> Val {
let v = value_into(into, 3)
if b { value_num_set(v, 1) }
return v
}
# a list result: `into`'s items are kept and changed in place where they are already that kind
function value_into_list(into: Val, n: int) -> Val {
if into == null { return value_list() }
into.tag = 5
value_num_set(into, 0)
into.txt = null
value_lists(into)
while len(into.kids) > n { List.pop(into.kids) }
return into
}
function value_into_ints(into: Val, xs: []int) -> Val {
let l = value_into_list(into, len(xs))
for i in 0 .. len(xs) {
let v = value_item(l, i, 1)
value_num_set(v, xs[i])
}
return l
}
function value_into_floats(into: Val, xs: []float) -> Val {
let l = value_into_list(into, len(xs))
for i in 0 .. len(xs) {
let v = value_item(l, i, 7)
value_num_set(v, float_bits(xs[i]))
}
return l
}
function value_into_strs(into: Val, xs: []string) -> Val {
let l = value_into_list(into, len(xs))
for i in 0 .. len(xs) {
let v = value_item(l, i, 4)
v.txt = xs[i]
}
return l
}
function value_into_bools(into: Val, xs: []bool) -> Val {
let l = value_into_list(into, len(xs))
for i in 0 .. len(xs) {
let v = value_item(l, i, 3)
value_num_set(v, 0)
if xs[i] { value_num_set(v, 1) }
}
return l
}
# a number set where it is kept: its text (value_num_text) is dropped only when the number changes
function value_num_set(v: Val, n: int) -> void {
if v.num == n { return }
v.num = n
if v.tag != 4 { v.txt = null }
}
# a number's text, kept on the Value until the number changes (a count shown in a HUD every frame wrote
# its text every frame; Ludic frees nothing)
function value_num_text(v: Val) -> string {
if v.txt != null { return v.txt }
if v.tag == 1 { v.txt = string(v.num) }
else if v.tag == 7 {
let f = float_from_bits(v.num)
if f == float(int(f)) { v.txt = string(int(f)) } else { v.txt = string(f) }
}
else if v.tag == 2 { v.txt = json_fixed_str(v.num) }
if v.txt == null { return "" }
return v.txt
}
# a list or an object emptied in place, its room kept - for one filled again every frame
function value_clear(v: Val) -> void {
if v.kids == null { return }
List.clear(v.kids)
List.clear(v.keys)
}
function value_as_int(v: Val) -> int {
if v.tag == 7 { return int(float_from_bits(v.num)) }
return v.num
}
# a number as a float, whichever kind it was written as
function value_as_float(v: Val) -> float {
if v.tag == 7 { return float_from_bits(v.num) }
if v.tag == 2 { return float(v.num) / 65536.0 }
return float(v.num)
}
function value_as_str(v: Val) -> string { if v.txt == null { return "" }; return v.txt }
function value_at(list: Val, i: int) -> Val {
if i < 0 or i >= value_n(list) { return value_null() }
return list.kids[i]
}
function value_key_at(obj: Val, i: int) -> string {
if i < 0 or i >= value_n(obj) { return "" }
return obj.keys[i]
}
function value_get(obj: Val, key: pointer) -> Val {
var i = 0
while i < value_n(obj) { if obj.keys[i] == key { return obj.kids[i] }; i += 1 }
return value_null()
}
function value_has(obj: Val, key: pointer) -> int {
var i = 0
while i < value_n(obj) { if obj.keys[i] == key { return 1 }; i += 1 }
return 0
}
# --- JSON encode ------------------------------------------------------------
# a raw Q16.16 fixed -> its EXACT decimal string. The denominator is 2^16, so the
# decimal always terminates (in <=16 fractional digits): emit digits until the
# remainder hits zero. This is the exact inverse of jp_number's fixed decode, so
# a value_fixed round-trips through JSON bit-for-bit; short values (0.5, 2.0) stay
# short. Each step keeps frac < 655360, well within i32.
function json_fixed_str(raw: int) -> string {
var a = raw
var sign = ""
if a < 0 { sign = "-"; a = -a }
let ip = a / 65536
var frac = a % 65536
if frac == 0 { return sign + string(ip) + ".0" }
var fs = ""
while frac != 0 {
frac *= 10
fs += string(frac / 65536)
frac = frac % 65536
}
return sign + string(ip) + "." + fs
}
# The encoder writes into one buffer the runtime keeps, grown only when a document is bigger than
# any before: a save once built its text by `+`, keeping every piece and every number's text, and
# the answer was one more string a game could never free. `Json.encode` copies the answer out once;
# `Json.write_file` writes it through Fs.write_text (the .tmp and the rename) and keeps nothing.
export state RtJsonState {
jb: pointer = null, # the text so far, NUL-terminated when handed on
jcap: int = 0,
jn: int = 0
}
function jo_room(st: mut RtJsonState, more: int) -> void {
if st.jn + more + 1 <= st.jcap { return }
var cap = st.jcap
if cap < 4096 { cap = 4096 }
while cap < st.jn + more + 1 { cap = cap * 2 }
let nb = bytes(cap)
if st.jb != null {
let ob: bytes = st.jb
for i in 0 .. st.jn { nb[i] = ob[i] }
free(st.jb)
}
st.jb = nb
st.jcap = cap
}
function jo_put(st: mut RtJsonState, c: int) -> void {
jo_room(st, 1)
let b: bytes = st.jb
b[st.jn] = c
st.jn += 1
}
function jo_str(st: mut RtJsonState, s: pointer) -> void {
let n = len(s)
jo_room(st, n)
let b: bytes = st.jb
for i in 0 .. n { b[st.jn + i] = s[i] }
st.jn += n
}
# an int's digits, written in place (no text made for it)
function jo_int(st: mut RtJsonState, v: int) -> void {
if v == 0 {
jo_put(st, '0')
return
}
var x: long = v
if x < 0 {
jo_put(st, '-')
x = -x
}
var div: long = 1
while div * 10 <= x { div = div * 10 }
while div > 0 {
jo_put(st, 48 + int(x / div))
x = x % div
div = div / 10
}
}
# a raw Q16.16 fixed, exactly (json_fixed_str's digits, written in place)
function jo_fixed(st: mut RtJsonState, raw: int) -> void {
var a: long = raw
if a < 0 {
jo_put(st, '-')
a = -a
}
jo_int(st, int(a / 65536))
jo_put(st, '.')
var frac = int(a % 65536)
if frac == 0 {
jo_put(st, '0')
return
}
while frac != 0 {
frac *= 10
jo_put(st, 48 + frac / 65536)
frac = frac % 65536
}
}
function jo_quote(st: mut RtJsonState, s: pointer) -> void {
jo_put(st, '"')
let n = len(s)
for i in 0 .. n {
let c = s[i]
if c == '"' or c == '\\' {
jo_put(st, '\\')
jo_put(st, c)
} else if c == '\n' {
jo_put(st, '\\')
jo_put(st, 'n')
} else { jo_put(st, c) }
}
jo_put(st, '"')
}
function jo_val(st: mut RtJsonState, v: Val) -> void {
if v.tag == 0 { jo_str(st, "null") }
else if v.tag == 1 { jo_int(st, v.num) }
else if v.tag == 2 { jo_fixed(st, v.num) }
else if v.tag == 3 { if v.num != 0 { jo_str(st, "true") } else { jo_str(st, "false") } }
else if v.tag == 4 { jo_quote(st, value_as_str(v)) }
else if v.tag == 7 {
let t = string(float_from_bits(v.num))
jo_str(st, t)
free(t)
} else if v.tag == 5 {
jo_put(st, '[')
for i in 0 .. value_n(v) {
if i > 0 { jo_put(st, ',') }
jo_val(st, v.kids[i])
}
jo_put(st, ']')
} else {
jo_put(st, '{')
for i in 0 .. value_n(v) {
if i > 0 { jo_put(st, ',') }
jo_quote(st, v.keys[i])
jo_put(st, ':')
jo_val(st, v.kids[i])
}
jo_put(st, '}')
}
}
# the whole document into the kept buffer, NUL-terminated
function jo_doc(st: mut RtJsonState, v: Val) -> void {
st.jn = 0
jo_val(st, v)
jo_room(st, 0)
let b: bytes = st.jb
b[st.jn] = 0
}
function json_encode(rt_json_st: mut RtJsonState, v: Val) -> string {
jo_doc(rt_json_st, v)
let out = bytes(rt_json_st.jn + 1)
let b: bytes = rt_json_st.jb
for i in 0 .. rt_json_st.jn + 1 { out[i] = b[i] }
let s: string = out
return s
}
# v written to path as JSON, replacing it whole (the .tmp and the rename); nothing kept per call
function json_write_file(rt_json_st: mut RtJsonState, v: Val, path: string) -> bool {
jo_doc(rt_json_st, v)
let s: string = rt_json_st.jb
return Fs.write_text(path, s)
}
# --- JSON parse -------------------------------------------------------------
# a tiny recursive-descent parser over a byte string. `JP` carries the cursor so
# the recursion threads position without a global. Malformed input yields a null
# node and leaves the cursor where it stopped (best-effort, not a validator).
property JP { s: pointer = null, i: int = 0, n: int = 0 }
function jp_skip_ws(p: JP) -> void {
while p.i < p.n {
let c = p.s[p.i]
if c == ' ' or c == '\t' or c == '\n' or c == '\r' { p.i += 1 }
else { return }
}
}
function json_parse(s: pointer) -> Val {
let p = new JP
p.s = s; p.i = 0; p.n = len(s)
let v = jp_value(p)
free(p)
return v
}
# Let a parsed tree go once what it describes is built: every node and its lists. Its strings stay -
# a caller may keep a name it read out of the tree - and a tree put together by hand, which may share
# a node or hold a literal, is not for this (Ludic has no collector; plan 23 of maroon-lake).
function value_free(v: Val) -> void {
if v == null { return }
if v.kids != null {
for i in 0 .. len(v.kids) { value_free(v.kids[i]) }
free(v.kids)
free(v.keys)
}
free(v)
}
function json_free(v: Val) -> void { value_free(v) }
# ... and its strings too - every string value and object key the parser made - for a tree whose
# reader copied what it keeps (render3d's glTF documents): a parse left otherwise gives back the
# nodes and keeps every name, ~640 KB a model
function value_free_all(v: Val) -> void {
if v == null { return }
if v.tag == 4 and v.txt != null { free(v.txt) }
if v.kids != null {
for i in 0 .. len(v.kids) { value_free_all(v.kids[i]) }
if v.keys != null { for i in 0 .. len(v.keys) { if v.keys[i] != null { free(v.keys[i]) } } }
free(v.kids)
free(v.keys)
}
free(v)
}
function json_free_all(v: Val) -> void { value_free_all(v) }
function jp_value(p: JP) -> Val {
jp_skip_ws(p)
if p.i >= p.n { return value_null() }
let c = p.s[p.i]
if c == '{' { return jp_object(p) } # '{'
if c == '[' { return jp_list(p) } # '['
if c == '"' { return value_str(jp_string(p)) } # '"'
if c == 't' { p.i += 4; return value_bool(1) } # true
if c == 'f' { p.i += 5; return value_bool(0) } # false
if c == 'n' { p.i += 4; return value_null() } # null
return jp_number(p)
}
# read a quoted string (cursor on the opening quote) -> the unescaped contents. One allocation for a
# string with no escape in it: built a character at a time, every step was a string never freed
function jp_string(p: JP) -> string {
p.i += 1 # skip opening quote
let a = p.i
while p.i < p.n {
let c = p.s[p.i]
if c == '"' {
let out = p.s[a..p.i]
p.i += 1
return out
}
if c == '\\' {
p.i = a
return jp_string_esc(p)
}
p.i += 1
}
return p.s[a..p.n]
}
# the same with escapes in it, the rare case, a character at a time
function jp_string_esc(p: JP) -> string {
var out = ""
while p.i < p.n {
let c = p.s[p.i]
if c == '"' { p.i += 1; return out } # closing quote
if c == '\\' { # escape
p.i += 1
if p.i < p.n {
let e = p.s[p.i]
if e == 'n' { out += "\n" }
else { out += p.s[p.i..p.i + 1] } # \" \\ \/ -> the literal char
p.i += 1
}
} else {
out += p.s[p.i..p.i + 1]
p.i += 1
}
}
return out
}
# read a number; a '.' makes it a fixed node, otherwise an int node.
function jp_number(p: JP) -> Val {
var neg = 0
if p.i < p.n and p.s[p.i] == '-' { neg = 1; p.i += 1 } # '-'
var ip = 0
while p.i < p.n and p.s[p.i] >= '0' and p.s[p.i] <= '9' {
ip = ip * 10 + (p.s[p.i] - 48)
p.i += 1
}
if p.i < p.n and p.s[p.i] == '.' { # '.', a fixed
p.i += 1
let digits = new []int
while p.i < p.n and p.s[p.i] >= '0' and p.s[p.i] <= '9' {
push(digits, p.s[p.i] - 48)
p.i += 1
}
# exact inverse of json_fixed_str's generation: fold the digits back from the
# last, frac_{i-1} = (d_i*65536 + frac_i)/10. Every intermediate stays < 2^16*10,
# so this is overflow-free and reproduces the raw Q16.16 for a generated decimal
# (an arbitrary hand-written decimal lands within one raw unit).
var frac = 0
var di = len(digits) - 1
while di >= 0 {
frac = (digits[di] * 65536 + frac) / 10
di -= 1
}
free(digits) # one list per decimal in the document, never given back
var raw = ip * 65536 + frac
raw = jp_exponent(p, raw)
if neg != 0 { raw = -raw }
return value_fixed(raw)
}
if p.i < p.n and (p.s[p.i] == 'e' or p.s[p.i] == 'E') { # 1e-05: an exponent makes it a fixed
var raw = jp_exponent(p, ip * 65536)
if neg != 0 { raw = -raw }
return value_fixed(raw)
}
if neg != 0 { ip = -ip }
return value_int(ip)
}
# an optional exponent after a number's digits, applied to a raw Q16.16 value. Exporters
# write noise like 7.49e-09 for a zero; a fixed rounds that to 0, which is what it was.
function jp_exponent(p: JP, raw0: int) -> int {
var raw = raw0
if p.i >= p.n or (p.s[p.i] != 'e' and p.s[p.i] != 'E') { return raw }
p.i += 1
var eneg = 0
if p.i < p.n and p.s[p.i] == '-' { eneg = 1; p.i += 1 }
else if p.i < p.n and p.s[p.i] == '+' { p.i += 1 }
var e = 0
while p.i < p.n and p.s[p.i] >= '0' and p.s[p.i] <= '9' {
e = e * 10 + (p.s[p.i] - 48)
p.i += 1
}
if e > 12 { e = 12 }
var k = 0
while k < e {
if eneg != 0 { raw = raw / 10 } else { raw = raw * 10 }
k += 1
}
return raw
}
function jp_list(p: JP) -> Val {
let out = value_list()
p.i += 1 # '['
jp_skip_ws(p)
if p.i < p.n and p.s[p.i] == ']' { p.i += 1; return out } # empty ']'
while p.i < p.n {
push(out.kids, jp_value(p))
jp_skip_ws(p)
if p.i < p.n and p.s[p.i] == ',' { p.i += 1; continue } # ','
break
}
jp_skip_ws(p)
if p.i < p.n and p.s[p.i] == ']' { p.i += 1 }
return out
}
function jp_object(p: JP) -> Val {
let out = value_object()
p.i += 1 # '{'
jp_skip_ws(p)
if p.i < p.n and p.s[p.i] == '}' { p.i += 1; return out } # empty '}'
while p.i < p.n {
jp_skip_ws(p)
let key = jp_string(p)
jp_skip_ws(p)
if p.i < p.n and p.s[p.i] == ':' { p.i += 1 } # ':'
push(out.keys, key)
push(out.kids, jp_value(p))
jp_skip_ws(p)
if p.i < p.n and p.s[p.i] == ',' { p.i += 1; continue } # ','
break
}
jp_skip_ws(p)
if p.i < p.n and p.s[p.i] == '}' { p.i += 1 }
return out
}
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