Add hex support

lexing.cpp

@@ -37,6 +37,13 @@ lex_is_numeric(U8 c){
   return result;
 }
 
+function B32
+lex_is_numeric_base16(U8 c){
+  B32 result = (c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') ||
+               (c >= 'a' && c <= 'f');
+  return result;
+}
+
 function B32
 lex_is_alphanumeric(U8 c){
   B32 result = lex_is_numeric(c) || lex_is_alphabetic(c);
@@ -73,20 +80,25 @@ token_error(Token *t, String error_val){
 }
 
 function void
-lex_parse_u64(Lexer *lexer, Token *t){
+lex_parse_u64(Lexer *lexer, Token *t, S64 base){
   Scratch scratch;
   Set_BigInt_Allocator(scratch);
 
   t->kind = TK_Integer;
-  BigInt m = bigint_u64(1); // @leak, it accumulates and potentially needs allocation
-  BigInt val10 = bigint_u64(10);
+  BigInt m = bigint_u64(1);
+  BigInt base_mul = bigint_u64(base);
   BigInt result = bigint_u64(0);
 
   for(S64 i = t->len - 1; i >= 0; --i){
-    BigInt val = bigint_u64(t->str[i] - '0'); // I dont think this is a leak, too small
-    BigInt new_val = bigint_mul(&val, &m); // @leak
-    result = bigint_add(&result, &new_val); // @leak
-    m = bigint_mul(&m, &val10); // @leak
+    U64 value = t->str[i];
+    if(t->str[i] >= 'a') value = value - 'a' + 10;
+    else if(t->str[i] >= 'A') value = value - 'A' + 10;
+    else value -= '0';
+
+    BigInt val = bigint_u64(value);
+    BigInt new_val = bigint_mul(&val, &m);
+    result = bigint_add(&result, &new_val);
+    m = bigint_mul(&m, &base_mul);
   }
 
   t->int_val = bigint_copy(lexer->arena, &result);
@@ -475,7 +487,23 @@ lex__stream(Lexer *lexer){
         }
       } break;
 
-      case '0':case '1':case '2':case '3':case '4':
+      case '0':{
+        if(lexc(s) == 'x'){
+          lex_advance(s);
+          while(lex_is_numeric_base16(lexc(s)))
+            lex_advance(s);
+          lex_set_len(s, &t);
+          t.str += 2;
+          t.len -= 2;
+          if(t.len == 0)
+            token_error(&t, "Hex constant doesn't have value"_s);
+          else
+            lex_parse_u64(lexer, &t, 16);
+          break;
+        }
+
+      }
+      case '1':case '2':case '3':case '4':
       case '5':case '6':case '7':case '8':case '9':{
         B32 found_dot = false;
         for(;;){
@@ -494,7 +522,7 @@ lex__stream(Lexer *lexer){
         }
         lex_set_len(s, &t);
         if(found_dot) lex_parse_f64(&t);
-        else          lex_parse_u64(lexer, &t);
+        else          lex_parse_u64(lexer, &t, 10);
 
       } break;