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import re

from itertools import count

from parso.utils import PythonVersionInfo

from parso.utils import split_lines

from parso.python.tokenize import Token

from parso import parser

from parso.tree import TypedLeaf, ErrorNode, ErrorLeaf

version36 = PythonVersionInfo(3, 6)

class TokenNamespace:

_c = count()

LBRACE = next(_c)

RBRACE = next(_c)

ENDMARKER = next(_c)

COLON = next(_c)

CONVERSION = next(_c)

PYTHON_EXPR = next(_c)

EXCLAMATION_MARK = next(_c)

UNTERMINATED_STRING = next(_c)

token_map = dict((v, k) for k, v in locals().items() if not k.startswith('_'))

@classmethod

def generate_token_id(cls, string):

if string == '{':

return cls.LBRACE

elif string == '}':

return cls.RBRACE

elif string == '!':

return cls.EXCLAMATION_MARK

elif string == ':':

return cls.COLON

return getattr(cls, string)

GRAMMAR = """

fstring: expression* ENDMARKER

format_spec: ':' expression*

expression: '{' PYTHON_EXPR [ '!' CONVERSION ] [ format_spec ] '}'

"""

_prefix = r'((?:[^{}]+)*)'

_expr = _prefix + r'(\{|\}|$)'

_in_expr = r'([^{}\[\]:"\'!]*)(.?)'

# There's only one conversion character allowed. But the rules have to be

# checked later anyway, so allow more here. This makes error recovery nicer.

_conversion = r'([^={}:]*)(.?)'

_compiled_expr = re.compile(_expr)

_compiled_in_expr = re.compile(_in_expr)

_compiled_conversion = re.compile(_conversion)

def tokenize(code, start_pos=(1, 0)):

def add_to_pos(string):

lines = split_lines(string)

l = len(lines[-1])

if len(lines) > 1:

start_pos[0] += len(lines) - 1

start_pos[1] = l

else:

start_pos[1] += l

def tok(value, type=None, prefix=''):

if type is None:

type = TokenNamespace.generate_token_id(value)

add_to_pos(prefix)

token = Token(type, value, tuple(start_pos), prefix)

add_to_pos(value)

return token

start = 0

recursion_level = 0

added_prefix = ''

start_pos = list(start_pos)

while True:

match = _compiled_expr.match(code, start)

prefix = added_prefix + match.group(1)

found = match.group(2)

start = match.end()

if not found:

# We're at the end.

break

if found == '}':

if recursion_level == 0 and len(code) > start and code[start] == '}':

# This is a }} escape.

added_prefix = prefix + '}}'

start += 1

continue

recursion_level = max(0, recursion_level - 1)

yield tok(found, prefix=prefix)

added_prefix = ''

else:

assert found == '{'

if recursion_level == 0 and len(code) > start and code[start] == '{':

# This is a {{ escape.

added_prefix = prefix + '{{'

start += 1

continue

recursion_level += 1

yield tok(found, prefix=prefix)

added_prefix = ''

expression = ''

squared_count = 0

curly_count = 0

while True:

expr_match = _compiled_in_expr.match(code, start)

expression += expr_match.group(1)

found = expr_match.group(2)

start = expr_match.end()

if found == '{':

curly_count += 1

expression += found

elif found == '}' and curly_count > 0:

curly_count -= 1

expression += found

elif found == '[':

squared_count += 1

expression += found

elif found == ']':

# Use a max function here, because the Python code might

# just have syntax errors.

squared_count = max(0, squared_count - 1)

expression += found

elif found == ':' and (squared_count or curly_count):

expression += found

elif found in ('"', "'"):

search = found

if len(code) > start + 1 and \

code[start] == found == code[start+1]:

search *= 3

start += 2

index = code.find(search, start)

if index == -1:

yield tok(expression, type=TokenNamespace.PYTHON_EXPR)

yield tok(

found + code[start:],

type=TokenNamespace.UNTERMINATED_STRING,

)

start = len(code)

break

expression += found + code[start:index+1]

start = index + 1

elif found == '!' and len(code) > start and code[start] == '=':

# This is a python `!=` and not a conversion.

expression += found

else:

yield tok(expression, type=TokenNamespace.PYTHON_EXPR)

if found:

yield tok(found)

break

if found == '!':

conversion_match = _compiled_conversion.match(code, start)

found = conversion_match.group(2)

start = conversion_match.end()

yield tok(conversion_match.group(1), type=TokenNamespace.CONVERSION)

if found:

yield tok(found)

if found == '}':

recursion_level -= 1

# We don't need to handle everything after ':', because that is

# basically new tokens.

yield tok('', type=TokenNamespace.ENDMARKER, prefix=prefix)

class Parser(parser.BaseParser):

def parse(self, tokens):

node = super(Parser, self).parse(tokens)

if isinstance(node, self.default_leaf): # Is an endmarker.

# If there's no curly braces we get back a non-module. We always

# want an fstring.

node = self.default_node('fstring', [node])

return node

def convert_leaf(self, pgen_grammar, type, value, prefix, start_pos):

# TODO this is so ugly.

leaf_type = TokenNamespace.token_map[type].lower()

return TypedLeaf(leaf_type, value, start_pos, prefix)

def error_recovery(self, pgen_grammar, stack, arcs, typ, value, start_pos, prefix,

add_token_callback):

if not self._error_recovery:

return super(Parser, self).error_recovery(

pgen_grammar, stack, arcs, typ, value, start_pos, prefix,

add_token_callback

)

token_type = TokenNamespace.token_map[typ].lower()

if len(stack) == 1:

error_leaf = ErrorLeaf(token_type, value, start_pos, prefix)

stack[0][2][1].append(error_leaf)

else:

dfa, state, (type_, nodes) = stack[1]

stack[0][2][1].append(ErrorNode(nodes))

stack[1:] = []

add_token_callback(typ, value, start_pos, prefix)