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Merged
asionesjia merged 3 commits into from
Aug 27, 2026
Merged

fix(pdf): keep positioned math out of tables #87

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fea1ac6
fix(pdf): keep positioned math out of tables
asionesjia Aug 27, 2026
91d20f3
fix(pdf): remap superior digits and keep signed numeric tables
cursoragent Aug 27, 2026
d468c44
fix(pdf): count minus in numbered math layout
cursoragent Aug 27, 2026
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239 changes: 229 additions & 10 deletions packages/pdf/src/pdf.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -143,7 +143,9 @@ async function convertUniqueImages(

function finishPdf(extracted: ExtractedPdf, imageBlocks: MarkdownBlock[]): string {
const markdown = itemsToMarkdown(
mergeNumericFragments(mergeScriptItems(dedupeOverlappingItems(extracted.items))),
mergeNumericFragments(
mergeStackedMath(mergeScriptItems(dedupeOverlappingItems(extracted.items))),
),
extracted.strokeLines,
extracted.pageRects,
imageBlocks,
Expand Down Expand Up @@ -2939,6 +2941,105 @@ function dedupeOverlappingItems(items: TextItem[]): TextItem[] {
const SUP = ['⁰', '¹', '²', '³', '⁴', '⁵', '⁶', '⁷', '⁸', '⁹'];
const SUB = ['₀', '₁', '₂', '₃', '₄', '₅', '₆', '₇', '₈', '₉'];

const SUP_CHARS: Record<string, string> = {
'0': '⁰',
'1': '¹',
'2': '²',
'3': '³',
'4': '⁴',
'5': '⁵',
'6': '⁶',
'7': '⁷',
'8': '⁸',
'9': '⁹',
'+': '⁺',
'-': '⁻',
'−': '⁻',
'=': '⁼',
'(': '⁽',
')': '⁾',
a: 'ᵃ',
b: 'ᵇ',
c: 'ᶜ',
d: 'ᵈ',
e: 'ᵉ',
f: 'ᶠ',
g: 'ᵍ',
h: 'ʰ',
i: 'ⁱ',
j: 'ʲ',
k: 'ᵏ',
l: 'ˡ',
m: 'ᵐ',
n: 'ⁿ',
o: 'ᵒ',
p: 'ᵖ',
r: 'ʳ',
s: 'ˢ',
t: 'ᵗ',
u: 'ᵘ',
v: 'ᵛ',
w: 'ʷ',
x: 'ˣ',
y: 'ʸ',
z: 'ᶻ',
A: 'ᴬ',
B: 'ᴮ',
D: 'ᴰ',
E: 'ᴱ',
G: 'ᴳ',
H: 'ᴴ',
I: 'ᴵ',
J: 'ᴶ',
K: 'ᴷ',
L: 'ᴸ',
M: 'ᴹ',
N: 'ᴺ',
O: 'ᴼ',
P: 'ᴾ',
R: 'ᴿ',
T: 'ᵀ',
U: 'ᵁ',
V: 'ⱽ',
W: 'ᵂ',
};

const SUB_CHARS: Record<string, string> = {
'0': '₀',
'1': '₁',
'2': '₂',
'3': '₃',
'4': '₄',
'5': '₅',
'6': '₆',
'7': '₇',
'8': '₈',
'9': '₉',
'+': '₊',
'-': '₋',
'−': '₋',
'=': '₌',
'(': '₍',
')': '₎',
a: 'ₐ',
e: 'ₑ',
h: 'ₕ',
i: 'ᵢ',
j: 'ⱼ',
k: 'ₖ',
l: 'ₗ',
m: 'ₘ',
n: 'ₙ',
o: 'ₒ',
p: 'ₚ',
r: 'ᵣ',
s: 'ₛ',
t: 'ₜ',
u: 'ᵤ',
v: 'ᵥ',
x: 'ₓ',
};

function scriptDigits(text: string): string | undefined {
const t = text.trim();
if (t.length === 0 || t.length > 4) return undefined;
Expand All @@ -2955,18 +3056,47 @@ function scriptDigits(text: string): string | undefined {
return out;
}

function isScriptCandidate(text: string): boolean {
const t = text.trim();
if (t.length === 0 || t.length > 4) return false;
if (scriptDigits(t) !== undefined) return true;
if (/^[+\-−+=()]$/.test(t)) return true;
return /^[\p{L}]$/u.test(t);
}

function toScript(text: string, sub: boolean): string {
const map = sub ? SUB_CHARS : SUP_CHARS;
const digits = scriptDigits(text);
let out = '';
for (const c of digits ?? text.trim()) out += map[c] ?? c;
return out;
}
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function canAttachScript(parent: TextItem, item: TextItem): boolean {
if (parent.page !== item.page) return false;
if (item.fontSize <= 0) return false;
if (scriptDigits(item.text) === undefined) return false;
if (parent.fontSize < item.fontSize * 1.15) return false;
if (!isScriptCandidate(item.text)) return false;
const t = item.text.trim();
const digits = scriptDigits(t) !== undefined;
const last = [...parent.text.trimEnd()].at(-1);
if (last === undefined) return false;
if (!/[\p{L}\p{N}\p{P}]/u.test(last)) return false;
const ratio = item.fontSize > 0 ? parent.fontSize / item.fontSize : 1;
if (ratio < 1.2) return false;
if (!digits && ratio > 1.9) return false;
const scripted =
Object.values(SUP_CHARS).includes(last) ||
Object.values(SUB_CHARS).includes(last) ||
SUP.includes(last) ||
SUB.includes(last);
if (!scripted && !/[\p{L}\p{N}\p{P}]/u.test(last)) return false;
const fs = Math.max(parent.fontSize, 8);
const gap = item.x - (parent.x + parent.width);
if (gap >= fs * 0.35 || gap <= -fs * 0.5) return false;
if (Math.abs(item.y - parent.y) > Math.max(fs * 0.8, 8)) return false;
const gapMax = digits ? fs * 0.35 : fs * 0.4;
if (gap >= gapMax || gap <= -fs * 0.5) return false;
const yOff = Math.abs(item.y - parent.y);
const yMax = digits ? Math.max(fs * 0.8, 8) : fs * 0.55;
if (yOff > yMax) return false;
if (yOff < fs * 0.12 && !digits) return false;
return true;
}

Expand Down Expand Up @@ -3019,16 +3149,16 @@ function mergeScriptItems(items: TextItem[]): TextItem[] {
const merged: TextItem[] = [];
for (const item of pageItems) {
let attached = false;
if (scriptDigits(item.text) !== undefined) {
if (isScriptCandidate(item.text)) {
for (let i = merged.length - 1; i >= 0; i -= 1) {
const parent = merged[i]!;
if (parent.x > item.x) continue;
if (!canAttachScript(parent, item)) continue;
const digits = scriptDigits(item.text)!;
const lowered = item.y < parent.y - parent.fontSize * 0.12;
const table = lowered ? SUB : SUP;
parent.text += [...digits].map((c) => table[Number(c)]!).join('');
parent.text += toScript(item.text, lowered);
parent.width = Math.max(parent.width, item.x + item.width - parent.x);
const span = Math.abs(item.y - parent.y) + item.height;
parent.height = Math.max(parent.height, item.height, span);
attached = true;
break;
}
Expand All @@ -3040,6 +3170,73 @@ function mergeScriptItems(items: TextItem[]): TextItem[] {
return result;
}

function isFractionNumerator(text: string): boolean {
const t = text.trim();
if (t.length === 0 || t.length > 6) return false;
if (/[∂∑∫√∞]/.test(t)) return true;
return t === 'd';
}

function isFractionDenominator(text: string): boolean {
const t = text.trim();
if (t.length === 0 || t.length > 6) return false;
if (/[∂∑∫√∞]/.test(t)) return true;
return /^(?:dt|dx|dy|dq)$/.test(t);
}

function mergeStackedMath(items: TextItem[]): TextItem[] {
if (items.length < 2) return items;
const sorted = items.slice().sort((a, b) => a.page - b.page || b.y - a.y || a.x - b.x);
const used = new Set<number>();
const out: TextItem[] = [];
for (let i = 0; i < sorted.length; i += 1) {
if (used.has(i)) continue;
const top = sorted[i]!;
if (!isFractionNumerator(top.text)) {
out.push(top);
continue;
}
const fsTop = Math.max(top.fontSize, 8);
let best = -1;
let bestScore = 0;
for (let j = i + 1; j < sorted.length; j += 1) {
if (used.has(j)) continue;
const bot = sorted[j]!;
if (bot.page !== top.page) break;
if (!isFractionDenominator(bot.text)) continue;
const gap = top.y - bot.y;
const fs = Math.max(fsTop, bot.fontSize, 8);
if (gap < fs * 0.45 || gap > fs * 1.7) continue;
const overlap =
Math.min(top.x + Math.max(top.width, 1), bot.x + Math.max(bot.width, 1)) -
Math.max(top.x, bot.x);
const minW = Math.min(Math.max(top.width, 4), Math.max(bot.width, 4));
if (overlap < minW * 0.35) continue;
const score = overlap / Math.max(gap, 1);
if (score > bestScore) {
bestScore = score;
best = j;
}
}
if (best < 0) {
out.push(top);
continue;
}
const bot = sorted[best]!;
used.add(best);
const x = Math.min(top.x, bot.x);
out.push({
...top,
text: `${top.text.trim()}/${bot.text.trim()}`,
x,
y: (top.y + bot.y) / 2,
width: Math.max(top.x + Math.max(top.width, 0), bot.x + Math.max(bot.width, 0)) - x,
height: Math.max(top.height, top.y - bot.y + bot.height),
});
}
return out;
}

// ---------------------------------------------------------------------------
// Line grouping + markdown
// ---------------------------------------------------------------------------
Expand Down Expand Up @@ -3133,6 +3330,26 @@ function formatLine(items: TextItem[], bold: boolean, italic: boolean, deco: boo
return result;
}

function isEquationNumberLine(text: string): boolean {
return /^\(?\d+(?:\.\d+)*[a-z]?\)?$/.test(text.trim());
}

function isMathHeading(text: string): boolean {
const t = text.trim();
if (isEquationNumberLine(t)) return true;
const ops = t.match(/[=≠≈≤≥±∂∑∫√∞×·−]/g)?.length ?? 0;
const words = t.split(/\s+/).filter((w) => /\p{L}{3,}/u.test(w)).length;
return ops >= 1 && words <= 1;
}

function isFalseIsolatedHeading(text: string): boolean {
const t = text.trim();
if (/^[\p{Ll}]/u.test(t)) return true;
if (/[:,]$/.test(t)) return true;
if (/\band$/i.test(t)) return true;
return isMathHeading(t);
}

function isListItem(text: string): boolean {
const t = text.trimStart();
if (
Expand Down Expand Up @@ -3321,6 +3538,7 @@ function itemsToMarkdown(
const wc = plain.split(/\s+/).filter(Boolean).length;
if (wc < 1 || wc > 6 || plain.length <= 3) continue;
if (line[0]!.fontSize < base * 0.95) continue;
if (isFalseIsolatedHeading(plain)) continue;
const prev = lines[i - 1];
const next = lines[i + 1];
const before = !prev || prev[0]!.page !== line[0]!.page || prev[0]!.y - line[0]!.y > paraTh;
Expand All @@ -3330,6 +3548,7 @@ function itemsToMarkdown(

const headerLevel = (i: number, line: TextItem[], plain: string): number | undefined => {
if (plain.length <= 3 || plain.split(/\s+/).filter(Boolean).length > 15) return undefined;
if (isMathHeading(plain) || /^[\p{Ll}]/u.test(plain)) return undefined;
const fs = line[0]!.fontSize;
const ratio = fs / base;
if (ratio >= 1.2) {
Expand Down
21 changes: 20 additions & 1 deletion packages/pdf/src/tables.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -688,7 +688,8 @@ function acceptBorderless(
looksLikeChartValues(grid, run) ||
looksLikeNumericScatter(grid) ||
looksLikeLabeledTicks(grid) ||
looksLikeHeaderlessJunk(grid)
looksLikeHeaderlessJunk(grid) ||
looksLikeMathLayout(grid)
) {
return false;
}
Expand Down Expand Up @@ -778,6 +779,24 @@ function looksLikeLabeledTicks(grid: string[][]): boolean {
return percentAt >= 0 && labelAt >= 0 && percentAt < labelAt;
}

function looksLikeMathLayout(grid: string[][]): boolean {
const cells = grid.flat().filter((c) => c.length > 0);
if (cells.length < 3) return false;
const eqNums = cells.filter((c) => /\(\d+(?:\.\d+)*[a-z]?\)/.test(c)).length;
const ops = cells.filter((c) => /[=≠≈≤≥∂∑∫√∞×·]/.test(c)).length;
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const mathGlyphs = cells.filter((c) => /[∂∑∫√∞]/.test(c)).length;
const short = cells.filter((c) => [...c].length <= 10).length;
const tiny = cells.filter((c) => [...c].length <= 3).length;
const prose = cells.filter(
(c) => (wordCount(c) >= 3 || /\p{L}{5,}/u.test(c)) && !/[=∂∑∫]/.test(c),
).length;
if (prose >= 2) return false;
if (eqNums >= 1 && (ops >= 1 || cells.some((c) => /[±−]/.test(c)))) return true;
if (mathGlyphs >= 2) return true;
if (ops >= 2 && short / cells.length >= 0.65 && grid.length >= 3) return true;
return ops >= 1 && tiny >= 4 && short / cells.length >= 0.65;
}
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function looksLikeHeaderlessJunk(grid: string[][]): boolean {
if (grid.length !== 2 || grid[0]!.length < 3) return false;
const r0 = grid[0]!.filter((c) => c.length > 0);
Expand Down
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