"""ANTLR3 exception hierarchy"""
# begin[licence]
#
# [The "BSD licence"]
# Copyright (c) 2005-2012 Terence Parr
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from .constants import INVALID_TOKEN_TYPE
class BacktrackingFailed(Exception):
"""@brief Raised to signal failed backtrack attempt"""
pass
class RecognitionException(Exception):
"""@brief The root of the ANTLR exception hierarchy.
To avoid English-only error messages and to generally make things
as flexible as possible, these exceptions are not created with strings,
but rather the information necessary to generate an error. Then
the various reporting methods in Parser and Lexer can be overridden
to generate a localized error message. For example, MismatchedToken
exceptions are built with the expected token type.
So, don't expect getMessage() to return anything.
Note that as of Java 1.4, you can access the stack trace, which means
that you can compute the complete trace of rules from the start symbol.
This gives you considerable context information with which to generate
useful error messages.
ANTLR generates code that throws exceptions upon recognition error and
also generates code to catch these exceptions in each rule. If you
want to quit upon first error, you can turn off the automatic error
handling mechanism using rulecatch action, but you still need to
override methods mismatch and recoverFromMismatchSet.
In general, the recognition exceptions can track where in a grammar a
problem occurred and/or what was the expected input. While the parser
knows its state (such as current input symbol and line info) that
state can change before the exception is reported so current token index
is computed and stored at exception time. From this info, you can
perhaps print an entire line of input not just a single token, for example.
Better to just say the recognizer had a problem and then let the parser
figure out a fancy report.
"""
def __init__(self, input=None):
super().__init__()
# What input stream did the error occur in?
self.input = None
# What is index of token/char were we looking at when the error
# occurred?
self.index = None
# The current Token when an error occurred. Since not all streams
# can retrieve the ith Token, we have to track the Token object.
# For parsers. Even when it's a tree parser, token might be set.
self.token = None
# If this is a tree parser exception, node is set to the node with
# the problem.
self.node = None
# The current char when an error occurred. For lexers.
self.c = None
# Track the line at which the error occurred in case this is
# generated from a lexer. We need to track this since the
# unexpected char doesn't carry the line info.
self.line = None
self.charPositionInLine = None
# If you are parsing a tree node stream, you will encounter som
# imaginary nodes w/o line/col info. We now search backwards looking
# for most recent token with line/col info, but notify getErrorHeader()
# that info is approximate.
self.approximateLineInfo = False
if input:
self.input = input
self.index = input.index()
# late import to avoid cyclic dependencies
from .streams import TokenStream, CharStream
from .tree import TreeNodeStream
if isinstance(self.input, TokenStream):
self.token = self.input.LT(1)
self.line = self.token.line
self.charPositionInLine = self.token.charPositionInLine
if isinstance(self.input, TreeNodeStream):
self.extractInformationFromTreeNodeStream(self.input)
else:
if isinstance(self.input, CharStream):
self.c = self.input.LT(1)
self.line = self.input.line
self.charPositionInLine = self.input.charPositionInLine
else:
self.c = self.input.LA(1)
def extractInformationFromTreeNodeStream(self, nodes):
from .tree import Tree, CommonTree
from .tokens import CommonToken
self.node = nodes.LT(1)
adaptor = nodes.adaptor
payload = adaptor.getToken(self.node)
if payload:
self.token = payload
if payload.line <= 0:
# imaginary node; no line/pos info; scan backwards
i = -1
priorNode = nodes.LT(i)
while priorNode:
priorPayload = adaptor.getToken(priorNode)
if priorPayload and priorPayload.line > 0:
# we found the most recent real line / pos info
self.line = priorPayload.line
self.charPositionInLine = priorPayload.charPositionInLine
self.approximateLineInfo = True
break
i -= 1
priorNode = nodes.LT(i)
else: # node created from real token
self.line = payload.line
self.charPositionInLine = payload.charPositionInLine
elif isinstance(self.node, Tree):
self.line = self.node.line
self.charPositionInLine = self.node.charPositionInLine
if isinstance(self.node, CommonTree):
self.token = self.node.token
else:
type = adaptor.getType(self.node)
text = adaptor.getText(self.node)
self.token = CommonToken(type=type, text=text)
def getUnexpectedType(self):
"""Return the token type or char of the unexpected input element"""
from .streams import TokenStream
from .tree import TreeNodeStream
if isinstance(self.input, TokenStream):
return self.token.type
elif isinstance(self.input, TreeNodeStream):
adaptor = self.input.treeAdaptor
return adaptor.getType(self.node)
else:
return self.c
unexpectedType = property(getUnexpectedType)
class MismatchedTokenException(RecognitionException):
"""@brief A mismatched char or Token or tree node."""
def __init__(self, expecting, input):
super().__init__(input)
self.expecting = expecting
def __str__(self):
return "MismatchedTokenException({!r}!={!r})".format(
self.getUnexpectedType(), self.expecting
)
__repr__ = __str__
class UnwantedTokenException(MismatchedTokenException):
"""An extra token while parsing a TokenStream"""
def getUnexpectedToken(self):
return self.token
def __str__(self):
exp = ", expected {}".format(self.expecting)
if self.expecting == INVALID_TOKEN_TYPE:
exp = ""
if not self.token:
return "UnwantedTokenException(found={}{})".format(None, exp)
return "UnwantedTokenException(found={}{})".format(self.token.text, exp)
__repr__ = __str__
class MissingTokenException(MismatchedTokenException):
"""
We were expecting a token but it's not found. The current token
is actually what we wanted next.
"""
def __init__(self, expecting, input, inserted):
super().__init__(expecting, input)
self.inserted = inserted
def getMissingType(self):
return self.expecting
def __str__(self):
if self.token:
if self.inserted:
return "MissingTokenException(inserted {!r} at {!r})".format(
self.inserted, self.token.text)
return "MissingTokenException(at {!r})".format(self.token.text)
return "MissingTokenException"
__repr__ = __str__
class MismatchedRangeException(RecognitionException):
"""@brief The next token does not match a range of expected types."""
def __init__(self, a, b, input):
super().__init__(input)
self.a = a
self.b = b
def __str__(self):
return "MismatchedRangeException({!r} not in [{!r}..{!r}])".format(
self.getUnexpectedType(), self.a, self.b
)
__repr__ = __str__
class MismatchedSetException(RecognitionException):
"""@brief The next token does not match a set of expected types."""
def __init__(self, expecting, input):
super().__init__(input)
self.expecting = expecting
def __str__(self):
return "MismatchedSetException({!r} not in {!r})".format(
self.getUnexpectedType(), self.expecting
)
__repr__ = __str__
class MismatchedNotSetException(MismatchedSetException):
"""@brief Used for remote debugger deserialization"""
def __str__(self):
return "MismatchedNotSetException({!r}!={!r})".format(
self.getUnexpectedType(), self.expecting
)
__repr__ = __str__
class NoViableAltException(RecognitionException):
"""@brief Unable to decide which alternative to choose."""
def __init__(
self, grammarDecisionDescription, decisionNumber, stateNumber, input
):
super().__init__(input)
self.grammarDecisionDescription = grammarDecisionDescription
self.decisionNumber = decisionNumber
self.stateNumber = stateNumber
def __str__(self):
return "NoViableAltException({!r}!=[{!r}])".format(
self.unexpectedType, self.grammarDecisionDescription
)
__repr__ = __str__
class EarlyExitException(RecognitionException):
"""@brief The recognizer did not match anything for a (..)+ loop."""
def __init__(self, decisionNumber, input):
super().__init__(input)
self.decisionNumber = decisionNumber
class FailedPredicateException(RecognitionException):
"""@brief A semantic predicate failed during validation.
Validation of predicates
occurs when normally parsing the alternative just like matching a token.
Disambiguating predicate evaluation occurs when we hoist a predicate into
a prediction decision.
"""
def __init__(self, input, ruleName, predicateText):
super().__init__(input)
self.ruleName = ruleName
self.predicateText = predicateText
def __str__(self):
return "FailedPredicateException({},{{{}}}?)".format(
self.ruleName, self.predicateText)
__repr__ = __str__
class MismatchedTreeNodeException(RecognitionException):
"""@brief The next tree mode does not match the expected type."""
def __init__(self, expecting, input):
super().__init__(input)
self.expecting = expecting
def __str__(self):
return "MismatchedTreeNodeException({!r}!={!r})".format(
self.getUnexpectedType(), self.expecting
)
__repr__ = __str__