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# EFILTER Forensic Query Language
#
# Copyright 2015 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
This module implements the DottySQL grammar (on tokens, not on a query string).
"""
__author__ = "Adam Sindelar <adamsh@google.com>"
from efilter import ast
from efilter import errors
from efilter.parsers.common import ast_transforms as transforms
from efilter.parsers.common import grammar as common
# DottySQL's operator table. The parser only supports pure prefix and infix
# operators, as well as infix operators that have a suffix (like x[y]).
#
# Circumfix and pure suffix operators can be declared, but won't do anything.
OPERATORS = common.OperatorTable(
# Infix operators:
common.Operator(name="or", precedence=0, assoc="left",
handler=ast.Union, docstring="Logical OR.",
prefix=None, suffix=None,
infix=common.Token("symbol", "or")),
common.Operator(name="and", precedence=1, assoc="left",
handler=ast.Intersection, docstring="Logical AND.",
prefix=None, suffix=None,
infix=common.Token("symbol", "and")),
common.Operator(name="==", precedence=3, assoc="left",
handler=ast.Equivalence,
docstring="Equivalence.",
prefix=None, suffix=None,
infix=common.Token("symbol", "==")),
common.Operator(name="=", precedence=3, assoc="left",
handler=ast.Equivalence,
docstring="Equivalence (same as '==').",
prefix=None, suffix=None,
infix=common.Token("symbol", "=")),
common.Operator(name="=~", precedence=3, assoc="left",
handler=ast.RegexFilter,
docstring="Left-hand operand where regex.",
prefix=None, suffix=None,
infix=common.Token("symbol", "=~")),
common.Operator(name="!=", precedence=3, assoc="left",
handler=transforms.ComplementEquivalence,
docstring="Inequivalence (same as not (x == y)).",
prefix=None, suffix=None,
infix=common.Token("symbol", "!=")),
common.Operator(name="not in", precedence=3, assoc="left",
handler=transforms.ComplementMembership,
docstring="Left-hand operand is not in list.",
prefix=None, suffix=None,
infix=(common.Token("symbol", "not"),
common.Token("symbol", "in"))),
common.Operator(name="in", precedence=3, assoc="left",
handler=ast.Membership,
docstring="Left-hand operand is in list.",
prefix=None, suffix=None,
infix=common.Token("symbol", "in")),
common.Operator(name="isa", precedence=3, assoc="left",
handler=ast.IsInstance,
docstring="LHS must be instance of RHS.",
prefix=None, suffix=None,
infix=common.Token("symbol", "isa")),
common.Operator(name=">=", precedence=3, assoc="left",
handler=ast.PartialOrderedSet,
docstring="Equal-or-greater-than.", prefix=None,
suffix=None, infix=common.Token("symbol", ">=")),
common.Operator(name="<=", precedence=3, assoc="left",
handler=transforms.ReversePartialOrderedSet,
docstring="Equal-or-less-than.", prefix=None,
suffix=None, infix=common.Token("symbol", "<=")),
common.Operator(name=">", precedence=3, assoc="left",
handler=ast.StrictOrderedSet,
docstring="Greater-than.", prefix=None, suffix=None,
infix=common.Token("symbol", ">")),
common.Operator(name="<", precedence=3, assoc="left",
handler=transforms.ReverseStrictOrderedSet,
docstring="Less-than.", prefix=None, suffix=None,
infix=common.Token("symbol", "<")),
common.Operator(name="+", precedence=4, assoc="left", handler=ast.Sum,
docstring="Arithmetic addition.", prefix=None,
suffix=None, infix=common.Token("symbol", "+")),
common.Operator(name="-", precedence=4, assoc="left",
handler=ast.Difference,
docstring="Arithmetic subtraction.", prefix=None,
suffix=None, infix=common.Token("symbol", "-")),
common.Operator(name="*", precedence=6, assoc="left",
handler=ast.Product,
docstring="Arithmetic multiplication.", prefix=None,
suffix=None, infix=common.Token("symbol", "*")),
common.Operator(name="/", precedence=6, assoc="left",
handler=ast.Quotient,
docstring="Arithmetic division.", prefix=None,
suffix=None, infix=common.Token("symbol", "/")),
common.Operator(name=":", precedence=10, assoc="left",
handler=ast.Pair,
docstring="Key/value pair.", prefix=None,
suffix=None, infix=common.Token("symbol", ":")),
common.Operator(name=".", precedence=12, assoc="left",
handler=ast.Resolve,
docstring="OBJ.MEMBER -> return MEMBER of OBJ.",
prefix=None, suffix=None,
infix=common.Token("symbol", ".")),
# Mixfix:
common.Operator(name="[]", precedence=12, assoc="left",
handler=ast.Select, docstring="Array subscript.",
prefix=None, infix=common.Token("lbracket", "["),
suffix=common.Token("rbracket", "]")),
common.Operator(name="()", precedence=11, assoc="left",
handler=ast.Apply, docstring="Function application.",
prefix=None, infix=common.Token("lparen", "("),
suffix=common.Token("rparen", ")")),
# Prefix:
common.Operator(name="not", precedence=6, assoc="right",
handler=ast.Complement, docstring="Logical NOT.",
suffix=None, infix=None,
prefix=common.Token("symbol", "not")),
common.Operator(name="unary -", precedence=5, assoc="right",
handler=transforms.NegateValue,
docstring="Unary -.", infix=None, suffix=None,
prefix=common.Token("symbol", "-")),
)
# These keywords are not allowed outside of the SELECT expression. They are not
# the full list of SQL keywords (for example LIMIT and OFFSET are not included),
# just ones that will be rejected by the parser unless they follow in proper
# order after SELECT.
SQL_RESERVED_KEYWORDS = frozenset([
"SELECT", "FROM", "ANY", "WHERE", "DESC", "ASC", "ORDER BY",
])
# Builtin pseudo-functions which cannot be overriden.
BUILTINS = {
"map": ast.Map,
"sort": ast.Sort,
"filter": ast.Filter,
"bind": ast.Bind,
"any": ast.Any,
"each": ast.Each,
"cast": ast.Cast
}
# Additional grammar used by the parser.
def bool_literal(tokens):
match = common.keyword(tokens, "true")
if match:
return match._replace(value=True)
match = common.keyword(tokens, "false")
if match:
return match._replace(value=False)
def literal(tokens):
return bool_literal(tokens) or common.literal(tokens)
def prefix(tokens):
return common.prefix(tokens, OPERATORS)
def infix(tokens):
return common.infix(tokens, OPERATORS)
def param(tokens):
return common.token_name(tokens, "param")
def builtin(tokens):
"""Matches a call to a builtin pseudo-function (like map or sort)."""
return common.keywords(tokens, BUILTINS)
def let(tokens):
"""Matches a let expression."""
return common.keyword(tokens, "let")
def let_assign(tokens):
"""Matches a '=' in the let expression."""
return common.keyword(tokens, "=")
def application(tokens):
"""Matches function call (application)."""
tokens = iter(tokens)
func = next(tokens)
paren = next(tokens)
if func and func.name == "symbol" and paren.name == "lparen":
# We would be able to unambiguously parse function application with
# whitespace between the function name and the lparen, but let's not
# do that because it's unexpected in most languages.
if func.end != paren.start:
raise errors.EfilterParseError(
start=func.start, end=paren.end,
message="No whitespace allowed between function and paren.")
return common.TokenMatch(None, func.value, (func, paren))
def if_if(tokens):
"""Matches an if-else block."""
return common.keyword(tokens, "if")
def if_then(tokens):
return common.keyword(tokens, "then")
def if_else_if(tokens):
return common.multi_keyword(tokens, ("else", "if"))
def if_else(tokens):
return common.keyword(tokens, "else")
# SQL subgrammar:
def select(tokens):
return common.keyword(tokens, "select")
def select_any(tokens):
return common.keyword(tokens, "any")
def select_all(tokens):
return common.keyword(tokens, "*")
def select_as(tokens):
return common.keyword(tokens, "as")
def select_from(tokens):
return common.keyword(tokens, "from")
def select_where(tokens):
return common.keyword(tokens, "where")
def select_limit(tokens):
return common.keyword(tokens, "limit")
def select_offset(tokens):
return common.keyword(tokens, "offset")
def select_order(tokens):
return common.multi_keyword(tokens, ("order", "by"))
def select_asc(tokens):
return common.keyword(tokens, "asc")
def select_desc(tokens):
return common.keyword(tokens, "desc")
def sql_keyword(tokens):
return (common.keywords(tokens, SQL_RESERVED_KEYWORDS)
or common.multi_keyword(tokens, ("order", "by")))
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