A. Bison Symbols
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 parse error, the
token
error
becomes the current look-ahead token. Actions
corresponding to error
are then executed, and the look-ahead
token is reset to the token that originally caused the violation.
See section 6. Error Recovery.
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 section The Parser Function yyparse
.
YYACCEPT
- Macro to pretend that a complete utterance of the language has been
read, by making
yyparse
return 0 immediately.
See section The Parser Function yyparse
.
YYBACKUP
- Macro to discard a value from the parser stack and fake a look-ahead
token. See section Special Features for Use in Actions.
YYERROR
- Macro to pretend that a syntax error has just been detected: call
yyerror
and then perform normal error recovery if possible
(see section 6. Error Recovery), or (if recovery is impossible) make
yyparse
return 1. See section 6. Error Recovery.
YYERROR_VERBOSE
- Macro that you define with
#define
in the Bison declarations
section to request verbose, specific error message strings when
yyerror
is called.
YYINITDEPTH
- Macro for specifying the initial size of the parser stack.
See section 5.8 Stack Overflow, and How to Avoid It.
YYLEX_PARAM
- Macro for specifying an extra argument (or list of extra arguments) for
yyparse
to pass to yylex
. See section Calling Conventions for Pure Parsers.
YYLTYPE
- Macro for the data type of
yylloc
; a structure with four
members. See section Textual Positions of Tokens.
yyltype
- Default value for YYLTYPE.
YYMAXDEPTH
- Macro for specifying the maximum size of the parser stack.
See section 5.8 Stack Overflow, and How to Avoid It.
YYPARSE_PARAM
- Macro for specifying the name of a parameter that
yyparse
should
accept. See section Calling Conventions for Pure Parsers.
YYRECOVERING
- Macro whose value indicates whether the parser is recovering from a
syntax error. See section Special Features for Use in Actions.
YYSTYPE
- Macro for the data type of semantic values;
int
by default.
See section Data Types of Semantic Values.
yychar
- External integer variable that contains the integer value of the
current look-ahead token. (In a pure parser, it is a local variable
within
yyparse
.) Error-recovery rule actions may examine this
variable. See section Special Features for Use in Actions.
yyclearin
- Macro used in error-recovery rule actions. It clears the previous
look-ahead token. See section 6. Error Recovery.
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 section Debugging Your Parser.
yyerrok
- Macro to cause parser to recover immediately to its normal mode
after a parse error. See section 6. Error Recovery.
yyerror
- User-supplied function to be called by
yyparse
on error. The
function receives one argument, a pointer to a character string
containing an error message. See section The Error Reporting Function yyerror
.
yylex
- User-supplied lexical analyzer function, called with no arguments
to get the next token. See section The Lexical Analyzer Function
yylex
.
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 section Semantic Values of Tokens.
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 section Textual Positions of Tokens.
yynerrs
- Global variable which Bison increments each time there is a parse
error. (In a pure parser, it is a local variable within
yyparse
.) See section The Error Reporting Function yyerror
.
yyparse
- The parser function produced by Bison; call this function to start
parsing. See section The Parser Function
yyparse
.
%left
- Bison declaration to assign left associativity to token(s).
See section Operator Precedence.
%no_lines
- Bison declaration to avoid generating
#line
directives in the
parser file. See section 3.6.8 Bison Declaration Summary.
%nonassoc
- Bison declaration to assign nonassociativity to token(s).
See section Operator Precedence.
%prec
- Bison declaration to assign a precedence to a specific rule.
See section Context-Dependent Precedence.
%pure_parser
- Bison declaration to request a pure (reentrant) parser.
See section A Pure (Reentrant) Parser.
%raw
- Bison declaration to use Bison internal token code numbers in token
tables instead of the usual Yacc-compatible token code numbers.
See section 3.6.8 Bison Declaration Summary.
%right
- Bison declaration to assign right associativity to token(s).
See section Operator Precedence.
%start
- Bison declaration to specify the start symbol. See section The Start-Symbol.
%token
- Bison declaration to declare token(s) without specifying precedence.
See section Token Type Names.
%token_table
- Bison declaration to include a token name table in the parser file.
See section 3.6.8 Bison Declaration Summary.
%type
- Bison declaration to declare nonterminals. See section Nonterminal Symbols.
%union
- Bison declaration to specify several possible data types for semantic
values. See section The Collection of Value Types.
These are the punctuation and delimiters used in Bison input:
- `%%'
- Delimiter used to separate the grammar rule section from the
Bison declarations section or the additional C code section.
See section The Overall Layout of a Bison Grammar.
- `%{ %}'
- All code listed between `%{' and `%}' is copied directly
to the output file uninterpreted. Such code forms the "C
declarations" section of the input file. See section Outline of a Bison Grammar.
- `/*...*/'
- Comment delimiters, as in C.
- `:'
- Separates a rule's result from its components. See section Syntax of Grammar Rules.
- `;'
- Terminates a rule. See section Syntax of Grammar Rules.
- `|'
- Separates alternate rules for the same result nonterminal.
See section Syntax of Grammar Rules.
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