StringTable: Added columnCharCounts property

Author: orchetect

Sources/TextFileKit/StringTable.swift

@@ -52,3 +52,34 @@ extension StringTable {
         }
     }
 }
+
+extension StringTable {
+    /// Returns the min and max character count for each column.
+    /// The `upperBound` can be useful for resizing columns to fit the column's data.
+    ///
+    /// - Returns: `[Column Index: Min Char Count ... Max Char Count]`
+    public var columnCharCounts: [Int: ClosedRange<Int>] {
+        reduce(into: [:]) { dict, rowValues in
+            // iterate columns for current row
+            for (columnOffset, rowValue) in rowValues.enumerated() {
+                let cellCharCount = rowValue.count
+                let defaultRange = cellCharCount ... cellCharCount
+                
+                // ensure all columns have a value, even if it's default of 0
+                if dict[columnOffset] == nil {
+                    dict[columnOffset] = defaultRange
+                }
+                
+                // update stored range if cell character count is outside stored range
+                var range = dict[columnOffset] ?? defaultRange
+                if range.upperBound < cellCharCount {
+                    range = range.lowerBound ... cellCharCount
+                }
+                if range.lowerBound > cellCharCount {
+                    range = cellCharCount ... range.upperBound
+                }
+                if dict[columnOffset] != range { dict[columnOffset] = range }
+            }
+        }
+    }
+}

Tests/TextFileKitTests/StringTable Tests.swift

@@ -144,6 +144,67 @@ class StringTable_Tests: XCTestCase {
         st[safe: 3, 0] = "4A"
         XCTAssertEqual(st[safe: 3, 0], nil)
     }
+    
+    func testColumnCharCountsA() {
+        let table: StringTable = []
+        let ranges = table.columnCharCounts
+        XCTAssertEqual(ranges.count, 0)
+    }
+    
+    func testColumnCharCountsB() {
+        let table: StringTable = [[]]
+        let ranges = table.columnCharCounts
+        XCTAssertEqual(ranges.count, 0)
+    }
+    
+    func testColumnCharCountsC() {
+        let table: StringTable = [["H1"]]
+        let ranges = table.columnCharCounts
+        XCTAssertEqual(ranges.count, 1)
+        
+        XCTAssertEqual(ranges[0], 2 ... 2)
+    }
+    
+    func testColumnCharCountsD() {
+        let table: StringTable = [["H1", "H2", "H3"]]
+        let ranges = table.columnCharCounts
+        XCTAssertEqual(ranges.count, 3)
+        
+        XCTAssertEqual(ranges[0], 2 ... 2)
+        XCTAssertEqual(ranges[1], 2 ... 2)
+        XCTAssertEqual(ranges[2], 2 ... 2)
+    }
+    
+    func testColumnCharCountsE() {
+        let table: StringTable = [["H1", "", "H3_"]]
+        let ranges = table.columnCharCounts
+        XCTAssertEqual(ranges.count, 3)
+        
+        XCTAssertEqual(ranges[0], 2 ... 2)
+        XCTAssertEqual(ranges[1], 0 ... 0)
+        XCTAssertEqual(ranges[2], 3 ... 3)
+    }
+    
+    func testColumnCharCountsF() {
+        let table: StringTable = [["H1"], [""], ["R2"]]
+        let ranges = table.columnCharCounts
+        XCTAssertEqual(ranges.count, 1)
+        
+        XCTAssertEqual(ranges[0], 0 ... 2)
+    }
+    
+    func testColumnCharCountsG() {
+        let table: StringTable = [
+            ["H1", "H2", "H3"],
+            ["", "abc", "ab"]
+        ]
+        let ranges = table.columnCharCounts
+        XCTAssertEqual(ranges.count, 3)
+        
+        XCTAssertEqual(ranges[0], 0 ... 2)
+        XCTAssertEqual(ranges[1], 2 ... 3)
+        XCTAssertEqual(ranges[2], 2 ... 2)
+    }
 }
 
 #endif