Table of Symbols (Bison 3.8.1)

Appendix A Bison Symbols

Variable: @$ ¶: In an action, the location of the left-hand side of the rule. See Tracking Locations.

Variable: @n ¶

Symbol: @n ¶

In an action, the location of the n-th symbol of the right-hand side of the rule. See Tracking Locations.

In a grammar, the Bison-generated nonterminal symbol for a midrule action with a semantic value. See Midrule Action Translation.

Variable: @name ¶
Variable: @[name] ¶: In an action, the location of a symbol addressed by name. See Tracking Locations.

Symbol: $@n ¶: In a grammar, the Bison-generated nonterminal symbol for a midrule action with no semantics value. See Midrule Action Translation.

Variable: $$ ¶: In an action, the semantic value of the left-hand side of the rule. See Actions.

Variable: $n ¶: In an action, the semantic value of the n-th symbol of the right-hand side of the rule. See Actions.

Variable: $name ¶
Variable: $[name] ¶: In an action, the semantic value of a symbol addressed by name. See Actions.

Delimiter: %% ¶: Delimiter used to separate the grammar rule section from the Bison declarations section or the epilogue. See The Overall Layout of a Bison Grammar.

Delimiter: %{code%} ¶: All code listed between ‘%{’ and ‘%}’ is copied verbatim to the parser implementation file. Such code forms the prologue of the grammar file. See Outline of a Bison Grammar.

Directive: %?{expression} ¶: Predicate actions. This is a type of action clause that may appear in rules. The expression is evaluated, and if false, causes a syntax error. In GLR parsers during nondeterministic operation, this silently causes an alternative parse to die. During deterministic operation, it is the same as the effect of YYERROR. See Controlling a Parse with Arbitrary Predicates.

Construct: /* … */ ¶
Construct: // … ¶: Comments, as in C/C++.

Delimiter: : ¶: Separates a rule’s result from its components. See Grammar Rules.

Delimiter: ; ¶: Terminates a rule. See Grammar Rules.

Delimiter: | ¶: Separates alternate rules for the same result nonterminal. See Grammar Rules.

Directive: <*> ¶

Used to define a default tagged %destructor or default tagged %printer.

See Freeing Discarded Symbols.

Directive: <> ¶

Used to define a default tagless %destructor or default tagless %printer.

See Freeing Discarded Symbols.

Symbol: $accept ¶: The predefined nonterminal whose only rule is ‘$accept: start $end’, where start is the start symbol. See The Start-Symbol. It cannot be used in the grammar.

Directive: %code {code} ¶
Directive: %code qualifier {code} ¶: Insert code verbatim into the output parser source at the default location or at the location specified by qualifier. See %code Summary.

Directive: %debug ¶: Equip the parser for debugging. See Bison Declaration Summary.

Directive: %define variable ¶
Directive: %define variable value ¶
Directive: %define variable {value} ¶
Directive: %define variable "value" ¶: Define a variable to adjust Bison’s behavior. See %define Summary.

Directive: %defines ¶
Directive: %defines defines-file ¶: Historical name for %header. See Bison Declaration Summary.

Directive: %destructor ¶: Specify how the parser should reclaim the memory associated to discarded symbols. See Freeing Discarded Symbols.

Directive: %dprec ¶: Bison declaration to assign a precedence to a rule that is used at parse time to resolve reduce/reduce conflicts. See Writing GLR Parsers.

Directive: %empty ¶: Bison declaration to declare make explicit that a rule has an empty right-hand side. See Empty Rules.

Symbol: $end ¶: The predefined token marking the end of the token stream. It cannot be used in the grammar.

Symbol: error ¶: A token name reserved for error recovery. This token may be used in grammar rules so as to allow the Bison parser to recognize an error in the grammar without halting the process. In effect, a sentence containing an error may be recognized as valid. On a syntax error, the token error becomes the current lookahead token. Actions corresponding to error are then executed, and the lookahead token is reset to the token that originally caused the violation. See Error Recovery.

Directive: %error-verbose ¶: An obsolete directive standing for ‘%define parse.error verbose’.

Directive: %file-prefix "prefix" ¶: Bison declaration to set the prefix of the output files. See Bison Declaration Summary.

Directive: %glr-parser ¶: Bison declaration to produce a GLR parser. See Writing GLR Parsers.

Directive: %header ¶: Bison declaration to create a parser header file, which is usually meant for the scanner. See Bison Declaration Summary.

Directive: %header header-file ¶: Same as above, but save in the file header-file. See Bison Declaration Summary.

Directive: %initial-action ¶: Run user code before parsing. See Performing Actions before Parsing.

Directive: %language ¶: Specify the programming language for the generated parser. See Bison Declaration Summary.

Directive: %left ¶: Bison declaration to assign precedence and left associativity to token(s). See Operator Precedence.

Directive: %lex-param {argument-declaration} … ¶: Bison declaration to specifying additional arguments that yylex should accept. See Calling Conventions for Pure Parsers.

Directive: %merge ¶: Bison declaration to assign a merging function to a rule. If there is a reduce/reduce conflict with a rule having the same merging function, the function is applied to the two semantic values to get a single result. See Writing GLR Parsers.

Directive: %name-prefix "prefix" ¶

Obsoleted by the %define variable api.prefix (see Multiple Parsers in the Same Program).

Rename the external symbols (variables and functions) used in the parser so that they start with prefix instead of ‘yy’. Contrary to api.prefix, do no rename types and macros.

The precise list of symbols renamed in C parsers is yyparse, yylex, yyerror, yynerrs, yylval, yychar, yydebug, and (if locations are used) yylloc. If you use a push parser, yypush_parse, yypull_parse, yypstate, yypstate_new and yypstate_delete will also be renamed. For example, if you use ‘%name-prefix "c_"’, the names become c_parse, c_lex, and so on. For C++ parsers, see the %define api.namespace documentation in this section.

Directive: %no-lines ¶: Bison declaration to avoid generating #line directives in the parser implementation file. See Bison Declaration Summary.

Directive: %nonassoc ¶: Bison declaration to assign precedence and nonassociativity to token(s). See Operator Precedence.

Directive: %nterm ¶: Bison declaration to declare nonterminals. See Nonterminal Symbols.

Directive: %output "file" ¶: Bison declaration to set the name of the parser implementation file. See Bison Declaration Summary.

Directive: %param {argument-declaration} … ¶: Bison declaration to specify additional arguments that both yylex and yyparse should accept. See The Parser Function yyparse.

Directive: %parse-param {argument-declaration} … ¶: Bison declaration to specify additional arguments that yyparse should accept. See The Parser Function yyparse.

Directive: %prec ¶: Bison declaration to assign a precedence to a specific rule. See Context-Dependent Precedence.

Directive: %precedence ¶: Bison declaration to assign precedence to token(s), but no associativity See Operator Precedence.

Directive: %pure-parser ¶: Deprecated version of ‘%define api.pure’ (see %define Summary), for which Bison is more careful to warn about unreasonable usage.

Directive: %require "version" ¶: Require version version or higher of Bison. See Require a Version of Bison.

Directive: %right ¶: Bison declaration to assign precedence and right associativity to token(s). See Operator Precedence.

Directive: %skeleton ¶: Specify the skeleton to use; usually for development. See Bison Declaration Summary.

Directive: %start ¶: Bison declaration to specify the start symbol. See The Start-Symbol.

Directive: %token ¶: Bison declaration to declare token(s) without specifying precedence. See Token Kind Names.

Directive: %token-table ¶: Bison declaration to include a token name table in the parser implementation file. See Bison Declaration Summary.

Directive: %type ¶: Bison declaration to declare symbol value types. See Nonterminal Symbols.

Symbol: $undefined ¶: The predefined token onto which all undefined values returned by yylex are mapped. It cannot be used in the grammar, rather, use error.

Directive: %union ¶: Bison declaration to specify several possible data types for semantic values. See The Union Declaration.

Macro: YYABORT ¶

Macro to pretend that an unrecoverable syntax error has occurred, by making yyparse return 1 immediately. The error reporting function yyerror is not called. See The Parser Function yyparse.

For Java parsers, this functionality is invoked using return YYABORT; instead.

Macro: YYACCEPT ¶

Macro to pretend that a complete utterance of the language has been read, by making yyparse return 0 immediately. See The Parser Function yyparse.

For Java parsers, this functionality is invoked using return YYACCEPT; instead.

Macro: YYBACKUP ¶: Macro to discard a value from the parser stack and fake a lookahead token. See Special Features for Use in Actions.

Macro: YYBISON ¶: The version of Bison as an integer, for instance 30704 for version 3.7.4. Defined in yacc.c only. Before version 3.7.4, YYBISON was defined to 1.

Variable: yychar ¶: External integer variable that contains the integer value of the lookahead token. (In a pure parser, it is a local variable within yyparse.) Error-recovery rule actions may examine this variable. See Special Features for Use in Actions.

Variable: yyclearin ¶: Macro used in error-recovery rule actions. It clears the previous lookahead token. See Error Recovery.

Macro: YYDEBUG ¶: Macro to define to equip the parser with tracing code. See Tracing Your Parser.

Variable: yydebug ¶: External integer variable set to zero by default. If yydebug is given a nonzero value, the parser will output information on input symbols and parser action. See Tracing Your Parser.

Value: YYEMPTY ¶: The pseudo token kind when there is no lookahead token.

Value: YYEOF ¶: The token kind denoting is the end of the input stream.

Macro: yyerrok ¶: Macro to cause parser to recover immediately to its normal mode after a syntax error. See Error Recovery.

Macro: YYERROR ¶

Cause an immediate syntax error. This statement initiates error recovery just as if the parser itself had detected an error; however, it does not call yyerror, and does not print any message. If you want to print an error message, call yyerror explicitly before the ‘YYERROR;’ statement. See Error Recovery.

For Java parsers, this functionality is invoked using return YYERROR; instead.

Function: yyerror ¶: User-supplied function to be called by yyparse on error. See The Error Reporting Function yyerror.

Macro: YYFPRINTF ¶: Macro used to output run-time traces in C. See Enabling Traces.

Macro: YYINITDEPTH ¶: Macro for specifying the initial size of the parser stack. See Memory Management, and How to Avoid Memory Exhaustion.

Function: yylex ¶: User-supplied lexical analyzer function, called with no arguments to get the next token. See The Lexical Analyzer Function yylex.

Variable: yylloc ¶: External variable in which yylex should place the line and column numbers associated with a token. (In a pure parser, it is a local variable within yyparse, and its address is passed to yylex.) You can ignore this variable if you don’t use the ‘@’ feature in the grammar actions. See Textual Locations of Tokens. In semantic actions, it stores the location of the lookahead token. See Actions and Locations.

Type: YYLTYPE ¶: Data type of yylloc. By default in C, a structure with four members (start/end line/column). See Data Type of Locations.

Variable: yylval ¶: External variable in which yylex should place the semantic value associated with a token. (In a pure parser, it is a local variable within yyparse, and its address is passed to yylex.) See Semantic Values of Tokens. In semantic actions, it stores the semantic value of the lookahead token. See Actions.

Macro: YYMAXDEPTH ¶: Macro for specifying the maximum size of the parser stack. See Memory Management, and How to Avoid Memory Exhaustion.

Variable: yynerrs ¶: Global variable which Bison increments each time it reports a syntax error. (In a pure parser, it is a local variable within yyparse. In a pure push parser, it is a member of yypstate.) See The Error Reporting Function yyerror.

Macro: YYNOMEM ¶: Macro to pretend that memory is exhausted, by making yyparse return 2 immediately. The error reporting function yyerror is called. See The Parser Function yyparse.

Function: yyparse ¶: The parser function produced by Bison; call this function to start parsing. See The Parser Function yyparse.

Function: yypstate_delete ¶: The function to delete a parser instance, produced by Bison in push mode; call this function to delete the memory associated with a parser. See yypstate_delete. Does nothing when called with a null pointer.

Function: yypstate_new ¶: The function to create a parser instance, produced by Bison in push mode; call this function to create a new parser. See yypstate_new.

Function: yypull_parse ¶: The parser function produced by Bison in push mode; call this function to parse the rest of the input stream. See yypull_parse.

Function: yypush_parse ¶: The parser function produced by Bison in push mode; call this function to parse a single token. See yypush_parse.

Macro: YYRECOVERING ¶: The expression YYRECOVERING () yields 1 when the parser is recovering from a syntax error, and 0 otherwise. See Special Features for Use in Actions.

Macro: YYSTACK_USE_ALLOCA ¶

Macro used to control the use of alloca when the deterministic parser in C needs to extend its stacks. If defined to 0, the parser will use malloc to extend its stacks and memory exhaustion occurs if malloc fails (see Memory Management, and How to Avoid Memory Exhaustion). If defined to 1, the parser will use alloca. Values other than 0 and 1 are reserved for future Bison extensions. If not defined, YYSTACK_USE_ALLOCA defaults to 0.

In the all-too-common case where your code may run on a host with a limited stack and with unreliable stack-overflow checking, you should set YYMAXDEPTH to a value that cannot possibly result in unchecked stack overflow on any of your target hosts when alloca is called. You can inspect the code that Bison generates in order to determine the proper numeric values. This will require some expertise in low-level implementation details.

Type: YYSTYPE ¶: In C, data type of semantic values; int by default. Deprecated in favor of the %define variable api.value.type. See Data Types of Semantic Values.

Type: yysymbol_kind_t ¶: An enum of all the symbols, tokens and nonterminals, of the grammar. See The Syntax Error Reporting Function yyreport_syntax_error. The symbol kinds are used internally by the parser, and should not be confused with the token kinds: the symbol kind of a terminal symbol is not equal to its token kind! (Unless ‘%define api.token.raw’ was used.)

Type: yytoken_kind_t ¶: An enum of all the token kinds declared with %token (see Token Kind Names). These are the return values for yylex. They should not be confused with the symbol kinds, used internally by the parser.

Value: YYUNDEF ¶: The token kind denoting an unknown token.