1 files changed, 268 insertions, 0 deletions
diff --git a/sqlglot/dialects/dialect.py b/sqlglot/dialects/dialect.py
new file mode 100644
index 0000000..8045f7a
--- /dev/null
+++ b/sqlglot/dialects/dialect.py
@@ -0,0 +1,268 @@
+from enum import Enum
+
+from sqlglot import exp
+from sqlglot.generator import Generator
+from sqlglot.helper import csv, list_get
+from sqlglot.parser import Parser
+from sqlglot.time import format_time
+from sqlglot.tokens import Tokenizer
+from sqlglot.trie import new_trie
+
+
+class Dialects(str, Enum):
+    DIALECT = ""
+
+    BIGQUERY = "bigquery"
+    CLICKHOUSE = "clickhouse"
+    DUCKDB = "duckdb"
+    HIVE = "hive"
+    MYSQL = "mysql"
+    ORACLE = "oracle"
+    POSTGRES = "postgres"
+    PRESTO = "presto"
+    SNOWFLAKE = "snowflake"
+    SPARK = "spark"
+    SQLITE = "sqlite"
+    STARROCKS = "starrocks"
+    TABLEAU = "tableau"
+    TRINO = "trino"
+
+
+class _Dialect(type):
+    classes = {}
+
+    @classmethod
+    def __getitem__(cls, key):
+        return cls.classes[key]
+
+    @classmethod
+    def get(cls, key, default=None):
+        return cls.classes.get(key, default)
+
+    def __new__(cls, clsname, bases, attrs):
+        klass = super().__new__(cls, clsname, bases, attrs)
+        enum = Dialects.__members__.get(clsname.upper())
+        cls.classes[enum.value if enum is not None else clsname.lower()] = klass
+
+        klass.time_trie = new_trie(klass.time_mapping)
+        klass.inverse_time_mapping = {v: k for k, v in klass.time_mapping.items()}
+        klass.inverse_time_trie = new_trie(klass.inverse_time_mapping)
+
+        klass.tokenizer_class = getattr(klass, "Tokenizer", Tokenizer)
+        klass.parser_class = getattr(klass, "Parser", Parser)
+        klass.generator_class = getattr(klass, "Generator", Generator)
+
+        klass.tokenizer = klass.tokenizer_class()
+        klass.quote_start, klass.quote_end = list(klass.tokenizer_class.QUOTES.items())[
+            0
+        ]
+        klass.identifier_start, klass.identifier_end = list(
+            klass.tokenizer_class.IDENTIFIERS.items()
+        )[0]
+
+        return klass
+
+
+class Dialect(metaclass=_Dialect):
+    index_offset = 0
+    unnest_column_only = False
+    alias_post_tablesample = False
+    normalize_functions = "upper"
+    null_ordering = "nulls_are_small"
+
+    date_format = "'%Y-%m-%d'"
+    dateint_format = "'%Y%m%d'"
+    time_format = "'%Y-%m-%d %H:%M:%S'"
+    time_mapping = {}
+
+    # autofilled
+    quote_start = None
+    quote_end = None
+    identifier_start = None
+    identifier_end = None
+
+    time_trie = None
+    inverse_time_mapping = None
+    inverse_time_trie = None
+    tokenizer_class = None
+    parser_class = None
+    generator_class = None
+    tokenizer = None
+
+    @classmethod
+    def get_or_raise(cls, dialect):
+        if not dialect:
+            return cls
+        result = cls.get(dialect)
+        if not result:
+            raise ValueError(f"Unknown dialect '{dialect}'")
+        return result
+
+    @classmethod
+    def format_time(cls, expression):
+        if isinstance(expression, str):
+            return exp.Literal.string(
+                format_time(
+                    expression[1:-1],  # the time formats are quoted
+                    cls.time_mapping,
+                    cls.time_trie,
+                )
+            )
+        if expression and expression.is_string:
+            return exp.Literal.string(
+                format_time(
+                    expression.this,
+                    cls.time_mapping,
+                    cls.time_trie,
+                )
+            )
+        return expression
+
+    def parse(self, sql, **opts):
+        return self.parser(**opts).parse(self.tokenizer.tokenize(sql), sql)
+
+    def parse_into(self, expression_type, sql, **opts):
+        return self.parser(**opts).parse_into(
+            expression_type, self.tokenizer.tokenize(sql), sql
+        )
+
+    def generate(self, expression, **opts):
+        return self.generator(**opts).generate(expression)
+
+    def transpile(self, code, **opts):
+        return self.generate(self.parse(code), **opts)
+
+    def parser(self, **opts):
+        return self.parser_class(
+            **{
+                "index_offset": self.index_offset,
+                "unnest_column_only": self.unnest_column_only,
+                "alias_post_tablesample": self.alias_post_tablesample,
+                "null_ordering": self.null_ordering,
+                **opts,
+            },
+        )
+
+    def generator(self, **opts):
+        return self.generator_class(
+            **{
+                "quote_start": self.quote_start,
+                "quote_end": self.quote_end,
+                "identifier_start": self.identifier_start,
+                "identifier_end": self.identifier_end,
+                "escape": self.tokenizer_class.ESCAPE,
+                "index_offset": self.index_offset,
+                "time_mapping": self.inverse_time_mapping,
+                "time_trie": self.inverse_time_trie,
+                "unnest_column_only": self.unnest_column_only,
+                "alias_post_tablesample": self.alias_post_tablesample,
+                "normalize_functions": self.normalize_functions,
+                "null_ordering": self.null_ordering,
+                **opts,
+            }
+        )
+
+
+def rename_func(name):
+    return (
+        lambda self, expression: f"{name}({csv(*[self.sql(e) for e in expression.args.values()])})"
+    )
+
+
+def approx_count_distinct_sql(self, expression):
+    if expression.args.get("accuracy"):
+        self.unsupported("APPROX_COUNT_DISTINCT does not support accuracy")
+    return f"APPROX_COUNT_DISTINCT({self.sql(expression, 'this')})"
+
+
+def if_sql(self, expression):
+    expressions = csv(
+        self.sql(expression, "this"),
+        self.sql(expression, "true"),
+        self.sql(expression, "false"),
+    )
+    return f"IF({expressions})"
+
+
+def arrow_json_extract_sql(self, expression):
+    return f"{self.sql(expression, 'this')}->{self.sql(expression, 'path')}"
+
+
+def arrow_json_extract_scalar_sql(self, expression):
+    return f"{self.sql(expression, 'this')}->>{self.sql(expression, 'path')}"
+
+
+def inline_array_sql(self, expression):
+    return f"[{self.expressions(expression)}]"
+
+
+def no_ilike_sql(self, expression):
+    return self.like_sql(
+        exp.Like(
+            this=exp.Lower(this=expression.this),
+            expression=expression.args["expression"],
+        )
+    )
+
+
+def no_paren_current_date_sql(self, expression):
+    zone = self.sql(expression, "this")
+    return f"CURRENT_DATE AT TIME ZONE {zone}" if zone else "CURRENT_DATE"
+
+
+def no_recursive_cte_sql(self, expression):
+    if expression.args.get("recursive"):
+        self.unsupported("Recursive CTEs are unsupported")
+        expression.args["recursive"] = False
+    return self.with_sql(expression)
+
+
+def no_safe_divide_sql(self, expression):
+    n = self.sql(expression, "this")
+    d = self.sql(expression, "expression")
+    return f"IF({d} <> 0, {n} / {d}, NULL)"
+
+
+def no_tablesample_sql(self, expression):
+    self.unsupported("TABLESAMPLE unsupported")
+    return self.sql(expression.this)
+
+
+def no_trycast_sql(self, expression):
+    return self.cast_sql(expression)
+
+
+def str_position_sql(self, expression):
+    this = self.sql(expression, "this")
+    substr = self.sql(expression, "substr")
+    position = self.sql(expression, "position")
+    if position:
+        return f"STRPOS(SUBSTR({this}, {position}), {substr}) + {position} - 1"
+    return f"STRPOS({this}, {substr})"
+
+
+def struct_extract_sql(self, expression):
+    this = self.sql(expression, "this")
+    struct_key = self.sql(exp.Identifier(this=expression.expression, quoted=True))
+    return f"{this}.{struct_key}"
+
+
+def format_time_lambda(exp_class, dialect, default=None):
+    """Helper used for time expressions.
+
+    Args
+        exp_class (Class): the expression class to instantiate
+        dialect (string): sql dialect
+        default (Option[bool | str]): the default format, True being time
+    """
+
+    def _format_time(args):
+        return exp_class(
+            this=list_get(args, 0),
+            format=Dialect[dialect].format_time(
+                list_get(args, 1)
+                or (Dialect[dialect].time_format if default is True else default)
+            ),
+        )
+
+    return _format_time