27c88d4d26
Add range loop syntax:
- runtime for start..end (i) { } counting loop, cursor optional, end exclusive
- comptime inline for start..end (i) { } comptime-unrolled body
The inline form binds the cursor as an int_val comptime constant per
iteration, so xs[i] over a heterogeneous pack substitutes the concrete
per-position element -- the canonical's pack-iteration vehicle
(inline for 0..sources.len (i) { sources[i].addListener(...) }).
- AST: ForExpr.range_end, ForExpr.is_inline
- parser: parseForExpr range vs collection form; suppress_call flag so
N (i) is not read as a call N(i) while parsing a range bound
- lower: lowerRuntimeRangeFor / lowerInlineRangeFor; evalComptimeInt;
comptimeIndexOf extends pack-index resolution beyond int literals
Revises spec's inline for i in 0..N to the no-in, range-first, paren-cursor
form. Regression: examples/200-for-range.sx.
40 lines
1.2 KiB
Plaintext
40 lines
1.2 KiB
Plaintext
// Range-based for loops: `for start..end (i) { }` (cursor optional, `end`
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// exclusive) is a runtime counting loop; `inline for start..end (i) { }`
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// is comptime-unrolled — the cursor is a compile-time constant each
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// iteration, so `xs[i]` over a heterogeneous pack substitutes the concrete
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// per-position element (this is what drives pack iteration).
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#import "modules/std.sx";
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Show :: protocol {
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show :: () -> string;
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}
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A :: struct { x: s64; }
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B :: struct { s: string; }
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impl Show for A { show :: (self: *A) -> string => "A"; }
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impl Show for B { show :: (self: *B) -> string => "B"; }
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// Comptime-unrolled iteration over a pack; cursor `i` indexes the pack.
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each :: (..xs: Show) -> void {
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inline for 0..xs.len (i) {
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print("[{}]={}\n", i, xs[i].show());
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}
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}
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main :: () -> s32 {
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// Runtime range, cursor used.
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for 0..3 (i) { print("i={}\n", i); }
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// Runtime range, no cursor — body runs `end - start` times.
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n := 0;
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for 0..5 { n = n + 1; }
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print("n={}\n", n);
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// Non-zero start.
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for 2..5 (j) { print("j={}\n", j); }
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// Inline unroll over a heterogeneous pack.
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each(A.{ x = 1 }, B.{ s = "hi" }, A.{ x = 3 });
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0;
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}
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