public static void KeepInterpretingInConsole(this SScope scope, Func <string, SScope, SObject> evaluate)
{
while (true)
{
try
{
Console.ForegroundColor = ConsoleColor.Gray;
Console.Write(">> ");
string code;
if (string.IsNullOrWhiteSpace(code = Console.ReadLine()))
{
continue;
}
Console.ForegroundColor = ConsoleColor.Green;
if (code.Equals("quit", StringComparison.OrdinalIgnoreCase))
{
break;
}
Console.WriteLine(">> " + evaluate(code.PrefixConvert(), scope));
}
catch (Exception ex)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(">> " + ex.Message);
}
}
}
public static SList RetrieveSList(this SExpression[] expressions, SScope scope, string operationName)
{
SList list = null;
(expressions.Length == 1 && (list = expressions[0].Evaluate(scope) as SList) != null)
.OrThrows("<" + operationName + "> 必须是一个list");
return(list);
}
public SScope SpawnScopeWith(string[] names, SObject[] values)
{
(names.Length >= values.Length).OrThrows("参数过多");
var scope = new SScope(this);
for (var i = 0; i < values.Length; i++)
{
scope._variableTable.Add(names[i], values[i]);
}
return scope;
}
public static SBool ChainRelation(this SExpression[] expressions, SScope scope,
Func <SNumber, SNumber, bool> relation)
{
(expressions.Length > 1).OrThrows("该操作要求至少有一个操作符");
var current = (SNumber)expressions[0].Evaluate(scope);
foreach (var obj in expressions.Skip(1))
{
var next = (SNumber)obj.Evaluate(scope);
if (relation(current, next))
{
current = next;
}
else
{
return(SBool.False);
}
}
return(SBool.True);
}
public SObject Evaluate(SScope scope)
{
var current = this;
while (true)
{
if (current.Children.Count == 0)
{
long number;
return(long.TryParse(current.Value, out number) ? number : scope.Find(current.Value));
}
var first = current.Children[0];
switch (first.Value)
{
case "if":
var condition = (SBool)(current.Children[1].Evaluate(scope));
current = condition ? current.Children[2] : current.Children[3];
break;
case "def":
return(scope.Define(current.Children[1].Value, current.Children[2].Evaluate(new SScope(scope))));
case "begin":
SObject result = null;
foreach (var statement in current.Children.Skip(1))
{
result = statement.Evaluate(scope);
}
return(result);
case "func":
var body = current.Children[2];
var parameters = current.Children[1].Children.Select(exp => exp.Value).ToArray();
var newScope = new SScope(scope);
return(new SFunction(body, parameters, newScope));
case "list":
return(new SList(current.Children.Skip(1).Select(exp => exp.Evaluate(scope))));
default:
if (SScope.BuiltinFunctions.ContainsKey(first.Value))
{
var arguments = current.Children.Skip(1).ToArray();
return(SScope.BuiltinFunctions[first.Value](arguments, scope));
}
else
{
var function = first.Value == "("
? (SFunction)first.Evaluate(scope)
: (SFunction)scope.Find(first.Value);
var arguments = current.Children.Skip(1).Select(s => s.Evaluate(scope)).ToArray();
var newFunction = function.Update(arguments);
if (newFunction.IsPartial)
{
return(scope.Define($"{first}{"".CustomJoin(arguments)}", newFunction.Evaluate()));
}
current = newFunction.Body;
scope = newFunction.Scope;
}
break;
}
}
}
public static IEnumerable <SObject> Evaluate(this IEnumerable <SExpression> expressions, SScope scope)
{
return(expressions.Select(exp => exp.Evaluate(scope)));
}
public static IEnumerable <T> Evaluate <T>(this IEnumerable <SExpression> expressions, SScope scope)
where T : SObject
{
return(expressions.Evaluate(scope).Cast <T>());
}
public SFunction(SExpression body, string[] parameters, SScope scope)
{
Body = body;
Parameters = parameters;
Scope = scope;
}
public SScope(SScope parent)
{
Parent = parent;
_variableTable = new Dictionary<string, SObject>();
}