bdd0e96d78
A block's value is now its last statement ONLY when that statement is a trailing expression with no `;`. A trailing `;` discards the value, leaving the block void. This makes value-vs-statement explicit and lets the compiler reject "this block was supposed to produce a value". Compiler: - Parser records `Block.produces_value` (last stmt is a no-`;` trailing expression) + `Block.discarded_semi` (the `;` that discarded a value), via `expectSemicolonAfter`. A trailing expression before `}` may now omit its `;` (previously a parse error). Match-arm and else-arm bodies are built value-producing regardless of the arm `;` (arms are exempt — the `;` is an arm terminator). - Lowering: `lowerBlockValue` / the block-expr path / `inferExprType` respect `produces_value`. A value-position block that discards its value is a hard error (`lowerValueBody` for function bodies; the value-context `.block` path for if/else branches, `catch` bodies, value bindings, match arms). Pure-failable `-> !` bodies (value rides the error channel) and a value-if whose branches are void are handled without false errors. - `defer`/`onfail` cleanup bodies lower as statements (void), so a trailing `;` there is fine. Migration (behavior-preserving — output unchanged): - stdlib + ~210 examples: dropped the trailing `;` on value-position last expressions. `format` now ends with an explicit `#insert "return result;"` (it relied on `#insert`-as-block-value, which `;` discards). - Two `main :: () -> s32` examples that relied on the old silent default-return got an explicit trailing `0`. - Rejection snapshots 0412 / 1013 regenerated (their quoted source lines lost a `;`); the diagnostics themselves are unchanged. Docs/tests: specs.md "Block values" section; examples 0040 (rules) + 0041 (rejection); 3 parser unit tests. Filed issue 0066 (pre-existing match-arm negated-literal phi-width quirk, surfaced not caused here). Gates: zig build, zig build test, run_examples.sh -> 343 passed, cross_compile.sh -> 7 passed (also refreshed its stale example names).
77 lines
2.1 KiB
Plaintext
77 lines
2.1 KiB
Plaintext
// Generic struct `Animated($T: Lerpable)` monomorphized with a struct type — the
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// `#inline` protocol constraint participates in method dispatch via `self.from.lerp(...)`.
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#import "modules/std.sx";
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#import "modules/math";
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Lerpable :: protocol #inline {
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lerp :: (b: Self, t: f32) -> Self;
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}
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Size :: struct {
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width, height: f32;
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zero :: () -> Size => .{ width = 0.0, height = 0.0 };
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}
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impl Lerpable for Size {
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lerp :: (self: Size, b: Size, t: f32) -> Size {
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Size.{ width = self.width + (b.width - self.width) * t,
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height = self.height + (b.height - self.height) * t }
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}
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}
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Animated :: struct ($T: Lerpable) {
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current: T;
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from: T;
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to: T;
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elapsed: f32;
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duration: f32;
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active: bool;
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make :: (value: T) -> Animated(T) {
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Animated(T).{
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current = value, from = value, to = value,
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elapsed = 0.0, duration = 0.0, active = false
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}
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}
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set_immediate :: (self: *Animated(T), value: T) {
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self.current = value;
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self.from = value;
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self.to = value;
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self.active = false;
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}
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animate_to :: (self: *Animated(T), target: T, dur: f32) {
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self.from = self.current;
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self.to = target;
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self.elapsed = 0.0;
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self.duration = dur;
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self.active = true;
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}
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tick :: (self: *Animated(T), dt: f32) {
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if !self.active { return; }
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self.elapsed += dt;
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t := clamp(self.elapsed / self.duration, 0.0, 1.0);
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self.current = self.from.lerp(self.to, t);
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if t >= 1.0 {
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self.current = self.to;
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self.active = false;
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}
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}
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}
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main :: () -> void {
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anim := Animated(Size).make(Size.zero());
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anim.set_immediate(Size.{ width = 100.0, height = 50.0 });
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print("after set: {}x{}\n", anim.current.width, anim.current.height);
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anim.animate_to(Size.{ width = 200.0, height = 100.0 }, 1.0);
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anim.tick(0.5);
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print("mid anim: {}x{}\n", anim.current.width, anim.current.height);
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anim.tick(0.5);
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print("end anim: {}x{}\n", anim.current.width, anim.current.height);
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}
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