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Merge remote-tracking branch 'origin/maint'

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* origin/maint:
  news: prepare for forthcoming release
  doc: explain how mid-rule actions are translated
  error: use better locations for unused midrule values
  doc: various minor improvements and fixes
  tests: ignore more useless compiler warnings
  tests: be robust to C being compiled with a C++11 compiler
  build: beware of Clang++ not supporting POSIXLY_CORRECT
  maint: post-release administrivia
  version 2.6.90
  build: fix syntax-check error.
  cpp: simplify the Flex version checking macro
  news: improve the carets example and fix a typo
  cpp: improve the Flex version checking macro
  carets: improve the code
  maint: update news
  build: keep -Wmissing-declarations and -Wmissing-prototypes for modern GCCs
  build: drop -Wcast-qual
  gnulib: update

Conflicts:
	NEWS
	doc/Makefile.am
	doc/bison.texi
	gnulib
	src/reader.c
	tests/actions.at
	tests/atlocal.in
	tests/input.at
This commit is contained in:
Theophile Ranquet
2012-12-10 17:01:55 +01:00
parent f3ead217b8 d4fe9e88f3
commit 0906b12cd5
18 changed files with 611 additions and 278 deletions
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309
doc/bison.texi
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@@ -211,6 +211,12 @@ Defining Language Semantics
This says when, why and how to use the exceptional
action in the middle of a rule.
Actions in Mid-Rule
* Using Mid-Rule Actions:: Putting an action in the middle of a rule.
* Mid-Rule Action Translation:: How mid-rule actions are actually processed.
* Mid-Rule Conflicts:: Mid-rule actions can cause conflicts.
Tracking Locations
* Location Type:: Specifying a data type for locations.
@@ -2791,6 +2797,9 @@ The Bison grammar file conventionally has a name ending in @samp{.y}.
@node Grammar Outline
@section Outline of a Bison Grammar
@cindex comment
@findex // @dots{}
@findex /* @dots{} */
A Bison grammar file has four main sections, shown here with the
appropriate delimiters:
@@ -2810,8 +2819,8 @@ appropriate delimiters:
@end example
Comments enclosed in @samp{/* @dots{} */} may appear in any of the sections.
As a GNU extension, @samp{//} introduces a comment that
continues until end of line.
As a GNU extension, @samp{//} introduces a comment that continues until end
of line.
@menu
* Prologue:: Syntax and usage of the prologue.
@@ -3799,6 +3808,15 @@ Occasionally it is useful to put an action in the middle of a rule.
These actions are written just like usual end-of-rule actions, but they
are executed before the parser even recognizes the following components.
@menu
* Using Mid-Rule Actions:: Putting an action in the middle of a rule.
* Mid-Rule Action Translation:: How mid-rule actions are actually processed.
* Mid-Rule Conflicts:: Mid-rule actions can cause conflicts.
@end menu
@node Using Mid-Rule Actions
@subsubsection Using Mid-Rule Actions
A mid-rule action may refer to the components preceding it using
@code{$@var{n}}, but it may not refer to subsequent components because
it is run before they are parsed.
@@ -3831,10 +3849,16 @@ remove it afterward. Here is how it is done:
@example
@group
stmt:
LET '(' var ')'
@{ $<context>$ = push_context (); declare_variable ($3); @}
"let" '(' var ')'
@{
$<context>$ = push_context ();
declare_variable ($3);
@}
stmt
@{ $$ = $6; pop_context ($<context>5); @}
@{
$$ = $6;
pop_context ($<context>5);
@}
@end group
@end example
@@ -3845,8 +3869,27 @@ list of accessible variables) as its semantic value, using alternative
@code{context} in the data-type union. Then it calls
@code{declare_variable} to add the new variable to that list. Once the
first action is finished, the embedded statement @code{stmt} can be
parsed. Note that the mid-rule action is component number 5, so the
@samp{stmt} is component number 6.
parsed.
Note that the mid-rule action is component number 5, so the @samp{stmt} is
component number 6. Named references can be used to improve the readability
and maintainability (@pxref{Named References}):
@example
@group
stmt:
"let" '(' var ')'
@{
$<context>let = push_context ();
declare_variable ($3);
@}[let]
stmt
@{
$$ = $6;
pop_context ($<context>let);
@}
@end group
@end example
After the embedded statement is parsed, its semantic value becomes the
value of the entire @code{let}-statement. Then the semantic value from the
@@ -3880,13 +3923,13 @@ stmt:
let stmt
@{
$$ = $2;
pop_context ($1);
pop_context ($let);
@};
let:
LET '(' var ')'
"let" '(' var ')'
@{
$$ = push_context ();
$let = push_context ();
declare_variable ($3);
@};
@@ -3898,6 +3941,76 @@ Note that the action is now at the end of its rule.
Any mid-rule action can be converted to an end-of-rule action in this way, and
this is what Bison actually does to implement mid-rule actions.
@node Mid-Rule Action Translation
@subsubsection Mid-Rule Action Translation
@vindex $@@@var{n}
@vindex @@@var{n}
As hinted earlier, mid-rule actions are actually transformed into regular
rules and actions. The various reports generated by Bison (textual,
graphical, etc., see @ref{Understanding, , Understanding Your Parser})
reveal this translation, best explained by means of an example. The
following rule:
@example
exp: @{ a(); @} "b" @{ c(); @} @{ d(); @} "e" @{ f(); @};
@end example
@noindent
is translated into:
@example
$@@1: /* empty */ @{ a(); @};
$@@2: /* empty */ @{ c(); @};
$@@3: /* empty */ @{ d(); @};
exp: $@@1 "b" $@@2 $@@3 "e" @{ f(); @};
@end example
@noindent
with new nonterminal symbols @code{$@@@var{n}}, where @var{n} is a number.
A mid-rule action is expected to generate a value if it uses @code{$$}, or
the (final) action uses @code{$@var{n}} where @var{n} denote the mid-rule
action. In that case its nonterminal is rather named @code{@@@var{n}}:
@example
exp: @{ a(); @} "b" @{ $$ = c(); @} @{ d(); @} "e" @{ f = $1; @};
@end example
@noindent
is translated into
@example
@@1: /* empty */ @{ a(); @};
@@2: /* empty */ @{ $$ = c(); @};
$@@3: /* empty */ @{ d(); @};
exp: @@1 "b" @@2 $@@3 "e" @{ f = $1; @}
@end example
There are probably two errors in the above example: the first mid-rule
action does not generate a value (it does not use @code{$$} although the
final action uses it), and the value of the second one is not used (the
final action does not use @code{$3}). Bison reports these errors when the
@code{midrule-value} warnings are enabled (@pxref{Invocation, ,Invoking
Bison}):
@example
$ bison -fcaret -Wmidrule-value mid.y
@group
mid.y:2.6-13: warning: unset value: $$
exp: @{ a(); @} "b" @{ $$ = c(); @} @{ d(); @} "e" @{ f = $1; @};
^^^^^^^^
@end group
@group
mid.y:2.19-31: warning: unused value: $3
exp: @{ a(); @} "b" @{ $$ = c(); @} @{ d(); @} "e" @{ f = $1; @};
^^^^^^^^^^^^^
@end group
@end example
@node Mid-Rule Conflicts
@subsubsection Conflicts due to Mid-Rule Actions
Taking action before a rule is completely recognized often leads to
conflicts since the parser must commit to a parse in order to execute the
action. For example, the following two rules, without mid-rule actions,
@@ -3995,6 +4108,7 @@ compound:
Now Bison can execute the action in the rule for @code{subroutine} without
deciding which rule for @code{compound} it will eventually use.
@node Tracking Locations
@section Tracking Locations
@cindex location
@@ -5524,8 +5638,8 @@ I.e., if @samp{%locations %define api.pure} is passed then the prototypes for
@code{yyerror} are:
@example
void yyerror (char const *msg); /* Yacc parsers. */
void yyerror (YYLTYPE *locp, char const *msg); /* GLR parsers. */
void yyerror (char const *msg); // Yacc parsers.
void yyerror (YYLTYPE *locp, char const *msg); // GLR parsers.
@end example
But if @samp{%locations %define api.pure %parse-param @{int *nastiness@}} is
@@ -6662,7 +6776,6 @@ Actions}).
@end deffn
@deffn {Value} @@$
@findex @@$
Acts like a structure variable containing information on the textual
location of the grouping made by the current rule. @xref{Tracking
Locations}.
@@ -6721,7 +6834,7 @@ GNU Automake.
@item
@cindex bison-i18n.m4
Into the directory containing the GNU Autoconf macros used
by the package---often called @file{m4}---copy the
by the package ---often called @file{m4}--- copy the
@file{bison-i18n.m4} file installed by Bison under
@samp{share/aclocal/bison-i18n.m4} in Bison's installation directory.
For example:
@@ -8526,8 +8639,26 @@ clear the flag.
Developing a parser can be a challenge, especially if you don't understand
the algorithm (@pxref{Algorithm, ,The Bison Parser Algorithm}). This
chapter explains how to generate and read the detailed description of the
automaton, and how to enable and understand the parser run-time traces.
chapter explains how understand and debug a parser.
The first sections focus on the static part of the parser: its structure.
They explain how to generate and read the detailed description of the
automaton. There are several formats available:
@itemize @minus
@item
as text, see @ref{Understanding, , Understanding Your Parser};
@item
as a graph, see @ref{Graphviz,, Visualizing Your Parser};
@item
or as a markup report that can be turned, for instance, into HTML, see
@ref{Xml,, Visualizing your parser in multiple formats}.
@end itemize
The last section focuses on the dynamic part of the parser: how to enable
and understand the parser run-time traces (@pxref{Tracing, ,Tracing Your
Parser}).
@menu
* Understanding:: Understanding the structure of your parser.
@@ -8542,8 +8673,7 @@ automaton, and how to enable and understand the parser run-time traces.
As documented elsewhere (@pxref{Algorithm, ,The Bison Parser Algorithm})
Bison parsers are @dfn{shift/reduce automata}. In some cases (much more
frequent than one would hope), looking at this automaton is required to
tune or simply fix a parser. Bison provides two different
representation of it, either textually or graphically (as a DOT file).
tune or simply fix a parser.
The textual file is generated when the options @option{--report} or
@option{--verbose} are specified, see @ref{Invocation, , Invoking
@@ -8557,9 +8687,12 @@ The following grammar file, @file{calc.y}, will be used in the sequel:
@example
%token NUM STR
@group
%left '+' '-'
%left '*'
@end group
%%
@group
exp:
exp '+' exp
| exp '-' exp
@@ -8567,6 +8700,7 @@ exp:
| exp '/' exp
| NUM
;
@end group
useless: STR;
%%
@end example
@@ -8576,8 +8710,8 @@ useless: STR;
@example
calc.y: warning: 1 nonterminal useless in grammar
calc.y: warning: 1 rule useless in grammar
calc.y:11.1-7: warning: nonterminal useless in grammar: useless
calc.y:11.10-12: warning: rule useless in grammar: useless: STR
calc.y:12.1-7: warning: nonterminal useless in grammar: useless
calc.y:12.10-12: warning: rule useless in grammar: useless: STR
calc.y: conflicts: 7 shift/reduce
@end example
@@ -8671,7 +8805,7 @@ item is a production rule together with a point (@samp{.}) marking
the location of the input cursor.
@example
state 0
State 0
0 $accept: . exp $end
@@ -8701,7 +8835,7 @@ you want to see more detail you can invoke @command{bison} with
@option{--report=itemset} to list the derived items as well:
@example
state 0
State 0
0 $accept: . exp $end
1 exp: . exp '+' exp
@@ -8719,7 +8853,7 @@ state 0
In the state 1@dots{}
@example
state 1
State 1
5 exp: NUM .
@@ -8729,11 +8863,11 @@ state 1
@noindent
the rule 5, @samp{exp: NUM;}, is completed. Whatever the lookahead token
(@samp{$default}), the parser will reduce it. If it was coming from
state 0, then, after this reduction it will return to state 0, and will
State 0, then, after this reduction it will return to state 0, and will
jump to state 2 (@samp{exp: go to state 2}).
@example
state 2
State 2
0 $accept: exp . $end
1 exp: exp . '+' exp
@@ -8761,7 +8895,7 @@ The state 3 is named the @dfn{final state}, or the @dfn{accepting
state}:
@example
state 3
State 3
0 $accept: exp $end .
@@ -8776,7 +8910,7 @@ The interpretation of states 4 to 7 is straightforward, and is left to
the reader.
@example
state 4
State 4
1 exp: exp '+' . exp
@@ -8785,7 +8919,7 @@ state 4
exp go to state 8
state 5
State 5
2 exp: exp '-' . exp
@@ -8794,7 +8928,7 @@ state 5
exp go to state 9
state 6
State 6
3 exp: exp '*' . exp
@@ -8803,7 +8937,7 @@ state 6
exp go to state 10
state 7
State 7
4 exp: exp '/' . exp
@@ -8816,7 +8950,7 @@ As was announced in beginning of the report, @samp{State 8 conflicts:
1 shift/reduce}:
@example
state 8
State 8
1 exp: exp . '+' exp
1 | exp '+' exp .
@@ -8859,7 +8993,7 @@ with some set of possible lookahead tokens. When run with
@option{--report=lookahead}, Bison specifies these lookahead tokens:
@example
state 8
State 8
1 exp: exp . '+' exp
1 | exp '+' exp . [$end, '+', '-', '/']
@@ -8891,7 +9025,7 @@ The remaining states are similar:
@example
@group
state 9
State 9
1 exp: exp . '+' exp
2 | exp . '-' exp
@@ -8907,7 +9041,7 @@ state 9
@end group
@group
state 10
State 10
1 exp: exp . '+' exp
2 | exp . '-' exp
@@ -8922,7 +9056,7 @@ state 10
@end group
@group
state 11
State 11
1 exp: exp . '+' exp
2 | exp . '-' exp
@@ -8945,12 +9079,11 @@ state 11
@noindent
Observe that state 11 contains conflicts not only due to the lack of
precedence of @samp{/} with respect to @samp{+}, @samp{-}, and
@samp{*}, but also because the
associativity of @samp{/} is not specified.
precedence of @samp{/} with respect to @samp{+}, @samp{-}, and @samp{*}, but
also because the associativity of @samp{/} is not specified.
Note that Bison may also produce an HTML version of this output, via an XML
file and XSLT processing (@pxref{Xml}).
Bison may also produce an HTML version of this output, via an XML file and
XSLT processing (@pxref{Xml,,Visualizing your parser in multiple formats}).
@c ================================================= Graphical Representation
@@ -8970,7 +9103,10 @@ This file is generated when the @option{--graph} option is specified
(@pxref{Invocation, , Invoking Bison}). Its name is made by removing
@samp{.tab.c} or @samp{.c} from the parser implementation file name, and
adding @samp{.dot} instead. If the grammar file is @file{foo.y}, the
Graphviz output file is called @file{foo.dot}.
Graphviz output file is called @file{foo.dot}. A DOT file may also be
produced via an XML file and XSLT processing (@pxref{Xml,,Visualizing your
parser in multiple formats}).
The following grammar file, @file{rr.y}, will be used in the sequel:
@@ -8983,10 +9119,20 @@ b: "0";
@end group
@end example
The graphical output is very similar to the textual one, and as such it is
easier understood by making direct comparisons between them. See
@ref{Debugging, , Debugging Your Parser} for a detailled analysis of the
textual report.
The graphical output
@ifnotinfo
(see @ref{fig:graph})
@end ifnotinfo
is very similar to the textual one, and as such it is easier understood by
making direct comparisons between them. @xref{Debugging, , Debugging Your
Parser}, for a detailled analysis of the textual report.
@ifnotinfo
@float Figure,fig:graph
@image{figs/example, 430pt}
@caption{A graphical rendering of the parser.}
@end float
@end ifnotinfo
@subheading Graphical Representation of States
@@ -9011,7 +9157,7 @@ shift. The following describes a reduction in the @file{rr.output} file:
@example
@group
state 3
State 3
1 exp: a . ";"
@@ -9032,7 +9178,7 @@ action for the given state, there is no such label.
This is how reductions are represented in the verbose file @file{rr.output}:
@example
state 1
State 1
3 a: "0" . [";"]
4 b: "0" . ["."]
@@ -9051,17 +9197,14 @@ reduction, see @ref{Shift/Reduce, , Shift/Reduce Conflicts}. Discarded actions
are distinguished by a red filling color on these nodes, just like how they are
reported between square brackets in the verbose file.
The reduction corresponding to the rule number 0 is the acceptation state. It
is shown as a blue diamond, labelled "Acc".
The reduction corresponding to the rule number 0 is the acceptation
state. It is shown as a blue diamond, labelled ``Acc''.
@subheading Graphical representation of go tos
The @samp{go to} jump transitions are represented as dotted lines bearing
the name of the rule being jumped to.
Note that a DOT file may also be produced via an XML file and XSLT
processing (@pxref{Xml}).
@c ================================================= XML
@node Xml
@@ -9069,8 +9212,10 @@ processing (@pxref{Xml}).
@cindex xml
Bison supports two major report formats: textual output
(@pxref{Understanding}) when invoked with option @option{--verbose}, and DOT
(@pxref{Graphviz}) when invoked with option @option{--graph}. However,
(@pxref{Understanding, ,Understanding Your Parser}) when invoked
with option @option{--verbose}, and DOT
(@pxref{Graphviz,, Visualizing Your Parser}) when invoked with
option @option{--graph}. However,
another alternative is to output an XML file that may then be, with
@command{xsltproc}, rendered as either a raw text format equivalent to the
verbose file, or as an HTML version of the same file, with clickable
@@ -9078,7 +9223,7 @@ transitions, or even as a DOT. The @file{.output} and DOT files obtained via
XSLT have no difference whatsoever with those obtained by invoking
@command{bison} with options @option{--verbose} or @option{--graph}.
The textual file is generated when the options @option{-x} or
The XML file is generated when the options @option{-x} or
@option{--xml[=FILE]} are specified, see @ref{Invocation,,Invoking Bison}.
If not specified, its name is made by removing @samp{.tab.c} or @samp{.c}
from the parser implementation file name, and adding @samp{.xml} instead.
@@ -9092,19 +9237,19 @@ files to apply to the XML file. Their names are non-ambiguous:
@item xml2dot.xsl
Used to output a copy of the DOT visualization of the automaton.
@item xml2text.xsl
Used to output a copy of the .output file.
Used to output a copy of the @samp{.output} file.
@item xml2xhtml.xsl
Used to output an xhtml enhancement of the .output file.
Used to output an xhtml enhancement of the @samp{.output} file.
@end table
Sample usage (requires @code{xsltproc}):
Sample usage (requires @command{xsltproc}):
@example
$ bison -x input.y
$ bison -x gr.y
@group
$ bison --print-datadir
/usr/local/share/bison
@end group
$ xsltproc /usr/local/share/bison/xslt/xml2xhtml.xsl input.xml > input.html
$ xsltproc /usr/local/share/bison/xslt/xml2xhtml.xsl gr.xml >gr.html
@end example
@c ================================================= Tracing
@@ -9302,7 +9447,7 @@ Entering state 24
@noindent
The previous reduction demonstrates the @code{%printer} directive for
@code{<val>}: both the token @code{NUM} and the resulting non-terminal
@code{<val>}: both the token @code{NUM} and the resulting nonterminal
@code{exp} have @samp{1} as value.
@example
@@ -9617,7 +9762,7 @@ Show caret errors, in a manner similar to GCC's
@option{-fdiagnostics-show-caret}, or Clang's @option{-fcaret-diagnotics}. The
location provided with the message is used to quote the corresponding line of
the source file, underlining the important part of it with carets (^). Here is
an example, using the following file @file{input.y}:
an example, using the following file @file{in.y}:
@example
%type <ival> exp
@@ -9629,27 +9774,27 @@ When invoked with @option{-fcaret}, Bison will report:
@example
@group
input.y:3.20-23: error: ambiguous reference: '$exp'
in.y:3.20-23: error: ambiguous reference: '$exp'
exp: exp '+' exp @{ $exp = $1 + $2; @};
^^^^
@end group
@group
input.y:3.1-3: refers to: $exp at $$
in.y:3.1-3: refers to: $exp at $$
exp: exp '+' exp @{ $exp = $1 + $2; @};
^^^
@end group
@group
input.y:3.6-8: refers to: $exp at $1
in.y:3.6-8: refers to: $exp at $1
exp: exp '+' exp @{ $exp = $1 + $2; @};
^^^
@end group
@group
input.y:3.14-16: refers to: $exp at $3
in.y:3.14-16: refers to: $exp at $3
exp: exp '+' exp @{ $exp = $1 + $2; @};
^^^
@end group
@group
input.y:3.32-33: error: $2 of 'exp' has no declared type
in.y:3.32-33: error: $2 of 'exp' has no declared type
exp: exp '+' exp @{ $exp = $1 + $2; @};
^^
@end group
@@ -12040,18 +12185,23 @@ In an action, the location of the left-hand side of the rule.
@end deffn
@deffn {Variable} @@@var{n}
@deffnx {Symbol} @@@var{n}
In an action, the location of the @var{n}-th symbol of the right-hand side
of the rule. @xref{Tracking Locations}.
In a grammar, the Bison-generated nonterminal symbol for a mid-rule action
with a semantical value. @xref{Mid-Rule Action Translation}.
@end deffn
@deffn {Variable} @@@var{name}
In an action, the location of a symbol addressed by name. @xref{Tracking
Locations}.
@deffnx {Variable} @@[@var{name}]
In an action, the location of a symbol addressed by @var{name}.
@xref{Tracking Locations}.
@end deffn
@deffn {Variable} @@[@var{name}]
In an action, the location of a symbol addressed by name. @xref{Tracking
Locations}.
@deffn {Symbol} $@@@var{n}
In a grammar, the Bison-generated nonterminal symbol for a mid-rule action
with no semantical value. @xref{Mid-Rule Action Translation}.
@end deffn
@deffn {Variable} $$
@@ -12065,12 +12215,8 @@ right-hand side of the rule. @xref{Actions}.
@end deffn
@deffn {Variable} $@var{name}
In an action, the semantic value of a symbol addressed by name.
@xref{Actions}.
@end deffn
@deffn {Variable} $[@var{name}]
In an action, the semantic value of a symbol addressed by name.
@deffnx {Variable} $[@var{name}]
In an action, the semantic value of a symbol addressed by @var{name}.
@xref{Actions}.
@end deffn
@@ -12101,8 +12247,9 @@ More user feedback will help to determine whether it should become a permanent
feature.
@end deffn
@deffn {Construct} /*@dots{}*/
Comment delimiters, as in C.
@deffn {Construct} /* @dots{} */
@deffnx {Construct} // @dots{}
Comments, as in C/C++.
@end deffn
@deffn {Delimiter} :
@@ -12587,7 +12734,7 @@ Data type of semantic values; @code{int} by default.
@item Accepting state
A state whose only action is the accept action.
The accepting state is thus a consistent state.
@xref{Understanding,,}.
@xref{Understanding, ,Understanding Your Parser}.
@item Backus-Naur Form (BNF; also called ``Backus Normal Form'')
Formal method of specifying context-free grammars originally proposed

35
doc/figs/example.dot Normal file
View File

@@ -0,0 +1,35 @@
// Generated by GNU Bison 2.6.90.
// Report bugs to <bug-bison@gnu.org>.
// Home page: <http://www.gnu.org/software/bison/>.
digraph "/tmp/fo.y"
{
node [fontname = courier, shape = box, colorscheme = paired6]
edge [fontname = courier]
0 [label="State 0\n\l 0 $accept: . exp $end\l 1 exp: . a \";\"\l 2 | . b \".\"\l 3 a: . \"0\"\l 4 b: . \"0\"\l"]
0 -> 1 [style=solid label="\"0\""]
0 -> 2 [style=dashed label="exp"]
0 -> 3 [style=dashed label="a"]
0 -> 4 [style=dashed label="b"]
1 [label="State 1\n\l 3 a: \"0\" . [\";\"]\l 4 b: \"0\" . [\".\"]\l"]
1 -> "1R3" [style=solid]
"1R3" [label="R3", fillcolor=3, shape=diamond, style=filled]
1 -> "1R4" [label="[\".\"]", style=solid]
"1R4" [label="R4", fillcolor=3, shape=diamond, style=filled]
2 [label="State 2\n\l 0 $accept: exp . $end\l"]
2 -> 5 [style=solid label="$end"]
3 [label="State 3\n\l 1 exp: a . \";\"\l"]
3 -> 6 [style=solid label="\";\""]
4 [label="State 4\n\l 2 exp: b . \".\"\l"]
4 -> 7 [style=solid label="\".\""]
5 [label="State 5\n\l 0 $accept: exp $end .\l"]
5 -> "5R0" [style=solid]
"5R0" [label="Acc", fillcolor=1, shape=diamond, style=filled]
6 [label="State 6\n\l 1 exp: a \";\" .\l"]
6 -> "6R1" [style=solid]
"6R1" [label="R1", fillcolor=3, shape=diamond, style=filled]
7 [label="State 7\n\l 2 exp: b \".\" .\l"]
7 -> "7R2" [style=solid]
"7R2" [label="R2", fillcolor=3, shape=diamond, style=filled]
}

4
doc/figs/example.y Normal file
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@@ -0,0 +1,4 @@
%%
exp: a ";" | b ".";
a: "0";
b: "0";