What is SoulverCore?

SoulverCore is a math engine that calculates day-to-day mathematical expressions.

The design goals of SoulverCore are:

• Sensible defaults appropriate for most use-cases (simple things are easy!)
• A high level of customisability (complex things are possible!)
• Excellent performance

Can I rely on SoulverCore for my project?

SoulverCore is the math engine from the popular notepad calculator app Soulver. Soulver has been available on Apple's platforms since 2005.

Soulver uses exactly the same version of SoulverCore that is available here. Everything you can do in Soulver, you can do using SoulverCore.

SoulverCore has been designed to have no 3rd party dependencies. It is written in 100% Swift.

Apps using SoulverCore

• Lacona - a powerful natural language assistant/launcher for macOS
• Toolbox Pro - calculate with Soulver as part of your Siri Shortcuts on iOS

Requirements

• Xcode 12+
• Swift 5.4+
• SoulverCore is distributed as a binary framework (.xcframework) and includes builds for macOS (universal), iOS/iPadOS, and Mac Catalyst.

Installation using the Swift Package Manager (SPM)

Xcode 12 and later lets you integrate SoulverCore into your project using the Swift Package Manager.

In Xcode, go File > Swift Packages > Add Package Dependency and paste in the URL of this repository (https://github.com/soulverteam/SoulverCore).

Manual Installation

Drag SoulverCore.xcframework into the Frameworks, Libraries, and Embedded Content section of the General settings for your Mac or iOS target.

Getting Started

To calculate the result of a single expression, use a Calculator object:

import SoulverCore

let calculator = Calculator(customization: .standard)
let result = calculator.calculate("123 + 456")
print("The answer is \(result.stringValue)") // prints 579

SoulverCore can perform all sorts of calculations, including unit conversions, date & calendar math, rate calculations, percentage phrase functions, time zone conversions, and much more. It also cleverly ignores "meaningless" words:

calculator.calculate("$10 for lunch + 15% tip") // $11.50
calculator.calculate("65 kg in pounds") // 154.32 lb
calculator.calculate("40 as % of 90") // 44.44%
calculator.calculate("$150 is 25% on what") // $120
calculator.calculate("$25/hour * 14 hours of work") // $350.00
calculator.calculate("January 30 2020 + 3 months 2 weeks 5 days") // 19 May
calculator.calculate("9:35am in New York to Japan") // 10:35 pm
calculator.calculate("$25k over 10 years at 7.5%") // $51,525.79 (compound interest)

Variables

Use a VariableList to set values for words or phrases in your expression:

let variableList = VariableList(variables:
    [
        Variable(name: "a", value: "123"),
        Variable(name: "b", value: "456"),
    ]
)
calculator.calculate("a + b", with: variableList) // 579        

Multi-line Calculations

Use a LineCollection to represent a collection of lines to be evaluated. Like Calculator, you can customize the way a LineCollection interprets expressions with an EngineCustomization.

let multiLineText =
"""
a = 10
b = 20
c = a + b
"""
        
let lineCollection = LineCollection(multiLineText:
    multiLineText, customization: .standard)

/// Calculate the result of each line (synchronously)
lineCollection.evaluateAll()

/// Use subscripts to get access to particular lines' results
let result = lineCollection[2].result // 30

Locale Settings

SoulverCore respects the decimal separator and thousands separator of the system locale. Alternatively, you can convert the standard EngineCustomization to another locale:

let europeanLocale = Locale(identifier: "en_DE")
let localizedCustomization = EngineCustomization.standard.convertTo(locale: europeanLocale)

let calculator = Calculator(customization: localizedCustomization)

 /// In Germany a comma is used as a decimal separator
calculator.calculate("1,2 + 3,4") // 4,6

Output Formatting

Use a FormattingPreferences to customize the way your result is formatted (how many decimal places to include, should the thousands separator be inserted, etc).

var formattingPreferences = FormattingPreferences()
formattingPreferences.dp = 2 // decimal places
calculator.formattingPreferences = formattingPreferences

calculator.calculate("π") // 3.14

Live Real-World & Crypto-Currency Rates

The .standard EngineCustomization uses hard-coded rates for 190 real-world & crypto-currencies. You can (and should) provide SoulverCore with up-to-date rates by setting the currencyRateProvider on your EngineCustomization to an object that conforms to CurrencyRateProvider.

SoulverCore includes one CurrencyRateProvider you can use to fetch rates from the European Central Bank for 33 popular fiat currencies.

/// This is a currency rate provider that fetches 33 popular fiat currencies from the European Central Bank, no API key required
let ecbCurrencyRateProvider = ECBCurrencyRateProvider()

/// Create a customization with this rate provider
var customizationWithLiveCurrencyRates = EngineCustomization.standard
customizationWithLiveCurrencyRates.currencyRateProvider = ecbCurrencyRateProvider

/// Create a calculator that uses this customization
let calculator = Calculator(customization: customizationWithLiveCurrencyRates)

/// Update to the latest rates...
ecbCurrencyRateProvider.updateRates { success in
    
    if success {
        // The standard customization will now have access to the latest currency rates
        let result = calculator.calculate("10 USD in EUR")
        print(result.stringValue)
    }

}

You can create your own object that conforms to CurrencyRateProvider to provide rates for the currency codes you support. The CurrencyRateProvider protocol has a single method that returns the amount of a given currency that 1.0 USD can buy:

func rateFor(request: CurrencyRateRequest) -> Decimal? {

	let currencyCode = request.currencyCode // EUR, GBP, BTC, etc

	/// - Return an up-to-date rate in the form of how much 1 USD can purchase of the requested currency (i.e 1 USD = x EUR?)
	/// - If your rates are in terms of how much USD the requested currency can purchase (i.e 1 EUR = x USD?), remember to take the inverse by dividing 1 by your rate
            
	return <# Currency Rate #>
}

Rates are only requested from a CurrencyRateProvider at parse-time, so you don't need to recreate your LineCollection or Calculator with a new EngineCustomization any time your currency rate data source is updated. But remember to reevaluate your line or expression - the latest rates for any currencies used will be fetched from your provider if necessary.

Custom Units

You can add custom units to an EngineCustomization object required by the initializer on Calculator or LineCollection.

/// A good omakase EngineCustomization (the same used by Soulver.app)
var customization: EngineCustomization = .standard

/// Set an array of custom units defined in terms of an existing unit in SoulverCore
customization.customUnits = [
    CustomUnit(name: "parrots", definition: 15, equivalentUnit: .centimeters),
    CustomUnit(name: "python", definition: 570, equivalentUnit: .centimeters)
]

/// Create a Calculator using this customization
let calculator = Calculator(customization: customization)

/// python and parrots are now recognized as units
calculator.calculate("1 python in parrots") // 38 parrots

Localizations

In addition to English, SoulverCore is localized into German, Russian, and simplified Chinese.

Performance

Considering all the types of calculations it supports, SoulverCore is fast. With the complete feature set enabled expressions are processed in 1-5 ms on an Intel Mac, and < 1ms on an Apple Silicon device.

If you need even greater performance, you can disable any individual features you don't need (calendar calculations, unit conversions, word functions, etc) by editing the featureFlags property on your EngineCustomization.

See Also

Adding calculation capabilities to an NSTextView or UITextView

See the SoulverTextKit project for an example of how to integrate the SoulverCore math engine into a standard macOS or iOS text view.

Licence

You may use SoulverCore in personal or private projects. Please email us if you wish to use SoulverCore in a publicly available, or commercial project.

We have various options available depending on your user base size, including a free license (with attribution).

On request we are also able to offer an object that conforms to CurrencyRateProvider that provides live real-world & crypto-currency rates to SoulverCore.