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tables: expand multi-row cells in-place when fallback heuristic is empty (#71)

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* tables: expand multi-row TSR cells in place

Recover row-under-counted TSR tables by splitting overstuffed cells with native PDF text bands before falling back to heuristic extraction.

Made-with: Cursor

* docs: note multi-row expansion scope

Clarify that the row-band cap intentionally keeps v1 focused on common small row-loss cases while larger compressions continue to use heuristic fallback.

Made-with: Cursor
This commit is contained in:
Abimael Martell
2026-04-29 08:18:09 -07:00
committed by GitHub
parent 63b5573133
commit 5b1fe30c66
3 changed files with 603 additions and 87 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tests/integration_tests.rs
+166 -18
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@@ -1812,6 +1812,93 @@ fn synthetic_vector_grid_pdf(two_tables: bool) -> Vec<u8> {
bytes
}
fn synthetic_vector_grid_three_row_pdf() -> Vec<u8> {
use lopdf::content::{Content, Operation};
use lopdf::{dictionary, Document, Object, Stream};
let mut doc = Document::with_version("1.5");
let pages_id = doc.new_object_id();
let page_id = doc.new_object_id();
let font_id = doc.new_object_id();
let content_id = doc.new_object_id();
doc.objects.insert(
font_id,
dictionary! {
"Type" => "Font",
"Subtype" => "Type1",
"BaseFont" => "Helvetica",
}
.into(),
);
let mut operations = Vec::new();
for y in [740, 710, 680, 650] {
operations.push(Operation::new("m", vec![50.into(), y.into()]));
operations.push(Operation::new("l", vec![210.into(), y.into()]));
}
for x in [50, 130, 210] {
operations.push(Operation::new("m", vec![x.into(), 650.into()]));
operations.push(Operation::new("l", vec![x.into(), 740.into()]));
}
operations.push(Operation::new("S", vec![]));
operations.push(Operation::new("BT", vec![]));
operations.push(Operation::new("Tf", vec!["F1".into(), 10.into()]));
for (x, y, text) in [
(70, 724, "Branch"),
(150, 724, "Deposits"),
(70, 694, "Oak"),
(150, 694, "100"),
(70, 664, "Boardwalk"),
(150, 664, "200"),
] {
operations.push(Operation::new(
"Tm",
vec![1.into(), 0.into(), 0.into(), 1.into(), x.into(), y.into()],
));
operations.push(Operation::new("Tj", vec![Object::string_literal(text)]));
}
operations.push(Operation::new("ET", vec![]));
let content = Content { operations }.encode().unwrap();
doc.objects
.insert(content_id, Stream::new(dictionary! {}, content).into());
doc.objects.insert(
page_id,
dictionary! {
"Type" => "Page",
"Parent" => pages_id,
"MediaBox" => vec![0.into(), 0.into(), 300.into(), 800.into()],
"Resources" => dictionary! {
"Font" => dictionary! {
"F1" => font_id,
},
},
"Contents" => content_id,
}
.into(),
);
doc.objects.insert(
pages_id,
dictionary! {
"Type" => "Pages",
"Kids" => vec![page_id.into()],
"Count" => 1,
}
.into(),
);
let catalog_id = doc.add_object(dictionary! {
"Type" => "Catalog",
"Pages" => pages_id,
});
doc.trailer.set("Root", catalog_id);
let mut bytes = Vec::new();
doc.save_to(&mut bytes).unwrap();
bytes
}
fn assert_close(actual: f32, expected: f32) {
assert!(
(actual - expected).abs() < 0.75,
@@ -2319,7 +2406,7 @@ fn test_auto_passes_through_clean_tsr_output() {
}
#[test]
fn test_auto_falls_back_on_multi_row_in_cell() {
fn test_auto_expands_multi_row_in_cell() {
use pdf_inspector::{extract_tables_with_structure_auto_mem, TsrTableInput};
let buf = synthetic_dense_table_pdf();
@@ -2370,16 +2457,79 @@ fn test_auto_falls_back_on_multi_row_in_cell() {
assert_eq!(results.len(), 1);
assert_eq!(
results[0].fallback_reason.as_deref(),
Some("multi_row_in_cell"),
"expected multi_row_in_cell fallback, got {:?}",
Some("multi_row_in_cell_expanded"),
"expected multi_row_in_cell_expanded, got {:?}",
results[0].fallback_reason
);
// The heuristic-fallback markdown should preserve all three PDF rows.
// The in-place expansion should preserve all three PDF rows.
let md = &results[0].markdown;
assert!(md.contains("Oak Street"), "missing Oak Street: {md}");
assert!(md.contains("Boardwalk"), "missing Boardwalk: {md}");
assert!(md.contains("100"), "missing 100: {md}");
assert!(md.contains("200"), "missing 200: {md}");
assert!(
!md.contains("Oak Street Boardwalk"),
"rows should not remain compressed: {md}"
);
}
#[test]
fn test_auto_expands_under_counted_vector_grid_rows() {
use pdf_inspector::{extract_tables_with_structure_auto_mem, TsrTableInput};
let buf = synthetic_vector_grid_three_row_pdf();
let tokens: Vec<String> = [
"<table>",
"<thead>",
"<tr>",
"<th></th>",
"<th></th>",
"</tr>",
"</thead>",
"<tbody>",
"<tr>",
"<td></td>",
"<td></td>",
"</tr>",
"</tbody>",
"</table>",
]
.into_iter()
.map(String::from)
.collect();
let crop = [50.0, 60.0, 210.0, 150.0];
let cell_bboxes = vec![
poly(0.0, 0.0, 80.0, 30.0),
poly(80.0, 0.0, 160.0, 30.0),
poly(0.0, 30.0, 80.0, 90.0),
poly(80.0, 30.0, 160.0, 90.0),
];
let results = extract_tables_with_structure_auto_mem(
&buf,
&[TsrTableInput {
page: 0,
crop_pdf_pt_bbox: crop,
render_dpi: 72.0,
structure_tokens: tokens,
cell_bboxes,
}],
)
.unwrap();
assert_eq!(results.len(), 1);
assert_eq!(
results[0].fallback_reason.as_deref(),
Some("multi_row_in_cell_expanded")
);
let md = &results[0].markdown;
assert!(md.contains("|Branch|Deposits|"), "missing header: {md}");
assert!(md.contains("|Oak|100|"), "missing row 1: {md}");
assert!(md.contains("|Boardwalk|200|"), "missing row 2: {md}");
assert!(
!md.contains("Oak Boardwalk"),
"rows stayed compressed: {md}"
);
}
#[test]
@@ -2456,15 +2606,14 @@ fn test_auto_does_not_fire_on_legit_rowspan_cell() {
}
#[test]
fn test_auto_keeps_tsr_markdown_when_heuristic_returns_empty() {
fn test_auto_expands_when_heuristic_region_is_empty() {
use pdf_inspector::{extract_tables_with_structure_auto_mem, TsrTableInput};
let buf = synthetic_dense_table_pdf();
// Same shape as the multi_row_in_cell regression — a tall data cell
// that catches Oak Street + Boardwalk. But the crop bbox we pass
// points at a strip of the page that has NO text items, so the
// heuristic's region will be empty when it tries to extract there.
// The auto wrapper must keep the TSR markdown rather than ship "".
// that catches Oak Street + Boardwalk. The crop bbox we pass points
// at a strip of the page that has NO text items, so the old heuristic
// fallback would be empty. Expansion uses the cell bboxes directly.
let tokens: Vec<String> = [
"<table>",
"<thead>",
@@ -2510,20 +2659,19 @@ fn test_auto_keeps_tsr_markdown_when_heuristic_returns_empty() {
let r = &results[0];
assert_eq!(
r.fallback_reason.as_deref(),
Some("multi_row_in_cell_heuristic_empty"),
"expected _heuristic_empty suffix, got {:?}",
Some("multi_row_in_cell_expanded"),
"expected expansion despite empty heuristic region, got {:?}",
r.fallback_reason,
);
// TSR markdown should be preserved — non-empty, contains the cell
// text we know was assigned by the TSR path.
assert!(
!r.markdown.trim().is_empty(),
"expected TSR markdown to be preserved, got empty",
r.markdown.contains("|Oak Street|100|"),
"missing row 1: {}",
r.markdown
);
assert!(
r.markdown.contains("Oak Street") || r.markdown.contains("Boardwalk"),
"expected TSR markdown to contain at least one row, got: {}",
r.markdown,
r.markdown.contains("|Boardwalk|200|"),
"missing row 2: {}",
r.markdown
);
}