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from .AST import Primitive, UnaryOp, ContextValue, BinOp, FunctionCall, ValueAccess, Object, List
from collections import namedtuple
import re
from .shared import TemplateError
Token = namedtuple('Token', ['kind', 'value', 'start', 'end'])
expectedTokens = ["!", "(", "+", "-", "[", "false", "identifier", "null", "number", "string", "true", "{"]
class SyntaxError(TemplateError):
@classmethod
def unexpected(cls, got, exp):
exp = ', '.join(sorted(exp))
return cls('Found: {} token, expected one of: {}'.format(got.value, exp))
class Parser(object):
def __init__(self, source, tokenizer):
self.tokens = tokenizer.generate_tokens(source)
self.source = source
self.current_token = next(self.tokens)
self.unaryOpTokens = ["-", "+", "!"]
self.primitivesTokens = ["number", "null", "true", "false", "string"]
self.operatorsByPriority = [["||"], ["&&"], ["in"], ["==", "!="], ["<", ">", "<=", ">="], ["+", "-"],
["*", "/"], ["**"]]
def take_token(self, *kinds):
if not self.current_token:
raise SyntaxError('Unexpected end of input')
if kinds and self.current_token.kind not in kinds:
raise SyntaxError.unexpected(self.current_token, kinds)
try:
self.current_token = next(self.tokens)
except StopIteration:
self.current_token = None
except SyntaxError as exc:
raise exc
def parse(self, level=0):
""" expr : logicalAnd (OR logicalAnd)* """
""" logicalAnd : inStatement (AND inStatement)* """
""" inStatement : equality (IN equality)* """
""" equality : comparison (EQUALITY | INEQUALITY comparison)* """
""" comparison : addition (LESS | GREATER | LESSEQUAL | GREATEREQUAL addition)* """
""" addition : multiplication (PLUS | MINUS multiplication)* """
""" multiplication : exponentiation (MUL | DIV exponentiation)* """
""" exponentiation : propertyAccessOrFunc (EXP exponentiation)* """
if level == len(self.operatorsByPriority) - 1:
node = self.parse_property_access_or_func()
token = self.current_token
while token is not None and token.kind in self.operatorsByPriority[level]:
self.take_token(token.kind)
node = BinOp(token, self.parse(level), node)
token = self.current_token
else:
node = self.parse(level + 1)
token = self.current_token
while token is not None and token.kind in self.operatorsByPriority[level]:
self.take_token(token.kind)
node = BinOp(token, node, self.parse(level + 1))
token = self.current_token
return node
def parse_property_access_or_func(self):
""" propertyAccessOrFunc : unit (accessWithBrackets | DOT id | functionCall)* """
node = self.parse_unit()
token = self.current_token
operators = ["[", "(", "."]
while token is not None and token.kind in operators:
if token.kind == "[":
node = self.parse_access_with_brackets(node)
elif token.kind == ".":
token = self.current_token
self.take_token(".")
right_part = Primitive(self.current_token)
self.take_token("identifier")
node = BinOp(token, node, right_part)
elif token.kind == "(":
node = self.parse_function_call(node)
token = self.current_token
return node
def parse_unit(self):
# unit : unaryOp unit | primitives | contextValue | LPAREN expr RPAREN | list | object
token = self.current_token
if self.current_token is None:
raise SyntaxError('Unexpected end of input')
node = None
if token.kind in self.unaryOpTokens:
self.take_token(token.kind)
node = UnaryOp(token, self.parse_unit())
elif token.kind in self.primitivesTokens:
self.take_token(token.kind)
node = Primitive(token)
elif token.kind == "identifier":
self.take_token(token.kind)
node = ContextValue(token)
elif token.kind == "(":
self.take_token("(")
node = self.parse()
if node is None:
raise SyntaxError.unexpected(self.current_token, expectedTokens)
self.take_token(")")
elif token.kind == "[":
node = self.parse_list()
elif token.kind == "{":
node = self.parse_object()
return node
def parse_function_call(self, name):
"""functionCall: LPAREN (expr ( COMMA expr)*)? RPAREN"""
args = []
token = self.current_token
self.take_token("(")
if self.current_token.kind != ")":
node = self.parse()
args.append(node)
while self.current_token is not None and self.current_token.kind == ",":
if args[-1] is None:
raise SyntaxError.unexpected(self.current_token, expectedTokens)
self.take_token(",")
node = self.parse()
args.append(node)
self.take_token(")")
node = FunctionCall(token, name, args)
return node
def parse_list(self):
""" list: LSQAREBRAKET (expr (COMMA expr)*)? RSQAREBRAKET """
arr = []
token = self.current_token
self.take_token("[")
if self.current_token != "]":
node = self.parse()
arr.append(node)
while self.current_token and self.current_token.kind == ",":
if arr[-1] is None:
raise SyntaxError.unexpected(self.current_token, expectedTokens)
self.take_token(",")
node = self.parse()
arr.append(node)
self.take_token("]")
node = List(token, arr)
return node
def parse_access_with_brackets(self, node):
""" valueAccess : LSQAREBRAKET expr |(expr? COLON expr?) RSQAREBRAKET)"""
left = None
right = None
is_interval = False
token = self.current_token
self.take_token("[")
if self.current_token.kind == "]":
raise SyntaxError.unexpected(self.current_token, expectedTokens)
if self.current_token.kind != ":":
left = self.parse()
if self.current_token.kind == ":":
is_interval = True
self.take_token(":")
if self.current_token.kind != "]":
right = self.parse()
if is_interval and right is None and self.current_token.kind != "]":
raise SyntaxError.unexpected(self.current_token, expectedTokens)
self.take_token("]")
node = ValueAccess(token, node, is_interval, left, right)
return node
def parse_object(self):
# """ object : LCURLYBRACE ( STR | ID COLON expr (COMMA STR | ID COLON expr)*)?
# RCURLYBRACE """
obj = {}
objToken = self.current_token
self.take_token("{")
token = self.current_token
while token is not None and (token.kind == "string" or token.kind == "identifier"):
key = token.value
if token.kind == "string":
key = parse_string(key)
self.take_token(token.kind)
self.take_token(":")
value = self.parse()
if value is None:
raise SyntaxError.unexpected(self.current_token, expectedTokens)
obj[key] = value
if self.current_token and self.current_token.kind == "}":
break
else:
self.take_token(",")
token = self.current_token
self.take_token("}")
node = Object(objToken, obj)
return node
def parse_string(string):
return string[1:-1]
class Tokenizer(object):
def __init__(self, ignore, patterns, tokens):
self.ignore = ignore
self.patterns = patterns
self.tokens = tokens
# build a regular expression to generate a sequence of tokens
token_patterns = [
'({})'.format(self.patterns.get(t, re.escape(t)))
for t in self.tokens]
if self.ignore:
token_patterns.append('(?:{})'.format(self.ignore))
self.token_re = re.compile('^(?:' + '|'.join(token_patterns) + ')')
def generate_tokens(self, source):
offset = 0
while True:
start = offset
remainder = source[offset:]
mo = self.token_re.match(remainder)
if not mo:
if remainder:
raise SyntaxError(
"Unexpected input for '{}' at '{}'".format(source, remainder))
break
offset += mo.end()
# figure out which token matched (note that idx is 0-based)
indexes = [idx for idx, grp in enumerate(mo.groups()) if grp is not None]
if indexes:
idx = indexes[0]
yield Token(
kind=self.tokens[idx],
value=mo.group(idx + 1), # (mo.group is 1-based)
start=start,
end=offset)
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