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import std.stdio;
import std.string;
import chunk;
import parser;
//import value;
//import obj;
import dbg;
enum InterpretResult {
OK,
COMPILE_ERROR,
RUNTIME_ERROR,
}
class VM {
int topOffset = 0;
ubyte ip = 0;
Value[] stack;
//ObjFunction func;
Function func;
this(Function func) {
this.func = func;
}
Value peek(int offset) {
if (offset >= this.topOffset) {
writefln("offset of %d greater than stack size %d", offset, topOffset);
}
return this.stack[topOffset - offset - 1];
}
Value pop() {
if (this.topOffset > 0) {
this.topOffset--;
} else {
writeln("pop() on an empty stack!!");
}
return this.stack[this.topOffset];
}
//InterpretResult push(Value value) {
void push(Value value) {
if (this.stack.length > this.topOffset) {
this.stack[topOffset] = value;
} else {
this.stack ~= value;
}
this.topOffset++;
}
ubyte readByte() {
return this.func.chunk.code[this.ip++];
}
bool isNumber(Value value) {
return value.type == ValueType.NUMBER;
}
double asNumber(Value value) {
return value.as.number;
}
InterpretResult run() {
//int ip = 0; // TODO this is wrong
while (true) {
write(" ");
//foreach (Value val; this.stack) {
for (int i = 0; i < this.topOffset; i++) {
writef("[ %s ]", printableValue(this.stack[i]));
}
writeln("\n--");
disassemble(this.func.chunk, this.ip);
ubyte inst;
switch (inst = this.readByte()) {
case OpCode.OP_CONSTANT:
Value constant = this.func.chunk.constants[this.readByte()];
this.push(constant);
break;
case OpCode.OP_NEGATE:
if (!isNumber(peek(0))) {
writeln("negate operand must be a number");
return InterpretResult.RUNTIME_ERROR;
}
double val = asNumber(pop());
push(makeNumberValue(val * -1));
break;
case OpCode.OP_ADD:
Value b = this.pop();
if (!isNumber(b)) {
writeln("b is not a number!");
return InterpretResult.RUNTIME_ERROR; // TODO error
}
Value a = this.pop();
if (!isNumber(a)) {
writeln("a is not a number!");
return InterpretResult.RUNTIME_ERROR; // TODO error
}
double bnum = asNumber(b);
double anum = asNumber(a);
push(makeNumberValue(anum + bnum));
break;
case OpCode.OP_SUBTRACT:
Value b = this.pop();
if (!isNumber(b)) {
writeln("b is not a number!");
return InterpretResult.RUNTIME_ERROR; // TODO error
}
Value a = this.pop();
if (!isNumber(a)) {
writeln("a is not a number!");
return InterpretResult.RUNTIME_ERROR; // TODO error
}
double bnum = asNumber(b);
double anum = asNumber(a);
push(makeNumberValue(anum - bnum));
break;
case OpCode.OP_LESS:
Value b = this.pop();
if (!isNumber(b)) {
writeln("b is not a number!");
return InterpretResult.RUNTIME_ERROR; // TODO error
}
Value a = this.pop();
if (!isNumber(a)) {
writeln("a is not a number!");
return InterpretResult.RUNTIME_ERROR; // TODO error
}
double bnum = asNumber(b);
double anum = asNumber(a);
push(makeBooleanValue(anum < bnum));
break;
case OpCode.OP_RETURN:
Value ret = this.pop();
writefln("returned %s", printableValue(ret));
return InterpretResult.OK;
default:
writeln("unknown opcode to run");
break;
}
}
}
}
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