表达式计算 DataTable/DataRow/DataColumn Expression、JScript CodeDomProvider Eval
namespace ConsoleApplication
{
using System;
using System.Linq;
using System.Reflection;
using System.Collections.Generic;
using Microshaoft;
public class Class1
{
static void Main(string[] args)
{
string formula = "(({0}-{1})/{2}+{3})*{4}";
string result = JScriptEvaluator.ComputeFormula<double>
(
formula
, 1f
, 2.1
, 3.1
, 4.0
, 5.0
);
Console.WriteLine(result);
double x;
x = DataTableColumnExpression.ComputeFormula<double, double>
(
formula
, 1f
, 2.1
, 3.1
, 4.0
, 5.0
);
Console.WriteLine(x);
//=================================================================================================
formula = "IIF(1=2, F1, F2) + ((--F1) * F2) + F3";
Dictionary<string, int> dict = new Dictionary<string, int>();
dict.Add("F1", 2);
dict.Add("F2", 3);
dict.Add("F3", 4);
x = DataTableColumnExpression.ComputeFormula<double, int>(formula, dict);
Console.WriteLine(x);
Console.ReadLine();
}
}
}
namespace Microshaoft
{
using System;
using System.Data;
using System.Linq;
using System.Collections.Generic;
using System.Reflection;
using System.CodeDom.Compiler;
public class DataTableColumnExpression
{
private static MethodInfo _mi = typeof(string).GetMethods().First
(
m => m.Name.Equals("Format")
&& m.GetParameters().Length == 2
&& m.IsStatic
&& m.GetParameters()[1].Name == "args"
);
public static TResult ComputeFormula<TResult, TParameter>(string formula, params TParameter[] parameters)
{
var dt = new DataTable();
var list = parameters.ToList();
var parametersName = new List<string>(); ;
int i = 0;
list.ForEach
(
parameter =>
{
//string f = string.Format("{{{0}}}", i++);
string f = string.Format("F{0}", i++);
parametersName.Add(f);
var dc = new DataColumn(f, typeof(TParameter));
dt.Columns.Add(dc);
}
);
object[] ps = new object[parameters.Length];
Array.Copy(parametersName.ToArray(), 0, ps, 0, ps.Length);
string expression = (string) _mi.Invoke
(
null
, new object[]
{
formula
, ps
}
);
dt.Columns.Add(new DataColumn("Microshaoft", typeof(TResult), expression));
var dr = dt.NewRow();
i = 0;
list.ForEach
(
parameter =>
{
dr[i++] = parameter;
}
);
dt.Rows.Add(dr);
return (TResult) dr["Microshaoft"];
}
public static TResult ComputeFormula<TResult, TParameter>(string formula, IDictionary<string, TParameter> parameters)
{
var dt = new DataTable();
var list = parameters.ToList();
list.ForEach
(
kvp =>
{
var dc = new DataColumn(kvp.Key, typeof(TParameter));
dt.Columns.Add(dc);
}
);
dt.Columns.Add(new DataColumn("Microshaoft", typeof(TResult), formula));
var dr = dt.NewRow();
list.ForEach
(
kvp =>
{
dr[kvp.Key] = kvp.Value;
}
);
dt.Rows.Add(dr);
return (TResult) dr["Microshaoft"];
}
}
public class JScriptEvaluator
{
private static MethodInfo _mi = typeof(string).GetMethods().First
(
m => m.Name.Equals("Format")
&& m.GetParameters().Length == 2
&& m.IsStatic
&& m.GetParameters()[1].Name == "args"
);
public static string ComputeFormula<TParameter>(string formula, params TParameter[] parameters)
{
object[] ps = new object[parameters.Length];
Array.Copy(parameters.ToArray(), 0, ps, 0, ps.Length);
string expression = (string) _mi.Invoke
(
null
, new object[]
{
formula
, ps
}
);
return (string) JScriptEvaluator.Eval(expression);
}
public static object Eval(string statement)
{
return _evaluatorType.InvokeMember
(
"Eval"
, BindingFlags.InvokeMethod
, null
, _evaluator
, new object[]
{
statement
}
);
}
static JScriptEvaluator()
{
CodeDomProvider provider = CodeDomProvider.CreateProvider("JScript");
CompilerParameters parameters;
parameters = new CompilerParameters();
parameters.GenerateInMemory = true;
CompilerResults results;
results = provider.CompileAssemblyFromSource(parameters, _JScript);
Assembly assembly = results.CompiledAssembly;
_evaluatorType = assembly.GetType("Microshaoft.JScriptEvaluator");
_evaluator = Activator.CreateInstance(_evaluatorType);
}
private static object _evaluator = null;
private static Type _evaluatorType = null;
/// <summary>
/// JScript代码
/// </summary>
private static readonly string _JScript =
@"
package Microshaoft
{
class JScriptEvaluator
{
public function Eval(statement : String) : String
{
return eval(statement);
}
}
}
";
}
}
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