We know by the time this check was reached that neither EPSILON nor the LL(1)
symbol are in the lookahead set from the current state. Since EPSILON is not
included, the state cannot see to the end of the rule and thus nextTokens
contains the complete set of valid LL(1) symbols from the current state. It is
therefore impossible for the LL(1) symbol to be "expected" when considering
lookahead with full context.
This change updates the default sync() strategy to match the strategy used
for selecting an alternative when prediction leaves the decision rule prior
to reaching a syntax error.
Closes#1545
The consume method of the Parser class calls visitTerminal on both
TerminalNodes and ErrorNodes even if the comment above states that
ErrorNodes should be visited by visitErrorNodes. This behaviour
is also inconsitent with the Java target. The patch fixes this in
both Python targets.
The `removeOne` function of IntervalSet tries to directly
rewrite the start field of an immutable range variable when
splitting an existing interval. This causes AttributeError which
is fixed by the patch.
The Python implementations are completely synchronous
with the Java version even if some of the constructs
can be expressed with simpler Python solutions. These are
typically the all, any, count, next builtins or the list
comprehensions, etc. Beside using them makes the code
clearer, they are also prefered by the standard and can
result in performance speedup. The patch contains such
equivalent transformations in the Python targets.
The Java target initializes the conflictingAlt local variable
based on the conflictingAlts property of the target state.
However, the Python targets resets it to None. The patch makes the
initializations consistent.
The __contains__ method of ATNConfigSet used different hashing
function (hash) for indexing the config dictionary than the
getOrAdd method (hashCodeForConfigSet) which filled it.
Furthermore, they also used different methods for comparing
ATNConfig objects. The patch makes them consistent.
At the end of the nextToken() function, setting the eofToken field was
attempted without the 'self' keyword, resulting in accessing
and setting a new local and unused variable. The patch supplements
the missing 'self' keywords for both targets.
The root cause was that ATNConfigSet was not using he required custom hashing strategy for ParserATNSimulator.
The commit includes a number of additional fixes, related to code that was never executed before due to the root cause.
A similar issue is also likely to exist in the JavaScript runtime, I'll fix it later.
termination condition.
The PredictionMode::hasSLLConflictTerminatingPrediction method aims to
create ATNConfig objects from another ATNConfig and SemanticContext
objects. In case of the Python targets, the initialization
happened without keyword arguments. Since the called __init__
method had default values set for all the parameters, the parameter
substitution worked by indices. As a consequence, the first ATNConfig
parameter was wrongly interpreted as an ATNState and the SemanticContext as
an alternative. The patch fixes this by adding the missing keywords.
parrt
Ben Hamilton
Eric Vergnaud
Sam Harwell
Ivan Kochurkin
Renata Hodovan
ghosthope