/// <summary>
/// Main loop.
/// Good default for all the flags is `false`
/// </summary>
/// <param name="resetVars">If true, all scopes are DELETED before running</param>
/// <param name="traceExecution">If true, console output of state is written</param>
/// <param name="singleStep">If true, the interpreter will run a single step, then return. Internal `eval` statements will run to completion</param>
public ExecutionResult Execute(bool resetVars, bool traceExecution, bool singleStep)
{
double evalResult;
_runningVerbose = traceExecution;
if (resetVars)
{
_memory.Variables.Clear();
}
while (_position < program.Count)
{
_stepsTaken++;
//if (stepsTaken > 1000) throw new Exception("trap");
// Prevent stackoverflow.
// Ex: if(true 1 10 20)
if ((_stepsTaken & 127) == 0 && _valueStack.Count > 100)
{
var oldValues = _valueStack.ToArray();
_valueStack = new Stack <double>(oldValues.Skip(oldValues.Length - 100));
}
double word = program[_position];
if (traceExecution)
{
_output.WriteLine(" stack :" + string.Join(", ", _valueStack.ToArray().Select(t => _memory.DiagnosticString(t, DebugSymbols))));
_output.WriteLine(" #" + _stepsTaken + "; p=" + _position
+ "; w=" + _memory.DiagnosticString(word, DebugSymbols));
}
var type = NanTags.TypeOf(word);
switch (type)
{
case DataType.Invalid:
throw new Exception("Unknown code point at " + _position);
case DataType.Opcode:
// decode opcode and do stuff
NanTags.DecodeOpCode(word, out var codeClass, out var codeAction, out var p1, out var p2);
ProcessOpCode(codeClass, codeAction, p1, p2, ref _position, _valueStack, _returnStack, word);
break;
default:
_valueStack.Push(word); // these could be raw doubles, encoded real values, or references/pointers
break;
}
_position++;
if (singleStep)
{
return new ExecutionResult {
State = ExecutionState.Paused, Result = NanTags.EncodeNonValue(NonValueType.Not_a_Result)
}
}
;
}
if (_valueStack.Count != 0)
{
evalResult = _valueStack.Pop();
}
else
{
evalResult = NanTags.EncodeNonValue(NonValueType.Void);
}
_valueStack.Clear();
return(new ExecutionResult {
State = ExecutionState.Complete, Result = evalResult
});
}
private double EvaluateBuiltInFunction(ref int position, FuncDef kind, int nbParams, double[] param, Stack <int> returnStack, Stack <double> valueStack)
{
switch (kind)
{
// each element equal to the first
case FuncDef.Equal:
if (nbParams < 2)
{
throw new Exception("equals ( = ) must have at least two things to compare");
}
return(NanTags.EncodeBool(ListEquals(param)));
// Each element smaller than the last
case FuncDef.GreaterThan:
if (nbParams < 2)
{
throw new Exception("greater than ( > ) must have at least two things to compare");
}
return(NanTags.EncodeBool(FoldGreaterThan(param)));
// Each element larger than the last
case FuncDef.LessThan:
if (nbParams < 2)
{
throw new Exception("less than ( < ) must have at least two things to compare");
}
return(NanTags.EncodeBool(FoldLessThan(param)));
// Each element DIFFERENT TO THE FIRST (does not check set uniqueness!)
case FuncDef.NotEqual:
if (nbParams < 2)
{
throw new Exception("not-equal ( <> ) must have at least two things to compare");
}
return(NanTags.EncodeBool(!ListEquals(param)));
case FuncDef.Assert:
if (nbParams < 1)
{
return(NanTags.VoidReturn()); // assert nothing passes
}
var condition = param.ElementAt(0);
if (_memory.CastBoolean(condition) == false)
{
var msg = ConcatList(param, 1);
throw new Exception("Assertion failed: " + msg);
}
return(NanTags.VoidReturn());
case FuncDef.Random:
if (nbParams < 1)
{
return(rnd.NextDouble()); // 0 params - any size
}
if (nbParams < 2)
{
return(rnd.Next(_memory.CastInt(param.ElementAt(0)))); // 1 param - max size
}
return(rnd.Next(_memory.CastInt(param.ElementAt(0)), _memory.CastInt(param.ElementAt(1)))); // 2 params - range
case FuncDef.Eval:
var reader = new SourceCodeTokeniser();
var statements = _memory.CastString(param.ElementAt(0));
var programTmp = reader.Read(statements, false);
var bin = ToNanCodeCompiler.CompileRoot(programTmp, false);
var interpreter = new ByteCodeInterpreter();
interpreter.Init(new RuntimeMemoryModel(bin, _memory.Variables), _input, _output, DebugSymbols);
return(interpreter.Execute(false, _runningVerbose, false).Result);
case FuncDef.Call:
NanTags.DecodePointer(param.ElementAt(0), out var target, out var type);
if (type != DataType.PtrString && type != DataType.PtrStaticString)
{
throw new Exception("Tried to call a function by name, but passed a '" + type + "' at " + position);
}
// this should be a string, but we need a function name hash -- so calculate it:
var strName = _memory.DereferenceString(target);
var functionNameHash = NanTags.GetCrushedName(strName);
nbParams--;
var newParam = param.Skip(1).ToArray();
return(EvaluateFunctionCall(ref position, functionNameHash, nbParams, newParam, returnStack, valueStack));
case FuncDef.LogicNot:
if (nbParams != 1)
{
throw new Exception("'not' should be called with one argument");
}
var bval = _memory.CastBoolean(param.ElementAt(0));
return(NanTags.EncodeBool(!bval));
case FuncDef.LogicOr:
{
bool more = nbParams > 0;
int i = 0;
while (more)
{
var bresult = _memory.CastBoolean(param.ElementAt(i));
if (bresult)
{
return(NanTags.EncodeBool(true));
}
i++;
more = i < nbParams;
}
return(NanTags.EncodeBool(false));
}
case FuncDef.LogicAnd:
{
bool more = nbParams > 0;
int i = 0;
while (more)
{
var bresult = _memory.CastBoolean(param.ElementAt(i));
if (!bresult)
{
return(NanTags.EncodeBool(false));
}
i++;
more = i < nbParams;
}
return(NanTags.EncodeBool(true));
}
case FuncDef.ReadKey:
return(_memory.StoreStringAndGetReference(((char)_input.Read()).ToString()));
case FuncDef.ReadLine:
return(_memory.StoreStringAndGetReference(_input.ReadLine()));
case FuncDef.Print:
{
string lastStr = null;
foreach (var v in param)
{
lastStr = _memory.CastString(v);
_output.Write(lastStr);
}
if (lastStr != "")
{
_output.WriteLine();
}
}
return(NanTags.VoidReturn());
case FuncDef.Substring:
if (nbParams == 2)
{
var newString = _memory.CastString(param.ElementAt(0)).Substring(_memory.CastInt(param.ElementAt(1)));
return(_memory.StoreStringAndGetReference(newString));
}
else if (nbParams == 3)
{
int start = _memory.CastInt(param.ElementAt(1));
int length = _memory.CastInt(param.ElementAt(2));
string s = _memory.CastString(param.ElementAt(0)).Substring(start, length);
return(_memory.StoreStringAndGetReference(s));
}
else
{
throw new Exception("'Substring' should be called with 2 or 3 parameters");
}
case FuncDef.Length:
return(_memory.CastString(param.ElementAt(0)).Length);
case FuncDef.Replace:
if (nbParams != 3)
{
throw new Exception("'Replace' should be called with 3 parameters");
}
string exp = _memory.CastString(param.ElementAt(0));
string oldValue = _memory.CastString(param.ElementAt(1));
string newValue = _memory.CastString(param.ElementAt(2));
exp = exp.Replace(oldValue, newValue);
return(_memory.StoreStringAndGetReference(exp));
case FuncDef.Concat:
var builder = new StringBuilder();
foreach (var v in param)
{
builder.Append(_memory.CastString(v));
}
return(_memory.StoreStringAndGetReference(builder.ToString()));
case FuncDef.UnitEmpty:
{ // valueless marker (like an empty object)
return(NanTags.EncodeNonValue(NonValueType.Unit));
}
case FuncDef.MathAdd:
if (nbParams == 1)
{
return(param[0]);
}
return(param.ChainSum());
case FuncDef.MathSub:
if (nbParams == 1)
{
return(-param[0]);
}
return(param.ChainDifference());
case FuncDef.MathProd:
if (nbParams == 1)
{
throw new Exception("Uniary '*' is not supported");
}
return(param.ChainProduct());
case FuncDef.MathDiv:
if (nbParams == 1)
{
throw new Exception("Uniary '/' is not supported");
}
return(param.ChainDivide());
case FuncDef.MathMod:
if (nbParams == 1)
{
return(param[0] % 2);
}
return(param.ChainRemainder());
default:
throw new Exception("Unrecognised built-in! Type = " + ((int)kind));
}
}