along: =1+1+... with 4,096 operands (8,192 characters, exactly Excel's
limit, which Excel accepts and calculates) overflowed the stack when
entered, because the derived Clone of Expr recursed once per operand
down the chain's left spine. Saving hit the same in the XLSX writer.
- Expr: Clone, PartialEq, walk and map follow the left spine in a loop
and recurse only into right operands and real nesting.
- XLSX: _xlpm. prefixing and the implicit-intersection scan follow the
spine too. The scan's depth limit of 64 wrote any chain of more than
about 64 operands as a dynamic-array formula; such sums are plain
formulas again (ranges in the chain still get array evaluation).
- Evaluate Formula borrows sub-expressions instead of cloning each
operator's subtree (quadratic memory on a long chain).
- Spanish formula entry and display no longer refuse chains of more
than 256 operands; the left spine does not count as nesting.
Tests run on a 1 MiB stack (the Windows main thread) with Excel's
observed results: formula (clone/eq/walk/map/adjust at 4,096), calc
(401 and 4,096 operands, -, *, /, ^, &, %, comparisons, 1,500 refs),
xlsx (long chains written as scalar formulas), engine (cell.set, fill,
copy/paste, insert rows/columns, undo/redo, Evaluate Formula, XLSX save
and reopen), Spanish entry. Each fails without the fix.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Sheet names starting with '.' or reading as R1C1 (R, C, RC, R1C1...) were saved
unquoted, so Excel could not open the file; PivotTable sources and ADDRESS left
cell-like names (A1) bare. The quoting rule, unquoting and sheet splitting now
live once in gridcraft_core::addr and replace the copies in the formula printer,
pivot, ADDRESS, chart, xlsx, Solver, Go To and the Name Box (which now reads ''
as ').
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
AAA exponential smoothing (Hyndman et al. 2008, ETS(A,A,A)) over an evenly
spaced timeline: documented seasonality, data completion and aggregation
arguments, calendar-month date timelines, autocorrelation seasonality
detection, state-space prediction intervals, statistic types 1-8.
Smoothing parameters minimise the in-sample SSE (grid + clamped
Nelder-Mead). XLSX export treats the family's range arguments as
array-taking (no spurious dynamic-array metadata), FORECAST/FORECAST.LINEAR
included.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The file format has no `@` operator, but formulas with an explicit
implicit intersection were written with a literal `@`
(`<f>@A1:A3*2</f>`). Excel writes `@x` as `_xlfn.SINGLE(x)`, which only
dynamic-array formulas carry. The writer now does the same and marks such
formulas cm="1"; the parser reads `SINGLE(x)` back as `@x`, as it already
does for `ANCHORARRAY` and `#`.
Two cases in the #83 metadata test expected a redundant `@` (`SQRT(@A1:A3)`,
`@A1:A3*2`) to be written as an ordinary formula. Dropping the `@` there is
only lossless if the reader puts it back on legacy formulas, which it
doesn't yet (the read side of #64), so they now expect cm.
generated with Claude Code
Preserve array evaluation for non-spilling XLSX formulas
Rebased onto main with a maintainer fix-up (LET bindings via split_last/as_chunks for clippy, no slice indexing); the contributor's branch does not allow maintainer edits.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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