objects: the object graph as JSON, for a file that will not open anywhere else

[tannevaled]

BentoPDF's pdf-to-json. It writes what the file is made of rather than
what it says.

pdfops objects broken.pdf | jq '.objects["12 0"]'

⛔ The graph reachable from the trailer, not every object in the file. That
is the honest set because it is the one a reader sees: an object no reference
points at is in the bytes and in nobody's document.

⛔ A stream's bytes are not in it, its length and dictionary are. They are
the bulk of most files and they are binary, so including them would mean
base64 — a 35 MB file becoming a 47 MB JSON nobody reads.

A name keeps its slash and a string is wrapped, {"text": …} or
{"hex": …}, because the two have to be told apart and a PDF string may be
exactly /Catalog. Through reader.TextString, since the bytes of a text
string are not text. A reference that could not be read is named in
unread rather than dropped.

⛔ Two guards that masked each other

Found by a surviving mutation. A PDF is a graph — the page tree's Kids
point at the pages and every page's Parent points back — so an object is
marked seen before it is read. Remove that and the walk should never end.

It ended anyway: the depth guard cut it off at 256 and produced a finite,
enormous, wrong answer. "It terminated" cannot tell the two apart. Counting
the reads can, and the test now asserts one read per object.

And a sort that did nothing

encoding/json sorts a map's keys itself, so sorting them here only looked
like the thing making the output deterministic — a mutation reversing it
changed no test. Removed, with two runs of a real file compared byte for byte
to show determinism survived it.

The seam

The walker holds a getter rather than the document, which is what makes
the unreadable-reference branch testable: reader.Get is forgiving by design
— a reference to an object never written resolves to Null, not an error — so
no file reaches it.

How it is checked

100% of statements with no uncovered blocks, 14 mutations caught. One dead
case nil removed: reader says in its own words that a missing entry
resolves to Null "so callers never have to nil-check".

🤖 Generated with Claude Code