sqlglot/sqlglot/__init__.py

"""
.. include:: ../README.md
----
"""

from __future__ import annotations

import typing as t

from sqlglot import expressions as exp
from sqlglot.dialects import Dialect, Dialects
from sqlglot.diff import diff
from sqlglot.errors import ErrorLevel, ParseError, TokenError, UnsupportedError
from sqlglot.expressions import Expression
from sqlglot.expressions import alias_ as alias
from sqlglot.expressions import (
    and_,
    column,
    condition,
    except_,
    from_,
    intersect,
    maybe_parse,
    not_,
    or_,
    select,
    subquery,
)
from sqlglot.expressions import table_ as table
from sqlglot.expressions import to_column, to_table, union
from sqlglot.generator import Generator
from sqlglot.parser import Parser
from sqlglot.schema import MappingSchema, Schema
from sqlglot.tokens import Tokenizer, TokenType

__version__ = "10.6.0"

pretty = False
"""Whether to format generated SQL by default."""

schema = MappingSchema()
"""The default schema used by SQLGlot (e.g. in the optimizer)."""


def parse(
    sql: str, read: t.Optional[str | Dialect] = None, **opts
) -> t.List[t.Optional[Expression]]:
    """
    Parses the given SQL string into a collection of syntax trees, one per parsed SQL statement.

    Args:
        sql: the SQL code string to parse.
        read: the SQL dialect to apply during parsing (eg. "spark", "hive", "presto", "mysql").
        **opts: other `sqlglot.parser.Parser` options.

    Returns:
        The resulting syntax tree collection.
    """
    dialect = Dialect.get_or_raise(read)()
    return dialect.parse(sql, **opts)


def parse_one(
    sql: str,
    read: t.Optional[str | Dialect] = None,
    into: t.Optional[exp.IntoType] = None,
    **opts,
) -> Expression:
    """
    Parses the given SQL string and returns a syntax tree for the first parsed SQL statement.

    Args:
        sql: the SQL code string to parse.
        read: the SQL dialect to apply during parsing (eg. "spark", "hive", "presto", "mysql").
        into: the SQLGlot Expression to parse into.
        **opts: other `sqlglot.parser.Parser` options.

    Returns:
        The syntax tree for the first parsed statement.
    """

    dialect = Dialect.get_or_raise(read)()

    if into:
        result = dialect.parse_into(into, sql, **opts)
    else:
        result = dialect.parse(sql, **opts)

    for expression in result:
        if not expression:
            raise ParseError(f"No expression was parsed from '{sql}'")
        return expression
    else:
        raise ParseError(f"No expression was parsed from '{sql}'")


def transpile(
    sql: str,
    read: t.Optional[str | Dialect] = None,
    write: t.Optional[str | Dialect] = None,
    identity: bool = True,
    error_level: t.Optional[ErrorLevel] = None,
    **opts,
) -> t.List[str]:
    """
    Parses the given SQL string in accordance with the source dialect and returns a list of SQL strings transformed
    to conform to the target dialect. Each string in the returned list represents a single transformed SQL statement.

    Args:
        sql: the SQL code string to transpile.
        read: the source dialect used to parse the input string (eg. "spark", "hive", "presto", "mysql").
        write: the target dialect into which the input should be transformed (eg. "spark", "hive", "presto", "mysql").
        identity: if set to `True` and if the target dialect is not specified the source dialect will be used as both:
            the source and the target dialect.
        error_level: the desired error level of the parser.
        **opts: other `sqlglot.generator.Generator` options.

    Returns:
        The list of transpiled SQL statements.
    """
    write = write or read if identity else write
    return [
        Dialect.get_or_raise(write)().generate(expression, **opts)
        for expression in parse(sql, read, error_level=error_level)
    ]