Add keyword "int" and make variable definition mandatory

chibicc.h

@@ -37,6 +37,7 @@ void error_at(char *loc, char *fmt, ...);
 void error_tok(Token *tok, char *fmt, ...);
 bool equal(Token *tok, char *op);
 Token *skip(Token *tok, char *op);
+bool consume(Token **rest, Token *tok, char *str);
 Token *tokenize(char *input);
 
 //
@@ -48,6 +49,7 @@ typedef struct Var Var;
 struct Var {
   Var *next;
   char *name; // Variable name
+  Type *ty;   // Type
   int offset; // Offset from RBP
 };
 
@@ -118,12 +120,18 @@ typedef enum {
 
 struct Type {
   TypeKind kind;
+
+  // Pointer
   Type *base;
+
+  // Declaration
+  Token *name;
 };
 
 extern Type *ty_int;
 
 bool is_integer(Type *ty);
+Type *pointer_to(Type *base);
 void add_type(Node *node);
 
 //

parse.c

@@ -22,6 +22,7 @@
 // accumulated to this list.
 Var *locals;
 
+static Node *declaration(Token **rest, Token *tok);
 static Node *compound_stmt(Token **rest, Token *tok);
 static Node *stmt(Token **rest, Token *tok);
 static Node *expr_stmt(Token **rest, Token *tok);
@@ -74,14 +75,70 @@ static Node *new_var_node(Var *var, Token *tok) {
   return node;
 }
 
-static Var *new_lvar(char *name) {
+static Var *new_lvar(char *name, Type *ty) {
   Var *var = calloc(1, sizeof(Var));
   var->name = name;
+  var->ty = ty;
   var->next = locals;
   locals = var;
   return var;
 }
 
+static char *get_ident(Token *tok) {
+  if (tok->kind != TK_IDENT)
+    error_tok(tok, "expected an identifier");
+  return strndup(tok->loc, tok->len);
+}
+
+// typespec = "int"
+static Type *typespec(Token **rest, Token *tok) {
+  *rest = skip(tok, "int");
+  return ty_int;
+}
+
+// declarator = "*"* ident
+static Type *declarator(Token **rest, Token *tok, Type *ty) {
+  while (consume(&tok, tok, "*"))
+    ty = pointer_to(ty);
+
+  if (tok->kind != TK_IDENT)
+    error_tok(tok, "expected a variable name");
+
+  ty->name = tok;
+  *rest = tok->next;
+  return ty;
+}
+
+// declaration = typespec (declarator ("=" expr)? ("," declarator ("=" expr)?)*)? ";"
+static Node *declaration(Token **rest, Token *tok) {
+  Type *basety = typespec(&tok, tok);
+
+  Node head = {};
+  Node *cur = &head;
+  int i = 0;
+
+  while (!equal(tok, ";")) {
+    if (i++ > 0)
+      tok = skip(tok, ",");
+
+    Type *ty = declarator(&tok, tok, basety);
+    Var *var = new_lvar(get_ident(ty->name), ty);
+
+    if (!equal(tok, "="))
+      continue;
+
+    Node *lhs = new_var_node(var, ty->name);
+    Node *rhs = assign(&tok, tok->next);
+    Node *node = new_binary(ND_ASSIGN, lhs, rhs, tok);
+    cur = cur->next = new_unary(ND_EXPR_STMT, node, tok);
+  }
+
+  Node *node = new_node(ND_BLOCK, tok);
+  node->body = head.next;
+  *rest = tok->next;
+  return node;
+}
+
 // stmt = "return" expr ";"
 //      | "if" "(" expr ")" stmt ("else" stmt)?
 //      | "for" "(" expr-stmt expr? ";" expr? ")" stmt
@@ -141,14 +198,17 @@ static Node *stmt(Token **rest, Token *tok) {
   return expr_stmt(rest, tok);
 }
 
-// compound-stmt = stmt* "}"
+// compound-stmt = (declaration | stmt)* "}"
 static Node *compound_stmt(Token **rest, Token *tok) {
   Node *node = new_node(ND_BLOCK, tok);
 
   Node head = {};
   Node *cur = &head;
   while (!equal(tok, "}")) {
-    cur = cur->next = stmt(&tok, tok);
+    if (equal(tok, "int"))
+      cur = cur->next = declaration(&tok, tok);
+    else
+      cur = cur->next = stmt(&tok, tok);
     add_type(cur);
   }
 
@@ -369,7 +429,7 @@ static Node *primary(Token **rest, Token *tok) {
   if (tok->kind == TK_IDENT) {
     Var *var = find_var(tok);
     if (!var)
-      var = new_lvar(strndup(tok->loc, tok->len));
+      error_tok(tok, "undefined variable");
     *rest = tok->next;
     return new_var_node(var, tok);
   }

test.sh

@@ -46,14 +46,15 @@ assert 1 '{ return 1>=0; }'
 assert 1 '{ return 1>=1; }'
 assert 0 '{ return 1>=2; }'
 
-assert 3 '{ a=3; return a; }'
+assert 3 '{ int a; a=3; return a; }'
-assert 8 '{ a=3; z=5; return a+z; }'
+assert 3 '{ int a=3; return a; }'
+assert 8 '{ int a=3; int z=5; return a+z; }'
 
-assert 3 '{ a=3; return a; }'
+assert 3 '{ int a=3; return a; }'
-assert 8 '{ a=3; z=5; return a+z; }'
+assert 8 '{ int a=3; int z=5; return a+z; }'
-assert 6 '{ a=b=3; return a+b; }'
+assert 6 '{ int a; int b; a=b=3; return a+b; }'
-assert 3 '{ foo=3; return foo; }'
+assert 3 '{ int foo=3; return foo; }'
-assert 8 '{ foo123=3; bar=5; return foo123+bar; }'
+assert 8 '{ int foo123=3; int bar=5; return foo123+bar; }'
 
 assert 1 '{ return 1; 2; 3; }'
 assert 2 '{ 1; return 2; 3; }'
@@ -69,18 +70,25 @@ assert 2 '{ if (2-1) return 2; return 3; }'
 assert 4 '{ if (0) { 1; 2; return 3; } else { return 4; } }'
 assert 3 '{ if (1) { 1; 2; return 3; } else { return 4; } }'
 
-assert 55 '{ i=0; j=0; for (i=0; i<=10; i=i+1) j=i+j; return j; }'
+assert 55 '{ int i=0; int j=0; for (i=0; i<=10; i=i+1) j=i+j; return j; }'
-assert 3 '{ for (;;) {return 3;} return 5; }'
+assert 3 '{ for (;;) return 3; return 5; }'
 
-assert 10 '{ i=0; while(i<10) { i=i+1; } return i; }'
+assert 10 '{ int i=0; while(i<10) i=i+1; return i; }'
 
-assert 3 '{ x=3; return *&x; }'
+assert 3 '{ {1; {2;} return 3;} }'
-assert 3 '{ x=3; y=&x; z=&y; return **z; }'
+
-assert 5 '{ x=3; y=5; return *(&x+1); }'
+assert 10 '{ int i=0; while(i<10) i=i+1; return i; }'
-assert 3 '{ x=3; y=5; return *(&y-1); }'
+assert 55 '{ int i=0; int j=0; while(i<=10) {j=i+j; i=i+1;} return j; }'
-assert 5 '{ x=3; y=&x; *y=5; return x; }'
+
-assert 7 '{ x=3; y=5; *(&x+1)=7; return y; }'
+assert 3 '{ int x=3; return *&x; }'
-assert 7 '{ x=3; y=5; *(&y-2+1)=7; return x; }'
+assert 3 '{ int x=3; int *y=&x; int **z=&y; return **z; }'
-assert 5 '{ x=3; return (&x+2)-&x+3; }'
+assert 5 '{ int x=3; int y=5; return *(&x+1); }'
+assert 3 '{ int x=3; int y=5; return *(&y-1); }'
+assert 5 '{ int x=3; int *y=&x; *y=5; return x; }'
+assert 7 '{ int x=3; int y=5; *(&x+1)=7; return y; }'
+assert 7 '{ int x=3; int y=5; *(&y-2+1)=7; return x; }'
+assert 5 '{ int x=3; return (&x+2)-&x+3; }'
+assert 8 '{ int x, y; x=3; y=5; return x+y; }'
+assert 8 '{ int x=3, y=5; return x+y; }'
 
 echo OK

tokenize.c

@@ -48,6 +48,15 @@ Token *skip(Token *tok, char *op) {
   return tok->next;
 }
 
+bool consume(Token **rest, Token *tok, char *str) {
+  if (equal(tok, str)) {
+    *rest = tok->next;
+    return true;
+  }
+  *rest = tok;
+  return false;
+}
+
 // Create a new token and add it as the next token of `cur`.
 static Token *new_token(TokenKind kind, Token *cur, char *str, int len) {
   Token *tok = calloc(1, sizeof(Token));
@@ -73,7 +82,7 @@ static bool is_ident2(char c) {
 }
 
 static bool is_keyword(Token *tok) {
-  static char *kw[] = {"return", "if", "else", "for", "while"};
+  static char *kw[] = {"return", "if", "else", "for", "while", "int"};
 
   for (int i = 0; i < sizeof(kw) / sizeof(*kw); i++)
     if (equal(tok, kw[i]))

type.c

@@ -40,18 +40,19 @@ void add_type(Node *node) {
   case ND_NE:
   case ND_LT:
   case ND_LE:
-  case ND_VAR:
   case ND_NUM:
     node->ty = ty_int;
     return;
+  case ND_VAR:
+    node->ty = node->var->ty;
+    return;
   case ND_ADDR:
     node->ty = pointer_to(node->lhs->ty);
     return;
   case ND_DEREF:
-    if (node->lhs->ty->kind == TY_PTR)
+    if (node->lhs->ty->kind != TY_PTR)
-      node->ty = node->lhs->ty->base;
+      error_tok(node->tok, "invalid pointer dereference");
-    else
+    node->ty = node->lhs->ty->base;
-      node->ty = ty_int;
     return;
   }
 }