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Merge pull request #3 from prolificinteractive/feature/stack-data-str…
…ucture Added stack in data structures
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,63 @@ | ||
| // | ||
| // Stack.swift | ||
| // DevKit | ||
| // | ||
| // Created by Thibault Klein on 8/31/18. | ||
| // Copyright © 2018 Jonathan Samudio. All rights reserved. | ||
| // | ||
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| import Foundation | ||
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| /// Stack. | ||
| /// A stack is a collection of elements following a First-In-Last-Out (FILO) order. | ||
| /// | ||
| /// - Note: | ||
| /// Use a Stack if you need a sequence ordered as FILO. | ||
| open class Stack<T> { | ||
| // MARK: - Public Properties | ||
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| /// `true` if the stack is empty. `false` if not. | ||
| public var isEmpty: Bool { | ||
| return peek() == nil | ||
| } | ||
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| // MARK: - Private Properties | ||
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| private var storage: [T] = [] | ||
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| // MARK: - Initialization | ||
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| public init() { } | ||
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| // MARK: - Public Functions | ||
| // MARK: General Functions | ||
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| /// Returns the value at the top of the stack. | ||
| /// | ||
| /// - Complexity: O(1) | ||
| /// - Returns: The value at the top of the stack. | ||
| public func peek() -> T? { | ||
| return storage.last | ||
| } | ||
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| // MARK: Adding Functions | ||
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| /// Adds a value to the top of the stack. | ||
| /// | ||
| /// - Complexity: O(1) | ||
| /// - Parameter value: The value to add. | ||
| public func push(_ value: T) { | ||
| storage.append(value) | ||
| } | ||
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| // MARK: Removing Functions | ||
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| /// Returns the value at the top of the stack and removes it from it. | ||
| /// | ||
| /// - Complexity: O(1) | ||
| /// - Returns: The value at the top of the stack. | ||
| public func pop() -> T? { | ||
| return storage.popLast() | ||
| } | ||
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| } |
49 changes: 49 additions & 0 deletions
49
DevKit/DevKitTests/Classes/Data Structures/Stack/StackTests.swift
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,49 @@ | ||
| // | ||
| // StackTests.swift | ||
| // DevKitTests | ||
| // | ||
| // Created by Thibault Klein on 8/31/18. | ||
| // Copyright © 2018 Jonathan Samudio. All rights reserved. | ||
| // | ||
|
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| import DevKit | ||
| import XCTest | ||
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| class StackTests: XCTestCase { | ||
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| func test_stack_isEmpty() { | ||
| // Given | ||
| let stack = Stack<Int>() | ||
| XCTAssertTrue(stack.isEmpty) | ||
| // When | ||
| stack.push(1) | ||
| // Then | ||
| XCTAssertFalse(stack.isEmpty) | ||
| } | ||
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| func test_stack_push() { | ||
| // Given | ||
| let stack = Stack<Int>() | ||
| // When | ||
| stack.push(1) | ||
| stack.push(2) | ||
| // Then | ||
| XCTAssertFalse(stack.isEmpty) | ||
| XCTAssertEqual(stack.peek(), 2) | ||
| } | ||
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| func test_stack_pop() { | ||
| // Given | ||
| let stack = Stack<Int>() | ||
| // When | ||
| stack.push(1) | ||
| stack.push(2) | ||
| stack.push(3) | ||
| let poppedValue = stack.pop() | ||
| // Then | ||
| XCTAssertFalse(stack.isEmpty) | ||
| XCTAssertEqual(poppedValue, 3) | ||
| XCTAssertEqual(stack.peek(), 2) | ||
| } | ||
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| } |