feat: implement format strings

src/compiler/fzl_parser.c

@@ -151,6 +151,91 @@ fzl_node_t *parse_primary(fzl_parser_t *parser)
     fzl_token_t *tok = consume(parser);
     return fzl_mknode(FZL_NODETYPE_LITERAL, tok);
   }
+  else if (is(parser, FZL_TOKTYPE_STR_FORMAT_START))
+  {
+    consume(parser);
+
+    size_t remainder     = 2;
+    size_t count         = 0;
+    fzl_node_t **entries = malloc(remainder * sizeof(fzl_node_t *));
+    if (!entries)
+    {
+      snprintf(plast_err, sizeof(plast_err), "out of memory");
+      return NULL;
+    }
+
+    while (peek(parser) && peek(parser)->type != FZL_TOKTYPE_STR_FORMAT_END)
+    {
+      if (remainder <= count)
+      {
+        remainder *= 2;
+        entries = realloc(entries, remainder * sizeof(fzl_node_t *));
+        if (!entries)
+        {
+          snprintf(plast_err, sizeof(plast_err), "out of memory");
+          return NULL;
+        }
+      }
+
+      if (is(parser, FZL_TOKTYPE_STR_FORMAT_END))
+        break;
+
+      fzl_node_t *expr = parse_expression(parser);
+      if (!expr)
+      {
+        for (size_t i = 0; i < count; i++)
+          fzl_freeast(entries[i]);
+
+        free(entries);
+        return NULL;
+      }
+
+      entries[count++] = expr;
+    }
+    fzl_token_t *end = consume(parser);
+    if (end->type != FZL_TOKTYPE_STR_FORMAT_END)
+    {
+      snprintf(plast_err, sizeof(plast_err),
+               "'%s':%zu:%zu => unterminated format string",
+               last_known_tok->filename, last_known_tok->ln,
+               last_known_tok->cn);
+
+      for (size_t i = 0; i < count; i++)
+        fzl_freeast(entries[i]);
+
+      free(entries);
+    }
+
+    if (count < 1)
+    {
+      snprintf(plast_err, sizeof(plast_err),
+               "'%s':%zu:%zu => do you really need empty format string?",
+               last_known_tok->filename, last_known_tok->ln,
+               last_known_tok->cn);
+
+      for (size_t i = 0; i < count; i++)
+        fzl_freeast(entries[i]);
+
+      free(entries);
+      return NULL;
+    }
+
+    fzl_node_t *node = fzl_mknode(FZL_NODETYPE_FMT_STRING, entries[0]->token);
+    if (!node)
+    {
+      snprintf(plast_err, sizeof(plast_err), "out of memory");
+      for (size_t i = 0; i < count; i++)
+        fzl_freeast(entries[i]);
+
+      free(entries);
+      return NULL;
+    }
+
+    node->list.entries     = entries;
+    node->list.entry_count = count;
+
+    return node;
+  }
   else if (is(parser, FZL_TOKTYPE_LPAREN))
   {
     consume(parser);
@@ -1308,6 +1393,7 @@ void fzl_freeast(fzl_node_t *root)
       case FZL_NODETYPE_LITERAL:
         break;
 
+      case FZL_NODETYPE_FMT_STRING:
       case FZL_NODETYPE_BLOCK:
         if (root->list.entries)
         {