ludic/packages/ludic.ui/expr.ludic
Orkuncakilkaya 66a2bc2214 feat(lang): L11 views and templates - the UI is markup, not code
A `view Name { field = x; function q(..); on e(..) }` declaration is the one bridge between a
program and its UI: it writes view_<name>() -> UiView, whose model is a Value of every field and
whose call runs a query or an event by name.

ludic.ui is a template runtime:
- HTML-shaped XML screens and components, loaded at run time;
- {expression} bindings, if/else/each, props, slots, per-instance state;
- on-press / onclick actions (event, set, emit);
- component libraries (export="true", <import src as>).

Styling:
- stylesheets in <style> or importable .lss files (@import);
- CSS selectors (#id, .class, [attr=v], descendant and > combinators, :hover, :disabled,
  :first-child, :last-child, :nth-child, :not) weighed by specificity;
- the box model and flex under CSS's property names.

Also:
- default parameters, and positional-then-named calls;
- Value gains a float kind;
- a function shadowing a runtime one is refused;
- an index is evaluated before the slice is read;
- runtime errors name the right file.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-09-24 15:58:47 +03:00

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# expr.ludic - a template's expressions: `{pick == i}`, `{f.cost}`, `{placed(i) > 0 ? 'out' : ''}`.
# Read once when the template loads, evaluated against the view's model every frame.
const X_LIT: int = 0
const X_NAME: int = 1
const X_MEMBER: int = 2
const X_INDEX: int = 3
const X_CALL: int = 4
const X_NOT: int = 5
const X_NEG: int = 6
const X_BIN: int = 7
const X_AND: int = 8
const X_OR: int = 9
const X_COND: int = 10
const X_TEXT: int = 11
export property UiExpr {
op: int = 0
s: string = ""
v: Val = null
a: UiExpr = null
b: UiExpr = null
c: UiExpr = null
args: []UiExpr = null
}
# the text being read, and where the reading is
property UiRd {
s: string = ""
i: int = 0
err: string = ""
}
function ex_new(op: int) -> UiExpr {
let e = new UiExpr
e.op = op
e.args = new []UiExpr
return e
}
function ex_lit(v: Val) -> UiExpr {
let e = ex_new(X_LIT)
e.v = v
return e
}
function rd_ws(r: UiRd) -> void {
while r.i < len(r.s) and (r.s[r.i] == 32 or r.s[r.i] == 9 or r.s[r.i] == 10 or r.s[r.i] == 13) { r.i += 1 }
}
function rd_c(r: UiRd, k: int) -> int {
if r.i + k < len(r.s) { return r.s[r.i + k] }
return 0
}
# the operator `op` is next: take it
function rd_op(r: UiRd, op: string) -> bool {
rd_ws(r)
let n = len(op)
if r.i + n > len(r.s) { return false }
if r.s[r.i..r.i + n] != op { return false }
r.i += n
return true
}
function rd_is_word(c: int) -> bool { return (c >= 97 and c <= 122) or (c >= 65 and c <= 90) or c == 95 or (c >= 48 and c <= 57) }
# the word `w` is next, whole: take it
function rd_word(r: UiRd, w: string) -> bool {
rd_ws(r)
let at = r.i
if not rd_op(r, w) { return false }
if rd_is_word(rd_c(r, 0)) {
r.i = at
return false
}
return true
}
function rd_name(r: UiRd) -> string {
rd_ws(r)
let at = r.i
while r.i < len(r.s) and rd_is_word(r.s[r.i]) { r.i += 1 }
if r.i == at {
rd_fail(r, "a name")
return ""
}
return r.s[at..r.i]
}
function rd_fail(r: UiRd, want: string) -> void {
if r.err == "" { r.err = `expected {want} at {r.i + 1} in "{r.s}"` }
}