SwiftScanner

SwiftScanner is a pure native Swift implementation of a string scanner; with no dependecies, full unicode support (who does not love emoji?), lots of useful featurs and swift in mind, StringScanner is a good alternative to built-in Apple's NSScanner.

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Main Features

SwiftScanner is initialized with a string and mantain an internal index used to navigate backward and forward through the string using two main concepts:

• scan to return string which also increment the internal index
• peek to return a string without incrementing the internal index

Results of these operations returns collected String or Indexes. If operation fail due to an error (ie. eof, notFound, invalidInt...) and exception is thrown, in pure Swift style.

API Documentation

• scanChar()
• scanInt()
• scanFloat()
• scanHexInt()
• scan(upTo: UnicodeScalar)
• scan(upTo: CharacterSet)
• scan(untilIn: CharacterSet)
• scan(upTo: String)
• scan(until: Test)
• scan(length: Int)
• peek(upTo: UnicodeScalar)
• peek(upTo: CharacterSet)
• peek(untilIn: CharacterSet)
• peek(upTo: String)
• peek(until: Test)
• match(UnicodeScalar)
• match(String)
• reset()
• peekAtEnd()
• skip(length: Int)
• back(length: Int)

Other

• Installation
• Tests
• Requirements
• Credits

scan functions

#### `func scanChar() throws -> UnicodeScalar` `scanChar` allows you to scan the next character after the current's scanner `position` and return it as `UnicodeScalar`. If operation succeded internal scanner's `position` is advanced by 1 character (as unicode). If operation fails an exception is thrown.

Example:

let scanner = StringScanner("Hello this is SwiftScanner")
let firstChar = try! scanner.scanChar() // get 'H'

#### `func scanInt() throws -> Int` Scan the next integer value after the current scanner's `position`; consume scalars from {0...9} until a non numeric value is encountered. Return the integer representation in base 10. Throw `.invalidInt` if scalar at current position is not in allowed range (may also return `.eof`). If operation succeded internal scanner's `position` is advanced by the number of character which represent an integer. If operation fails an exception is thrown.

Example:

let scanner = StringScanner("15 apples")
let parsedInt = try! scanner.scanInt() // get Int=15

#### `func scanFloat() throws -> Float` Scan for a float value (in format ##.##) and convert it to a valid Floast. If scan succeded scanner's `position` is updated at the end of the represented string, otherwise an exception (`.invalidFloat`, `.eof`) is thrown and index is not touched.

Example:

let scanner = StringScanner("45.54 $")
let parsedFloat = try! scanner.scanFloat() // get Int=45.54

#### `func scanHexInt(digits: BitDigits) throws -> Int` Scan an HEX digit expressed in these formats:

• 0x[VALUE] (example: 0x0000000000564534)
• 0X[VALUE] (example: 0x0929)
• #[VALUE] (example: #1602)

If scan succeded scanner's position is updated at the end of the represented string, otherwise an exception ((.notFound, ).invalidHex, .eof) is thrown and index is not touched.

Example:

let scanner = StringScanner("#1602")
let value = try! scanner.scanHexInt(.bit16) // get Int=5634

let scanner = StringScanner("#0x0929")
let value = try! scanner.scanHexInt(.bit16) // get Int=2345

let scanner = StringScanner("#0x0000000000564534")
let value = try! scanner.scanHexInt(.bit64) // get Int=5653812

#### `public func scan(upTo char: UnicodeScalar) throws -> String?` Scan until given character is found starting from current scanner `position` till the end of the source string. Scanner's `position` is updated only if character is found and set just before it. Throw an exception if `.eof` is reached or `.notFound` if char was not found (in this case scanner's position is not updated)

Example:

let scanner = StringScanner("Hello <bold>Daniele</bold>")
let partialString = try! scanner.scan(upTo: "<bold>") // get "Hello "

#### `func scan(upTo charSet: CharacterSet) throws -> String?` Scan until given character's is found. Index is reported before the start of the sequence, scanner's `position` is updated only if sequence is found. Throw an exception if `.eof` is reached or `.notFound` if sequence was not found.

Example:

let scanner = StringScanner("Hello, I've at least 15 apples")
let partialString = try! scanner.scan(upTo: CharacterSet.decimalDigits) // get "Hello, I've at least "

#### `func scan(untilIn charSet: CharacterSet) throws -> String?` Scan, starting from scanner's `position` until the next character of the scanner is contained into given character set. Scanner's `position` is updated automatically at the end of the sequence if validated, otherwise it will not touched.

Example:

let scanner = StringScanner("HELLO i'm mark")
let partialString = try! scanner.scan(untilIn: CharacterSet.lowercaseLetters) // get "HELLO"

#### `func scan(upTo string: String) throws -> String?` Scan, starting from scanner's `position` until specified string is encountered. Scanner's `position` is updated automatically at the end of the sequence if validated, otherwise it will not touched.

Example:

let scanner = StringScanner("This is a simple test I've made")
let partialString = try! scanner.scan(upTo: "I've") // get "This is a simple test "

#### `func scan(untilTrue test: ((UnicodeScalar) -> (Bool))) -> String` Scan and consume at the scalar starting from current `position`, testing it with function test. If test returns `true`, the `position` increased. If `false`, the function returns.

Example:

let scanner = StringScanner("Never be satisfied 💪 and always push yourself! 😎 Do the things people say cannot be done")
let delimiters = CharacterSet(charactersIn: "💪😎")
while !scanner.isAtEnd {
  let block = scanner.scan(untilTrue: { char in
    return (delimiters.contains(char) == false)
  })
  // Print:
  // "Never be satisfied " (first iteration)
  // "and always push yourself!" (second iteration)
  // "Do the things people say cannot be done" (third iteration)
  print("Block: \(block)")
	try scanner.skip() // push over the character
}

#### `func scan(length: Int=1) -> String` Read next length characters and accumulate it If operation is succeded scanner's `position` are updated according to consumed scalars. If fails an exception is thrown and `position` is not updated.

Example:

let scanner = StringScanner("Never be satisfied")
let partialString = scanner.scan(5) // "Never"

peek functions

Peek functions are the same as concept of scan() but unless it it does not update internal scanner's position index. These functions usually return only starting index of matched pattern.

#### `func peek(upTo char: UnicodeScalar) -> String.UnicodeScalarView.Index` Peek until chracter is found starting from current scanner's `position`. Scanner's `position` is never updated. Throw an exception if `.eof` is reached or `.notFound` if char was not found.

Example:

let scanner = StringScanner("Never be satisfied")
let index = try! scanner.peek(upTo: "b") // return 6

#### `func peek(upTo charSet: CharacterSet) -> String.UnicodeScalarView.Index` Peek until one the characters specified by set is encountered Index is reported before the start of the sequence, but scanner's `position` is never updated. Throw an exception if .eof is reached or .notFound if sequence was not found

Example:

let scanner = StringScanner("You are in queue: 123 is your position")
let index = try! scanner.peek(upTo: CharacterSet.decimalDigits) // return 18

#### `func peek(untilIn charSet: CharacterSet) -> String.UnicodeScalarView.Index` Peek until the next character of the scanner is contained into given. Scanner's `position` is never updated.

Example:

let scanner = StringScanner("654 apples")
let index = try! scanner.peek(untilIn: CharacterSet.decimalDigits) // return 3

#### `func peek(upTo string: String) -> String.UnicodeScalarView.Index` Iterate until specified string is encountered without updating indexes. Scanner's `position` is never updated but it's reported the index just before found occourence.

Example:

let scanner = StringScanner("654 apples in the bug")
let index = try! scanner.peek(upTo: "in") // return 11

#### `func peek(untilTrue test: ((UnicodeScalar) -> (Bool))) -> String.UnicodeScalarView.Index` Peeks at the scalar at the current position, testing it with function test. It only peeks so current scanner's `position` is not increased at the end of the operation

Example:

let scanner = StringScanner("I'm very 💪 and 😎 Go!")
let delimiters = CharacterSet(charactersIn: "💪😎")
while !scanner.isAtEnd {
  let prevIndex = scanner.position
  let finalIndex = scanner.peek(untilTrue: { char in
    return (delimiters.contains(char) == false)
	})
  // Distance will return:
  // - 9 (first iteration)
  // - 5 (second iteration)
  // - 4 (third iteration)
	let distance = scanner.string.distance(from: prevIndex, to: finalIndex)
	try scanner.skip(length: distance + 1)
}

Other Functions

#### `func match(_ char: UnicodeScalar) -> Bool` Return false if the scalar at the current position don't match given scalar. Advance scanner's `position` to the end of the match if match.

let scanner = StringScanner("💪 and 😎")
let match = scanner.match("😎") // return false

#### `func match(_ match: String) -> Bool` Return false if scalars starting at the current position don't match scalars in given string. Advance scanner's `position` to the end of the match string if match.

let scanner = StringScanner("I'm very 💪 and 😎 Go!")
scanner.match("I'm very") // return true

#### `func reset()` Move scanner's internal `position` to the start of the string. #### `func peekAtEnd()` Move to the index's end index. #### `func skip(length: Int = 1) throws` Attempt to advance scanner's by length If operation is not possible (reached the end of the string) it throws and current scanner's `position` of the index did not change If operation succeded scanner's `position` is updated. #### `func back(length: Int = 1) throws` Attempt to advance the position back by length If operation fails scanner's `position` is not touched If operation succeded scaner's `position` is modified according to new value ## Installation You can install Swiftline using CocoaPods, carthage and Swift package manager

CocoaPods

use_frameworks!
pod 'SwiftScanner'

Carthage

github 'malcommac/SwiftScanner'

Swift Package Manager

Add swiftline as dependency in your Package.swift

  import PackageDescription

  let package = Package(name: "YourPackage",
    dependencies: [
      .Package(url: "https://github.com/malcommac/SwiftScanner.git", majorVersion: 0),
    ]
  )

## Tests Tests can be found [here](https://github.com/malcommac/SwiftScanner/tree/master/Tests).

Run them with

swift test

## Requirements

Current version is compatible with:

• Swift 4.x >= 1.0.4

• Swift 3.x: up to 1.0.3

• iOS 8 or later

• macOS 10.10 or later

• watchOS 2.0 or later

• tvOS 9.0 or later

• ...and virtually any platform which is compatible with Swift 3 and implements the Swift Foundation Library

## Credits & License SwiftScanner is owned and maintained by [Daniele Margutti](http://www.danielemargutti.com/).

As open source creation any help is welcome!

The code of this library is licensed under MIT License; you can use it in commercial products without any limitation.

The only requirement is to add a line in your Credits/About section with the text below:

Portions SwiftScanner - http://github.com/malcommac/SwiftScanner
Created by Daniele Margutti and licensed under MIT License.