Crate vermouth 

Fortification against sin. A new kind of parser for procedural macros.

This crate aims to be a (not-quite) drop-in replacement for David Tolnay’s proc-macro2 and quote crates, and an opinionated alternative to syn. Opposing syn, this crate is designed around the philosophy that malformed input should be handled gracefully by procedural macros.

See our quote macro and the TokenQueue type for stream-building operations. See the Parser type for structural documentation on parsing.

The design of this crate is still in flux. Expect frequent breaking changes and temporary (🤞) API inconsistencies.

Stable Features

• complete — Enables the complete suite of parsing utilities.
• quote (enabled by default) — Enables quasi quoting.
• parse — Enables parsing.
• attributes — Provides support and utilities for parsing and handling Rust attributes.
• warnings — Enables emitting diagnostic warnings through the Diagnostic API.

Unstable Features

Tread lightly. These features may require a nightly compiler, and enabling any of them in a crate’s dependencies explicitly voids all semver guarantees your crate may promise.

• proc-macro2 — Rewires this crate to build on top of the proc-macro2 crate, instead of the default, officially supported proc_macro crate.

  You may use this to build testing infrastructure for your proc-macros, but are advised against enabling this in a library.

• unstable-diagnostics-backend-stdlib — Enables the standard library’s experimental proc_macro_diagnostic feature for higher quality diagnostics.

• unstable-diagnostics-backend-format-json — Enables experimental support for custom diagnostics through passing JSON messages directly to cargo.

MSRV

Note that while we don’t have an official policy with regards to our MSRV, expect it to be tied high for some time.

Modules

attributesattributes

Provides utilities for parsing attributes.

Macros

for_all_punct_seqs

Expands a macro with every distinct (supported) sequence of punctuation.

punct_decompose

Decomposes a larger token into a sequence of chars.

punct_patparse

Transforms a sequence of punctuation (e.g. && or ..=) into a PunctPat.

quotequote

Lazy quasi-quoting for Rust source.

verbatimquote

Quotes a single token (either a literal, an identifier, or a lifetime) in exactly the format supplied.

Structs

Checkpointparse

A location in the stream of a Parser.

Diagnosticparse

The universal type used for parsing diagnostics.

Drquote

The dollar doctor. Evaluates to $. Useful for escaping.

Eosparse

Matches the end of the stream.

Expectedparse

Builds a diagnostic which represents some syntax which was expected.

Parserparse

A simple parser for Rust source which traverses TokenTrees.

ParserPosparse

A reference to a position within the internal stream of a Parser.

PunctPatparse

A pattern representing a sequence of Puncts.

Spanned

A simple wrapper which provides span information for any value.

TokenQueue

General purpose buffer for token composition.

Transcriberquote

A lazily-evaluated sequence of quoted tokens (what quote evaluates to).

Verbatim

A verbatim token. See the verbatim macro.

Enums

DiagnosticLevelparse

The severity level of a custom Diagnostic.

VerbatimKind

What sort of token this Verbatim represents.

Traits

IntoTokens

Methods for converting by-value into TokenQueue.

Parseparse

A common interface for parsing values from a Parser.

Patternparse

Performs simple pattern-matched parsing through a Parser object.

PushToken

A marker trait indicating that this IntoTokens implementation executes in amortized constant time.

RefToTokens

Marks a type as cheaply-clonable and suitable for an automatic &T: IntoTokens implementation.

ToSpan

Enables conversion between different span formats.

TokenTreeExt

A trait extending the behaviour of TokenTrees.

Type Aliases

Resultparse

An alias for the standard library Result.