Deleting unnecessary dynamodb2 file
This commit is contained in:
Matthew Stevens
Garrett Heel
parent
8a90971ba1
commit
9450328527
@ -1,617 +0,0 @@
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import re
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import json
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import enum
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from collections import deque
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from collections import namedtuple
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class Kind(enum.Enum):
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"""Defines types of nodes in the syntax tree."""
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# Condition nodes
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# ---------------
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OR = enum.auto()
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AND = enum.auto()
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NOT = enum.auto()
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PARENTHESES = enum.auto()
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FUNCTION = enum.auto()
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BETWEEN = enum.auto()
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IN = enum.auto()
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COMPARISON = enum.auto()
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# Operand nodes
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# -------------
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EXPRESSION_ATTRIBUTE_VALUE = enum.auto()
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PATH = enum.auto()
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# Literal nodes
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# --------------
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LITERAL = enum.auto()
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class Nonterminal(enum.Enum):
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"""Defines nonterminals for defining productions."""
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CONDITION = enum.auto()
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OPERAND = enum.auto()
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COMPARATOR = enum.auto()
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FUNCTION_NAME = enum.auto()
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IDENTIFIER = enum.auto()
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AND = enum.auto()
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OR = enum.auto()
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NOT = enum.auto()
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BETWEEN = enum.auto()
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IN = enum.auto()
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COMMA = enum.auto()
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LEFT_PAREN = enum.auto()
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RIGHT_PAREN = enum.auto()
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WHITESPACE = enum.auto()
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Node = namedtuple('Node', ['nonterminal', 'kind', 'text', 'value', 'children'])
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class ConditionExpressionParser:
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def __init__(self, condition_expression, expression_attribute_names,
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expression_attribute_values):
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self.condition_expression = condition_expression
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self.expression_attribute_names = expression_attribute_names
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self.expression_attribute_values = expression_attribute_values
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def parse(self):
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"""Returns a syntax tree for the expression.
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The tree, and all of the nodes in the tree are a tuple of
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- kind: str
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- children/value:
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list of nodes for parent nodes
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value for leaf nodes
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Raises AssertionError if the condition expression is invalid
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Raises KeyError if expression attribute names/values are invalid
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Here are the types of nodes that can be returned.
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The types of child nodes are denoted with a colon (:).
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An arbitrary number of children is denoted with ...
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Condition:
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('OR', [lhs : Condition, rhs : Condition])
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('AND', [lhs: Condition, rhs: Condition])
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('NOT', [argument: Condition])
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('PARENTHESES', [argument: Condition])
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('FUNCTION', [('LITERAL', function_name: str), argument: Operand, ...])
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('BETWEEN', [query: Operand, low: Operand, high: Operand])
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('IN', [query: Operand, possible_value: Operand, ...])
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('COMPARISON', [lhs: Operand, ('LITERAL', comparator: str), rhs: Operand])
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Operand:
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('EXPRESSION_ATTRIBUTE_VALUE', value: dict, e.g. {'S': 'foobar'})
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('PATH', [('LITERAL', path_element: str), ...])
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NOTE: Expression attribute names will be expanded
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Literal:
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('LITERAL', value: str)
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"""
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if not self.condition_expression:
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return None
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nodes = self._lex_condition_expression()
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nodes = self._parse_paths(nodes)
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self._print_debug(nodes)
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nodes = self._apply_comparator(nodes)
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self._print_debug(nodes)
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nodes = self._apply_in(nodes)
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self._print_debug(nodes)
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nodes = self._apply_between(nodes)
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self._print_debug(nodes)
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nodes = self._apply_functions(nodes)
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self._print_debug(nodes)
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nodes = self._apply_parens_and_booleans(nodes)
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self._print_debug(nodes)
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node = nodes[0]
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return self._make_node_tree(node)
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def _lex_condition_expression(self):
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nodes = deque()
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remaining_expression = self.condition_expression
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while remaining_expression:
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node, remaining_expression = \
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self._lex_one_node(remaining_expression)
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if node.nonterminal == Nonterminal.WHITESPACE:
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continue
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nodes.append(node)
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return nodes
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def _lex_one_node(self, remaining_expression):
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attribute_regex = '(:|#)?[A-z0-9\-_]+'
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patterns = [(
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Nonterminal.WHITESPACE, re.compile('^ +')
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), (
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Nonterminal.COMPARATOR, re.compile(
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'^('
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'=|'
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'<>|'
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'<|'
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'<=|'
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'>|'
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'>=)'),
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), (
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Nonterminal.OPERAND, re.compile(
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'^' +
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attribute_regex + '(\.' + attribute_regex + ')*')
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), (
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Nonterminal.COMMA, re.compile('^,')
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), (
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Nonterminal.LEFT_PAREN, re.compile('^\(')
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), (
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Nonterminal.RIGHT_PAREN, re.compile('^\)')
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)]
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for nonterminal, pattern in patterns:
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match = pattern.match(remaining_expression)
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if match:
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match_text = match.group()
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break
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else:
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raise AssertionError("Cannot parse condition starting at: " +
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remaining_expression)
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value = match_text
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node = Node(
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nonterminal=nonterminal,
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kind=Kind.LITERAL,
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text=match_text,
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value=match_text,
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children=[])
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remaining_expression = remaining_expression[len(match_text):]
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return node, remaining_expression
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def _parse_paths(self, nodes):
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output = deque()
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while nodes:
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node = nodes.popleft()
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if node.nonterminal == Nonterminal.OPERAND:
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path = node.value.split('.')
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children = [
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self._parse_path_element(name)
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for name in path]
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if len(children) == 1:
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child = children[0]
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if child.nonterminal != Nonterminal.IDENTIFIER:
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output.append(child)
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continue
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else:
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for child in children:
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self._assert(
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child.nonterminal == Nonterminal.IDENTIFIER,
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"Cannot use %s in path" % child.text, [node])
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output.append(Node(
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nonterminal=Nonterminal.OPERAND,
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kind=Kind.PATH,
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text=node.text,
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value=None,
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children=children))
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else:
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output.append(node)
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return output
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def _parse_path_element(self, name):
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reserved = {
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'AND': Nonterminal.AND,
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'OR': Nonterminal.OR,
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'IN': Nonterminal.IN,
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'BETWEEN': Nonterminal.BETWEEN,
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'NOT': Nonterminal.NOT,
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}
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functions = {
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'attribute_exists',
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'attribute_not_exists',
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'attribute_type',
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'begins_with',
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'contains',
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'size',
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}
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if name in reserved:
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nonterminal = reserved[name]
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return Node(
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nonterminal=nonterminal,
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kind=Kind.LITERAL,
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text=name,
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value=name,
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children=[])
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elif name in functions:
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return Node(
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nonterminal=Nonterminal.FUNCTION_NAME,
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kind=Kind.LITERAL,
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text=name,
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value=name,
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children=[])
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elif name.startswith(':'):
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return Node(
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nonterminal=Nonterminal.OPERAND,
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kind=Kind.EXPRESSION_ATTRIBUTE_VALUE,
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text=name,
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value=self._lookup_expression_attribute_value(name),
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children=[])
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elif name.startswith('#'):
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return Node(
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nonterminal=Nonterminal.IDENTIFIER,
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kind=Kind.LITERAL,
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text=name,
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value=self._lookup_expression_attribute_name(name),
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children=[])
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else:
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return Node(
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nonterminal=Nonterminal.IDENTIFIER,
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kind=Kind.LITERAL,
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text=name,
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value=name,
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children=[])
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def _lookup_expression_attribute_value(self, name):
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return self.expression_attribute_values[name]
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def _lookup_expression_attribute_name(self, name):
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return self.expression_attribute_names[name]
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# NOTE: The following constructions are ordered from high precedence to low precedence
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# according to
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# https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.OperatorsAndFunctions.html#Expressions.OperatorsAndFunctions.Precedence
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#
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# = <> < <= > >=
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# IN
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# BETWEEN
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# attribute_exists attribute_not_exists begins_with contains
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# Parentheses
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# NOT
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# AND
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# OR
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#
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# The grammar is taken from
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# https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.OperatorsAndFunctions.html#Expressions.OperatorsAndFunctions.Syntax
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#
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# condition-expression ::=
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# operand comparator operand
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# operand BETWEEN operand AND operand
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# operand IN ( operand (',' operand (, ...) ))
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# function
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# condition AND condition
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# condition OR condition
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# NOT condition
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# ( condition )
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#
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# comparator ::=
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# =
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# <>
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# <
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# <=
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# >
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# >=
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#
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# function ::=
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# attribute_exists (path)
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# attribute_not_exists (path)
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# attribute_type (path, type)
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# begins_with (path, substr)
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# contains (path, operand)
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# size (path)
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def _matches(self, nodes, production):
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"""Check if the nodes start with the given production.
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Parameters
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----------
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nodes: list of Node
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production: list of str
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The name of a Nonterminal, or '*' for anything
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"""
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if len(nodes) < len(production):
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return False
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for i in range(len(production)):
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if production[i] == '*':
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continue
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expected = getattr(Nonterminal, production[i])
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if nodes[i].nonterminal != expected:
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return False
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return True
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def _apply_comparator(self, nodes):
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"""Apply condition := operand comparator operand."""
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output = deque()
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while nodes:
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if self._matches(nodes, ['*', 'COMPARATOR']):
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self._assert(
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self._matches(nodes, ['OPERAND', 'COMPARATOR', 'OPERAND']),
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"Bad comparison", list(nodes)[:3])
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lhs = nodes.popleft()
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comparator = nodes.popleft()
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rhs = nodes.popleft()
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output.append(Node(
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nonterminal=Nonterminal.CONDITION,
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kind=Kind.COMPARISON,
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text=" ".join([
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lhs.text,
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comparator.text,
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rhs.text]),
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value=None,
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children=[lhs, comparator, rhs]))
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else:
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output.append(nodes.popleft())
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return output
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def _apply_in(self, nodes):
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"""Apply condition := operand IN ( operand , ... )."""
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output = deque()
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while nodes:
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if self._matches(nodes, ['*', 'IN']):
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self._assert(
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self._matches(nodes, ['OPERAND', 'IN', 'LEFT_PAREN']),
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"Bad IN expression", list(nodes)[:3])
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lhs = nodes.popleft()
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in_node = nodes.popleft()
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left_paren = nodes.popleft()
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all_children = [lhs, in_node, left_paren]
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rhs = []
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while True:
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if self._matches(nodes, ['OPERAND', 'COMMA']):
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operand = nodes.popleft()
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separator = nodes.popleft()
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all_children += [operand, separator]
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rhs.append(operand)
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elif self._matches(nodes, ['OPERAND', 'RIGHT_PAREN']):
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operand = nodes.popleft()
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separator = nodes.popleft()
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all_children += [operand, separator]
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rhs.append(operand)
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break # Close
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else:
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self._assert(
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False,
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"Bad IN expression starting at", nodes)
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output.append(Node(
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nonterminal=Nonterminal.CONDITION,
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kind=Kind.IN,
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text=" ".join([t.text for t in all_children]),
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value=None,
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children=[lhs] + rhs))
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else:
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output.append(nodes.popleft())
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return output
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def _apply_between(self, nodes):
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"""Apply condition := operand BETWEEN operand AND operand."""
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output = deque()
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while nodes:
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if self._matches(nodes, ['*', 'BETWEEN']):
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self._assert(
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self._matches(nodes, ['OPERAND', 'BETWEEN', 'OPERAND',
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'AND', 'OPERAND']),
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"Bad BETWEEN expression", list(nodes)[:5])
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lhs = nodes.popleft()
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between_node = nodes.popleft()
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low = nodes.popleft()
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and_node = nodes.popleft()
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high = nodes.popleft()
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all_children = [lhs, between_node, low, and_node, high]
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output.append(Node(
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nonterminal=Nonterminal.CONDITION,
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kind=Kind.BETWEEN,
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text=" ".join([t.text for t in all_children]),
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value=None,
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children=[lhs, low, high]))
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else:
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output.append(nodes.popleft())
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return output
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def _apply_functions(self, nodes):
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"""Apply condition := function_name (operand , ...)."""
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output = deque()
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expected_argument_kind_map = {
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'attribute_exists': [{Kind.PATH}],
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'attribute_not_exists': [{Kind.PATH}],
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'attribute_type': [{Kind.PATH}, {Kind.EXPRESSION_ATTRIBUTE_VALUE}],
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'begins_with': [{Kind.PATH}, {Kind.EXPRESSION_ATTRIBUTE_VALUE}],
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'contains': [{Kind.PATH}, {Kind.PATH, Kind.EXPRESSION_ATTRIBUTE_VALUE}],
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'size': [{Kind.PATH}],
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}
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while nodes:
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if self._matches(nodes, ['FUNCTION_NAME']):
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self._assert(
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self._matches(nodes, ['FUNCTION_NAME', 'LEFT_PAREN',
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'OPERAND', '*']),
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"Bad function expression at", list(nodes)[:4])
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function_name = nodes.popleft()
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left_paren = nodes.popleft()
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all_children = [function_name, left_paren]
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arguments = []
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while True:
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if self._matches(nodes, ['OPERAND', 'COMMA']):
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operand = nodes.popleft()
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separator = nodes.popleft()
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all_children += [operand, separator]
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arguments.append(operand)
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elif self._matches(nodes, ['OPERAND', 'RIGHT_PAREN']):
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operand = nodes.popleft()
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separator = nodes.popleft()
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all_children += [operand, separator]
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arguments.append(operand)
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break # Close paren
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else:
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self._assert(
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False,
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"Bad function expression", all_children + list(nodes)[:2])
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expected_kinds = expected_argument_kind_map[function_name.value]
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self._assert(
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len(arguments) == len(expected_kinds),
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"Wrong number of arguments in", all_children)
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for i in range(len(expected_kinds)):
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self._assert(
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arguments[i].kind in expected_kinds[i],
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"Wrong type for argument %d in" % i, all_children)
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output.append(Node(
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nonterminal=Nonterminal.CONDITION,
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kind=Kind.FUNCTION,
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text=" ".join([t.text for t in all_children]),
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value=None,
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children=[function_name] + arguments))
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else:
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output.append(nodes.popleft())
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return output
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def _apply_parens_and_booleans(self, nodes, left_paren=None):
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"""Apply condition := ( condition ) and booleans."""
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output = deque()
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while nodes:
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if self._matches(nodes, ['LEFT_PAREN']):
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parsed = self._apply_parens_and_booleans(nodes, left_paren=nodes.popleft())
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self._assert(
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len(parsed) >= 1,
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"Failed to close parentheses at", nodes)
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parens = parsed.popleft()
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self._assert(
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parens.kind == Kind.PARENTHESES,
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"Failed to close parentheses at", nodes)
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output.append(parens)
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nodes = parsed
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elif self._matches(nodes, ['RIGHT_PAREN']):
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self._assert(
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left_paren is not None,
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"Unmatched ) at", nodes)
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close_paren = nodes.popleft()
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children = self._apply_booleans(output)
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all_children = [left_paren, *children, close_paren]
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return deque([
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Node(
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nonterminal=Nonterminal.CONDITION,
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kind=Kind.PARENTHESES,
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text=" ".join([t.text for t in all_children]),
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value=None,
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children=list(children),
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), *nodes])
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else:
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output.append(nodes.popleft())
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self._assert(
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left_paren is None,
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"Unmatched ( at", list(output))
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return self._apply_booleans(output)
|
||||
|
||||
def _apply_booleans(self, nodes):
|
||||
"""Apply and, or, and not constructions."""
|
||||
nodes = self._apply_not(nodes)
|
||||
nodes = self._apply_and(nodes)
|
||||
nodes = self._apply_or(nodes)
|
||||
# The expression should reduce to a single condition
|
||||
self._assert(
|
||||
len(nodes) == 1,
|
||||
"Unexpected expression at", list(nodes)[1:])
|
||||
self._assert(
|
||||
nodes[0].nonterminal == Nonterminal.CONDITION,
|
||||
"Incomplete condition", nodes)
|
||||
return nodes
|
||||
|
||||
def _apply_not(self, nodes):
|
||||
"""Apply condition := NOT condition."""
|
||||
output = deque()
|
||||
while nodes:
|
||||
if self._matches(nodes, ['NOT']):
|
||||
self._assert(
|
||||
self._matches(nodes, ['NOT', 'CONDITION']),
|
||||
"Bad NOT expression", list(nodes)[:2])
|
||||
not_node = nodes.popleft()
|
||||
child = nodes.popleft()
|
||||
output.append(Node(
|
||||
nonterminal=Nonterminal.CONDITION,
|
||||
kind=Kind.NOT,
|
||||
text=" ".join([not_node['text'], value['text']]),
|
||||
value=None,
|
||||
children=[child]))
|
||||
else:
|
||||
output.append(nodes.popleft())
|
||||
|
||||
return output
|
||||
|
||||
def _apply_and(self, nodes):
|
||||
"""Apply condition := condition AND condition."""
|
||||
output = deque()
|
||||
while nodes:
|
||||
if self._matches(nodes, ['*', 'AND']):
|
||||
self._assert(
|
||||
self._matches(nodes, ['CONDITION', 'AND', 'CONDITION']),
|
||||
"Bad AND expression", list(nodes)[:3])
|
||||
lhs = nodes.popleft()
|
||||
and_node = nodes.popleft()
|
||||
rhs = nodes.popleft()
|
||||
all_children = [lhs, and_node, rhs]
|
||||
output.append(Node(
|
||||
nonterminal=Nonterminal.CONDITION,
|
||||
kind=Kind.AND,
|
||||
text=" ".join([t.text for t in all_children]),
|
||||
value=None,
|
||||
children=[lhs, rhs]))
|
||||
else:
|
||||
output.append(nodes.popleft())
|
||||
|
||||
return output
|
||||
|
||||
def _apply_or(self, nodes):
|
||||
"""Apply condition := condition OR condition."""
|
||||
output = deque()
|
||||
while nodes:
|
||||
if self._matches(nodes, ['*', 'OR']):
|
||||
self._assert(
|
||||
self._matches(nodes, ['CONDITION', 'OR', 'CONDITION']),
|
||||
"Bad OR expression", list(nodes)[:3])
|
||||
lhs = nodes.popleft()
|
||||
or_node = nodes.popleft()
|
||||
rhs = nodes.popleft()
|
||||
all_children = [lhs, or_node, rhs]
|
||||
output.append(Node(
|
||||
nonterminal=Nonterminal.CONDITION,
|
||||
kind=Kind.OR,
|
||||
text=" ".join([t.text for t in all_children]),
|
||||
value=None,
|
||||
children=[lhs, rhs]))
|
||||
else:
|
||||
output.append(nodes.popleft())
|
||||
|
||||
return output
|
||||
|
||||
def _make_node_tree(self, node):
|
||||
if len(node.children) > 0:
|
||||
return (
|
||||
node.kind.name,
|
||||
[
|
||||
self._make_node_tree(child)
|
||||
for child in node.children
|
||||
])
|
||||
else:
|
||||
return (node.kind.name, node.value)
|
||||
|
||||
def _print_debug(self, nodes):
|
||||
print('ROOT')
|
||||
for node in nodes:
|
||||
self._print_node_recursive(node, depth=1)
|
||||
|
||||
def _print_node_recursive(self, node, depth=0):
|
||||
if len(node.children) > 0:
|
||||
print(' ' * depth, node.nonterminal, node.kind)
|
||||
for child in node.children:
|
||||
self._print_node_recursive(child, depth=depth + 1)
|
||||
else:
|
||||
print(' ' * depth, node.nonterminal, node.kind, node.value)
|
||||
|
||||
|
||||
|
||||
def _assert(self, condition, message, nodes):
|
||||
if not condition:
|
||||
raise AssertionError(message + " " + " ".join([t.text for t in nodes]))
|
||||
Loading…
Reference in New Issue
Block a user