Function tree_sitter::ffi::ts_parser_parse

source · 
pub unsafe extern "C" fn ts_parser_parse(
    self_: *mut TSParser,
    old_tree: *const TSTree,
    input: TSInput
) -> *mut TSTree
Expand description

Use the parser to parse some source code and create a syntax tree.

If you are parsing this document for the first time, pass NULL for the old_tree parameter. Otherwise, if you have already parsed an earlier version of this document and the document has since been edited, pass the previous syntax tree so that the unchanged parts of it can be reused. This will save time and memory. For this to work correctly, you must have already edited the old syntax tree using the ts_tree_edit function in a way that exactly matches the source code changes.

The TSInput parameter lets you specify how to read the text. It has the following three fields:

  1. read: A function to retrieve a chunk of text at a given byte offset and (row, column) position. The function should return a pointer to the text and write its length to the bytes_read pointer. The parser does not take ownership of this buffer; it just borrows it until it has finished reading it. The function should write a zero value to the bytes_read pointer to indicate the end of the document.
  2. payload: An arbitrary pointer that will be passed to each invocation of the read function.
  3. encoding: An indication of how the text is encoded. Either TSInputEncodingUTF8 or TSInputEncodingUTF16.

This function returns a syntax tree on success, and NULL on failure. There are four possible reasons for failure:

  1. The parser does not have a language assigned. Check for this using the ts_parser_language function.
  2. Parsing was cancelled due to a timeout that was set by an earlier call to the ts_parser_set_timeout_micros function. You can resume parsing from where the parser left out by calling ts_parser_parse again with the same arguments. Or you can start parsing from scratch by first calling ts_parser_reset.
  3. Parsing was cancelled using a cancellation flag that was set by an earlier call to ts_parser_set_cancellation_flag. You can resume parsing from where the parser left out by calling ts_parser_parse again with the same arguments.
  4. Parsing was cancelled due to the progress callback returning true. This callback is passed in ts_parser_parse_with_options inside the TSParseOptions struct.