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#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include "common.h"
#include "compiler.h"
#include "debug.h"
#include "memory.h"
#include "object.h"
#include "vm.h"
VM vm;
static void resetStack() { vm.stackTop = vm.stack; }
static void runtimeError(const char *format, ...) {
va_list args;
va_start(args, format);
vfprintf(stderr, format, args);
va_end(args);
fputs("\n", stderr);
size_t instruction = vm.ip - vm.chunk->code - 1;
int line = vm.chunk->lines[instruction];
fprintf(stderr, "[line %d] in script\n", line);
resetStack();
}
void initVM() {
resetStack();
vm.objects = NULL;
initTable(&vm.globals);
initTable(&vm.strings);
}
void freeVM() {
freeTable(&vm.globals);
freeTable(&vm.strings);
freeObjects();
}
void push(Value value) {
*vm.stackTop = value;
vm.stackTop++;
}
Value pop() {
vm.stackTop--;
return *vm.stackTop;
}
static Value peek(int distance) { return vm.stackTop[-1 - distance]; }
static bool isFalsey(Value value) {
return IS_NIL(value) || (IS_BOOL(value) && !AS_BOOL(value));
}
static void concatenate() {
ObjString *b = AS_STRING(pop());
ObjString *a = AS_STRING(pop());
int length = a->length + b->length;
char *chars = ALLOCATE(char, length + 1);
memcpy(chars, a->chars, a->length);
memcpy(chars + a->length, b->chars, b->length);
chars[length] = '\0';
ObjString *result = takeString(chars, length);
push(OBJ_VAL(result));
}
static InterpretResult run() {
#define READ_BYTE() (*vm.ip++)
#define READ_CONSTANT() (vm.chunk->constants.values[READ_BYTE()])
#define READ_STRING() AS_STRING(READ_CONSTANT())
#define BINARY_OP(valueType, op) \
do { \
if (!IS_NUMBER(peek(0)) || !IS_NUMBER(peek(1))) { \
runtimeError("Operands must be numbers."); \
} \
double b = AS_NUMBER(pop()); \
double a = AS_NUMBER(pop()); \
push(valueType(a op b)); \
} while (false)
for (;;) {
#ifdef DEBUG_TRACE_EXECUTION
printf(" ");
for (Value *slot = vm.stack; slot < vm.stackTop; slot++) {
printf("[ ");
printValue(*slot);
printf(" ]");
}
printf("\n");
disassembleInstruction(vm.chunk, (int)(vm.ip - vm.chunk->code));
#endif
uint8_t instruction;
switch (instruction = READ_BYTE()) {
case OP_CONSTANT: {
Value constant = READ_CONSTANT();
push(constant);
break;
}
case OP_NIL:
push(NIL_VAL);
break;
case OP_TRUE:
push(BOOL_VAL(true));
break;
case OP_FALSE:
push(BOOL_VAL(false));
break;
case OP_POP:
pop();
break;
case OP_DEFINE_GLOBAL: {
ObjString *name = READ_STRING();
tableSet(&vm.globals, name, peek(0));
pop();
break;
}
case OP_EQUAL: {
Value b = pop();
Value a = pop();
push(BOOL_VAL(valuesEqual(a, b)));
break;
}
case OP_GREATER:
BINARY_OP(BOOL_VAL, >);
break;
case OP_LESS:
BINARY_OP(BOOL_VAL, <);
break;
case OP_ADD: {
if (IS_STRING(peek(0)) && IS_STRING(peek(1))) {
concatenate();
} else if (IS_NUMBER(peek(0)) && IS_NUMBER(peek(1))) {
double b = AS_NUMBER(pop());
double a = AS_NUMBER(pop());
push(NUMBER_VAL(a + b));
} else {
runtimeError("Operands must be two numbers or two strings.");
return INTERPRET_RUNTIME_ERROR;
}
break;
}
case OP_SUBTRACT:
BINARY_OP(NUMBER_VAL, -);
break;
case OP_MULTIPLY:
BINARY_OP(NUMBER_VAL, *);
break;
case OP_DIVIDE:
BINARY_OP(NUMBER_VAL, /);
break;
case OP_NOT:
push(BOOL_VAL(isFalsey(pop())));
break;
case OP_NEGATE:
if (!IS_NUMBER(peek(0))) {
runtimeError("Operand must be a number.");
return INTERPRET_RUNTIME_ERROR;
}
push(NUMBER_VAL(-AS_NUMBER(pop())));
break;
case OP_PRINT: {
printValue(pop());
printf("\n");
break;
}
case OP_RETURN: {
/* The book said to remove this, but when I do I get an infinite loop and
then a segfault because it keeps trying to add the constant 1 to the
stack. */
printValue(pop());
printf("\n");
return INTERPRET_OK;
}
}
}
#undef READ_BYTE
#undef READ_CONSTANT
#undef READ_STRING
#undef BINARY_OP
}
InterpretResult interpret(const char *source) {
Chunk chunk;
initChunk(&chunk);
if (!compile(source, &chunk)) {
freeChunk(&chunk);
return INTERPRET_COMPILE_ERROR;
}
vm.chunk = &chunk;
vm.ip = vm.chunk->code;
InterpretResult result = run();
freeChunk(&chunk);
return result;
}
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