Module wire 

The wire: a display structure as bytes, with a version in front of it.

JSON is what the content tree serializes to, because a person reads it. The display structure is machine output: every glyph of every page, produced once per keystroke and decoded on someone’s main thread. So it crosses as postcard, which packs varints, sends no field names, and needs no tree of maps built before the first page can be read.

The encoding is positional, which is the price of that: a host’s decoder reads fields in declaration order and has no way to notice that the order changed. So a version leads the bytes, VERSION moves whenever what crosses changes shape, and a host that reads a number it does not know refuses at the first byte instead of painting nonsense.

A reply need not carry the whole book: encode_range sends a slice of the pages and says where it falls, so a host looking at one page pays for one page. Layout still runs over the whole book either way; what a range saves is serializing and decoding the pages nobody asked for. fonts, assets and warnings are never sliced, since none of them is per page.

An EPUB crosses the same wall behind the same version, with the warnings writing it raised: see encode_epub. Its files can cross one by one instead: see encode_epub_files.

Structs

Epub

An EPUB as one wire reply, and what writing it warned about.

EpubFile

One file of an EPUB.

EpubFiles

An EPUB as its files, not zipped, and what writing it warned about.

EpubSpineEntry

One document of an EPUB’s spine.

Reply

What one wire reply carried, and where it falls in the book.

Enums

WireError

Why a buffer could not be read as a display structure.

Constants

VERSION

What the encoding is. A host checks this before reading anything else, and a mismatch is a refusal rather than a best effort.

Functions

decode

Reads a reply back, refusing a version this build does not write.

decode_epub

Reads an EPUB reply back, refusing a version this build does not write.

decode_epub_files

Reads an EPUB’s files back, refusing a version this build does not write.

encode

Encodes the whole display structure, version first.

encode_epub

Encodes an EPUB and its warnings, version first.

encode_epub_files

Encodes an EPUB’s files, version first.

encode_range

Encodes count pages starting at first, version first. A range past the end of the book is clamped rather than refused: an edit that shortens the book while a page past its new end is still being asked for gets back whatever is left, not a panic.

version

The version a buffer leads with, without reading the rest of it.