@c -*-texinfo-*-
@c This is part of the GNU Guile Reference Manual.
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@c   Free Software Foundation, Inc.
@c See the file guile.texi for copying conditions.

@node LALR(1) Parsing
@section LALR(1) Parsing

The @code{(system base lalr)} module provides the
@uref{https://github.com/schemeway/lalr-scm/, @code{lalr-scm} LALR(1) parser
generator by Dominique Boucher}.  @code{lalr-scm} uses the same algorithm as GNU
Bison (@pxref{Introduction, Introduction to Bison,, bison, Bison@comma{} The
Yacc-compatible Parser Generator}).  Parsers are defined using the
@code{lalr-parser} macro.

@deffn {Scheme Syntax} lalr-parser [@var{options}] @var{tokens} @var{rules}...
Generate an LALR(1) syntax analyzer.  @var{tokens} is a list of symbols
representing the terminal symbols of the grammar.  @var{rules} are the grammar
production rules.

Each rule has the form @code{(@var{non-terminal} (@var{rhs} ...) : @var{action}
...)}, where @var{non-terminal} is the name of the rule, @var{rhs} are the
right-hand sides, i.e., the production rule, and @var{action} is a semantic
action associated with the rule.

The generated parser is a two-argument procedure that takes a
@dfn{tokenizer} and a @dfn{syntax error procedure}.  The tokenizer
should be a thunk that returns lexical tokens as produced by
@code{make-lexical-token}.  The syntax error procedure may be called
with at least an error message (a string), and optionally the lexical
token that caused the error.
@end deffn

Please refer to the @code{lalr-scm} documentation for details.