public static IASTNode Compile(SymbolTable symTable, object exp)
{
if (exp is string) {
return new ASTNode_GetVar { address = SymbolTable.Lookup(symTable, (string)exp) };
} else if (exp is INumber) {
return new ASTNode_Literal { value = exp };
}
List<object> form = exp as List<object>;
switch (form[0] as string) {
case "quote":
return new ASTNode_Literal { value = ListProcess.ListExpToPairExp(form[1]) };
case "if":
return new ASTNode_If { predNode = Compile(symTable, form[1]), thenNode = Compile(symTable, form[2]), elseNode = Compile(symTable, form[3]) };
case "begin":
return new ASTNode_Begin { nodes = form.Skip(1).Select(e => Compile(symTable, e)).ToList() };
case "lambda": {
SymbolTable newSymTable = new SymbolTable(symTable);
var formals = ((List<object>)form[1]).Cast<string>();
foreach (var name in formals) {
newSymTable.DefineLocalSymbol(name);
}
List<string> defines = new List<string>();
ListProcess.FindDefinition(defines, (List<object>)form[2], 1);
foreach (var name in defines) {
newSymTable.DefineLocalSymbol(name);
}
IASTNode body = Compile(newSymTable, form[2]);
var finder = new ASTNodeVisitor_FindFreeAddresses(body);
return new ASTNode_Lambda {
formalCount = ((List<object>)form[1]).Count,
locals = formals.Concat(defines).ToList(),
bodyNode = body,
bodyFreeAddresses = finder.BodyFreeAddresses.ToList(),
childrenFreeAddresses = finder.ChildrenFreeAddresses.ToList(),
};
}
case "define":
case "set!":
return new ASTNode_SetVar { address = SymbolTable.Lookup(symTable, (string)form[1]), rightNode = Compile(symTable, form[2]) };
default:
return new ASTNode_Application {
procedureNode = Compile(symTable, form[0]),
actualNodes = form.Skip(1).Select(e => Compile(symTable, e)).ToList(),
};
}
}
public static object Lookup(SymbolTable table, string name)
{
if (table != null && table.mSym2Address.ContainsKey(name)) {
return new LocalAddress { index = table.mSym2Address[name] };
}
int envIndex = 0;
while (table != null && !table.mSym2Address.ContainsKey(name)) {
table = table.mPrevTable;
++envIndex;
}
if (table == null) {
return DefineOrGetGlobalSymbol(name);
} else {
return new FreeAddress { envIndex = envIndex, index = table.mSym2Address[name] };
}
}
public SymbolTable(SymbolTable prevTable)
{
mPrevTable = prevTable;
}
private ASTInterpreter()
{
Utils.QueryPerformanceCounter(out sTimerStart);
Utils.QueryPerformanceFrequency(out sTimerFreq);
Dictionary <string, object> builtinVars = new Dictionary <string, object>()
{
{ "true", true },
{ "false", false },
{ "else", true },
{ "null", null },
};
Dictionary <string, Procedure> builtinProcedures = new Dictionary <string, Procedure>()
{
{ "not", (args) => !(bool)args[0] },
{ "identity", (args) => args[0] },
{ "sqr", (args) => { var a = args[0] as INumber; return(a.Mul(a)); } },
{ "+", (args) => ((INumber)args[0]).Add((INumber)args[1]) },
{ "-", (args) => ((INumber)args[0]).Sub((INumber)args[1]) },
{ "*", (args) => ((INumber)args[0]).Mul((INumber)args[1]) },
{ "/", (args) => ((INumber)args[0]).Div((INumber)args[1]) },
{ "quotient", (args) => ((INumber)args[0]).Div((INumber)args[1]).CastToInteger() },
{ "remainder", (args) => ((INumber)args[0]).Mod((INumber)args[1]) },
{ "=", (args) => (args[0].Equals(args[1])) },
{ "<", (args) => (args[0] as IComparable).CompareTo(args[1]) < 0 },
{ "<=", (args) => (args[0] as IComparable).CompareTo(args[1]) <= 0 },
{ ">", (args) => (args[0] as IComparable).CompareTo(args[1]) > 0 },
{ ">=", (args) => (args[0] as IComparable).CompareTo(args[1]) >= 0 },
{ "eq?", (args) => object.ReferenceEquals(args[0], args[1]) },
{ "cons", (args) => new Pair()
{
Car = args[0], Cdr = args[1]
} },
{ "car", (args) => ((Pair)args[0]).Car },
{ "cdr", (args) => ((Pair)args[0]).Cdr },
{ "drop", (args) => {
Pair l = (Pair)args[0]; int n = ((NumberInteger)args[1]).value;
for (; n > 0; --n)
{
l = (Pair)l.Cdr;
}
return(l);
} },
{ "length", (args) => {
int n = 0;
for (Pair l = (Pair)args[0]; l != null; ++n, l = (Pair)l.Cdr)
{
;
}
return(Number.Create(n));
} },
{ "append", (args) => {
var l = ListProcess.PairToList((Pair)args[0]);
l.InsertRange(l.Count, ListProcess.PairToList((Pair)args[1]));
return(ListProcess.ListToPair(l));
} },
{ "empty?", (args) => args[0] == null },
{ "pretty-print", (args) => {
ListProcess.PrintPairExp(args[0]);
return(null);
} },
{ "display", (args) => {
ListProcess.PrintListExp(ListProcess.PairExpToListExp(args[0]));
return(null);
} },
{ "current-inexact-milliseconds", (args) => {
long now;
Utils.QueryPerformanceCounter(out now);
return(Number.Create((decimal)(now - sTimerStart) * 1000 / sTimerFreq));
} },
{ "exit", (args) => {
Environment.Exit(0);
return(null);
} },
{ "random", (args) => Number.Create(sRandom.Next(((NumberInteger)args[0]).value)) },
{ "eval", (args) => Instance().Interpret(ListProcess.PairExpToListExp(args[0])) },
};
Env.ReserveGlobalVariables(builtinVars.Count + builtinProcedures.Count);
foreach (KeyValuePair <string, object> kv in builtinVars)
{
Env.DefineBuiltin(SymbolTable.DefineOrGetGlobalSymbol(kv.Key), kv.Value);
}
foreach (KeyValuePair <string, Procedure> kv in builtinProcedures)
{
Env.DefineBuiltin(SymbolTable.DefineOrGetGlobalSymbol(kv.Key), kv.Value);
}
}
