public object Cons(object pObject)
{
var deepCopy = new SharpList();
deepCopy.Add (pObject);
foreach (var item in this) {
deepCopy.Add (item);
}
return deepCopy;
}
public object Rest()
{
if (this.Count == 0) {
return null;
} else {
if (Count <= 1) {
return null;
}
var deepCopy = new SharpList ();
for(int i = 1; i < Count; i++) {
deepCopy.Add (this[i]);
}
return deepCopy;
}
}
private object Set(SharpList pList, Scope pCurrentScope)
{
string symbolName = (pList [1] as SymbolToken).value;
Scope s = pCurrentScope.TryResolveScope (symbolName);
s.SetVar (symbolName, Eval(pList [2], pCurrentScope));
return s.vars[symbolName];
}
SharpList ReadList()
{
var list = new SharpList ();
_indent++;
while (CurrentToken().type != TokenType.RIGHT_PAREN) {
object child = Read ();
list.Add (child);
//Console.WriteLine (GetIndentSpaces() + "Added " + child.ToString() + " to list");
}
Step (); // skip the right parenthesis
_indent--;
return list;
}
private object Let(SharpList pList, Scope pCurrentScope)
{
SharpVector bindingsVector = pList [1] as SharpVector;
if(bindingsVector == null) {
Error ("The first argument to let is not a bindings vector", pList);
}
Scope letScope = new Scope ("Let" + _letScopeCounter++, pCurrentScope);
#if LOG_SCOPES
Console.WriteLine ("Created new let scope: " + letScope.name);
#endif
for (int i = 0; i < bindingsVector.Count; i += 2) {
SymbolToken symbolToken = bindingsVector [i] as SymbolToken;
if(symbolToken == null) {
Error("Argument " + (i).ToString() + " in let binding is not a symbol", pList);
}
letScope.SetVar (symbolToken.value, Eval (bindingsVector[i + 1], pCurrentScope));
}
SharpList copy = new SharpList ();
for (int i = 2; i < pList.Count; i++) {
copy.Add(pList[i]);
}
object lastResult = null;
foreach(var item in copy) {
//Console.WriteLine("Time to eval " + item);
lastResult = Eval (item, letScope);
}
return lastResult;
}
private object Quote(SharpList pList, Scope pCurrentScope)
{
return pList [1];
}
object GetEvaled(SharpList pList, int pPosition, Scope pCurrentScope)
{
return Eval(pList [pPosition], pCurrentScope);
}
private object If(SharpList pList, Scope pCurrentScope)
{
object condition = GetEvaled (pList, 1, pCurrentScope);
bool isTrue = (condition != null);
if (condition is bool) {
isTrue = (bool)condition;
}
object result = null;
if (isTrue) {
result = GetEvaled (pList, 2, pCurrentScope);
} else if(pList.Count > 3) {
result = GetEvaled (pList, 3, pCurrentScope);
}
return result;
}
private object Fn(SharpList pList, Scope pCurrentScope)
{
SharpVector argBindings = pList [1] as SharpVector;
if(argBindings == null) {
Error ("The first argument to fn is not a vector of args", pList);
}
SharpVector argBindingsDeepCopy = new SharpVector ();
foreach(var argBinding in argBindings) {
argBindingsDeepCopy.Add (argBinding);
}
SharpList body = new SharpList ();
for (int i = 2; i < pList.Count; i++) {
body.Add(pList[i]);
}
Scope closure = new Scope ("Closure" + _closureCounter++, pCurrentScope);
#if LOG_SCOPES
Console.WriteLine ("Created new closure: " + closure.name);
#endif
string functionName = "Fn" + _functionCounter++;
return new SharpFunction(args => {
Scope functionCallScope = new Scope ("FunctionCallScope" + _functionCallScopeCounter++, closure);
#if LOG_SCOPES
Console.WriteLine ("Created new function call scope: " + functionCallScope.name);
#endif
int argPos = 0;
for(int argBindingPos = 0; argBindingPos < argBindingsDeepCopy.Count; argBindingPos++) {
var argBinding = argBindingsDeepCopy[argBindingPos];
if(argBinding is ReservedToken && (argBinding as ReservedToken).type == TokenType.AMPERSAND) {
argBindingPos++;
SymbolToken finalSymbol = argBindingsDeepCopy[argBindingPos] as SymbolToken;
if(finalSymbol == null) {
Error ("Final arg binding after ampersand is not a symbol: " + argBindingsDeepCopy[argBindingPos], pList);
}
var restOfArgs = new SharpList ();
while (argPos < args.Length) {
restOfArgs.Add(args[argPos++]);
}
functionCallScope.SetVar(finalSymbol.value, restOfArgs);
break;
}
SymbolToken symbol = argBinding as SymbolToken;
if(symbol == null) {
Error("Arg binding is not a symbol: " + symbol, pList);
}
functionCallScope.SetVar(symbol.value, args[argPos++]);
}
// Console.WriteLine(functionName + " was called with " + args.Length + " arguments:");
// foreach(var arg in args) {
// if(arg == null) {
// Console.WriteLine("null");
// } else {
// Console.WriteLine(arg.ToString());
// }
// }
object lastResult = null;
foreach(var item in body) {
//Console.WriteLine("Time to eval " + item);
lastResult = Eval (item, functionCallScope);
}
return lastResult;
}, functionName);
}
private object FunctionCall(SharpList pList, Scope pCurrentScope)
{
List<object> evaledArgs = new List<object> ();
for (int i = 1; i < pList.Count; i++) {
if(pList[i] != null) {
evaledArgs.Add(GetEvaled (pList, i, pCurrentScope));
} else {
evaledArgs.Add (null);
}
}
SharpFunction f = GetEvaled(pList, 0, pCurrentScope) as SharpFunction;
object result = f.function (evaledArgs.ToArray());
//Console.WriteLine ("(" + f + (evaledArgs.Count > 0 ? " " : "") + string.Join(" ", evaledArgs) + ") -> " + result);
return result;
}
private object EvalList(SharpList pList, Scope pCurrentScope)
{
if (pList.Count == 0) {
return pList;
}
if (pList[0] is SymbolToken) {
//Console.WriteLine ("Found symbol token " + pList[0]);
if (_macroDefinitions.ContainsKey (((SymbolToken)pList[0]).value)) {
SymbolToken macroName = pList [0] as SymbolToken;
object result = CallMacro (_macroDefinitions[macroName.value], pList, pCurrentScope);
return result;
}
}
object firstItem = GetEvaled (pList, 0, pCurrentScope);
if (firstItem is ReservedToken) {
ReservedToken token = firstItem as ReservedToken;
if (token.type == TokenType.DEF) {
return Def (pList, pCurrentScope);
}
if (token.type == TokenType.FN) {
return Fn (pList, pCurrentScope);
}
if (token.type == TokenType.LET) {
return Let (pList, pCurrentScope);
}
if (token.type == TokenType.IF) {
return If (pList, pCurrentScope);
}
if (token.type == TokenType.DEFMACRO) {
return DefMacro (pList, pCurrentScope);
}
if (token.type == TokenType.QUOTE) {
return Quote (pList, pCurrentScope);
}
if (token.type == TokenType.SET) {
return Set (pList, pCurrentScope);
}
throw new Exception("Can't understand ReservedToken: " + token);
}
if (firstItem is SharpFunction) {
return FunctionCall (pList, pCurrentScope);
}
Error ("Can't eval function with first item '" + firstItem, pList);
return null;
}
private void Error(string pDescription, SharpList pList)
{
throw new Exception (pDescription + " (line " + pList.line + " and position " + pList.position + ")");
}
private object DefMacro(SharpList pList, Scope pCurrentScope)
{
SymbolToken macroNameSymbol = pList [1] as SymbolToken;
if (macroNameSymbol == null) {
Error("The first argument to defmacro is not a string", pList);
}
_macroDefinitions[macroNameSymbol.value] = pList;
return pList;
}
private object Def(SharpList pList, Scope pCurrentScope)
{
SymbolToken symbolToken = pList [1] as SymbolToken;
if(symbolToken == null) {
Error ("The first argument to def is not a symbol", pList);
}
globalScope.SetVar(symbolToken.value, GetEvaled(pList, 2, pCurrentScope));
return symbolToken;
}
private object CallMacro(SharpList pMacroForm, SharpList pInvokingList, Scope pCurrentScope)
{
SymbolToken macroNameSymbol = pMacroForm [1] as SymbolToken;
if (macroNameSymbol == null) {
Error("The first argument to macro is not a string", pInvokingList);
}
//Console.WriteLine ("Calling macro " + macroNameSymbol.value);
var argBindings = pMacroForm [2] as SharpVector;
if (argBindings == null) {
Error("The second argument to macro is not a vector of args", pInvokingList);
}
List<object> args = new List<object> ();
for (int i = 1; i < pInvokingList.Count; i++) {
args.Add (pInvokingList[i]);
}
int argPos = 0;
Scope macroScope = new Scope ("Macro scope " + _macroScopeCounter++, pCurrentScope);
for(int argBindingPos = 0; argBindingPos < argBindings.Count; argBindingPos++) {
var argBinding = argBindings [argBindingPos];
if(argBinding is ReservedToken && (argBinding as ReservedToken).type == TokenType.AMPERSAND) {
argBindingPos++;
SymbolToken finalSymbol = argBindings[argBindingPos] as SymbolToken;
if(finalSymbol == null) {
Error("Final arg binding after ampersand is not a symbol: " + argBindings[argBindingPos], pInvokingList);
}
var restOfArgs = new SharpList ();
while (argPos < args.Count) {
restOfArgs.Add(args[argPos++]);
}
macroScope.SetVar(finalSymbol.value, restOfArgs);
break;
}
SymbolToken symbol = argBinding as SymbolToken;
if (symbol == null) {
Error ("One of the bindings to the macro is not a symbol", pInvokingList);
}
macroScope.SetVar(symbol.value, args[argPos]);
#if MACRODEBUG
Console.WriteLine ("Setting " + symbol.value + " to " + args[argPos] + " at arg pos " + argPos);
#endif
argPos++;
}
List<object> compiledForms = new List<object> ();
for(int i = 3; i < pMacroForm.Count; i++) {
object compiledBody = CompileMacro(pMacroForm [i], macroScope);
compiledForms.Add (compiledBody);
}
#if MACRODEBUG
Console.WriteLine("Compiled macro " + macroNameSymbol.value + " to the following forms: ");
foreach(var form in compiledForms) {
if(form != null) {
Console.WriteLine(form.ToString ());
}
else {
Console.WriteLine("null");
}
}
#endif
object lastResult = null;
foreach(var form in compiledForms) {
//Console.WriteLine ("Eval form " + form.ToString());
lastResult = Eval (form, pCurrentScope);
}
return lastResult;
}
