Module edit 

Editing a Doc.

This is the half of a block editor that has nothing to do with gpui: text goes in and out of a Text, marks move with it, and blocks split, merge and indent. Keeping it pure is what makes it testable — the guarantee below is checked over generated edit sequences, not over the handful of cases anyone thinks to write down.

The guarantee is [crate::serialize]’s, preserved. Call Doc::normalize and the document round-trips: serialize, parse, and nothing moves. An editor that can reach a state its own serializer cannot express is an editor that corrupts the file on save, and no amount of UI polish recovers from that.

Normalizing is a save step rather than a keystroke step, and deliberately. Markdown cannot hold a space at the end of a line, but stripping one the moment it is typed takes it away mid-word — so the model carries it and sheds it on the way out, which is what every editor that writes markdown does.

Marks are left-sticky: text typed at the end of a bold run is bold, text typed at its start is not. The caret inherits formatting from the character before it, which is what every editor does and what nobody notices until it is wrong.

Structs

Splice

What a Doc::replace did, for anything holding a position it moved.

Enums

Shortcut

A markdown prefix typed at the start of a block, and what it turns it into.

Functions

inline_rule

A closing inline delimiter just typed, and the run it closes.

shortcut

Match a markdown prefix at the start of a block, returning it and how many bytes it occupied.