eec7c0529c
This PR adds the beginnings of [AUTOVACUUM](https://www.sqlite.org/lang_vacuum.html) to Limbo. It adds a feature flag called `omit_autovacuum` which is analogous to `SQLITE_OMIT_AUTOVACUUM`. It is off by default, same as SQLite. It introduces the concept of [pointer map pages](https://www.sqlite.org/ fileformat.html#pointer_map_or_ptrmap_pages) which are reverse index pages used to map pages to their parents. This is used to swap pages (when a table is deleted for instance) to keep root pages clustered at the beginning of the file. It's also used while creating a table to ensure that root pages are clustered at the beginning (although, this isn't completely implemented yet) Finally, it also adds a couple of missing instructions like `Int64` that are required for `PRAGMA` commands related to `auto_vacuum` settings <img width="1512" alt="Screenshot 2025-05-28 at 8 47 51 PM" src="https://github.com/user- attachments/assets/d52eb74f-5b79-4d52-9401-1bdc2dcc304d" /> Closes #1600
LEMON parser generator modified to generate Rust code.
Lemon source and SQLite3 grammar were last synced as of July 2024.
Unsupported
Unsupported Grammar syntax
%token_destructor: Code to execute to destroy token data%default_destructor: Code for the default non-terminal destructor%destructor: Code which executes whenever this symbol is popped from the stack during error processing
https://www.codeproject.com/Articles/1056460/Generating-a-High-Speed-Parser-Part-Lemon https://www.sqlite.org/lemon.html
SQLite
SQLite lexer and SQLite parser have been ported from C to Rust. The parser generates an AST.
Lexer/Parser:
- Keep track of position (line, column).
- Streamable (stop at the end of statement).
- Resumable (restart after the end of statement).
Lexer and parser have been tested with the following scripts:
- https://github.com/bkiers/sqlite-parser/tree/master/src/test/resources
- https://github.com/codeschool/sqlite-parser/tree/master/test/sql/official-suite which can be updated with script in https://github.com/codeschool/sqlite-parser/tree/master/test/misc
TODO:
- Check generated AST (reparse/reinject)
- If a keyword in double quotes is used in a context where it cannot be resolved to an identifier but where a string literal is allowed, then the token is understood to be a string literal instead of an identifier.
- Tests
- Do not panic while parsing
- CREATE VIRTUAL TABLE args
- Zero copy (at least tokens)
Unsupported by Rust
#linedirective
API change
- No
ParseAlloc/ParseFreeanymore
Features not tested
- NDEBUG
- YYNOERRORRECOVERY
- YYERRORSYMBOL
To be fixed
- RHS are moved. Maybe it is not a problem if they are always used once. Just add a check in lemon...
%extra_argumentis not supported.- Terminal symbols generated by lemon should be dumped in a specified file.
Raison d'être
-
lemon_rust does the same thing but with an old version of
lemon. And it seems not possible to useyystackas a stack because items may be access randomly and thetop+1item can be used. -
lalrpop would be the perfect alternative but it does not support fallback/streaming (see this issue) and compilation/generation is slow.
Minimum supported Rust version (MSRV)
Latest stable Rust version at the time of release. It might compile with older versions.