42 lines
1.4 KiB
Markdown
42 lines
1.4 KiB
Markdown
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Index Operator — Design (Phase‑20.31 scoped)
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Scope (Phase‑1)
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- Support bracket indexing for Array/Map:
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- Read: expr[index]
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- Write: expr[index] = value
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- Semantics (lowering):
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- Array
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- Read → nyash.array.get_h(handle, idx)
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- Write → nyash.array.set_h(handle, idx, val)
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- Map
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- Read → nyash.map.get_hh(handle, key_any)
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- Write → nyash.map.set_hh(handle, key_any, val_any)
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- Out of scope in Phase‑1: String indexing/ranges.
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Parser/AST
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- Add IndexExpr(target, index)
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- Permit Assign(IndexExpr, value) on the LHS.
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MIR Lowering (Fail‑Fast contract)
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- If receiver is neither Array nor Map → error: "index operator is only supported for Array/Map".
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- For Map keys/values:
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- If arguments are SSA values (handles), pass as is; otherwise wrap primitive i64 as IntegerBox via available builder utilities.
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Error Policy
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- Fail‑Fast, no silent fallback.
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- Stable diagnostics for unsupported types and malformed LHS.
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Rollout / Flags
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- Implement in Rust parser first; Ny parser later.
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- If needed, guard with a dev flag for initial rollout (HAKO_INDEX_OPERATOR_DEV=1), default ON in dev profile, OFF in prod profiles.
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Tests (canaries)
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- arr_read: [1,2][0] == 1 → true
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- arr_write: arr[1]=3; arr[1]==3 → true
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- map_rw: m[10]=7; m[10]==7 → true
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- negative: "hello"[0] (Phase‑1) → error
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Notes
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- This leverages existing NyRT dotted externs already implemented for Array/Map, minimizing surface area and risk.
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