john-bodley / lacquer

SQL Parser derived from Presto, written in Python with the PLY framework

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lacquer is a python port of Presto's SQL Parser.

Currently, it doesn't support all the same features as Presto's parser, but it can parse most SELECT queries and produce the python-equivalent syntax tree, as well as write the tree back out to SQL.

It was written for LSST to support the Astronomical Data Query Language, which is roughly equivalent to SQL-92.

Advantages

  • Only two dependencies, PLY and future. Runs on Python 2 and 3 (tested on 2.7 and 3.5).
  • Uses the Presto AST IR and Visitor patterns
    • Code can easily be ported to lacquer from Python

Known issues

Only SELECT statements are currently supported. This is mostly the case with Presto as well.

In the porting, the grammar was ported from LL (ANTLRv4) to LALR (PLY). There's a few shift/reduce errors, but most queries parse just fine, but you may run across a few errors, for example:

select 1 from foo where bar in ((select 1 from baz), 2)

License

This work is licensed under Apache 2.0, the same as Presto.

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SQL Parser derived from Presto, written in Python with the PLY framework

License:Apache License 2.0


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