使用正則表達式或C＃

Question

我需要驗證的邏輯表達式一樣，如何驗證邏輯表達式

((var1 == var2) && (var2 >= var4 || var1 > var5)) 

(var1 < var2) 

(var1 == var2 || var3 != var4) 

每一個括號，變量和邏輯運算符是由單個空格隔開。

我需要一個正則表達式來解析它。

或告訴我一些邏輯來驗證這與C＃。

謝謝。

Answer 1

要麼建立你自己的解析器，或看下面（找到here）。您需要稍微改變一下以考慮變量，但這不應該太難。要麼在將它們傳遞給函數之前解析它們，要麼將函數更改爲除變量名稱和值以外的函數。

using System.CodeDom.Compiler; 
    using Microsoft.CSharp; 
    using System.Reflection; 
    /// <summary> 
    /// A simple function to get the result of a C# expression (basic and advanced math possible) 
    /// </summary> 
    /// <param name="command">String value containing an expression that can evaluate to a double.</param> 
    /// <returns>a Double value after evaluating the command string.</returns> 
    private double ProcessCommand(string command) 
    { 
     //Create a C# Code Provider 
     CSharpCodeProvider myCodeProvider = new CSharpCodeProvider(); 
     // Build the parameters for source compilation. 
     CompilerParameters cp = new CompilerParameters(); 
     cp.GenerateExecutable = false;//No need to make an EXE file here. 
     cp.GenerateInMemory = true; //But we do need one in memory. 
     cp.OutputAssembly = "TempModule"; //This is not necessary, however, if used repeatedly, causes the CLR to not need to 
              //load a new assembly each time the function is run. 
     //The below string is basically the shell of a C# program, that does nothing, but contains an 
     //Evaluate() method for our purposes. I realize this leaves the app open to injection attacks, 
     //But this is a simple demonstration. 
     string TempModuleSource = "namespace ns{" + 
            "using System;" + 
            "class class1{" + 
            "public static double Evaluate(){return " + command + ";}}} "; //Our actual Expression evaluator 

     CompilerResults cr = myCodeProvider.CompileAssemblyFromSource(cp,TempModuleSource); 
     if (cr.Errors.Count > 0) 
     { 
      //If a compiler error is generated, we will throw an exception because 
      //the syntax was wrong - again, this is left up to the implementer to verify syntax before 
      //calling the function. The calling code could trap this in a try loop, and notify a user 
      //the command was not understood, for example. 
      throw new ArgumentException("Expression cannot be evaluated, please use a valid C# expression"); 
     } 
     else 
     { 
      MethodInfo Methinfo = cr.CompiledAssembly.GetType("ns.class1").GetMethod("Evaluate"); 
      return (double)Methinfo.Invoke(null, null); 
     } 
    } 

Answer 2

如果我是這樣做的，我想要做它作爲一個正則表達式，我將創建每次通過消除驗證子情形多次通過算法（例如更換驗證「（X == Y）」與「 X」

也許東西開始：s/\b\w+ $op \w+\b/^^MAGICTOKEN^^/g

那麼任何/ $ OP /將是非法的

然後在循環專注於每括號：s/\(([^\)]+)\)/^^MAGICTOKEN^^/

雖然專注於1美元，但減少：s/ $MAGICTOKRE $BOOL $MAGICTOKRE/^^MAGICTOKEN^^ / 在循環中運行減少直到它停止減少。 如果$1 ne " ^^MAGICTOKEN^^ "，錯誤

聚焦循環後，最有可能的$expression ne "^^MAGICTOKEN^^"將指示一個錯誤。