Accept multiple statements separated by semicolons

chibicc.h

@@ -38,22 +38,24 @@ Token *tokenize(char *input);
 //
 
 typedef enum {
-  ND_ADD, // +
-  ND_SUB, // -
-  ND_MUL, // *
-  ND_DIV, // /
-  ND_NEG, // unary -
-  ND_EQ,  // ==
-  ND_NE,  // !=
-  ND_LT,  // <
-  ND_LE,  // <=
-  ND_NUM, // Integer
+  ND_ADD,       // +
+  ND_SUB,       // -
+  ND_MUL,       // *
+  ND_DIV,       // /
+  ND_NEG,       // unary -
+  ND_EQ,        // ==
+  ND_NE,        // !=
+  ND_LT,        // <
+  ND_LE,        // <=
+  ND_EXPR_STMT, // Expression statement
+  ND_NUM,       // Integer
 } NodeKind;
 
 // AST node type
 typedef struct Node Node;
 struct Node {
   NodeKind kind; // Node kind
+  Node *next;    // Next node
   Node *lhs;     // Left-hand side
   Node *rhs;     // Right-hand side
   int val;       // Used if kind == ND_NUM

codegen.c

@@ -64,12 +64,23 @@ static void gen_expr(Node *node) {
   error("invalid expression");
 }
 
+static void gen_stmt(Node *node) {
+  if (node->kind == ND_EXPR_STMT) {
+    gen_expr(node->lhs);
+    return;
+  }
+
+  error("invalid statement");
+}
+
 void codegen(Node *node) {
   printf("  .globl main\n");
   printf("main:\n");
 
-  gen_expr(node);
-  printf("  ret\n");
+  for (Node *n = node; n; n = n->next) {
+    gen_stmt(n);
+    assert(depth == 0);
+  }
 
-  assert(depth == 0);
+  printf("  ret\n");
 }

parse.c

@@ -1,6 +1,7 @@
 #include "chibicc.h"
 
 static Node *expr(Token **rest, Token *tok);
+static Node *expr_stmt(Token **rest, Token *tok);
 static Node *equality(Token **rest, Token *tok);
 static Node *relational(Token **rest, Token *tok);
 static Node *add(Token **rest, Token *tok);
@@ -33,6 +34,18 @@ static Node *new_num(int val) {
   return node;
 }
 
+// stmt = expr-stmt
+static Node *stmt(Token **rest, Token *tok) {
+  return expr_stmt(rest, tok);
+}
+
+// expr-stmt = expr ";"
+static Node *expr_stmt(Token **rest, Token *tok) {
+  Node *node = new_unary(ND_EXPR_STMT, expr(&tok, tok));
+  *rest = skip(tok, ";");
+  return node;
+}
+
 // expr = equality
 static Node *expr(Token **rest, Token *tok) {
   return equality(rest, tok);
@@ -157,9 +170,11 @@ static Node *primary(Token **rest, Token *tok) {
   error_tok(tok, "expected an expression");
 }
 
+// program = stmt*
 Node *parse(Token *tok) {
-  Node *node = expr(&tok, tok);
-  if (tok->kind != TK_EOF)
-    error_tok(tok, "extra token");
-  return node;
+  Node head = {};
+  Node *cur = &head;
+  while (tok->kind != TK_EOF)
+    cur = cur->next = stmt(&tok, tok);
+  return head.next;
 }

test.sh

@@ -16,34 +16,36 @@ assert() {
   fi
 }
 
-assert 0 0
-assert 42 42
-assert 21 '5+20-4'
-assert 41 ' 12 + 34 - 5 '
-assert 47 '5+6*7'
-assert 15 '5*(9-6)'
-assert 4 '(3+5)/2'
-assert 10 '-10+20'
-assert 10 '- -10'
-assert 10 '- - +10'
+assert 0 '0;'
+assert 42 '42;'
+assert 21 '5+20-4;'
+assert 41 ' 12 + 34 - 5 ;'
+assert 47 '5+6*7;'
+assert 15 '5*(9-6);'
+assert 4 '(3+5)/2;'
+assert 10 '-10+20;'
+assert 10 '- -10;'
+assert 10 '- - +10;'
 
-assert 0 '0==1'
-assert 1 '42==42'
-assert 1 '0!=1'
-assert 0 '42!=42'
+assert 0 '0==1;'
+assert 1 '42==42;'
+assert 1 '0!=1;'
+assert 0 '42!=42;'
 
-assert 1 '0<1'
-assert 0 '1<1'
-assert 0 '2<1'
-assert 1 '0<=1'
-assert 1 '1<=1'
-assert 0 '2<=1'
+assert 1 '0<1;'
+assert 0 '1<1;'
+assert 0 '2<1;'
+assert 1 '0<=1;'
+assert 1 '1<=1;'
+assert 0 '2<=1;'
 
-assert 1 '1>0'
-assert 0 '1>1'
-assert 0 '1>2'
-assert 1 '1>=0'
-assert 1 '1>=1'
-assert 0 '1>=2'
+assert 1 '1>0;'
+assert 0 '1>1;'
+assert 0 '1>2;'
+assert 1 '1>=0;'
+assert 1 '1>=1;'
+assert 0 '1>=2;'
+
+assert 3 '1; 2; 3;'
 
 echo OK