Merge pull request #16 from presto95/feature/slicing2

JCSooHwanCho · web-flow · commit d5cc9fb762d0 · 2019-11-11T11:39:44.000+09:00
Add slicing using characters
diff --git a/Sources/String/Utility.swift b/Sources/String/Utility.swift
@@ -142,3 +142,52 @@ extension String {
         return self.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
     }
 }
+
+// MARK: - Slicing using characters
+
+extension String {
+
+    /// Returns a sliced string of given string
+    /// from the first `start` character to the last `end` character.
+    ///
+    /// If the lower bound is greater than the upper bound, it returns an empty string.
+    /// If the given string doesn't contain given characters, it also returns an empty string.
+    ///
+    /// - Parameters:
+    ///   - start:    The character value being the lower bound of the given string.
+    ///   - end:      The character value being the upper bound of the given string.
+    ///   - inversed: A boolean value that indicates whether the sliced string is inversed.
+    ///               The Default value is `false`.
+    ///
+    /// - Returns: A sliced string of given string.
+    public func sliced(from start: Character, to end: Character, inversed: Bool = false) -> String {
+         guard let startCharacterIndex = firstIndex(of: start),
+             let endCharacterIndex = lastIndex(of: end),
+             startCharacterIndex <= endCharacterIndex
+             else { return "" }
+         let slicedSubstring = self[startCharacterIndex ... endCharacterIndex]
+         return !inversed ? String(slicedSubstring) : String(slicedSubstring.reversed())
+    }
+
+    /// Slices a given string
+    /// from the first `start` character to the last `end` character.
+    ///
+    /// If the lower bound is greater than the upper bound, it becomes an empty string.
+    /// If the given string doesn't contain given characters, it also becomes an emtpy string.
+    ///
+    /// - Parameters:
+    ///   - start:    The character value being the lower bound of the given string.
+    ///   - end:      The character value being the upper bound of the given string.
+    ///   - inversed: A boolean value that indicates whether the sliced string is inversed.
+    ///               The Default value is `false`.
+    public mutating func slice(from start: Character, to end: Character, inversed: Bool = false) {
+        guard let startCharacterIndex = firstIndex(of: start),
+            let endCharacterIndex = lastIndex(of: end),
+            startCharacterIndex <= endCharacterIndex else {
+                self = ""
+                return
+        }
+        let slicedSubstring = self[startCharacterIndex ... endCharacterIndex]
+        self = !inversed ? String(slicedSubstring) : String(slicedSubstring.reversed())
+    }
+}
diff --git a/Tests/AGStringTests.swift b/Tests/AGStringTests.swift
@@ -108,4 +108,34 @@ class AGStringTests: XCTestCase {
             str.trim()
         }
     }
+
+    func testSliced() {
+        XCTAssertEqual("abcdef".sliced(from: "a", to: "d"), "abcd")
+        XCTAssertEqual("abcdef".sliced(from: "a", to: "a"), "a")
+        XCTAssertEqual("abcdef".sliced(from: "a", to: "d", inversed: true), "dcba")
+        XCTAssertEqual("abcdef".sliced(from: "a", to: "a", inversed: true), "a")
+        XCTAssertEqual("abcdef".sliced(from: "a", to: "g"), "")
+        XCTAssertEqual("abcdef".sliced(from: "g", to: "g"), "")
+    }
+
+    func testSlice() {
+        var string = "abcdef"
+        string.slice(from: "a", to: "d")
+        XCTAssertEqual(string, "abcd")
+        string = "abcdef"
+        string.slice(from: "a", to: "a")
+        XCTAssertEqual(string, "a")
+        string = "abcdef"
+        string.slice(from: "a", to: "d", inversed: true)
+        XCTAssertEqual(string, "dcba")
+        string = "abcdef"
+        string.slice(from: "a", to: "a", inversed: true)
+        XCTAssertEqual(string, "a")
+        string = "abcdef"
+        string.slice(from: "a", to: "g")
+        XCTAssertEqual(string, "")
+        string = "abcdef"
+        string.slice(from: "g", to: "g")
+        XCTAssertEqual(string, "")
+    }
 }
