9523c29173
A method `name :: (self: *T, value: V) #set { ... }` (or `=> expr;`) is the
write counterpart of a `#get` accessor: `obj.name = rhs` dispatches to it as
`obj.name(rhs)` when no real field matches. Plumbed parallel to `#get`:
- lexer/token `#set`; `FnDecl.is_set` + `Function.is_set`; parsed in the same
marker slot as `#get` (no return type, exactly self + one value param).
- get+set coexistence: a setter registers/mangles/dispatches under an effective
`name$set` name (`$` is illegal in sx identifiers, so unmistakable), keeping a
same-name `#get` under the plain `name`. Resolution is declaration-order-
independent: a plain read query picks the non-setter, a `name$set` write query
picks the setter (accessorEffName / accessorNameMatches / structMethodFn).
- write dispatch in lowerAssignment via tryLowerPropertyAssignment: plain assign
synthesizes `obj.name$set(rhs)`; compound `OP=` is get-modify-set and
evaluates the receiver EXACTLY ONCE (bound to a synthetic local); read-only
(#get-only) and write-only (#set-only + compound) emit clear diagnostics; a
real field of the same name still wins. Multi-assign property targets dispatch
the setter too (tryLowerPropertyStore, via a pre-lowered-Ref binding).
Payoff: List gains a `len` #set, so `xs.len = n` works; the `.items.len = N`
write workarounds in sched.sx + ui/* + platform/* revert to `xs.len = N`.
issues/0160 records an optional-chain interaction surfaced by the review (a
pre-existing `?T` value-optional read miscompile that blocks getter-through-`?.`).
44 lines
1.6 KiB
Plaintext
44 lines
1.6 KiB
Plaintext
// List is `{ items: []T; cap }` — `items` is a `[]T` slice whose `.len` IS the
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// live element count, so a List is directly iterable with a `for`-each, and
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// `xs.len` reads the live count via a `#get` accessor. Exercises append (incl.
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// a realloc past the initial cap of 4), for-each, parallel for-with-index,
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// empty iteration, direct `for xs` over the List, and truncation via `xs.len = 0`.
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#import "modules/std.sx";
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main :: () -> i64 {
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xs : List(i64) = .{};
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i := 0;
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while i < 6 { xs.append((i + 1) * 10); i = i + 1; } // 10..60; grows 4 -> 8
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print("len={} cap>={}\n", xs.len, if xs.cap >= 6 then 1 else 0); // len=6 cap>=1
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// for-each over the items slice
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sum := 0;
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for xs.items (e) { sum = sum + e; }
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print("foreach sum={}\n", sum); // 210
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// parallel for with index
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print("indexed:");
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for xs.items, 0.. (e, ix) { if ix % 2 == 0 { print(" {}@{}", e, ix); } }
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print("\n"); // 10@0 30@2 50@4
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// direct `for xs` over the List value (listView path)
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s2 := 0;
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for xs (e) { s2 = s2 + e; }
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print("for-list sum={}\n", s2); // 210
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// len via #get used as a loop bound + indexing
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acc := 0;
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j := 0;
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while j < xs.len { acc = acc + xs.items[j]; j = j + 1; }
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print("indexed sum={}\n", acc); // 210
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// truncate to empty via the `len` #set accessor, then iterate (zero iters)
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xs.len = 0;
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cnt := 0;
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for xs.items (e) { cnt = cnt + 1; }
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print("after trunc: len={} iters={}\n", xs.len, cnt); // len=0 iters=0
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return 0;
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}
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