185df9afb7
(*x) binds x to a pointer into the collection (index_gep) instead of a per-element value copy: passing it on (e.g. to a *T param) is zero-copy and mutations write back. In a value position x auto-derefs — a binary-op operand loads the element, a pointer-typed slot keeps the pointer, and an 'if x == {...}' match derefs the pointee for its tag/payload. Arrays GEP through their storage so writes hit the original. Regression test: examples/for-by-ref-capture.sx.
26 lines
741 B
Plaintext
26 lines
741 B
Plaintext
// `for xs: (*x)` binds each element by pointer — no per-element copy.
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// Mutations write back, and a pointer subject matches through the deref.
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#import "modules/std.sx";
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Shape :: enum {
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circle: f32;
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none;
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}
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main :: () -> s32 {
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// By-ref mutation writes back into the array (impossible with a value copy).
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xs : [3]s64 = .[1, 2, 3];
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for xs: (*x) { x.* = x + 100; }
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print("{} {} {}\n", xs[0], xs[1], xs[2]);
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// Pointer subject matches through the deref; payload reads through the ref.
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shapes : [2]Shape = .[.circle(2.0), .none];
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for shapes: (*s) {
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if s == {
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case .circle: (r) { print("circle {}\n", r); }
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case .none: { print("none\n"); }
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}
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}
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0;
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}
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