/// <summary>
/// Process the arguments passed to a closure, and add them to the given enviroment.
/// </summary>
/// <param name="argumentNameList">The list of names and kewords the closure was created with.</param>
/// <param name="argumentList">The arguments passed to the closure.</param>
/// <param name="localEnvironment">The closure's local variables.</param>
/// <returns>Nothing.</returns>
public static void ProcessArguments(Cons argumentNameList, Cons argumentList, Environment localEnvironment)
{
while (argumentNameList != null)
{
// Get the name for the closure's parameter. Then check to see if it's a keyword, if it is then
// process the keyword. Otherwise set up that parameter in the closure's enviroment with the
// caller specified value.
Symbol argumentName = (Symbol)argumentNameList.Car();
switch (argumentName.ToString())
{
case "&rest":
argumentName = (Symbol)argumentNameList.Cadr();
localEnvironment.AssignLocal(argumentName, argumentList);
argumentNameList = null;
argumentList = null;
break;
case "&optional":
ProcessOptionalArguments((Cons)argumentNameList.Cdr(), argumentList, localEnvironment);
argumentNameList = null;
argumentList = null;
break;
case "&key":
ProcessKeyArguments((Cons)argumentNameList.Cdr(), argumentList, localEnvironment);
argumentNameList = null;
argumentList = null;
break;
default:
if (argumentList == null)
{
throw new LSharpException("Not enough parameters given.");
}
localEnvironment.AssignLocal(argumentName, argumentList.Car());
argumentList = (Cons)argumentList.Cdr();
argumentNameList = (Cons)argumentNameList.Cdr();
break;
}
}
// Looks like the caller has supplied more parameters than the closure can use.
if (argumentList != null)
{
throw new LSharpException("Too many parameters given.");
}
}
private static void ProcessOptionalArguments(Cons argumentNameList, Cons argumentList,
Environment localEnvironment)
{
// We need to add all the arguments to the closure's environment.
while (argumentNameList != null)
{
Symbol argumentName = null;
object argumentValue = null;
// We need to get the name of the argument, it can either be just the name or, it can be
// it's own Cons with the name and an expression for the default value.
if (argumentNameList.Car() is Cons)
{
// It is a Cons, so extract the name and the default value.
argumentName = (Symbol)argumentNameList.Caar();
argumentValue = argumentNameList.Cadar();
}
else
{
argumentName = (Symbol)argumentNameList.Car();
}
// Now, if the caller has specified a value for this argument, get it now.
if (argumentList != null)
{
argumentValue = argumentList.Car();
argumentList = (Cons)argumentList.Cdr();
}
// Finally add the parameter to the closure's list and then move onto the next argument.
// Because the default can be any expression, we need to evaluate the value every time the
// function is called.
localEnvironment.AssignLocal(argumentName, Runtime.Eval(argumentValue, localEnvironment));
argumentNameList = (Cons)argumentNameList.Cdr();
}
// Looks like the caller has supplied more parameters than the closure can use.
if (argumentList != null)
{
throw new LSharpException("Too many parameters given.");
}
}
public override bool Equals(object obj)
{
if (obj is Cons)
{
Cons that = (Cons)obj;
bool carsEqual = Primitives.Eql(this.Car(), that.Car());
bool cdrsEqual = Primitives.Eql(this.Cdr(), that.Cdr());
return(carsEqual && cdrsEqual);
}
else
{
return(false);
}
}
public bool MoveNext()
{
object o = list.Cdr();
if (o == null)
{
return(false);
}
if (o is Cons)
{
list = (Cons)o;
}
else
{
list = new Cons(o);
}
return(true);
}
public static Object With(Cons args, Environment environment)
{
Environment localEnvironment = new Environment(environment);
Cons bindings = (Cons)args.First();
while ((bindings != null) && (bindings.Length() > 1))
{
localEnvironment.AssignLocal((Symbol)bindings.First(), Runtime.Eval(bindings.Second(), environment));
bindings = (Cons)bindings.Cddr();
}
object result = null;
foreach (object item in (Cons)args.Cdr())
{
result = Runtime.Eval(item, localEnvironment);
}
return(result);
}
/// <summary>
/// (with ((symbol value)* ) expression*)
/// Binds new local variables symbols to values in a new local
/// lexical environment, before evaluating expressions. Similar to
/// let, but allows multiple local variables to be bound.
/// </summary>
/// <param name="args"></param>
/// <param name="environment"></param>
/// <returns></returns>
public static Object With(Cons args, Environment environment)
{
Environment localEnvironment = new Environment(environment);
Cons bindings = (Cons)args.First();
while ((bindings != null) && (bindings.Length() > 1))
{
localEnvironment.AssignLocal((Symbol)bindings.First(), Runtime.Eval(bindings.Second(), localEnvironment));
bindings = (Cons)bindings.Cddr();
}
object result = null;
foreach (object item in (Cons)args.Cdr())
{
result = Runtime.Eval(item, localEnvironment);
}
return result;
}
/// <summary>
/// (macro arguments expression*)
/// Defines a macro. Similar in some respects to defining a clsoure using fn
/// except that the expressions are expanded using macroexpand in the current
/// environment before being evaluated.
/// </summary>
/// <param name="args"></param>
/// <param name="environment"></param>
/// <returns></returns>
public static Object Macro(Cons args, Environment environment)
{
return new Macro((Cons)args.First(),(Cons)args.Cdr(),environment);
}
/// <summary>
/// (fn arguments body)
/// Defines a closure with the specified list of arguments and the specified body,
/// an L Sharp expression. Not unlike a lambda expression in Common Lisp.NB arguments
/// is a simple list, we dont yet support keyword or optional arguments.
/// </summary>
/// <param name="args"></param>
/// <param name="environment"></param>
/// <returns></returns>
public static Object Fn(Cons args, Environment environment)
{
return new Closure((Cons)args.First(),(Cons)args.Cdr(),environment);
}
/// <summary>
/// Evaluates an expression in a given lexical environment
/// </summary>
/// <param name="form"></param>
/// <param name="environment"></param>
/// <returns></returns>
public static Object Eval(Object expression, Environment environment)
{
profiler.TraceCall(expression);
if (expression == Reader.EOFVALUE)
{
return(profiler.TraceReturn(expression));
}
if (expression == null)
{
return(profiler.TraceReturn(null));
}
// The expression is either an atom or a list
if (Primitives.IsAtom(expression))
{
// Number
if (expression is double)
{
return(profiler.TraceReturn(expression));
}
if (expression is int)
{
return(profiler.TraceReturn(expression));
}
// Character
if (expression is char)
{
return(profiler.TraceReturn(expression));
}
// String
if (expression is string)
{
return(profiler.TraceReturn(expression));
}
Symbol sym = expression as Symbol;
if (sym == Symbol.TRUE)
{
return(profiler.TraceReturn(true));
}
if (sym == Symbol.FALSE)
{
return(profiler.TraceReturn(false));
}
if (sym == Symbol.NULL)
{
return(profiler.TraceReturn(null));
}
// If the symbol is bound to a value in this lexical environment
if (environment.Contains(sym))
{
// Then it's a variable so return it's value
return(profiler.TraceReturn(environment.GetValue(sym)));
}
else
{
// Otherwise symbols evaluate to themselves
return(profiler.TraceReturn(expression));
}
}
else
{
// The expression must be a list
Cons cons = (Cons)expression;
// Lists are assumed to be of the form (function arguments)
// See if there is a binding to a function, clsoure, macro or special form
// in this lexical environment
object function = environment.GetValue((Symbol)cons.First());
// If there is no binding, then use the function name directly - it's probably
// the name of a .NET method
if (function == null)
{
function = cons.First();
}
// If it's a special form
if (function is SpecialForm)
{
return(profiler.TraceReturn(((SpecialForm)function)((Cons)cons.Cdr(), environment)));
}
// If its a macro application
if (function is Macro)
{
object expansion = ((Macro)function).Expand((Cons)cons.Cdr());
return(profiler.TraceReturn(Runtime.Eval(expansion, environment)));
}
// It must be a function, closure or method invocation,
// so call apply
Object arguments = EvalList((Cons)cons.Cdr(), environment);
return(profiler.TraceReturn(Runtime.Apply(function, arguments, environment)));
}
}
public static Object Fn(Cons args, Environment environment)
{
return(new Closure(args.First() as Cons, args.Cdr() as Cons, environment));
}
/// <summary>
/// (with ((symbol value)* ) expression*)
/// </summary>
public static Object With(Cons args, LSharp.Environment environment)
{
string v = //"//(with " + Printer.ConsToString(args) + ")" + NewLine +
"{" + NewLine;
Cons bindings = (Cons)args.First();
LSharp.Environment localEnvironment = new LSharp.Environment(environment);
while ((bindings != null) && (bindings.Length() > 1))
{
v += GenerateAssignLocal((Symbol) bindings.First(), Generate(bindings.Second(),environment), localEnvironment);
bindings = (Cons)bindings.Cddr();
}
foreach (object item in (Cons)args.Cdr())
{
v += Generate(item, localEnvironment);
}
return v + "}";
}
/// <summary>
/// Process the arguments passed to a closure, and add them to the given enviroment.
/// </summary>
/// <param name="argumentNameList">The list of names and kewords the closure was created with.</param>
/// <param name="argumentList">The arguments passed to the closure.</param>
/// <param name="localEnvironment">The closure's local variables.</param>
/// <returns>Nothing.</returns>
public static void ProcessArguments(Cons argumentNameList, Cons argumentList, Environment localEnvironment)
{
while (argumentNameList != null)
{
// Get the name for the closure's parameter. Then check to see if it's a keyword, if it is then
// process the keyword. Otherwise set up that parameter in the closure's enviroment with the
// caller specified value.
Symbol argumentName = (Symbol)argumentNameList.Car();
switch (argumentName.ToString())
{
case "&rest":
argumentName = (Symbol)argumentNameList.Cadr();
localEnvironment.AssignLocal(argumentName, argumentList);
argumentNameList = null;
argumentList = null;
break;
case "&optional":
ProcessOptionalArguments((Cons)argumentNameList.Cdr(), argumentList, localEnvironment);
argumentNameList = null;
argumentList = null;
break;
case "&key":
ProcessKeyArguments((Cons)argumentNameList.Cdr(), argumentList, localEnvironment);
argumentNameList = null;
argumentList = null;
break;
default:
if (argumentList == null)
{
throw new LSharpException("Not enough parameters given.");
}
localEnvironment.AssignLocal(argumentName, argumentList.Car());
argumentList = (Cons)argumentList.Cdr();
argumentNameList = (Cons)argumentNameList.Cdr();
break;
}
}
// Looks like the caller has supplied more parameters than the closure can use.
if (argumentList != null)
{
throw new LSharpException("Too many parameters given.");
}
}
private static void ProcessKeyArguments(Cons argumentNameList, Cons argumentList,
Environment localEnvironment)
{
// Make sure that all of the defined key arguments are inserted to the local enviroment with their
// defaults.
while (argumentNameList != null)
{
Symbol argumentName = null;
object argumentValue = null;
// We need to get the name of the argument, it can either be just the name or, it can be
// it's own Cons with the name and an expression for the default value.
if (argumentNameList.Car().GetType() == typeof(Cons))
{
// It is a Cons, so extract the name and the default value. Because the default can be
// any expression, we need to evaluate the value every time the function is called.
argumentName = (Symbol)argumentNameList.Caar();
argumentValue = Runtime.Eval(argumentNameList.Cadar(), localEnvironment);
}
else
{
argumentName = (Symbol)argumentNameList.Car();
}
// Add this variable to the closure's environment, then advance to the next parameter.
localEnvironment.AssignLocal(argumentName, argumentValue);
argumentNameList = (Cons)argumentNameList.Cdr();
}
// Now that the parameters and their defaults have been added to the environment we can now
// process the supplied arguments.
while (argumentList != null)
{
// Because these are keyed parameters, the caller needs to specify the name of each
// parameter.
if (argumentList.Car().GetType() != typeof(Symbol))
{
throw new LSharpException("Key parameters must be specified by name.");
}
// Grab the current parameter and the value associated with it. Then make sure that this
// is a keyword.
Symbol keywordName = (Symbol)argumentList.Car();
object argumentValue = argumentList.Cadr();
if (keywordName.Name[0] != ':')
{
throw new LSharpException(keywordName + " is not a valid keyword.");
}
// Now that we know they supplied a keyword, create a symbol out of it and make sure that
// it exists.
//keywordName = new Symbol(keywordName.Name.Substring(1));
keywordName = Symbol.FromName(keywordName.Name.Substring(1));
if (localEnvironment.Contains(keywordName) == false)
{
throw new LSharpException(keywordName + " is not a recognised keyword.");
}
// Update the parameter with the value that the user specified and then move onto the next
// argument in the list.
localEnvironment.AssignLocal(keywordName, argumentValue);
argumentList = (Cons)argumentList.Cddr();
}
}
private static void ProcessOptionalArguments(Cons argumentNameList, Cons argumentList,
Environment localEnvironment)
{
// We need to add all the arguments to the closure's environment.
while (argumentNameList != null)
{
Symbol argumentName = null;
object argumentValue = null;
// We need to get the name of the argument, it can either be just the name or, it can be
// it's own Cons with the name and an expression for the default value.
if (argumentNameList.Car().GetType() == typeof(Cons))
{
// It is a Cons, so extract the name and the default value.
argumentName = (Symbol)argumentNameList.Caar();
argumentValue = argumentNameList.Cadar();
}
else
{
argumentName = (Symbol)argumentNameList.Car();
}
// Now, if the caller has specified a value for this argument, get it now.
if (argumentList != null)
{
argumentValue = argumentList.Car();
argumentList = (Cons)argumentList.Cdr();
}
// Finally add the parameter to the closure's list and then move onto the next argument.
// Because the default can be any expression, we need to evaluate the value every time the
// function is called.
localEnvironment.AssignLocal(argumentName, Runtime.Eval(argumentValue, localEnvironment));
argumentNameList = (Cons)argumentNameList.Cdr();
}
// Looks like the caller has supplied more parameters than the closure can use.
if (argumentList != null)
{
throw new LSharpException("Too many parameters given.");
}
}
private static void ProcessKeyArguments(Cons argumentNameList, Cons argumentList,
Environment localEnvironment)
{
// Make sure that all of the defined key arguments are inserted to the local enviroment with their
// defaults.
while (argumentNameList != null)
{
Symbol argumentName = null;
object argumentValue = null;
// We need to get the name of the argument, it can either be just the name or, it can be
// it's own Cons with the name and an expression for the default value.
if (argumentNameList.Car() is Cons)
{
// It is a Cons, so extract the name and the default value. Because the default can be
// any expression, we need to evaluate the value every time the function is called.
argumentName = (Symbol)argumentNameList.Caar();
argumentValue = Runtime.Eval(argumentNameList.Cadar(), localEnvironment);
}
else
{
argumentName = (Symbol)argumentNameList.Car();
}
// Add this variable to the closure's environment, then advance to the next parameter.
localEnvironment.AssignLocal(argumentName, argumentValue);
argumentNameList = (Cons)argumentNameList.Cdr();
}
// Now that the parameters and their defaults have been added to the environment we can now
// process the supplied arguments.
while (argumentList != null)
{
// Because these are keyed parameters, the caller needs to specify the name of each
// parameter.
if (argumentList.Car().GetType() != typeof(Symbol))
{
throw new LSharpException("Key parameters must be specified by name.");
}
// Grab the current parameter and the value associated with it. Then make sure that this
// is a keyword.
Symbol keywordName = (Symbol)argumentList.Car();
object argumentValue = argumentList.Cadr();
if (keywordName.Name[0] != ':')
{
throw new LSharpException(keywordName + " is not a valid keyword.");
}
// Now that we know they supplied a keyword, create a symbol out of it and make sure that
// it exists.
//keywordName = new Symbol(keywordName.Name.Substring(1));
keywordName = Symbol.FromName(keywordName.Name.Substring(1));
if (localEnvironment.Contains(keywordName) == false)
{
throw new LSharpException(keywordName + " is not a recognised keyword.");
}
// Update the parameter with the value that the user specified and then move onto the next
// argument in the list.
localEnvironment.AssignLocal(keywordName, argumentValue);
argumentList = (Cons)argumentList.Cddr();
}
}
public static string WriteToString(Object x)
{
if (x == null)
{
return("null");
}
if (x == Reader.EOFVALUE)
{
return("EOF");
}
Type type = x.GetType();
if (x is string)
{
return(string.Format("\"{0}\"", (string)x));
}
if (x is bool)
{
return(x.ToString().ToLower());
}
if (x is char)
{
return(string.Format("#\\{0}", x));
}
if (x is Symbol)
{
return(string.Format("{0}", x));
}
if (x is Cons)
{
bool wasquote = true;
Cons cons = (Cons)x;
StringBuilder stringBuilder = new StringBuilder();
Symbol car = cons.Car() as Symbol;
if (car == Symbol.QUOTE)
{
stringBuilder.Append("'");
}
else if (car == Symbol.BACKQUOTE)
{
stringBuilder.Append("`");
}
else if (car == Symbol.SPLICE)
{
stringBuilder.Append(",@");
}
else if (car == Symbol.UNQUOTE)
{
stringBuilder.Append(",");
}
else
{
wasquote = false;
stringBuilder.Append("(");
stringBuilder.Append(WriteToString(cons.Car()));
stringBuilder.Append(" ");
}
Object o;
o = cons.Cdr();
while (o != null)
{
if (o is Cons)
{
cons = (Cons)o;
stringBuilder.Append(WriteToString(cons.Car()));
o = cons.Cdr();
if (o != null)
{
stringBuilder.Append(" ");
}
}
else
{
stringBuilder.Append(". ");
stringBuilder.Append(WriteToString(o));
o = null;
}
}
string op = stringBuilder.ToString().Trim();
if (wasquote)
{
return(op);
}
else
{
return(op + ")");
}
}
return(x.ToString().Trim());
}
public static Object Macro(Cons args, Environment environment)
{
return(new Macro((Cons)args.First(), (Cons)args.Cdr(), environment));
}
