Macro repetition
Macro repetition is declarative syntax for matching or expanding a token sequence zero or more, one or more, or optionally repeated times.
Learn Rust in a Month of Lunches
Macro repetition is declarative macro syntax for matching or expanding zero or more or one or more repeated token sequences with optional separators.
- How it is used
- Uses repetition to match variable-length macro input and reproduce matched tokens in expansions.
- How deep it goes
- Works through separators and all three repetition operators, including empty input and optional clauses, without descending into compiler internals.
- Examples
- Shows a printing macro accepting empty and comma-separated calls, a function-generating macro, and optional syntax in `matches!`.
- What you can do after
- Build it from scratch: write macro rules for repeated inputs and optional syntax, then adjust separators to match intended calls.
Read how Learn Rust in a Month of Lunches explains macro repetition →
Write Powerful Rust Macros
A macro repetition operator specifies whether a repeated macro pattern occurs zero or more, one or more, or zero or one times.
- How it is used
- Uses repetition operators to accept repeated expressions and emit corresponding repeated statements in declarative macros.
- How deep it goes
- Defines *, +, and ?, demonstrates matcher-transcriber depth, and notes an unresolved operator-mismatch bug.
- Examples
- Uses a repeated-expression macro that pushes each capture into a vector and rejects mixed input types.
- What you can do after
- Apply it via Rust declarative macros to accept repeated expressions and generate repeated operations.
Read how Write Powerful Rust Macros explains macro repetition →
Related concepts
- macro matcherconfigures · A macro matcher is the pattern portion of a declarative macro rule that determines which invocation tokens the rule accepts.
- quantifiercontrasts with · A regular-expression quantifier is syntax that specifies how many times a preceding pattern element may or must match.
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