Add left/right shift operator support (#3)

Parse "<<" and ">>" operator. Relevant test cases were appended.

codegen_x64.c

@@ -314,6 +314,12 @@ static void emit_binop_int_arith(Ast *ast)
         break;
     case '/':
         break;
+    case PUNCT_LSHIFT:
+        op = "sal";
+        break;
+    case PUNCT_RSHIFT:
+        op = "sar";
+        break;
     default:
         error("invalid operator '%d'", ast->type);
     }
@@ -327,6 +333,8 @@ static void emit_binop_int_arith(Ast *ast)
     if (ast->type == '/') {
         emit("mov $0, %%edx");
         emit("idiv %%rcx");
+    } else if (ast->type == PUNCT_LSHIFT || ast->type == PUNCT_RSHIFT) {
+        emit("%s %%cl, %%rax", op);
     } else {
         emit("%s %%rcx, %%rax", op);
     }

lexer.c

@@ -173,8 +173,6 @@ static Token *read_token_int(void)
     case ']':
     case '{':
     case '}':
-    case '<':
-    case '>':
     case '!':
     case '?':
     case ':':
@@ -195,6 +193,10 @@ static Token *read_token_int(void)
         return read_rep('&', '&', PUNCT_LOGAND);
     case '|':
         return read_rep('|', '|', PUNCT_LOGOR);
+    case '<':
+        return read_rep('<', '<', PUNCT_LSHIFT);
+    case '>':
+        return read_rep('>', '>', PUNCT_RSHIFT);
     case '"':
         return read_string();
     case '\'':

mzcc.h

@@ -43,6 +43,8 @@ enum {
     PUNCT_LOGAND,
     PUNCT_LOGOR,
     PUNCT_ARROW,
+    PUNCT_LSHIFT,
+    PUNCT_RSHIFT,
 };
 
 enum {

parser.c

@@ -321,6 +321,10 @@ static int eval_intexpr(Ast *ast)
         return eval_intexpr(ast->left) * eval_intexpr(ast->right);
     case '/':
         return eval_intexpr(ast->left) / eval_intexpr(ast->right);
+    case PUNCT_LSHIFT:
+        return eval_intexpr(ast->left) >> eval_intexpr(ast->right);
+    case PUNCT_RSHIFT:
+        return eval_intexpr(ast->left) << eval_intexpr(ast->right);
     default:
         error("Integer expression expected, but got %s", ast_to_string(ast));
         return 0; /* non-reachable */
@@ -343,6 +347,9 @@ static int priority(Token *tok)
     case '+':
     case '-':
         return 4;
+    case PUNCT_LSHIFT:
+    case PUNCT_RSHIFT:
+        return 5;
     case '<':
     case '>':
         return 6;
@@ -659,6 +666,11 @@ static Ast *read_expr_int(int prec)
         Ast *rest = read_expr_int(prec2 + (is_right_assoc(tok) ? 1 : 0));
         if (!rest)
             error("second operand missing");
+        if (is_punct(tok, PUNCT_LSHIFT) || is_punct(tok, PUNCT_RSHIFT)) {
+            if ((ast->ctype != ctype_int && ast->ctype != ctype_char) ||
+                (rest->ctype != ctype_int && rest->ctype != ctype_char))
+                error("invalid operand to shift");
+        }
         ast = ast_binop(get_punct(tok), ast, rest);
     }
 }
@@ -889,7 +901,8 @@ static Ast *read_if_stmt(void)
     expect(')');
     Ast *then = read_stmt();
     Token *tok = read_token();
-    if (!tok || get_ttype(tok) != TTYPE_IDENT || strcmp(get_ident(tok), "else")) {
+    if (!tok || get_ttype(tok) != TTYPE_IDENT ||
+        strcmp(get_ident(tok), "else")) {
         unget_token(tok);
         return ast_if(cond, then, NULL);
     }

tests/arith.c

@@ -61,6 +61,12 @@ int test_bitand()
     expect(1, 1 & 3);
 }
 
+int test_shift()
+{
+    expect(8, 4 << 1);
+    expect(3, 7 >> 1);
+}
+
 int main()
 {
     test_basic();
@@ -69,6 +75,6 @@ int main()
     test_ternary();
     test_logand();
     test_bitand();
-
+    test_shift();
     return 0;
 }