Read data from files using a Fortran format specification.

Fortran is great, isn't it? But do you have lots of data sitting in Fortran-formatted files that you would like to access using Swift for your own nefarious purposes? Yes, I thought so. All of the boilerplate you need is here.

How to read from a Fortran formatted file.

Step 1. Create a format.

let format = try FortranFile.format(from: "1x,4i1,i5,12i3,f15.11,2f18.11,f14.11,f20.11")

Step 2. Use the format to read a single line of input.

let result = try FortranFile.read(input: input, using: format)

The result is an array of any FortranFile.Value corresponding to the values read from the input.

Step 3. Create a reader to efficiently read multiple lines of input.

Create a Reader instance to read multiple lines:

let reader = FortranFile.makeReader(using: format)

for line in lines {
  let result = try reader.read(input: line)
}

Types of FortranFile.Value.

Each value read from the input is represented by a type conforming to the FortranFile.Value protocol. The underlying Swift value can be accessed using the value property. The type of the value property varies to match the type of Fortran value read from the input in accordance with the format string.

• FortanDouble: wraps a Swift Double representing a real number.
• FortranInteger: wraps a Swift Int representing an integer.
• FortranLogical: wraps a Swift Bool representing a logical value.
• FortranString: wraps a Swift String representing text.
• FortranArray: wraps an array of any FortranFile.Value representing repeated values.

Note: Arrays of repeated values can be automatically flattened by a reading configuration option.

Reading configuration.

A reading configuration can be provided to a Reader instance to allow reading behaviour to be customised.

public struct ReadingConfiguration: Sendable {
  public static let common = ReadingConfiguration()
  public var defaultZeroiseBlanks = false
  public var shouldAllowCommaTermination = false
  public var shouldFlattenArrays = false
}

Supported format specifiers.

Real numbers.

• Dw.d
• Ew.d
• Fw.d
• Gw.d

Integers.

• Iw

Logicals.

• Lw

Text.

• Aw

Horizontal skip.

• nX

Blank editing.

• B
• BN
• BZ

Scale factor.

• nP