---
title: One
framework: regexbuilder
role: symbol
role_heading: Structure
path: regexbuilder/one
---

# One

A regex component that matches exactly one occurrence of its underlying component.

## Declaration

```swift
struct One<Output>
```

## Topics

### Initializers

- [init(_:)](regexbuilder/one/init(_:).md)

## Relationships

### Conforms To

- [RegexComponent](swift/regexcomponent.md)

## See Also

### Quantifiers

- [Optionally](regexbuilder/optionally.md)
- [ZeroOrMore](regexbuilder/zeroormore.md)
- [OneOrMore](regexbuilder/oneormore.md)
- [Repeat](regexbuilder/repeat.md)
- [Local](regexbuilder/local.md)