Add character literal

test/literal.c

+#include "test.h"
+
+int main() {
+  ASSERT(97, 'a');
+  ASSERT(10, '\n');
+  ASSERT(-128, '\x80');
+
+  printf("OK\n");
+  return 0;
+}

tokenize.c

@@ -205,6 +205,26 @@ static Token *read_string_literal(Token *cur, char *start) {
   return tok;
 }
 
+static Token *read_char_literal(Token *cur, char *start) {
+  char *p = start + 1;
+  if (*p == '\0')
+    error_at(start, "unclosed char literal");
+
+  char c;
+  if (*p == '\\')
+    c = read_escaped_char(&p, p + 1);
+  else
+    c = *p++;
+
+  char *end = strchr(p, '\'');
+  if (!end)
+    error_at(p, "unclosed char literal");
+
+  Token *tok = new_token(TK_NUM, cur, start, end - start + 1);
+  tok->val = c;
+  return tok;
+}
+
 static void convert_keywords(Token *tok) {
   for (Token *t = tok; t->kind != TK_EOF; t = t->next)
     if (is_keyword(t))
@@ -273,6 +293,13 @@ static Token *tokenize(char *filename, char *p) {
       continue;
     }
 
+    // Character literal
+    if (*p == '\'') {
+      cur = read_char_literal(cur, p);
+      p += cur->len;
+      continue;
+    }
+
     // Identifier or keyword
     if (is_ident1(*p)) {
       char *q = p++;