Question

我已经看过所有以前对这类问题的回复，并没有看到任何似乎合适的回答。给我错误的行是：

"÷" : .binaryOperation(/,{$0 + "÷" + $1}, {$1 == 0 ? "Division by zero" : nil}),

当我将其更改为此代码时，代码编译时没有错误：

"÷" : .binaryOperation(/,{$0 + "÷" + $1}, {_,_ nil}),

完整的表达式i：

    private var operations:Dictionary<String,Operation> =
        [
            "rand": .nullOperation({Double(arc4random()) / Double(UInt32.max)}, "rand()"),
            "π" : .constant(M_PI),
            "e" : .constant(M_E),
            "√" : .unaryOperation(sqrt,{"√(" + $0 + ")"},{$0 < 0 ? "Sqrt of negative number" : nil}),
            "cos" :.unaryOperation(cos,{"cos(" + $0 + ")"},{ _ in nil}),
            "∓" : .unaryOperation({-$0},{"-(" + $0 + ")"},{ _ in nil}),
            "x²" :.unaryOperation({ pow($0, 2) }, { "(" + $0 + ")²" },{ _ in nil}),
            "x³" :.unaryOperation({ pow($0, 3) }, { "(" + $0 + ")³" },{ _ in nil}),
            "x⁻¹" :.unaryOperation({ 1 / $0 }, {  "(" + $0 + ")⁻¹" },{ _ in nil}),
            "sin" :.unaryOperation(sin, { "sin(" + $0 + ")" },{ _ in nil}),
            "tan" :.unaryOperation(tan, { "tan(" + $0 + ")" },{ _ in nil}),
            "sinh" :.unaryOperation(sinh, { "sinh(" + $0 + ")" },{ _ in nil}),
            "cosh" :.unaryOperation(cosh, { "cosh(" + $0 + ")" },{ _ in nil}),
            "tanh" :.unaryOperation(tanh, { "tanh(" + $0 + ")" },{ _ in nil}),
            "ln" :  .unaryOperation(log, { "ln(" + $0 + ")" },{ _ in nil}),
            "log" : .unaryOperation(log10, { "log(" + $0 + ")" },{ _ in nil}),
            "eˣ" :.unaryOperation(exp, { "e^(" + $0 + ")" },{ _ in nil}),
            "10ˣ" :.unaryOperation({ pow(10, $0) }, { "10^(" + $0 + ")" },{ _ in nil}),
            "x!" :.unaryOperation(factorial, { "(" + $0 + ")!" },{ _ in nil}),
            "xʸ" :.binaryOperation(pow, { $0 + "^" + $1 },{ _,_ in nil}),
            "+" : .binaryOperation(+,{$0 + "+" + $1},{ _,_ in nil}),
            "−" : .binaryOperation(-,{$0 + "-" + $1},{ _,_ in nil}),
            "÷" : .binaryOperation(/,{$0 + "÷" + $1}, {$1 == 0 ? "Division by zero" : nil}),
            "×" : .binaryOperation(*,{$0 + "*" + $1},{ _,_ in nil}),
            "=" : .equals
    ]

编辑：这是Operation enum

private enum Operation { 
    case constant(Double) 
    case nullOperation(() -> Double, String) 
    case unaryOperation((Double) -> Double, (String) -> String, (Double) -> String?) 
    case binaryOperation((Double,Double) -> Double, (String, String) -> String, (Double,Double) -> String?)
    case equals 
}

Answer 1

编辑：在游乐场进行测试表明这不会帮助。我把它留在这里，以便其他人知道不要尝试它;）

＆LT;猜＆GT;

你能否尝试明确你的最后一个块的参数，例如

"÷" : .binaryOperation(/,{$0 + "÷" + $1}, { (_, denom: Double) -> String? in 
    return denom == 0 ? "Division by zero" : nil
}),

＆LT; /猜测＆GT;

Answer 2

单独将每行添加到字典中，但速度并不快：）

private var operations: [String: Operation] = [:]

operations["rand"] = .nullOperation({Double(arc4random()) / Double(UInt32.max)}, "rand()")
operations["π"] = .constant(.pi)
operations["e"] = .constant(M_E)
operations["√"] = .unaryOperation(sqrt,{"√(" + $0 + ")"},{$0 < 0 ? "Sqrt of negative number" : nil})
operations["cos"] = .unaryOperation(cos,{"cos(" + $0 + ")"},{ _ in nil})
operations["∓"] = .unaryOperation({-$0},{"-(" + $0 + ")"},{ _ in nil})
operations["x²"] = .unaryOperation({ pow($0, 2) }, { "(" + $0 + ")²" },{ _ in nil})
operations["x³"] = .unaryOperation({ pow($0, 3) }, { "(" + $0 + ")³" },{ _ in nil})
operations["x⁻¹"] = .unaryOperation({ 1 / $0 }, {  "(" + $0 + ")⁻¹" },{ _ in nil})
operations["sin"] = .unaryOperation(sin, { "sin(" + $0 + ")" },{ _ in nil})
operations["tan"] = .unaryOperation(tan, { "tan(" + $0 + ")" },{ _ in nil})
operations["sinh"] = .unaryOperation(sinh, { "sinh(" + $0 + ")" },{ _ in nil})
operations["cosh"] = .unaryOperation(cosh, { "cosh(" + $0 + ")" },{ _ in nil})
operations["tanh"] = .unaryOperation(tanh, { "tanh(" + $0 + ")" },{ _ in nil})
operations["ln"] = .unaryOperation(log, { "ln(" + $0 + ")" },{ _ in nil})
operations["log"] = .unaryOperation(log10, { "log(" + $0 + ")" },{ _ in nil})
operations["eˣ"] = .unaryOperation(exp, { "e^(" + $0 + ")" },{ _ in nil})
operations["10ˣ"] = .unaryOperation({ pow(10, $0) }, { "10^(" + $0 + ")" },{ _ in nil})
operations["x!"] = .unaryOperation(factorial, { "(" + $0 + ")!" },{ _ in nil})
operations["xʸ"] = .binaryOperation(pow, { $0 + "^" + $1 },{ _,_ in nil})
operations["+"] = .binaryOperation(+,{$0 + "+" + $1},{ _,_ in nil})
operations["−"] = .binaryOperation(-,{$0 + "-" + $1},{ _,_ in nil})
operations["÷"] = .binaryOperation(/,{$0 + "÷" + $1}, { $1 == Double(0) ? "Division by zero" : nil})
operations["×"] = .binaryOperation(*,{$0 + "*" + $1},{ _,_ in nil})
operations["="] = .equals

我得到的错误表达太复杂，无法在合理的时间内解决;考虑将表达式分解为不同的子表达式

2 个答案: