On Thu, 9 May 2024 18:26:17 GMT, Maurizio Cimadamore <mcimadam...@openjdk.org> wrote:
>> Consider this layout: >> >> >> MemoryLayout SEQ = MemoryLayout.sequenceLayout(5, >> MemoryLayout.sequenceLayout(10, JAVA_INT)); >> >> >> And the corresponding offset handle: >> >> >> MethodHandle offsetHandle = SEQ.offsetHandle(PathElement.sequenceLayout(), >> PathElement.sequenceLayout()); >> >> >> The resulting method handle takes two additional `long` indices. The >> implementation checks that the dynamically provided indices conform to the >> bound available at construction: that is, the first index must be < 5, while >> the second must be < 10. If this is not true, an `IndexOutOfBoundException` >> is thrown. >> >> However, the javadoc for `MemoryLayout::byteOffsetHandle` doesn't claim >> anything in this direction. There are only some vague claims in the javadoc >> for `PathElement::sequenceElement()` and `PathElement::sequenceElement(long, >> long, long)` which make some claims on which indices are actually allowed, >> but the text seems more in the tone of a discussion, rather than actual >> normative text. >> >> I've tweaked the javadoc for `MemoryLayout::byteOffsetHandle` to actually >> state that the indices will be checked against the "size" of the >> corresponding open path element (this is a new concept that I also have >> defined in the javadoc). >> >> I also added a test for `byteOffsetHandle` as I don't think we had a test >> for that specifically (although this method is tested indirectly, via >> `MemoryLayout::varHandle`). > > Maurizio Cimadamore has updated the pull request incrementally with two > additional commits since the last revision: > > - Update copyright > - Add javadoc to other MemoryLayout methods returning VarHandle/MethodHandle > to describe which exception can be thrown by returned handle src/java.base/share/classes/java/lang/foreign/MemoryLayout.java line 574: > 572: * {@code c_1}, {@code c_2}, ... {@code c_m} are other > <em>static</em> offset > 573: * constants (such as field offsets) which are derived from the > layout path. > 574: * <p> Can we connected back to the prior paragraph? e.g., for any given dynamic argument `x_n`, the index into the sequence associated with the n'th open path element whose size is `size_n`,`x_n` must be `>= 0` or `< size_n` ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/19158#discussion_r1595836040