10.2.4 Java Parser Interface

The name of the generated parser class defaults to YYParser. The YY prefix may be changed using the %name-prefix directive or the ‘-p’/‘--name-prefix’ option. Alternatively, use %define parser_class_name "name" to give a custom name to the class. The interface of this class is detailed below.

By default, the parser class has package visibility. A declaration %define public will change to public visibility. Remember that, according to the Java language specification, the name of the ‘.java’ file should match the name of the class in this case. Similarly, you can use abstract, final and strictfp with the %define declaration to add other modifiers to the parser class.

The Java package name of the parser class can be specified using the %define package directive. The superclass and the implemented interfaces of the parser class can be specified with the %define extends and %define implements directives.

The parser class defines an inner class, Location, that is used for location tracking (see Java Location Values), and a inner interface, Lexer (see Java Scanner Interface). Other than these inner class/interface, and the members described in the interface below, all the other members and fields are preceded with a yy or YY prefix to avoid clashes with user code.

The parser class can be extended using the %parse-param directive. Each occurrence of the directive will add a protected final field to the parser class, and an argument to its constructor, which initialize them automatically.

Token names defined by %token and the predefined EOF token name are added as constant fields to the parser class.

Constructor on YYParser: YYParser (lex_param, …, parse_param, …)

Build a new parser object with embedded %code lexer. There are no parameters, unless %parse-params and/or %lex-params are used.

Constructor on YYParser: YYParser (Lexer lexer, parse_param, …)

Build a new parser object using the specified scanner. There are no additional parameters unless %parse-params are used.

If the scanner is defined by %code lexer, this constructor is declared protected and is called automatically with a scanner created with the correct %lex-params.

Method on YYParser: boolean parse ()

Run the syntactic analysis, and return true on success, false otherwise.

Method on YYParser: boolean recovering ()

During the syntactic analysis, return true if recovering from a syntax error. See section Error Recovery.

Method on YYParser: java.io.PrintStream getDebugStream ()

Method on YYParser: void setDebugStream (java.io.printStream o)

Get or set the stream used for tracing the parsing. It defaults to System.err.

Method on YYParser: int getDebugLevel ()

Method on YYParser: void setDebugLevel (int l)

Get or set the tracing level. Currently its value is either 0, no trace, or nonzero, full tracing.