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yggdrasil.execution.expr.backends.sql

sql

SQL emitter with dialect flavors + hand-rolled lifter.

:func:to_sql walks the AST and produces a SQL string for the named dialect. Identifier quoting, string-literal escaping, and a handful of dialect-specific keywords (ILIKE, TIMESTAMP literals) come from :class:Dialect.

:func:from_sql parses a SQL predicate string back into our AST via the in-module tokenizer + recursive-descent parser below — no third-party SQL parser dependency. The grammar covers the predicate-language subset every yggdrasil backend needs: comparisons, AND / OR / NOT, IN, BETWEEN, LIKE / ILIKE, IS [NOT] NULL, CAST, typed temporal literals (TIMESTAMP '…' / DATE '…'), function-call temporal coercions (TIMESTAMP('…') / DATE('…')), and the +/-/*///% arithmetic operators between columns and literals. Anything outside that surface raises a ValueError pointing at the offending token.

to_sql 

to_sql(expr: Expression, *, dialect: 'Dialect | str | None' = None) -> str

Emit expr as a SQL string in the chosen dialect.

from_sql 

from_sql(sql: str, *, dialect: 'Dialect | str | None' = None) -> Expression

Parse a SQL predicate string into our AST.

The grammar covers comparisons, AND / OR / NOT, IN (literal value list), BETWEEN, LIKE / ILIKE, IS [NOT] NULL, CAST(… AS …), typed temporal literals (TIMESTAMP '…' / DATE '…'), the function-call temporal coercion form (TIMESTAMP('…') / DATE('…')), and +/-/*///% arithmetic on columns and literals. Tokens outside that surface raise ValueError with the offending position.

Dialect selection only affects identifier / string-literal quoting: Databricks and MySQL accept "…" as a string literal (and \`…\``` as the identifier quote); ANSI / Postgres / SQLite treat"…"`` as the identifier quote.