/usr/lib/python2.7/dist-packages/jmespath/parser.py is in python-jmespath 0.2.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import ply.yacc
import ply.lex
from jmespath import ast
from jmespath import lexer
from jmespath.compat import with_str_method
@with_str_method
class ParseError(ValueError):
def __init__(self, lex_position, token_value, token_type):
super(ParseError, self).__init__(lex_position, token_value, token_type)
self.lex_position = lex_position
self.token_value = token_value
self.token_type = token_type
# Whatever catches the ParseError can fill in the full expression
self.expression = None
def __str__(self):
# self.lex_position +1 to account for the starting double quote char.
underline = ' ' * (self.lex_position + 1) + '^'
return (
'Invalid jmespath expression: Parse error at column %s near '
'token "%s" (%s) for expression:\n"%s"\n%s' % (
self.lex_position, self.token_value, self.token_type,
self.expression, underline))
class IncompleteExpressionError(ParseError):
def set_expression(self, expression):
self.expression = expression
self.lex_position = len(expression)
self.token_type = None
self.token_value = None
def __str__(self):
# self.lex_position +1 to account for the starting double quote char.
underline = ' ' * (self.lex_position + 1) + '^'
return (
'Invalid jmespath expression: Incomplete expression:\n'
'"%s"\n%s' % (self.expression, underline))
class Grammar(object):
precedence = (
('right', 'DOT', 'LBRACKET'),
)
def p_jmespath_subexpression(self, p):
""" expression : expression DOT expression
| STAR
"""
if len(p) == 2:
# Then this is the STAR rule.
p[0] = ast.WildcardValues()
else:
# This is the expression DOT expression rule.
p[0] = ast.SubExpression(p[1], p[3])
def p_jmespath_index(self, p):
"""expression : expression bracket-spec
| bracket-spec
"""
if len(p) == 3:
p[0] = ast.SubExpression(p[1], p[2])
elif len(p) == 2:
# Otherwise this is just a bracket-spec, which is valid as a root
# level node (e.g. [2]) so we just assign the root node to the
# bracket-spec.
p[0] = p[1]
def p_jmespath_bracket_specifier(self, p):
"""bracket-spec : LBRACKET STAR RBRACKET
| LBRACKET NUMBER RBRACKET
| LBRACKET RBRACKET
"""
if len(p) == 3:
p[0] = ast.ListElements()
elif p[2] == '*':
p[0] = ast.WildcardIndex()
else:
p[0] = ast.Index(p[2])
def p_jmespath_identifier(self, p):
"""expression : IDENTIFIER
| NUMBER
"""
p[0] = ast.Field(p[1])
def p_jmespath_multiselect(self, p):
"""expression : LBRACE keyval-exprs RBRACE
"""
p[0] = ast.MultiFieldDict(p[2])
def p_jmespath_multiselect_list(self, p):
"""expression : LBRACKET expressions RBRACKET
"""
p[0] = ast.MultiFieldList(p[2])
def p_jmespath_keyval_exprs(self, p):
"""keyval-exprs : keyval-exprs COMMA keyval-expr
| keyval-expr
"""
if len(p) == 2:
p[0] = [p[1]]
elif len(p) == 4:
p[1].append(p[3])
p[0] = p[1]
def p_jmespath_keyval_expr(self, p):
"""keyval-expr : IDENTIFIER COLON expression
"""
p[0] = ast.KeyValPair(p[1], p[3])
def p_jmespath_multiple_expressions(self, p):
"""expressions : expressions COMMA expression
| expression
"""
if len(p) == 2:
p[0] = [p[1]]
elif len(p) == 4:
p[1].append(p[3])
p[0] = p[1]
def p_jmespath_or_expression(self, p):
"""expression : expression OR expression"""
p[0] = ast.ORExpression(p[1], p[3])
def p_error(self, t):
if t is not None:
raise ParseError(t.lexpos, t.value, t.type)
else:
raise IncompleteExpressionError(None, None, None)
class Parser(object):
# The _max_size most recent expressions are cached in
# _cache dict.
_cache = {}
_max_size = 64
def __init__(self, lexer_definition=None, grammar=None,
debug=False):
if lexer_definition is None:
lexer_definition = lexer.LexerDefinition
if grammar is None:
grammar = Grammar
self._lexer_definition = lexer_definition
self._grammar = grammar
self.tokens = self._lexer_definition.tokens
self._debug = debug
def parse(self, expression):
cached = self._cache.get(expression)
if cached is not None:
return cached
lexer = ply.lex.lex(module=self._lexer_definition(),
debug=self._debug,
reflags=self._lexer_definition.reflags)
grammar = self._grammar()
grammar.tokens = self._lexer_definition.tokens
parser = ply.yacc.yacc(module=grammar, debug=self._debug,
write_tables=False)
parsed = self._parse_expression(parser=parser, expression=expression,
lexer_obj=lexer)
self._cache[expression] = parsed
if len(self._cache) > self._max_size:
self._free_cache_entries()
return parsed
def _parse_expression(self, parser, expression, lexer_obj):
try:
parsed = parser.parse(input=expression, lexer=lexer_obj)
return parsed
except lexer.LexerError as e:
e.expression = expression
raise e
except IncompleteExpressionError as e:
e.set_expression(expression)
raise e
except ParseError as e:
e.expression = expression
raise e
def _free_cache_entries(self):
# This logic is borrowed from the new regex library which
# uses similar eviction strategies.
for key in random.sample(self._cache.keys(), int(self._max_size / 2)):
del self._cache[key]
@classmethod
def purge(cls):
"""Clear the expression compilation cache."""
cls._cache.clear()
|