Chapter 21.1 - 21.3

clox/src/chunk.h

@@ -9,6 +9,8 @@ typedef enum {
   OP_NIL,
   OP_TRUE,
   OP_FALSE,
+  OP_POP,
+  OP_DEFINE_GLOBAL,
   OP_EQUAL,
   OP_GREATER,
   OP_LESS,
@@ -18,6 +20,7 @@ typedef enum {
   OP_DIVIDE,
   OP_NOT,
   OP_NEGATE,
+  OP_PRINT,
   OP_RETURN,
 } OpCode;
 

clox/src/compiler.c

@@ -88,6 +88,15 @@ static void consume(TokenType type, const char *message) {
   errorAtCurrent(message);
 }
 
+static bool check(TokenType type) { return parser.current.type == type; }
+
+static bool match(TokenType type) {
+  if (!check(type))
+    return false;
+  advance();
+  return true;
+}
+
 static void emitByte(uint8_t byte) {
   writeChunk(currentChunk(), byte, parser.previous.line);
 }
@@ -123,8 +132,12 @@ static void endCompiler() {
 }
 
 static void expression();
+static void statement();
+static void declaration();
 static ParseRule *getRule(TokenType type);
 static void parsePrecedence(Precedence precedence);
+static uint8_t parseVariable(const char *name);
+static void defineVariable(uint8_t global);
 
 static void binary() {
   TokenType operatorType = parser.previous.type;
@@ -185,6 +198,74 @@ static void literal() {
 
 static void expression() { parsePrecedence(PREC_ASSIGNMENT); }
 
+static void varDeclaration() {
+  uint8_t global = parseVariable("Expect variable name.");
+
+  if (match(TOKEN_EQUAL)) {
+    expression();
+  } else {
+    emitByte(OP_NIL);
+  }
+  consume(TOKEN_SEMICOLON, "Expect ';' after variable declaration.");
+
+  defineVariable(global);
+}
+
+static void expressionStatement() {
+  expression();
+  consume(TOKEN_SEMICOLON, "Expect ';' after expression.");
+  emitByte(OP_POP);
+}
+
+static void printStatement() {
+  expression();
+  consume(TOKEN_SEMICOLON, "Expect ';' after value.");
+  emitByte(OP_PRINT);
+}
+
+static void synchronize() {
+  parser.panicMode = false;
+
+  while (parser.current.type != TOKEN_EOF) {
+    if (parser.previous.type == TOKEN_SEMICOLON)
+      return;
+    switch (parser.current.type) {
+    case TOKEN_CLASS:
+    case TOKEN_FUN:
+    case TOKEN_VAR:
+    case TOKEN_FOR:
+    case TOKEN_IF:
+    case TOKEN_WHILE:
+    case TOKEN_PRINT:
+    case TOKEN_RETURN:
+      return;
+
+    default:; /* Do nothing */
+    }
+  }
+
+  advance();
+}
+
+static void declaration() {
+  if (match(TOKEN_VAR)) {
+    varDeclaration();
+  } else {
+    statement();
+  }
+
+  if (parser.panicMode)
+    synchronize();
+}
+
+static void statement() {
+  if (match(TOKEN_PRINT)) {
+    printStatement();
+  } else {
+    expressionStatement();
+  }
+}
+
 static void number() {
   double value = strtod(parser.previous.start, NULL);
   emitConstant(NUMBER_VAL(value));
@@ -279,6 +360,19 @@ static void parsePrecedence(Precedence precedence) {
   }
 }
 
+static uint8_t identifierConstant(Token *name) {
+  return makeConstant(OBJ_VAL(copyString(name->start, name->length)));
+}
+
+static uint8_t parseVariable(const char *errorMessage) {
+  consume(TOKEN_IDENTIFIER, errorMessage);
+  return identifierConstant(&parser.previous);
+}
+
+static void defineVariable(uint8_t global) {
+  emitBytes(OP_DEFINE_GLOBAL, global);
+}
+
 static ParseRule *getRule(TokenType type) { return &rules[type]; }
 
 bool compile(const char *source, Chunk *chunk) {
@@ -289,8 +383,11 @@ bool compile(const char *source, Chunk *chunk) {
   parser.panicMode = false;
 
   advance();
-  expression();
-  consume(TOKEN_EOF, "Expect end of expression.");
+
+  while (!match(TOKEN_EOF)) {
+    declaration();
+  }
+
   endCompiler();
   return !parser.hadError;
 }

clox/src/debug.c

@@ -42,6 +42,10 @@ int disassembleInstruction(Chunk *chunk, int offset) {
     return simpleInstruction("OP_TRUE", offset);
   case OP_FALSE:
     return simpleInstruction("OP_FALSE", offset);
+  case OP_POP:
+    return simpleInstruction("OP_POP", offset);
+  case OP_DEFINE_GLOBAL:
+    return constantInstruction("OP_DEFINE_GLOBAL", chunk, offset);
   case OP_EQUAL:
     return simpleInstruction("OP_EQUAL", offset);
   case OP_GREATER:
@@ -60,6 +64,8 @@ int disassembleInstruction(Chunk *chunk, int offset) {
     return simpleInstruction("OP_NOT", offset);
   case OP_NEGATE:
     return simpleInstruction("OP_NEGATE", offset);
+  case OP_PRINT:
+    return simpleInstruction("OP_PRINT", offset);
   case OP_RETURN:
     return simpleInstruction("OP_RETURN", offset);
   default:

clox/src/main.c

@@ -66,7 +66,7 @@ int main(int argc, const char *argv[]) {
 
   if (argc == 1) {
     repl();
-  } else if (argc = 2) {
+  } else if (argc == 2) {
     runFile(argv[1]);
   } else {
     fprintf(stderr, "Usage: clox [path]\n");

clox/src/vm.c

@@ -29,10 +29,13 @@ static void runtimeError(const char *format, ...) {
 void initVM() {
   resetStack();
   vm.objects = NULL;
+
+  initTable(&vm.globals);
   initTable(&vm.strings);
 }
 
 void freeVM() {
+  freeTable(&vm.globals);
   freeTable(&vm.strings);
   freeObjects();
 }
@@ -70,6 +73,7 @@ static void concatenate() {
 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))) {                          \
@@ -108,6 +112,15 @@ static InterpretResult run() {
     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();
@@ -152,7 +165,15 @@ static InterpretResult run() {
       }
       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;
@@ -162,6 +183,7 @@ static InterpretResult run() {
 
 #undef READ_BYTE
 #undef READ_CONSTANT
+#undef READ_STRING
 #undef BINARY_OP
 }
 

clox/src/vm.h

@@ -12,6 +12,7 @@ typedef struct {
   uint8_t *ip;
   Value stack[STACK_MAX];
   Value *stackTop;
+  Table globals;
   Table strings;
   Obj *objects;
 } VM;