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fix(parser): avoid Math.max spread on large files #25

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Merged
daggerok merged 1 commit into from
Oct 25, 2026
Merged

fix(parser): avoid Math.max spread on large files #25

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22 changes: 11 additions & 11 deletions src/main.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -403,6 +403,13 @@ function parseCSVText(text: string): string[][] {
return rows;
}

/** Longest row length. A loop, not Math.max(...rows): spreading ~150k+ arguments overflows the V8 stack. */
function maxRowLength(rows: readonly (readonly unknown[])[], min = 0): number {
let max = min;
for (const row of rows) if (row.length > max) max = row.length;
return max;
}

function extractValidTableData(rawText: string): string[][] {
const parsedLines = parseCSVText(rawText).filter(row => row.some(cell => cell !== ''));
if (parsedLines.length === 0) return [];
Expand All @@ -412,7 +419,7 @@ function extractValidTableData(rawText: string): string[][] {
for (const [lengthStr, count] of Object.entries(colCounts)) {
if (count > maxOccurrences) { maxOccurrences = count; targetColLength = parseInt(lengthStr, 10); }
}
if (targetColLength === 0) targetColLength = Math.max(...parsedLines.map(r => r.length));
if (targetColLength === 0) targetColLength = maxRowLength(parsedLines);
// Rows one field shorter belong to the table too: Fidelity data rows end with a comma, so the
// header has one field less than every data row and used to be dropped. Rows are padded, never cut
const tableData: string[][] = [];
Expand All @@ -426,7 +433,7 @@ function extractValidTableData(rawText: string): string[][] {
} else if (isRecording && row.length < targetColLength - 1) { break; }
}
if (tableData.length === 0) return parsedLines;
let width = Math.max(...tableData.map(r => r.length));
let width = maxRowLength(tableData);
// a trailing column that is empty in every row (the trailing comma) is not a column
while (width > 1 && tableData.every(r => (r[width - 1] ?? '') === '')) width--;
return tableData.map(r => (r.length >= width ? r.slice(0, width) : [...r, ...Array.from({ length: width - r.length }, () => '')]));
Expand Down Expand Up @@ -610,7 +617,7 @@ function applyFilters(rows: string[][], filters: Record<number, string>, getColT
const ci = parseInt(s, 10); const ct = getColType(ci); const ex = parseFilterExpression(f, ct);
if (ex) parsed.push({ colIndex: ci, expression: ex, colType: ct });
}
const width = rows.reduce((max, row) => Math.max(max, row.length), 0);
const width = maxRowLength(rows);
const usable = parsed.filter(({ colIndex }) => colIndex < width);
if (usable.length === 0) return rows;
return rows.filter(row => usable.every(({ colIndex, expression, colType }) => matchesFilter(row[colIndex] || '', expression, colType)));
Expand Down Expand Up @@ -1552,14 +1559,7 @@ const App: React.FC = () => {
return { fileName: dataset.fileName, headers, rows: sorted };
});

const maxCols = Math.max(
1,
...blocks.map(block => Math.max(
block.headers.length,
...block.rows.map(r => r.length),
1
))
);
const maxCols = blocks.reduce((max, block) => Math.max(max, block.headers.length, maxRowLength(block.rows)), 1);

const mergedRows: string[][] = [];
for (const block of blocks) {
Expand Down
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