Merge pull request #107 from BANKEX/develop

improve formatter for edge cases of 1e-18 balances

Author: shamatar

web3swift/Web3/Classes/Web3+Utils.swift

@@ -142,9 +142,9 @@ extension Web3.Utils {
         return mainPart
     }
 
-    public static func formatToEthereumUnits(_ bigNumber: BigInt, toUnits: Web3.Utils.Units = .eth, decimals: Int = 4) -> String? {
+    public static func formatToEthereumUnits(_ bigNumber: BigInt, toUnits: Web3.Utils.Units = .eth, decimals: Int = 4, decimalSeparator: String = ".") -> String? {
         let magnitude = bigNumber.magnitude
-        guard let formatted = formatToEthereumUnits(magnitude, toUnits: toUnits, decimals: decimals) else {return nil}
+        guard let formatted = formatToEthereumUnits(magnitude, toUnits: toUnits, decimals: decimals, decimalSeparator: decimalSeparator) else {return nil}
         switch bigNumber.sign {
         case .plus:
             return formatted
@@ -153,19 +153,48 @@ extension Web3.Utils {
         }
     }
 
-    public static func formatToEthereumUnits(_ bigNumber: BigUInt, toUnits: Web3.Utils.Units = .eth, decimals: Int = 4) -> String? {
-        let unitDecimals = toUnits.decimals
-        var toDecimals = decimals
+    public static func formatToPrecision(_ bigNumber: BigInt, numberDecimals: Int = 18, formattingDecimals: Int = 4, decimalSeparator: String = ".") -> String? {
+        let magnitude = bigNumber.magnitude
+        guard let formatted = formatToPrecision(magnitude, numberDecimals: numberDecimals, formattingDecimals: formattingDecimals, decimalSeparator: decimalSeparator) else {return nil}
+        switch bigNumber.sign {
+        case .plus:
+            return formatted
+        case .minus:
+            return "-" + formatted
+        }
+    }
+    
+    public static func formatToEthereumUnits(_ bigNumber: BigUInt, toUnits: Web3.Utils.Units = .eth, decimals: Int = 4, decimalSeparator: String = ".", fallbackToScientific: Bool = false) -> String? {
+        return formatToPrecision(bigNumber, numberDecimals: toUnits.decimals, formattingDecimals: decimals, decimalSeparator: decimalSeparator, fallbackToScientific: fallbackToScientific);
+    }
+    
+    public static func formatToPrecision(_ bigNumber: BigUInt, numberDecimals: Int = 18, formattingDecimals: Int = 4, decimalSeparator: String = ".", fallbackToScientific: Bool = false) -> String? {
+        let unitDecimals = numberDecimals
+        var toDecimals = formattingDecimals
         if unitDecimals < toDecimals {
             toDecimals = unitDecimals
         }
         let divisor = BigUInt(10).power(unitDecimals)
         let (quotient, remainder) = bigNumber.quotientAndRemainder(dividingBy: divisor)
-        let remainderPadded = String(remainder).leftPadding(toLength: unitDecimals, withPad: "0")[0..<toDecimals]
-        if (decimals == 0) {
+        let fullRemainder = String(remainder);
+        let fullPaddedRemainder = fullRemainder.leftPadding(toLength: unitDecimals, withPad: "0")
+        let remainderPadded = fullPaddedRemainder[0..<toDecimals]
+        if remainderPadded == String(repeating: "0", count: toDecimals) && quotient == 0 {
+            var firstDigit = 0
+            for char in fullPaddedRemainder {
+                if (char == "0") {
+                    firstDigit = firstDigit + 1;
+                } else {
+                    firstDigit = firstDigit + 1;
+                    break
+                }
+            }
+            return fullRemainder + "e-" + String(firstDigit)
+        }
+        if (toDecimals == 0) {
             return String(quotient)
         }
-        return String(quotient) + "." + remainderPadded
+        return String(quotient) + decimalSeparator + remainderPadded
     }
 
     static public func personalECRecover(_ personalMessage: String, signature: String) -> EthereumAddress? {

web3swiftTests/web3swiftTests.swift

@@ -2237,6 +2237,36 @@ class web3swiftTests: XCTestCase {
         XCTAssert(decoded!["_to"] as? EthereumAddress == EthereumAddress("0xcdd45864e794fe5e3e1b0045b77e62f4c43b8bd9"))
     }
 
+    func testNumberFormattingUtil() {
+        let balance = BigInt("-1000000000000000000")!
+        let formatted = Web3.Utils.formatToPrecision(balance, numberDecimals: 18, formattingDecimals: 4, decimalSeparator: ",")
+        XCTAssert(formatted == "-1,0000")
+    }
+    
+    func testNumberFormattingUtil2() {
+        let balance = BigInt("-1000000000000000")!
+        let formatted = Web3.Utils.formatToPrecision(balance, numberDecimals: 18, formattingDecimals: 4, decimalSeparator: ",")
+        XCTAssert(formatted == "-0,0010")
+    }
+    
+    func testNumberFormattingUtil3() {
+        let balance = BigInt("-1000000000000")!
+        let formatted = Web3.Utils.formatToPrecision(balance, numberDecimals: 18, formattingDecimals: 4, decimalSeparator: ",")
+        XCTAssert(formatted == "-0,0000")
+    }
+    
+    func testNumberFormattingUtil4() {
+        let balance = BigInt("-1000000000000")!
+        let formatted = Web3.Utils.formatToPrecision(balance, numberDecimals: 18, formattingDecimals: 9, decimalSeparator: ",")
+        XCTAssert(formatted == "-0,000001000")
+    }
+    
+    func testNumberFormattingUtil5() {
+        let balance = BigInt("-1")!
+        let formatted = Web3.Utils.formatToPrecision(balance, numberDecimals: 18, formattingDecimals: 9, decimalSeparator: ",")
+        XCTAssert(formatted == "-1e-18")
+    }
+    
     func testPerformanceExample() {
         // This is an example of a performance test case.
         self.measure {