Crate antlr_rust[−][src]
Expand description
Antlr4 runtime
This is a Rust runtime for ANTLR4 parser generator. It is required to use parsers and lexers generated by ANTLR4 parser generator
This documentation refers to particular api used by generated parsers,lexers and syntax trees.
For info on what is ANTLR4 and how to generate parser please refer to:
Customization
All input and output can be customized and optimized for particular usecase by implementing related trait. Each of them already has different implementations that should be enough for most cases. For more details see docs for corresponding trait and containing module.
Currently available are:
CharStream
- Lexer input, stream of char values with slicing supportTokenFactory
- How lexer creates tokens.Token
- Element ofTokenStream
TokenStream
- Parser input, created from lexer or other token source.ParserRuleContext
- Node of created syntax tree.
Zero-copy and lifetimes
This library supports full zero-copy parsing. To allow this
'input
lifetime is used everywhere inside to refer to data borrowed by parser/lexer.
Besides references to input it also can be TokenFactory
if it returns references to tokens.
See ArenaFactory
as an example of such behavior.
It allocates tokens in Arena
and returns references.
Using generated parse tree you should be careful to not require longer lifetime after the parsing. If that’s the case you will likely get “does not live long enough” error on the input string, despite actual lifetime conflict is happening much later
If you need to generate owned versions of parse tree or you want simpler usage,
you can opt out zero-copy by requiring 'input
to be static. In this case it is easier to also use
types that contains “owned” in their name or constructor function like OwningTokenFactory
or InputStream::new_owned()
.
Visitors and Listeners
Parse listeners must outlive 'input
because they have to be stored inside of the parser.
It still allows to retrieve borrowed data from parse tree which should be enough to cover 99% use cases.
ParseTreeWalker
can accept listeners with arbitrary lifetime.
Visitor
s also can have arbitrary lifetime.
Downcasting
Rule context trait object support downcasting even for zero-copy case.
Also generic types(currently these are H:ErrorStrategy
and I:
TokenStream
) that you can
access in generated parser from embedded actions also can be downcasted to concrete types.
To do it TidExt::downcast_*
extension methods should be used.
Re-exports
pub use input_stream::InputStream;
Modules
IntStream
extension for Lexer that allows subslicing of underlying data
Channel based TokenStream
Error reporting
Error handling and recovery
Error types
Input to lexer
<ost generic stream of symbols
Lexer implementation
Implementation of lexer automata(DFA)
Base parser implementation
Base parser implementation
Full parser node
Minimal parser node
Symbols that parser works on
How Lexer should produce tokens
IntStream
that produces tokens for Parser
General AST
A set of utility routines useful for all kinds of ANTLR trees.
Mapping from symbol type to its string representation
Structs
This implementation of ANTLRErrorStrategy
responds to syntax errors
by immediately canceling the parse operation with a
ParseCancellationException
. The implementation ensures that the
ParserRuleContext.exception
field is set for all parse tree nodes
that were not completed prior to encountering the error.
Default implementation of Lexer
Main underlying Parser struct
This is the default implementation of ErrorStrategy
used for
error reporting and recovery in ANTLR parsers.
Allows to safely cast listener back to user type
Enums
This enum defines the prediction modes available in ANTLR 4 along with utility methods for analyzing configuration sets for conflicts and/or ambiguities.
Traits
The interface for defining strategies to deal with syntax errors encountered during a parse by ANTLR-generated parsers. We distinguish between three different kinds of errors:
Lexer functionality required by LexerATNSimulator
to work properly
parser functionality required for ParserATNSimulator
to work
Produces tokens to be used by parser.
TokenStream
implementations are responsible for buffering tokens for parser lookahead