Crafting a parser in Rust

Before any grammar rule runs, a lexer turns characters into spanned tokens — and that token shape decides everything downstream.

One function per grammar rule, the call stack as the parse tree, and why left recursion is a trap.

Enums all the way down, spans on every node, and keeping semantics out of the syntax tree.

One loop and a binding-power table replace a forest of precedence functions.

Report many errors per run and keep a usable tree — panic-mode recovery, sync points, and messages that don't lie.

The dangling else, the less-than-versus-generics problem, and how much backtracking is honest.

IDE-grade parsing: lossless trees, errors as the normal path, and reparsing only the edited subtree.

Snapshot the tree, round-trip for fidelity, and fuzz to enforce the never-panic contract.