Data update
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Ingy döt Net
parent
5150844a7d
commit
4bb20c9b71
7735 changed files with 38060 additions and 199180 deletions
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@ -3,198 +3,198 @@ import Foundation
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// Using arrays for both stack and queue
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struct Stack<T> {
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private(set) var elements = [T]()
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var isEmpty: Bool {
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elements.isEmpty
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}
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var top: T? {
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elements.last
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}
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mutating func push(_ newElement: T) {
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elements.append(newElement)
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}
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mutating func pop() -> T? {
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self.isEmpty ? nil : elements.removeLast()
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}
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private(set) var elements = [T]()
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var isEmpty: Bool {
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elements.isEmpty
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}
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var top: T? {
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elements.last
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}
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mutating func push(_ newElement: T) {
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elements.append(newElement)
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}
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mutating func pop() -> T? {
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self.isEmpty ? nil : elements.removeLast()
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}
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}
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struct Queue<T> {
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private(set) var elements = [T]()
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var isEmpty: Bool {
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elements.isEmpty
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}
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mutating func enqueue(_ newElement: T) {
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elements.append(newElement)
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}
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mutating func dequeue() -> T {
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return elements.removeFirst()
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}
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private(set) var elements = [T]()
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var isEmpty: Bool {
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elements.isEmpty
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}
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mutating func enqueue(_ newElement: T) {
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elements.append(newElement)
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}
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mutating func dequeue() -> T {
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return elements.removeFirst()
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}
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}
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enum Associativity {
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case Left, Right
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case Left, Right
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}
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// Protocol can be used to restrict Set extension
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protocol OperatorType: Comparable, Hashable {
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var name: String { get }
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var precedence: Int { get }
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var associativity: Associativity { get }
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var name: String { get }
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var precedence: Int { get }
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var associativity: Associativity { get }
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}
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struct Operator: OperatorType {
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let name: String
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let precedence: Int
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let associativity: Associativity
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// Duplicate operator names are not allowed
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func hash(into hasher: inout Hasher) {
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hasher.combine(self.name)
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}
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init(_ name: String, _ precedence: Int, _ associativity: Associativity) {
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self.name = name; self.precedence = precedence; self.associativity = associativity
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}
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let name: String
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let precedence: Int
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let associativity: Associativity
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// Duplicate operator names are not allowed
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func hash(into hasher: inout Hasher) {
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hasher.combine(self.name)
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}
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init(_ name: String, _ precedence: Int, _ associativity: Associativity) {
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self.name = name; self.precedence = precedence; self.associativity = associativity
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}
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}
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func ==(x: Operator, y: Operator) -> Bool {
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// Identified by name
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x.name == y.name
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// Identified by name
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x.name == y.name
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}
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func <(x: Operator, y: Operator) -> Bool {
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// Take precedence and associavity into account
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(x.associativity == .Left && x.precedence == y.precedence) || x.precedence < y.precedence
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// Take precedence and associavity into account
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(x.associativity == .Left && x.precedence == y.precedence) || x.precedence < y.precedence
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}
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extension Set where Element: OperatorType {
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func contains(_ operatorName: String) -> Bool {
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contains { $0.name == operatorName }
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}
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subscript (operatorName: String) -> Element? {
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get {
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filter { $0.name == operatorName }.first
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}
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}
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func contains(_ operatorName: String) -> Bool {
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contains { $0.name == operatorName }
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}
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subscript (operatorName: String) -> Element? {
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get {
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filter { $0.name == operatorName }.first
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}
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}
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}
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// Convenience
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extension String {
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var isNumber: Bool { return Double(self) != nil }
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var isNumber: Bool { return Double(self) != nil }
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}
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struct ShuntingYard {
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enum ParseError: Error {
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case MismatchedParenthesis(parenthesis: String, expression: String)
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case UnrecognizedToken(token: String, expression: String)
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case ExtraneousToken(token: String, expression: String)
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}
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static func parse(_ input: String, operators: Set<Operator>) throws -> String {
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var stack = Stack<String>()
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var output = Queue<String>()
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let tokens = input.components(separatedBy: " ")
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for token in tokens {
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// Number?
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if token.isNumber {
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// Add it to the output queue
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output.enqueue(token)
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continue
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}
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// Operator?
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if operators.contains(token) {
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// While there is a operator on top of the stack and has lower precedence than current operator (token)
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while let top = stack.top,
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operators.contains(top) && Self.hasLowerPrecedence(token, top, operators) {
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// Pop it off to the output queue
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output.enqueue(stack.pop()!)
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}
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// Push current operator (token) onto the operator stack
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stack.push(token)
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continue
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}
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// Left parenthesis?
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if token == "(" {
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// Push it onto the stack
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stack.push(token)
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continue
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}
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// Right parenthesis?
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if token == ")" {
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// Until the token at the top of the stack is a left parenthesis
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while let top = stack.top, top != "(" {
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// Pop operators off the stack onto the output queue.
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output.enqueue(stack.pop()!)
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}
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// Pop the left parenthesis from the stack without putting it onto the output queue
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guard let _ = stack.pop() else {
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// If the stack runs out, than there is no matching left parenthesis
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throw ParseError.MismatchedParenthesis(parenthesis: ")", expression: input)
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}
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continue
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}
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// Token not recognized!
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throw ParseError.UnrecognizedToken(token: token, expression: token)
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}
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// No more tokens
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// Still operators on the stack?
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while let top = stack.top,
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operators.contains(top) {
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// Put them onto the output queue
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output.enqueue(stack.pop()!)
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}
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// If the top of the stack is a (left) parenthesis, then there is no matching right parenthesis
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// Note: Assume that all operators has been popped and put onto the output queue
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if let top = stack.pop() {
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throw (
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top == "("
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? ParseError.MismatchedParenthesis(parenthesis: "(", expression: input)
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: ParseError.ExtraneousToken(token: top, expression: input)
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)
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}
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return output.elements.joined(separator: " ")
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}
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static private func hasLowerPrecedence(_ firstToken: String, _ secondToken: String, _ operators: Set<Operator>) -> Bool {
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guard let firstOperator = operators[firstToken],
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let secondOperator = operators[secondToken] else {
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return false
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}
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return firstOperator < secondOperator
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}
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enum ParseError: Error {
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case MismatchedParenthesis(parenthesis: String, expression: String)
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case UnrecognizedToken(token: String, expression: String)
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case ExtraneousToken(token: String, expression: String)
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}
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static func parse(_ input: String, operators: Set<Operator>) throws -> String {
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var stack = Stack<String>()
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var output = Queue<String>()
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let tokens = input.components(separatedBy: " ")
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for token in tokens {
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// Number?
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if token.isNumber {
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// Add it to the output queue
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output.enqueue(token)
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continue
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}
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// Operator?
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if operators.contains(token) {
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// While there is a operator on top of the stack and has lower precedence than current operator (token)
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while let top = stack.top,
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operators.contains(top) && Self.hasLowerPrecedence(token, top, operators) {
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// Pop it off to the output queue
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output.enqueue(stack.pop()!)
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}
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// Push current operator (token) onto the operator stack
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stack.push(token)
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continue
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}
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// Left parenthesis?
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if token == "(" {
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// Push it onto the stack
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stack.push(token)
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continue
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}
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// Right parenthesis?
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if token == ")" {
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// Until the token at the top of the stack is a left parenthesis
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while let top = stack.top, top != "(" {
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// Pop operators off the stack onto the output queue.
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output.enqueue(stack.pop()!)
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}
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// Pop the left parenthesis from the stack without putting it onto the output queue
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guard let _ = stack.pop() else {
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// If the stack runs out, than there is no matching left parenthesis
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throw ParseError.MismatchedParenthesis(parenthesis: ")", expression: input)
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}
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continue
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}
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// Token not recognized!
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throw ParseError.UnrecognizedToken(token: token, expression: token)
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}
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// No more tokens
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// Still operators on the stack?
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while let top = stack.top,
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operators.contains(top) {
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// Put them onto the output queue
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output.enqueue(stack.pop()!)
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}
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// If the top of the stack is a (left) parenthesis, then there is no matching right parenthesis
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// Note: Assume that all operators has been popped and put onto the output queue
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if let top = stack.pop() {
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throw (
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top == "("
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? ParseError.MismatchedParenthesis(parenthesis: "(", expression: input)
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: ParseError.ExtraneousToken(token: top, expression: input)
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)
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}
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return output.elements.joined(separator: " ")
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}
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static private func hasLowerPrecedence(_ firstToken: String, _ secondToken: String, _ operators: Set<Operator>) -> Bool {
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guard let firstOperator = operators[firstToken],
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let secondOperator = operators[secondToken] else {
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return false
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}
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return firstOperator < secondOperator
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}
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}
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/* Include in tests
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func testParse() throws {
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let input = "3 + 4 * 2 / ( 1 - 5 ) ^ 2 ^ 3"
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let operators: Set<Operator> = [
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Operator("^", 4, .Right),
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Operator("*", 3, .Left),
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Operator("/", 3, .Left),
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Operator("+", 2, .Left),
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Operator("-", 2, .Left)
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]
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let output = try! ShuntingYard.parse(input, operators: operators)
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XCTAssertEqual(output, "3 4 2 * 1 5 - 2 3 ^ ^ / +")
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let input = "3 + 4 * 2 / ( 1 - 5 ) ^ 2 ^ 3"
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let operators: Set<Operator> = [
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Operator("^", 4, .Right),
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Operator("*", 3, .Left),
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Operator("/", 3, .Left),
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Operator("+", 2, .Left),
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Operator("-", 2, .Left)
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]
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let output = try! ShuntingYard.parse(input, operators: operators)
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XCTAssertEqual(output, "3 4 2 * 1 5 - 2 3 ^ ^ / +")
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}
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*/
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