You can use evaluations with String extension or with Evaluation class just don’t forget to import library
import Evaluation
PostfixEvaluation class
This class gives you power to evaluate from postfix tokens.
public class PostfixEvaluation {
/// Serialized postfix in JSON format
public func serializedPostfix() throws -> Data
public func serializedPostfix() throws -> String
public var postfix: [PostfixEvaluation.Token] { get }
/// Construct from JSON
public init(postfix: [PostfixEvaluation.Token])
public init(postfix: String) throws
public init(postfixData: Data) throws
/// Evaluate
public func evaluate(with data: [String: Any] = [:]) throws -> Any?
}
InfixEvaluation class
InfixEvaluation class divide proccess to two parts, first token parsing and postfix transformation and second evaluates expression.
public class InfixEvaluation: PostfixEvaluation {
/// Serialized postfix in JSON format
public func serializedPostfix() throws -> Data
public func serializedPostfix() throws -> String
/// Perform lexical analysis and makes postfix notation of given expression
///
/// - Parameter string: expression
/// - Throws: lexical and syntax error as `EvaluationError`
public init(expression string: String) throws
/// Evaluate expression and return result
///
/// - Parameter data: Dictionary with variables used in expression
/// - Returns: result of expression
/// - Throws: EvaluationError
public func evaluate(with data: [String : Any] = default) throws -> Any?
}
String extension
We add string extenstion so all you need to write is:
try "1+5".evaluate() as! Int // 6
"1+5".evaluateAsInt()! // 6
You can use variables in evaluation if you pass [String: Any] to evaluate(with:) then you can access them with dot notation
let data: [String: Any] = [
"name": "John",
"sleeps": 8
]
// John is awake 16 hours per day
"name + \" is awake \" + String(24 - sleeps) + \" hours per day\"".evaluateAsString(with: data)!
Array function
If you are sure about variable type ([Any] or [String: Any]) you can use .count to get number of elements
import Evaluation
// If you wan to know if something goes wrong use Evaluation class
do {
let eval = try InfixEvaluation(expression: "1 + 5 < seven")
if let result = (try eval.evaluate(with: ["seven": 7])) as? Bool {
print(result) // true
}
} catch let error {
print(error)
}
// when you are interested only in result you can use extension
print("1 + 5".evaluateAsInt()!) // 6
let data = [
"person1": [
"name": "Matt",
"age": 21,
"male": true,
"children": [
"Ann",
"Matt Jr."
]
],
"person2": [
"name": "Miriam",
"age": 19,
"male": false,
"children": [String]()
]
]
print("person1.name != person2.name".evaluateAsBool(with: data)!) // true
print("person1.children.count == person2.children.count".evaluateAsBool(with: data)!) // false
// You can change type like this
print("Int( (Double(person1.age) + Double(person2.age)) / 2.0 )".evaluateAsInt(with: data)!) // 20
// JSON usage
do {
let infixEval = try InfixEvaluation(expression: "3 + 1")
let postfix: String = try infixEval.serializedPostfix()
print(postfix) // [{"type":{"int":"Int"},"value":"3"},{"type":{"int":"Int"},"value":"1"},{"type":{"operation":"+"},"value":"+"}]
let postfixEval = try PostfixEvaluation(postfix: postfix)
let result = try postfixEval.evaluate() as! Int
print(result) // 4
} catch let error {
print(error)
}
Errors
If something goes wrong Evaluation throw EvaluationError struct with attributes kind and description
public struct EvaluationError: Error, CustomStringConvertible {
public enum ErrorKind {
case canNotApplyBinOperand(oper: String, type1: String, type2: String)
case canNotApplyUnaryOperand(oper: String, type: String)
case unexpectedEnd(reading: String)
case unexpectedCharacter(reading: String, expected: String, got: String)
case syntaxError
case missingValue(forOperand: String)
case nilFound(expr: String)
case decodingError
case encodingError
case unknownOperation(operation: String)
}
/// Error kind
public let kind: ErrorKind
/// A textual representation of this instance.
public var description: String { get }
}
Evaluation
Evaluation is swift library which can evaluate content of String and return result or postfix notation. This library is runnable on Linux too :)
Operations
Operands must be same type
!Bool*Int,UInt,Double,Float/Int,UInt,Double,Float%Int,UInt+Int,UInt,Double,Float,String-Int,UInt,Double,Float??Any?==Int,UInt,Double,Float,String,Bool,nil!=Int,UInt,Double,Float,String,Bool,nil<Int,UInt,Double,Float,String<=Int,UInt,Double,Float,String>Int,UInt,Double,Float,String>=Int,UInt,Double,Float,String&&Bool||BoolCasting functions
You can cast with theese functions:
Usage
You can use evaluations with String extension or with
Evaluationclass just don’t forget to import libraryPostfixEvaluation class
This class gives you power to evaluate from postfix tokens.
InfixEvaluation class
InfixEvaluation class divide proccess to two parts, first token parsing and postfix transformation and second evaluates expression.
String extension
We add string extenstion so all you need to write is:
extension
Using variables
You can use variables in evaluation if you pass
[String: Any]toevaluate(with:)then you can access them with dot notationArray function
If you are sure about variable type ([Any] or [String: Any]) you can use
.countto get number of elementsExamples
Errors
If something goes wrong Evaluation throw
EvaluationErrorstruct with attributeskindanddescriptionInstallation
Package Manager
You can add this to Package.swift