Hojun-Cho
dd188ca460
`e is T` returns bool (variant tag == T's index); `e as T` unwraps to T or exit(1) on mismatch. Postfix, same precedence as `:` cast. TK_IS / N_TYPETEST / N_TYPEASSERT appended at the tail of their enums so every prior numeric value stays unchanged — the 990_selfhost wwdump-diff stays byte-clean. Cgen mirrors the match-case slot-based load (tag at +0, value at +8/+16), so an N_IDENT tagged-union local works just like a match scrutinee. Selfhost cgen inlines the slot resolution because the wwstage cgen drops sign bits on `*i32` output parameters in this position. Renames `errors.is` -> `errors.equal` (the only naming collision; the existing comment already noted it shared shape with strings.equal/bytes.equal).
31 lines
951 B
Plaintext
31 lines
951 B
Plaintext
// errors — error type (a string) and a few sentinels. Plan 9 model:
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// the empty string means OK, a non-empty string is the message.
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type error = str;
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def eEOF: error = "eof";
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def eShortRead: error = "short read";
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def eShortWrite: error = "short write";
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def eClosed: error = "closed";
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def eInvalid: error = "invalid argument";
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def ePerm: error = "permission denied";
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def eNotFound: error = "not found";
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def eExists: error = "already exists";
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export fn isnil(e: error) bool = {
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return e.len == 0;
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};
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// equal — compare an error against a sentinel (or any other error).
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// Pure byte equality. (Was `errors.is` before `is` became a keyword
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// for tagged-union type-tests; rename matches bytes.equal / strings.equal.)
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export fn equal(e: error, want: error) bool = {
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if (e.len != want.len) { return false; };
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let i: i32 = 0;
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for (i < e.len) {
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if (e[i] != want[i]) { return false; };
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i += 1;
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};
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return true;
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};
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