synkit

A toolkit for building round-trip parsers with logos.

What is synkit?

synkit generates syn-like parsing infrastructure from token definitions. Define your tokens once, and get:

• Token enum with logos lexer integration
• Token structs (EqToken, IdentToken, etc.) with typed values
• TokenStream with whitespace skipping, fork/rewind, and span tracking
• Parse/Peek/ToTokens traits for building parsers
• Printer for round-trip code formatting

When to use synkit

synkit is ideal when you need:

• Round-trip fidelity: Parse → modify → print without losing formatting
• Span tracking: Precise error locations and source mapping
• Type-safe AST: Strongly-typed nodes with Spanned<T> wrappers

Architecture

flowchart LR
    Source["Source<br/>String"] --> TokenStream["TokenStream<br/>(lexer)"]
    TokenStream --> AST["AST<br/>(parser)"]
    TokenStream --> Span["Span<br/>tracking"]
    AST --> Printer["Printer<br/>(output)"]

Quick Example

use synkit::parser_kit;

synkit::parser_kit! {
    error: MyError,
    skip_tokens: [Space],
    tokens: {
        #[token(" ")]
        Space,

        #[token("=")]
        Eq,

        #[regex(r"[a-z]+", |lex| lex.slice().to_string())]
        Ident(String),
    },
    delimiters: {},
    span_derives: [Debug, Clone, PartialEq],
    token_derives: [Debug, Clone, PartialEq],
}

This generates:

• Token enum with Eq, Ident(String) variants
• EqToken, IdentToken structs
• TokenStream with lex(), parse(), peek()
• Tok![=], Tok![ident] macros
• Parse, Peek, ToTokens, Diagnostic traits