This comes from https://github.com/janyou/ANTLR-Swift-Target and is
marked Copyright (c) 2016 janyou on top of the BSD license and Copyrights
for Terence Parr and Sam Harwell derived from the original ANTLR source.
Incorrect code was generated for $e.v in a rule like this one:
e returns [int v] ::=
INT {$v = $INT.int;}
| '(' e ')' {$v = $e.v;}
;
After parsing "(99)" the result would have v == 0 instead of 99.
- Mutexes have been consolidated. Instead of one per DFA (which can easily get to hundreds of them) we only have one mutex in the Recognizer class and all other parties use this for serialization. It's only about protected the DFA anyway, which is stored in a recognizer (lexer/parser).
- ATNState::getStateType() returns a size_t value now (actually an enum).
- Replaced checks via RTTI for transitions by the (serialization) type of the transition, for simplicity.
- Added some missing initialization for fields in certain ATN state classes.
- Fixed mem leak in DFA by shadowing the s0 field. That way still have a ref to the self created instance, even is s0 was replaced later.
- Added variable init in code generation for a rule context declaration (e.g. for labels).
There are 2 parts in an ANTLR genrated parser where memory is allocated: the actual parsing (with or w/o creating a parse tree) and the prediction part (via DFA/ATN etc.). The first part is highly volatile as it recreates parse tree instances (the class) on each parser run. In fact also lexer tokens belong to that part, but are already managed via unique pointers. This first part works without any smart pointer now. Instead there is a simple tracker class which holds all created references and frees them when the parser is reset or destroyed. This is a bit less optimal if the parser is set to create no parse tree, as created rule context objects are not freed immediately (like with smart pointers), but during reset. On the other hand this change gives (depending on the input) a nice speed up (0%-100%, after the warm up phase). Additionally memory consumption drops by a good amount.
Everything in the simulartors (and interpreters) remains unchanged. This is the shared prediction part.
- Had to adjust a comparison <= 0 to the new unsigned EOF.
- For testing: extended the runtime tests to all C++ tests.
- Install uuid-dev in Travis CI in order to be able to build the C++ runtime.
- Switched most symbolic signed constants to unsigned variants. Redefined EOF in particular to become (size)-1, to avoid having to use signed token type values.
- Introduced INVALID_INDEX for all previous -1 values to indicate e.g. not found indexes etc.
- Added 2 helpers to convert between symbolic and numeric form (mostly for intervals and toString()).
- Removed many no longer needed type casts to size_t.
- Updated templates for these changes.
- Limited runtime tests to C++ tests only, to see how Travis CI copes with that.
- Lesser use of shared_ptr, e.g. in listeners and some loops.
- Removed useless access methods for children in ParseRuleContext. The child list is public. Fixed initialization for start and stop nodes.
- Simplified parent + child organization in Tree and all derived classes. Instead of using overridable functions in various descendants we have now central parent + child fields in the base tree class (where they belong actually, considering this is about forming a tree). Users have to cast to the appropriate classes if necessary.
- Removed obsolete getChildren() function in Trees helper. We can just return the child vector.
- Changed edges member to an unordered_map, as this is a sparse container. This speeds up certain grammars by 1000% (e.g. highly recursive expression rules) and avoids wasting a lot of memory. This change also simplifies handling significantly.
- Had to escape tabs + linebreaks in DefaultErrorStrategy when generating a text representation. Also removed a few explicit string instance creations on the way.
- Member vars in parser context classes that take (optional) Token references must be initialized.
- Fixed a warning that copyFrom() would hide a virtual function in a ParserRuleContext.
- Another attempt to limit genrating double semicolons.
- Added new rule to test grammar to get code generation for wildcard capture.
- Updated the Cpp.stg template file for that.
- Made the Unicode hack (auto extend 0xFFFF to 0x10FFFF) dependent on a parameter, so we only use this hack when deserializing an ATN. This avoids trouble with intervals used in other contexts (like string offsets).
- Added a few operator != overloads, to fix compilation after recent changes.
- Simplified operands comparison in SemanticContext (uses the Arrays class now). Some cleanup in that class too.
- The abstract parse tree visitor now uses const& for Any references, to avoid reallocating new instances over and over again.
- The lexer counts syntax errors the same way as the parser does. So we can directly determine if there was any error by simply examining that (which avoids having to use a temporary listener).
The translation from Java generics to templates in C++ lead to the need of virtual template functions, which is not supported by C++. Instead we use now the Any class for results of visits and no longer need templates for that part.
No need to use shared_ptr for management. Listeners are, like the other main classes (parser, lexer, input stream etc.) provided by the application and hence managed there.
In order to lower the overhead when passing around Token instances via smart pointers and because the ownership is clear (token streams own them), these instances can be passed as raw pointers.
And some related fixes.
- Combined multiple blank lines between package decls into one
- Moved some doc comments to just above what they document
- Changed some doc comments to start with the documented thing's name
- Removed some redundant anchor and wrap ST options
- Changed an empty struct type containing just a newline to struct{}
- Added some missing doc comments to exported interface methods
- Removed unneeded parentheses around a single import
- Prevents generating empty const blocks
- Generates single-line package const decls if only one decl
- Indented switch case bodies
- Content checks for some template vars, e.g. if v defined then v else nothing
- Removed template redundancies, e.g. from <attrs:{a | <a>}> to <attrs>.
- Removed blank lines that group embedded types and fields separately
- Changed some trivial one-line func/method decls to mult-line
- Changed empty package slice decls to use nil, e.g. var foo []uint16
- Changed const int enums that used the ST <i> var to use iota instead
- Replaced separator in GoTarget.encodeIntAsCharEscape with a template separator
All shared_ptr<> now use const& for function parameters to avoid constant copies + locks. Ownership and lifetime control is still ensured by the owning containers. Code templates have been updated as well.
- Changed namespace chain (org::antlr::v4::runtime) to just antlr4 in all files.
- Fixed runtime tests for that.
- Added conversion of the xpath code, which compiles now (no tests, tho, as there are runtime tests for it).
- Removed TestRig stuff. That doesn't work in C++.
- Avoiding double semicolons is tricky with the kind of rule nesting. Previous changes for that caused the tests to break as there were semicolons missing then.
- VS complained about the shift code generated using 1L as base, which is signed. Changed that to 1ULL, which is what is actually intended.
- Reverted the change to avoid a warning in RuleSempredFunction() in Cpp.stg as the fix didn't work 100%. We need a different solution.
- Fixed all disabled tests and enabled them.
- Some more adjustments of the test template + target template was needed.
- Worked on semicolon usage in Cpp.stg to avoid double semicolons. Might need more work, tho.
- Allow loading new input instead of setting up a new input stream.
- Made is<> template function inline, for hopefully faster execution.
- A few other fixes in stream + lexer classes.
- Reverted another rename from context to _localctx in the Cpp.stg file as this is used for certain actions.
- Reverted the change from RecognitionException to exception_ptr (and removed the make_exception_ptr() call). This is not needed and only leads to object slicing. Instead we check directly the given exception object for the individual handling in reportError() and use std::current_exception() to get the exception pointer for our contexts.
- Removed precompiled header stuff from cmake file for the same reasons as I did in the XCode project (Visual Studio still pending).
In order to ease including the antlr runtime in other projects the include structure has been changed:
- Removed precompiled header usage (only OSX, VS + cmake still need updates).
- Created umbrella header antlr4-runtime.h that contains everything needed in a target application.
- Changed all includes to use relative paths, so it is enough to add the src folder to the header search path in an application.
- Also fixed a smaller issue in the C++ template wrt the serialized ATN storage for large grammars.
- In order to support UTF-8 the input streams now support loading data from UTF-8 strings and convert them internally to UTF32.
- Additionally, all the toString() functions that (unnecessarily) used wstring are now on string as well. Only some corner cases remain where we still have std::wstring (ATNSerializer).
- The transition classes use size_t instead of int now for vocabulary matching.
- The max char value in the lexer has been increased to 1FFFE, to allow matching the full Unicode range. This is also used in the Interval class to e.g. to negate sets.
- Renamed Strings.h to StringUtils.h, to avoid a conflict with an OSX header (used with Obj-C compilation, e.g. in a project that uses the runtime).
- Also the ArrayPredictionContext has parent references (like the SingletonPredictionContext) which need to be strong refs or we may lose some of the parent contexts if they are not held somewhere else.
- Don't use WCHAR_MIN as lower bounds for char input checks, it's not 0 as you would expect but -2G, making so EOF succeed even though it should fail this check.
- Don't resize the parents array when merging parents + return states in PredictionContext or we will try to access parents outside of the available range.
- Use an unordered set when merging parents in PredictionContext, so that the normal equality pattern kicks in when comparing contexts.
- Some parameters in AbstractParseTreeVisitor where wrongly outcommented where only the param name should.
C++ template:
- No longer include the DEFAULT_MODE in the generated lexer (it's defined elsewhere).
- Corrected formatting and finished some reference rules that were not done yet.
- Reversed the meaning of grammar sections members + declarations to maintain the same meaning for members between C++ and Java target. Now members are placed in the public section of a class, while declarations use the private section. This change helps to minimize language specific parts in grammar actions.
- Removed deleted cpp files from XCode project.
- Cpp.stg:
- Renamed all occurences of "result" back to "_localctx" as they appear in the Java.stg file. While the name "result" better fits the purpose the rename increases differences between targets, hence it was taken back, so we can use the same actions in all targets.
- TokenPropertyRef_text is now complete.
Some warnings in generated files cannot be fixed in a general way because usage of parameters depends on the grammar, hence we suppress unused-parameter warnings in the grammar (for lexer and parser files).
- @parser::context or @lexer::context are now also accepted for code that should be placed directly before the class declaration (e.g. additional types, like enums etc.)
- Reverted the removal of explicit EOF handling. Thought we can just live with the EOF macro, but that doesn't work out, so we go with the same approach as the ANTLR3 C target: #undef EOF and use EOF member constants as in the original Java code.
- Fixed a crash when trying to create a hash from a null parent in PredictionContext.cpp.
- Generated token and rule enums are now placed in the lexer/parser classes which allows to use them without qualfication within those classes, making so actions in a grammar more language independent. Outside code still has to use e.g. TParser::ID to access them.
- Made some lambda capture lists more explicit. Need to test yet if we can just use a default capture instead.
- Compiling with cmake brought up quite a number of new warnings. Some of them have to be disabled yet (dollar in identifier, four char constant, overloaded virtual). The others have all been fixed.
- Updated the README to include build instruction.
C++ target:
- More sections are now supported: pre + post include, declarations, definitions (in addition to header and members).
- Added specific variants of these sections for (base)listener + (base)visitor files (baselistenerpreinclude etc.).
Had to add named sections to VisitorFile.java + ListenerFile.java.
Also added the new namedActions parameter to all target stg files where needed.
One of the lambdas used in a "finally" expression executed already while defining the "finally" instance, which is way too early of course (others did not show this behavior), which happens only with the Visual Studio compiler, not clang. By changing the capture list to a general reference capture things started working as they should.
Sometimes in the prediction process temporary ATNConfig instances are created which either share their prediction context with other configs or get a new context which receives the context of another config as parent. Later in the process such temporary configs are released, but the set parent prediction context should stay alive as it is used later. Since there is no top level structure that would keep them alive we need a way to make them stay. For this effect the SinglePredictionContext (which is the only prediction context that keeps a parent reference) uses a shared_ptr instead of a weak_ptr for the parent reference.
- Changed the empty return state PredictionContext to max int (instead fixing it on int 16), like it's done in the Java runtime.
- Converted 2 static init lambdas in the Cpp.stg to normal code, as VS doesn't allow us to access private class members in such lambdas.
Originally the serialized ATN was coded as a wide string literal with embeded Unicode escapes (where necessary). This might fail on Windows however, as VS is very strict when checking Unicode code points and rejects compilation if it finds undefined code points. Hence this generation has been changed to hex numbers instead of that string literal.
- Removed ultra simple test grammar + parser. No longer needed.
- Removed long list of keywords from (regular) test grammar.
- Fixed a number of toString() methods to get better debug output.
- Moved Ref typedefs from Declarations.h to the individual classes as defining them on the forward declarations totally confuses the XCode debugger.
- Removed reference to the owning ATN in an ATNState. We cannot guarantee to have the correct address there due to the way the states are created. The reference is not needed anyway.
- ATNDeserializationOptions now has verifyATN set by default (as in the Java target).
- Had to add a workaround for a weird situation: static initialization in ATNDeseralizer stopped working for no apparent reason. Need to investigate this.
- Added a few support methods to the CPPUtils, mostly to ease debug output creation.
- Added console listener by default to the listeners list (as done in the Java target).
- Fixed translation mistakes in the CommonTokenStream class.
- Fixed some memory leaks and exception handling bugs.
The default pass statements were missing from the LL1AltBlock's
template in case of Python targets, which generated conditional statements
without body in some cases and ended in syntax error. The patch fixes this.
- Removed a few unused classes.
- More raw pointers to smart pointers conversion: RuleContext, ParserRuleContext, ParseTree, Token, ParseTreeWalker, Tree...
- BitSet is now used directly instead of all those dynamic allocations and is a derived class instead of a composite.
- Replced ATNState equals with == operator overload.
- Correct wrong iterator over ATNConfigsets.
- Added utilitiy function that mimics Java's generic toString().
- Exceptions are now consistently thrown by value and captured by reference. C++11 exception_ptr and nested_exception are used when exception references are neeeded or when implementing the equivalent of Java's nesting.
- The is<> helper didn't handle properly (const) references, which is now explicitly handled. Added new unit tests for that.
- Fixed a number of places where a catch all was used to implement a "finally" (which hides exceptions).
- Changed exceptions to hold (temporary) raw pointers instead of shared pointers, as otherwise it is tried to free wrapped pointers which might just be references to static objects. Might later be updated again when we continue with removing raw pointers.
- Some smaller fixes.
- The generated simple parser now runs through without any error (yet, it doesn't do anything useful).
- ANTLR C++ target template:
- Added getListener and genVisitor bool members to ANTLR's LexerFile + ParserFile classes, so can use them in the template.
- Made addition of listener #include dependent on the new genListener member, which allows to run parser generation without listeners/visitors.
- Added an even simpler grammar to ease debugging while getting the lib into a working state.
- Added helper template is<> to ease frequent type checks (for value types, ref types and shared_ptr). Added some unit tests for that as well.
- Changed the MurmurHash::hashCode() function to take shared_ptr as this is the only variant we need. Had to change the MurmurHash unit tests for that.
- Removed conflicting IntStream::_EOF (and other variants). We use the C runtime EOF value instead.
- Changed all references to semantic contexts, prediction context and the prediction context cache to use shared_ptr<>. Created *Ref typedefs to simplify usage.
- Adjusted the C++ string templates for that.
- Fixed a number of memory leaks + some cleanup.
- Reworked the exception hierarchy to conform with the Java hierarchy (where we mimic that). Ultimative base class is std::exception, which uses std::string (char* actually) for messages, so all exceptions use std::string for that as well. Consider that as first step to rework the entire lib to use std::string instead of std::wstring (with utf-8 for full Unicode support).
- Removed ASSERTException + TODOException and fixed the places where they were used.
- Removed ANTLRException, which was only an intermediate layer without an equivalent on Java side.
- Replaced some equals() calls by == (with defined operator overloading).
- Enhanced Arrays::equals() to ensure it compiles only if the actual types being compared support the != operator (both value + reference types).
- Made the Recognizer class template free by using plain polymorphism. Some adjustments were need also in the Cpp template to support that. Could convert the .inl file to .cpp then.
- Added IntervalSet unit tests. Fixed a few bugs found by that.
- Enhanced the demo grammar so that we use as many as possible template rules from Cpp.stg. Still not fully done it seems.
- Fixed bugs in size determination for arrays (vectors now).
- Simplified PredictionContext and SemanticContext (one template parameter less).
- Removed no longer used Utils.h/cpp. Fixed CPPUtils.h/cpp.
- Extended LexerXXCommand template rules to take a new grammar parameter (code gen has been updated) as we need this context in the Cpp target. This change requires to update all existing templates! Cannot do here as this is an old revision.
- Some cleanup.
- Added first real unit test set and enable code coverage collection in XCode (for ANTLRInputStream).
- Reworked ANTLRFileStream::load, which is now more flexible (supports Unicode BOM + 3 possible encodings), can load from Unicode file names and has almost no platform code.
- Enabled strict data size and sign checks in XCode (clang) and fixed a million places...
- Started converting int to size_t where it makes more sense.
- Started working on const correctness.
- Fixed a ton of memory leaks.
- The ATN and ATNConfigSet classes now entirely work as value types. Same for Interval(Set). These seem to be the most critical data structures (ATNConfig + ATNState are pending).
- The abstract IntSet class is gone now.
- Murmur hash code now works with size_t instead of int (need to add unit tests for that).
- Fixed a number of TODOs and other smaller things.
- The Cpp template now properly handles grammar rule return values.
ATNs are top level structures, which are created and kept by parser/lexer classes (or their simulator equivalents). Hence there are now value types in their controlling class and passed around as const &.
IRecognizer was a template class without real need, which has been changed to make it a simple interface easily usable without having to find C++ hacks for fancy Java wildcard generics.
- Reformatted every single file to have a consistent indentation style using only space chars, with 2 chars per indentation. Reduced huge indentation due to deep namespace nesting by not indenting namespaces.
- Reduced #include usage to a minimum.
- Made copyright header the first entry in all files.
- Moved the previously mac-only prefix file (antlrcpp-Prefix.h) to the runtime. It can now be used by all platforms and includes all necessary standard headers.
- Removed a number of unused files.
- ATN deserialization finally works.
- Changed a number of pointer to STL classes to just the STL classes and pass them around by const & where necessary.
- The demo now uses a real setup to parse something and print output.
- Replaced empty UUID implementation by the guid implementation from Graeme Hill. Fixed uuid handling in a few places.
- Removed some obsolete (and mostly empty) lib files.
- Mac: the XCode project now does regenerate the files only after a grammar change, not always.
- Simplified ATNDeserializer + ATNSerializer and fixed a few things there (e.g. feature determination, duplicate copy op of the input).
- Removed some deprecated functions from ATNSimulator.h
- Fixed some bugs (e.g. uninitialized vars + leaks).
- Corrected a mistake I did in CppTarget which lead to wrong serialized ATN output.
- Cpp template:
- Added proper static init code generation for Lexer + Parser classes.
- Added some missing functions.
- Created a new command line target in the XCode project. Win + Linux yet outstanding.
- Reorganized the C++ runtime folder structure a bit
* Put everything in a new folder "runtime"
* Added a "demo" folder for the demo grammar + app
* Renamed Apple folder to Mac in demo folder
* Added a script with some descriptions to run parser regeneration (via jar or classes). This is also used in the XCode project to regenerate the files.
* Moved all C++ runtime files up in the folder hierarchy. No need to mimic the deep nesting from Java.
- Some adjustments here and there in the C++ runtime for consistency.
- Overhaul of the Cpp.stg file to produce compilable code. Extracted file level templates into a new template Files.stg. Experimented with new named actions (@parser::listenerheader) but the result is not satisfying yet. Need to investigate more.
- Extended ANTLR to produce header files if a target class returns true in the new function needsHeader().
- Added generated folder from demo to .gitignore
- Added myself to contributors file + maven xml.
The parameter `RuleFunction rf` in `ActionTranslater#translateActionChunk` may be `null`.
The method's implementation takes care of this by checking `rf` before making its `ruleCtx` the translator's nodeContext:
```
if ( rf!=null ) translator.nodeContext = rf.ruleCtx;
```
However in the statement following this code the check for `rf!=null` is missing. This will lead to a `NullPointerException` when `altLabel` is defined and `rf` is `null`:
```
if ( altLabel!=null ) translator.nodeContext = rf.altLabelCtxs.get(altLabel);
```
To avoid the problem only access `rf.altLabelCtxs` when `rf` is not null:
```
if ( rf!=null ) {
translator.nodeContext = rf.ruleCtx;
if ( altLabel!=null ) translator.nodeContext = rf.altLabelCtxs.get(altLabel);
}
```
After loading and casting the parserClass in TestRig#process using
`cl.loadClass(parserName).asSubclass(Parser.class)` there is a check if
the class returned by `#asSubclass` is not null:
```
parserClass = cl.loadClass(parserName).asSubclass(Parser.class);
if ( parserClass==null ) {
System.err.println("Can't load "+parserName);
}
```
The method `#asSubclass` will never return `null`, but throw an
`ClassCastException` when the cast is not valid, therefore the check
can be removed.
See also: [TestRig#process Documentation](http://docs.oracle.com/javase/6/docs/api/java/lang/Class.html#asSubclass(java.lang.Class\))
The `selectedTree.getSelectionPath()` return null if nothing is selected.
Added check to avoid NPE:
```java
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at org.antlr.v4.gui.TreeViewer$4.valueChanged(TreeViewer.java:376)
at javax.swing.JTree.fireValueChanged(JTree.java:2921)
at javax.swing.JTree$TreeSelectionRedirector.valueChanged(JTree.java:3382)
at javax.swing.tree.DefaultTreeSelectionModel.fireValueChanged(DefaultTreeSelectionModel.java:635)
at javax.swing.tree.DefaultTreeSelectionModel.notifyPathChange(DefaultTreeSelectionModel.java:1093)
at javax.swing.tree.DefaultTreeSelectionModel.removeSelectionPaths(DefaultTreeSelectionModel.java:502)
at javax.swing.JTree.removeDescendantSelectedPaths(JTree.java:3714)
at javax.swing.JTree.setExpandedState(JTree.java:3597)
at javax.swing.JTree.collapsePath(JTree.java:2231)
at javax.swing.plaf.basic.BasicTreeUI.toggleExpandState(BasicTreeUI.java:2297)
at javax.swing.plaf.basic.BasicTreeUI.handleExpandControlClick(BasicTreeUI.java:2273)
at javax.swing.plaf.basic.BasicTreeUI.checkForClickInExpandControl(BasicTreeUI.java:2231)
at javax.swing.plaf.basic.BasicTreeUI$Handler.handleSelection(BasicTreeUI.java:3600)
at javax.swing.plaf.basic.BasicTreeUI$Handler.mousePressed(BasicTreeUI.java:3548)
at java.awt.Component.processMouseEvent(Component.java:6524)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6292)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4883)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4705)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4530)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
at java.awt.Container.dispatchEventImpl(Container.java:2278)
at java.awt.Window.dispatchEventImpl(Window.java:2739)
at java.awt.Component.dispatchEvent(Component.java:4705)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
at java.awt.EventQueue.access$400(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:697)
at java.awt.EventQueue$3.run(EventQueue.java:691)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:719)
at java.awt.EventQueue$4.run(EventQueue.java:717)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
```
The help and error message from the TestRig program refers to the old `runtime.misc` instead of the new `gui` package:
```
java org.antlr.v4.runtime.misc.TestRig GrammarName startRuleName
[-tokens] [-tree] [-gui] [-ps file.ps] [-encoding encodingname]
[-trace] [-diagnostics] [-SLL]
[input-filename(s)]
Use startRuleName='tokens' if GrammarName is a lexer grammar.
Omitting input-filename makes rig read from stdin.
```
These sync calls are truly redundant - when we are in a simple
alternative block, we can recover sufficiently with `recoverInline`, and
so the syncs do not add anything.