Parse with callback can't be cancelled

[ObserverOfTime]

The parse(String) method can be cancelled, but the parse(ParseCallback) method cannot.
Neither the timeout nor the cancellation flag work and I have no idea why.

[Sigma42]

I think cancelation works (on the current treesitter versions), and the problem is just the callback of the test(s).

With a callback like:

java-tree-sitter/src/test/java/io/github/treesitter/jtreesitter/ParserTest.java

Line 115 in c3464e7

ParseCallback callback = (offset, p) -> source.substring(offset, Integer.min(offset, source.length()));

and a starting offset of 0 it will be source.substring(0,0) and that will always be "".
Then treesitter interprets that as:

• parsing is done
  • before any actual parsing step happens, so the cancelation flag and timeout never get checked.
• sourcecode is empty
  • because Java's grammar accepts that as a 'program' node, both asserts succeeded

    java-tree-sitter/src/test/java/io/github/treesitter/jtreesitter/ParserTest.java

    Lines 118 to 119 in c3464e7

    	assertNull(tree.getText());
    	assertEquals("program", tree.getRootNode().getType());

If the callback reads, at least one byte each time it's called, it parses the file correctly, and it is canceled by flag and by timeout.
Examples (all of these tests succeed locally on my machine):

• reading 1 byte each callback call
• reading full text in first callback call
• timeout while reading 1 byte each callback call
• timeout while reading full text in first callback call
• cancelation while reading 1 byte each callback call
• cancelation while reading full text in first callback call