comparison rust/hg-core/src/revlog/index.rs @ 50979:4c5f6e95df84

rust: make `Revision` a newtype

This change is the one we've been building towards during this series.
The aim is to make `Revision` mean more than a simple integer, holding
the information that it is valid for a given revlog index.
While this still allows for programmer error, since creating a revision
directly and querying a different index with a "checked" revision are
still possible, the friction created by the newtype will hopefully make
us think twice about which type to use.

Enough of the Rust ecosystem relies on the newtype pattern to be
efficiently optimized away (even compiler in codegen tests¹), so I'm not
worried about this being a fundamental problem.

[1] https://github.com/rust-lang/rust/blob/7a70647f195f6b0a0f1ebd72b1542ba91a32f43a/tests/codegen/vec-in-place.rs#L47

50978:27e773aa607d

    fn get_entry_inline(
        &self,
        rev: Revision,
        offsets: &[usize],
    ) -> IndexEntry {
        let start = offsets[rev as usize];
        let end = start + INDEX_ENTRY_SIZE;
        let bytes = &self.bytes[start..end];

        // See IndexEntry for an explanation of this override.
        let offset_override = Some(end);

            offset_override,
        }
    }

    fn get_entry_separated(&self, rev: Revision) -> IndexEntry {
        let start = rev as usize * INDEX_ENTRY_SIZE;
        let end = start + INDEX_ENTRY_SIZE;
        let bytes = &self.bytes[start..end];

        // Override the offset of the first revision as its bytes are used
        // for the index's metadata (saving space because it is always 0)
        let offset_override = if rev == 0 { Some(0) } else { None };

        IndexEntry {
            bytes,
            offset_override,
        }

                is_general_delta: true,
                version: 1,
                offset: 0,
                compressed_len: 0,
                uncompressed_len: 0,
                base_revision_or_base_of_delta_chain: 0,
                link_revision: 0,
                p1: NULL_REVISION,
                p2: NULL_REVISION,
                node: NULL_NODE,
            }
        }

            }
            bytes.extend(&[0u8; 2]); // Revision flags.
            bytes.extend(&(self.compressed_len as u32).to_be_bytes());
            bytes.extend(&(self.uncompressed_len as u32).to_be_bytes());
            bytes.extend(
                &self.base_revision_or_base_of_delta_chain.to_be_bytes(),
            );
            bytes.extend(&self.link_revision.to_be_bytes());
            bytes.extend(&self.p1.to_be_bytes());
            bytes.extend(&self.p2.to_be_bytes());
            bytes.extend(self.node.as_bytes());
            bytes.extend(vec![0u8; 12]);
            bytes
        }
    }

    }

    #[test]
    fn test_base_revision_or_base_of_delta_chain() {
        let bytes = IndexEntryBuilder::new()
            .with_base_revision_or_base_of_delta_chain(1)
            .build();
        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,
        };

        assert_eq!(entry.base_revision_or_base_of_delta_chain(), 1.into())
    }

    #[test]
    fn link_revision_test() {
        let bytes = IndexEntryBuilder::new().with_link_revision(123).build();

        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,
        };

        assert_eq!(entry.link_revision(), 123.into());
    }

    #[test]
    fn p1_test() {
        let bytes = IndexEntryBuilder::new().with_p1(123).build();

        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,
        };

        assert_eq!(entry.p1(), 123.into());
    }

    #[test]
    fn p2_test() {
        let bytes = IndexEntryBuilder::new().with_p2(123).build();

        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,
        };

50979:4c5f6e95df84

    fn get_entry_inline(
        &self,
        rev: Revision,
        offsets: &[usize],
    ) -> IndexEntry {
        let start = offsets[rev.0 as usize];
        let end = start + INDEX_ENTRY_SIZE;
        let bytes = &self.bytes[start..end];

        // See IndexEntry for an explanation of this override.
        let offset_override = Some(end);

            offset_override,
        }
    }

    fn get_entry_separated(&self, rev: Revision) -> IndexEntry {
        let start = rev.0 as usize * INDEX_ENTRY_SIZE;
        let end = start + INDEX_ENTRY_SIZE;
        let bytes = &self.bytes[start..end];

        // Override the offset of the first revision as its bytes are used
        // for the index's metadata (saving space because it is always 0)
        let offset_override = if rev == Revision(0) { Some(0) } else { None };

        IndexEntry {
            bytes,
            offset_override,
        }

                is_general_delta: true,
                version: 1,
                offset: 0,
                compressed_len: 0,
                uncompressed_len: 0,
                base_revision_or_base_of_delta_chain: Revision(0),
                link_revision: Revision(0),
                p1: NULL_REVISION,
                p2: NULL_REVISION,
                node: NULL_NODE,
            }
        }

            }
            bytes.extend(&[0u8; 2]); // Revision flags.
            bytes.extend(&(self.compressed_len as u32).to_be_bytes());
            bytes.extend(&(self.uncompressed_len as u32).to_be_bytes());
            bytes.extend(
                &self.base_revision_or_base_of_delta_chain.0.to_be_bytes(),
            );
            bytes.extend(&self.link_revision.0.to_be_bytes());
            bytes.extend(&self.p1.0.to_be_bytes());
            bytes.extend(&self.p2.0.to_be_bytes());
            bytes.extend(self.node.as_bytes());
            bytes.extend(vec![0u8; 12]);
            bytes
        }
    }

    }

    #[test]
    fn test_base_revision_or_base_of_delta_chain() {
        let bytes = IndexEntryBuilder::new()
            .with_base_revision_or_base_of_delta_chain(Revision(1))
            .build();
        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,
        };

        assert_eq!(entry.base_revision_or_base_of_delta_chain(), 1.into())
    }

    #[test]
    fn link_revision_test() {
        let bytes = IndexEntryBuilder::new()
            .with_link_revision(Revision(123))
            .build();

        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,
        };

        assert_eq!(entry.link_revision(), 123.into());
    }

    #[test]
    fn p1_test() {
        let bytes = IndexEntryBuilder::new().with_p1(Revision(123)).build();

        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,
        };

        assert_eq!(entry.p1(), 123.into());
    }

    #[test]
    fn p2_test() {
        let bytes = IndexEntryBuilder::new().with_p2(Revision(123)).build();

        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,
        };