/// <summary>
/// Produces a pure function with optimizations from the given lambda
/// </summary>
/// <typeparam name="T">Function parameter type</typeparam>
/// <typeparam name="TResult">Function return type</typeparam>
/// <param name="ex">The function.
/// Note: The lambda will usually take the form of (funcName) => (parameter) => body, so that funcName(arg) can be called for self-recursion.</param>
/// <param name="caching">Enable result caching</param>
/// <param name="threaded">Enable multithreading</param>
/// <returns>Optimized pure function.</returns>
public static PureFunc <T, TResult> PureFunction <T, TResult>(Expression <Func <Func <T, TResult>, Func <T, TResult> > > ex, bool caching = true, bool threaded = true)
{
var methodVar = Expression.Variable(typeof(Func <T, TResult>), ex.Parameters[0].Name);
var paramVar = ((LambdaExpression)ex.Body).Parameters[0];
//Expression<PureFunc<Func<T,TResult>,PureFunc<T, TResult>>> makePure = (a) => new PureFunc<T, TResult>(a);
var resultingExpression = Expression.Lambda(Expression.Block(
new[] { methodVar },
Expression.Assign(methodVar,
ReplaceInstancesOfExpressionFactory(ex.Parameters[0], methodVar, caching, threaded, true)(ex.Body)
),
Expression.Invoke(methodVar, paramVar)
),
paramVar);
while (resultingExpression.CanReduce)
{
resultingExpression = (LambdaExpression)resultingExpression.Reduce();
}
var compiled = resultingExpression.Compile();
return(new PureFunc <T, TResult>((Func <T, TResult>)compiled));
}
/// <summary>
/// Create a recursive lambda.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <typeparam name="TResult"></typeparam>
/// <param name="ex">The expression for the Lambda.
/// Note: The lambda will usually take the form of (funcName) => (parameter) => body, so that funcName(arg) can be called for self-recursion.</param>
/// <returns></returns>
public static Func <T, TResult> RecursiveLambda <T, TResult>(Expression <Func <Func <T, TResult>, Func <T, TResult> > > ex)
{
var methodVar = Expression.Variable(typeof(Func <T, TResult>), ex.Parameters[0].Name);
var paramVar = ((LambdaExpression)ex.Body).Parameters[0];
var resultingExpression = Expression.Lambda(Expression.Block(
new[] { methodVar },
Expression.Assign(methodVar,
ReplaceInstancesOfExpressionFactory(ex.Parameters[0], methodVar)(ex.Body)
),
Expression.Invoke(methodVar, paramVar)
),
paramVar);
while (resultingExpression.CanReduce)
{
resultingExpression = (LambdaExpression)resultingExpression.Reduce();
}
var compiled = resultingExpression.Compile();
return((Func <T, TResult>)compiled);
}