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Re: RFC: doc: use only @example, not @smallexample
|
From: |
Akim Demaille |
|
Subject: |
Re: RFC: doc: use only @example, not @smallexample |
|
Date: |
Fri, 16 Mar 2012 14:35:30 +0100 |
Le 16 mars 2012 à 09:24, Paul Eggert a écrit :
> On 03/16/2012 01:20 AM, Akim Demaille wrote:
>> I prefer the following style (which does help to stay
>> within a more reasonable width).
>
> That style is OK by me. Some might prefer indenting the
> "|" and ";" lines by a couple of spaces, which would also
> be fine and would scale nearly as well.
I have tried to do that first, but one example did not fit
this way, and it was significantly more painful to adjust to
that style instead of sticking to colon 0 (where M-\ and C-x
r k are very effective tools).
I propose the attached changes.
From bb864b6a2304e0eea7595ea68788e4a1d1a3c9bb Mon Sep 17 00:00:00 2001
From: Akim Demaille <address@hidden>
Date: Fri, 16 Mar 2012 14:26:00 +0100
Subject: [PATCH 1/3] doc: reformat grammar snippets.
* doc/bison.texinfo: Convert the grammar examples to
use a narrower style. This helps fitting into the
@smallbook constraints.
http://lists.gnu.org/archive/html/bison-patches/2012-03/msg00011.html
---
doc/bison.texinfo | 819 ++++++++++++++++++++++++++++-------------------------
1 file changed, 430 insertions(+), 389 deletions(-)
diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index 9824781..b2012c6 100644
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -642,8 +642,7 @@ the statement; the naked semicolon, and the colon, are
Bison punctuation
used in every rule.
@example
-stmt: RETURN expr ';'
- ;
+stmt: RETURN expr ';' ;
@end example
@noindent
@@ -715,8 +714,7 @@ For example, here is a rule that says an expression can be
the sum of
two subexpressions:
@example
-expr: expr '+' expr @{ $$ = $1 + $3; @}
- ;
+expr: expr '+' expr @{ $$ = $1 + $3; @} ;
@end example
@noindent
@@ -896,30 +894,32 @@ parses a vastly simplified form of Pascal type
declarations.
%%
@group
-type_decl : TYPE ID '=' type ';'
- ;
+type_decl: TYPE ID '=' type ';' ;
@end group
@group
-type : '(' id_list ')'
- | expr DOTDOT expr
- ;
+type:
+ '(' id_list ')'
+| expr DOTDOT expr
+;
@end group
@group
-id_list : ID
- | id_list ',' ID
- ;
+id_list:
+ ID
+| id_list ',' ID
+;
@end group
@group
-expr : '(' expr ')'
- | expr '+' expr
- | expr '-' expr
- | expr '*' expr
- | expr '/' expr
- | ID
- ;
+expr:
+ '(' expr ')'
+| expr '+' expr
+| expr '-' expr
+| expr '*' expr
+| expr '/' expr
+| ID
+;
@end group
@end example
@@ -999,30 +999,35 @@ Let's consider an example, vastly simplified from a C++
grammar.
%%
-prog :
- | prog stmt @{ printf ("\n"); @}
- ;
+prog:
+ /* Nothing. */
+| prog stmt @{ printf ("\n"); @}
+;
-stmt : expr ';' %dprec 1
- | decl %dprec 2
- ;
+stmt:
+ expr ';' %dprec 1
+| decl %dprec 2
+;
-expr : ID @{ printf ("%s ", $$); @}
- | TYPENAME '(' expr ')'
- @{ printf ("%s <cast> ", $1); @}
- | expr '+' expr @{ printf ("+ "); @}
- | expr '=' expr @{ printf ("= "); @}
- ;
+expr:
+ ID @{ printf ("%s ", $$); @}
+| TYPENAME '(' expr ')'
+ @{ printf ("%s <cast> ", $1); @}
+| expr '+' expr @{ printf ("+ "); @}
+| expr '=' expr @{ printf ("= "); @}
+;
-decl : TYPENAME declarator ';'
- @{ printf ("%s <declare> ", $1); @}
- | TYPENAME declarator '=' expr ';'
- @{ printf ("%s <init-declare> ", $1); @}
- ;
+decl:
+ TYPENAME declarator ';'
+ @{ printf ("%s <declare> ", $1); @}
+| TYPENAME declarator '=' expr ';'
+ @{ printf ("%s <init-declare> ", $1); @}
+;
-declarator : ID @{ printf ("\"%s\" ", $1); @}
- | '(' declarator ')'
- ;
+declarator:
+ ID @{ printf ("\"%s\" ", $1); @}
+| '(' declarator ')'
+;
@end example
@noindent
@@ -1091,9 +1096,10 @@ other. To do so, you could change the declaration of
@code{stmt} as
follows:
@example
-stmt : expr ';' %merge <stmtMerge>
- | decl %merge <stmtMerge>
- ;
+stmt:
+ expr ';' %merge <stmtMerge>
+| decl %merge <stmtMerge>
+;
@end example
@noindent
@@ -1207,9 +1213,9 @@ evolve. We welcome user feedback.) For example,
@example
widget:
- address@hidden new_syntax @} "widget" id new_args @{ $$ = f($3,
$4); @}
- | address@hidden !new_syntax @} "widget" id old_args @{ $$ = f($3,
$4); @}
- ;
+ address@hidden new_syntax @} "widget" id new_args @{ $$ = f($3, $4); @}
+| address@hidden !new_syntax @} "widget" id old_args @{ $$ = f($3, $4); @}
+;
@end example
@noindent
@@ -1233,11 +1239,11 @@ For example, we could try to rewrite the previous
example as
@example
widget:
- @{ if (!new_syntax) YYERROR; @}
- "widget" id new_args @{ $$ = f($3, $4); @}
- | @{ if (new_syntax) YYERROR; @}
- "widget" id old_args @{ $$ = f($3, $4); @}
- ;
+ @{ if (!new_syntax) YYERROR; @}
+ "widget" id new_args @{ $$ = f($3, $4); @}
+| @{ if (new_syntax) YYERROR; @}
+ "widget" id old_args @{ $$ = f($3, $4); @}
+;
@end example
@noindent
@@ -1575,25 +1581,28 @@ Here are the grammar rules for the reverse polish
notation calculator.
@comment file: rpcalc.y
@example
@group
-input: /* empty */
- | input line
+input:
+ /* empty */
+| input line
;
@end group
@group
-line: '\n'
- | exp '\n' @{ printf ("%.10g\n", $1); @}
+line:
+ '\n'
+| exp '\n' @{ printf ("%.10g\n", $1); @}
;
@end group
@group
-exp: NUM @{ $$ = $1; @}
- | exp exp '+' @{ $$ = $1 + $2; @}
- | exp exp '-' @{ $$ = $1 - $2; @}
- | exp exp '*' @{ $$ = $1 * $2; @}
- | exp exp '/' @{ $$ = $1 / $2; @}
- | exp exp '^' @{ $$ = pow ($1, $2); @} /* Exponentiation */
- | exp 'n' @{ $$ = -$1; @} /* Unary minus */
+exp:
+ NUM @{ $$ = $1; @}
+| exp exp '+' @{ $$ = $1 + $2; @}
+| exp exp '-' @{ $$ = $1 - $2; @}
+| exp exp '*' @{ $$ = $1 * $2; @}
+| exp exp '/' @{ $$ = $1 / $2; @}
+| exp exp '^' @{ $$ = pow ($1, $2); @} /* Exponentiation */
+| exp 'n' @{ $$ = -$1; @} /* Unary minus */
;
@end group
%%
@@ -1629,8 +1638,9 @@ rule are referred to as @code{$1}, @code{$2}, and so on.
Consider the definition of @code{input}:
@example
-input: /* empty */
- | input line
+input:
+ /* empty */
+| input line
;
@end example
@@ -1663,8 +1673,9 @@ input tokens; we will arrange for the latter to happen at
end-of-input.
Now consider the definition of @code{line}:
@example
-line: '\n'
- | exp '\n' @{ printf ("%.10g\n", $1); @}
+line:
+ '\n'
+| exp '\n' @{ printf ("%.10g\n", $1); @}
;
@end example
@@ -1691,21 +1702,22 @@ The second handles an addition-expression, which looks
like two expressions
followed by a plus-sign. The third handles subtraction, and so on.
@example
-exp: NUM
- | exp exp '+' @{ $$ = $1 + $2; @}
- | exp exp '-' @{ $$ = $1 - $2; @}
- @dots{}
- ;
+exp:
+ NUM
+| exp exp '+' @{ $$ = $1 + $2; @}
+| exp exp '-' @{ $$ = $1 - $2; @}
address@hidden
+;
@end example
We have used @samp{|} to join all the rules for @code{exp}, but we could
equally well have written them separately:
@example
-exp: NUM ;
-exp: exp exp '+' @{ $$ = $1 + $2; @} ;
-exp: exp exp '-' @{ $$ = $1 - $2; @} ;
- @dots{}
+exp: NUM ;
+exp: exp exp '+' @{ $$ = $1 + $2; @};
+exp: exp exp '-' @{ $$ = $1 - $2; @};
address@hidden
@end example
Most of the rules have actions that compute the value of the expression in
@@ -1726,16 +1738,17 @@ not require it. You can add or change white space as
much as you wish.
For example, this:
@example
-exp : NUM | exp exp '+' @{$$ = $1 + $2; @} | @dots{} ;
+exp: NUM | exp exp '+' @{$$ = $1 + $2; @} | @dots{} ;
@end example
@noindent
means the same thing as this:
@example
-exp: NUM
- | exp exp '+' @{ $$ = $1 + $2; @}
- | @dots{}
+exp:
+ NUM
+| exp exp '+' @{ $$ = $1 + $2; @}
+| @dots{}
;
@end example
@@ -1983,26 +1996,29 @@ parentheses nested to arbitrary depth. Here is the
Bison code for
%% /* The grammar follows. */
@group
-input: /* empty */
- | input line
+input:
+ /* empty */
+| input line
;
@end group
@group
-line: '\n'
- | exp '\n' @{ printf ("\t%.10g\n", $1); @}
+line:
+ '\n'
+| exp '\n' @{ printf ("\t%.10g\n", $1); @}
;
@end group
@group
-exp: NUM @{ $$ = $1; @}
- | exp '+' exp @{ $$ = $1 + $3; @}
- | exp '-' exp @{ $$ = $1 - $3; @}
- | exp '*' exp @{ $$ = $1 * $3; @}
- | exp '/' exp @{ $$ = $1 / $3; @}
- | '-' exp %prec NEG @{ $$ = -$2; @}
- | exp '^' exp @{ $$ = pow ($1, $3); @}
- | '(' exp ')' @{ $$ = $2; @}
+exp:
+ NUM @{ $$ = $1; @}
+| exp '+' exp @{ $$ = $1 + $3; @}
+| exp '-' exp @{ $$ = $1 - $3; @}
+| exp '*' exp @{ $$ = $1 * $3; @}
+| exp '/' exp @{ $$ = $1 / $3; @}
+| '-' exp %prec NEG @{ $$ = -$2; @}
+| exp '^' exp @{ $$ = pow ($1, $3); @}
+| '(' exp ')' @{ $$ = $2; @}
;
@end group
%%
@@ -2066,9 +2082,10 @@ been added to one of the alternatives for @code{line}:
@example
@group
-line: '\n'
- | exp '\n' @{ printf ("\t%.10g\n", $1); @}
- | error '\n' @{ yyerrok; @}
+line:
+ '\n'
+| exp '\n' @{ printf ("\t%.10g\n", $1); @}
+| error '\n' @{ yyerrok; @}
;
@end group
@end example
@@ -2159,41 +2176,44 @@ wrong expressions or subexpressions.
@example
@group
-input : /* empty */
- | input line
+input:
+ /* empty */
+| input line
;
@end group
@group
-line : '\n'
- | exp '\n' @{ printf ("%d\n", $1); @}
+line:
+ '\n'
+| exp '\n' @{ printf ("%d\n", $1); @}
;
@end group
@group
-exp : NUM @{ $$ = $1; @}
- | exp '+' exp @{ $$ = $1 + $3; @}
- | exp '-' exp @{ $$ = $1 - $3; @}
- | exp '*' exp @{ $$ = $1 * $3; @}
+exp:
+ NUM @{ $$ = $1; @}
+| exp '+' exp @{ $$ = $1 + $3; @}
+| exp '-' exp @{ $$ = $1 - $3; @}
+| exp '*' exp @{ $$ = $1 * $3; @}
@end group
@group
- | exp '/' exp
- @{
- if ($3)
- $$ = $1 / $3;
- else
- @{
- $$ = 1;
- fprintf (stderr, "%d.%d-%d.%d: division by zero",
- @@3.first_line, @@3.first_column,
- @@3.last_line, @@3.last_column);
- @}
- @}
+| exp '/' exp
+ @{
+ if ($3)
+ $$ = $1 / $3;
+ else
+ @{
+ $$ = 1;
+ fprintf (stderr, "%d.%d-%d.%d: division by zero",
+ @@3.first_line, @@3.first_column,
+ @@3.last_line, @@3.last_column);
+ @}
+ @}
@end group
@group
- | '-' exp %prec NEG @{ $$ = -$2; @}
- | exp '^' exp @{ $$ = pow ($1, $3); @}
- | '(' exp ')' @{ $$ = $2; @}
+| '-' exp %prec NEG @{ $$ = -$2; @}
+| exp '^' exp @{ $$ = pow ($1, $3); @}
+| '(' exp ')' @{ $$ = $2; @}
@end group
@end example
@@ -2588,31 +2608,33 @@ those which mention @code{VAR} or @code{FNCT}, are new.
@example
%% /* The grammar follows. */
@group
-input: /* empty */
- | input line
+input:
+ /* empty */
+| input line
;
@end group
@group
line:
- '\n'
- | exp '\n' @{ printf ("%.10g\n", $1); @}
- | error '\n' @{ yyerrok; @}
+ '\n'
+| exp '\n' @{ printf ("%.10g\n", $1); @}
+| error '\n' @{ yyerrok; @}
;
@end group
@group
-exp: NUM @{ $$ = $1; @}
- | VAR @{ $$ = $1->value.var; @}
- | VAR '=' exp @{ $$ = $3; $1->value.var = $3; @}
- | FNCT '(' exp ')' @{ $$ = (*($1->value.fnctptr))($3); @}
- | exp '+' exp @{ $$ = $1 + $3; @}
- | exp '-' exp @{ $$ = $1 - $3; @}
- | exp '*' exp @{ $$ = $1 * $3; @}
- | exp '/' exp @{ $$ = $1 / $3; @}
- | '-' exp %prec NEG @{ $$ = -$2; @}
- | exp '^' exp @{ $$ = pow ($1, $3); @}
- | '(' exp ')' @{ $$ = $2; @}
+exp:
+ NUM @{ $$ = $1; @}
+| VAR @{ $$ = $1->value.var; @}
+| VAR '=' exp @{ $$ = $3; $1->value.var = $3; @}
+| FNCT '(' exp ')' @{ $$ = (*($1->value.fnctptr))($3); @}
+| exp '+' exp @{ $$ = $1 + $3; @}
+| exp '-' exp @{ $$ = $1 - $3; @}
+| exp '*' exp @{ $$ = $1 * $3; @}
+| exp '/' exp @{ $$ = $1 / $3; @}
+| '-' exp %prec NEG @{ $$ = -$2; @}
+| exp '^' exp @{ $$ = pow ($1, $3); @}
+| '(' exp ')' @{ $$ = $2; @}
;
@end group
/* End of grammar. */
@@ -3531,8 +3553,7 @@ A Bison grammar rule has the following general form:
@example
@group
address@hidden: @address@hidden
- ;
address@hidden: @address@hidden;
@end group
@end example
@@ -3545,8 +3566,7 @@ For example,
@example
@group
-exp: exp '+' exp
- ;
+exp: exp '+' exp;
@end group
@end example
@@ -3591,10 +3611,11 @@ be joined with the vertical-bar character @samp{|} as
follows:
@example
@group
address@hidden: @address@hidden
- | @address@hidden
- @dots{}
- ;
address@hidden:
+ @address@hidden
+| @address@hidden
address@hidden
+;
@end group
@end example
@@ -3607,15 +3628,17 @@ comma-separated sequence of zero or more @code{exp}
groupings:
@example
@group
-expseq: /* empty */
- | expseq1
- ;
+expseq:
+ /* empty */
+| expseq1
+;
@end group
@group
-expseq1: exp
- | expseq1 ',' exp
- ;
+expseq1:
+ exp
+| expseq1 ',' exp
+;
@end group
@end example
@@ -3635,9 +3658,10 @@ comma-separated sequence of one or more expressions:
@example
@group
-expseq1: exp
- | expseq1 ',' exp
- ;
+expseq1:
+ exp
+| expseq1 ',' exp
+;
@end group
@end example
@@ -3650,9 +3674,10 @@ the same construct is defined using @dfn{right
recursion}:
@example
@group
-expseq1: exp
- | exp ',' expseq1
- ;
+expseq1:
+ exp
+| exp ',' expseq1
+;
@end group
@end example
@@ -3676,15 +3701,17 @@ For example:
@example
@group
-expr: primary
- | primary '+' primary
- ;
+expr:
+ primary
+| primary '+' primary
+;
@end group
@group
-primary: constant
- | '(' expr ')'
- ;
+primary:
+ constant
+| '(' expr ')'
+;
@end group
@end example
@@ -3806,9 +3833,9 @@ Here is a typical example:
@example
@group
-exp: @dots{}
- | exp '+' exp
- @{ $$ = $1 + $3; @}
+exp:
address@hidden
+| exp '+' exp @{ $$ = $1 + $3; @}
@end group
@end example
@@ -3816,9 +3843,9 @@ Or, in terms of named references:
@example
@group
-exp[result]: @dots{}
- | exp[left] '+' exp[right]
- @{ $result = $left + $right; @}
+exp[result]:
address@hidden
+| exp[left] '+' exp[right] @{ $result = $left + $right; @}
@end group
@end example
@@ -3865,15 +3892,16 @@ is a case in which you can use this reliably:
@example
@group
-foo: expr bar '+' expr @{ @dots{} @}
- | expr bar '-' expr @{ @dots{} @}
- ;
+foo:
+ expr bar '+' expr @{ @dots{} @}
+| expr bar '-' expr @{ @dots{} @}
+;
@end group
@group
-bar: /* empty */
- @{ previous_expr = $0; @}
- ;
+bar:
+ /* empty */ @{ previous_expr = $0; @}
+;
@end group
@end example
@@ -3903,9 +3931,9 @@ in the rule. In this example,
@example
@group
-exp: @dots{}
- | exp '+' exp
- @{ $$ = $1 + $3; @}
+exp:
+ @dots{}
+| exp '+' exp @{ $$ = $1 + $3; @}
@end group
@end example
@@ -3972,11 +4000,11 @@ remove it afterward. Here is how it is done:
@example
@group
-stmt: LET '(' var ')'
- @{ $<context>$ = push_context ();
- declare_variable ($3); @}
- stmt @{ $$ = $6;
- pop_context ($<context>5); @}
+stmt:
+ LET '(' var ')'
+ @{ $<context>$ = push_context (); declare_variable ($3); @}
+ stmt
+ @{ $$ = $6; pop_context ($<context>5); @}
@end group
@end example
@@ -4018,15 +4046,19 @@ declare a destructor for that symbol:
%%
-stmt: let stmt
- @{ $$ = $2;
- pop_context ($1); @}
- ;
+stmt:
+ let stmt
+ @{
+ $$ = $2;
+ pop_context ($1);
+ @};
-let: LET '(' var ')'
- @{ $$ = push_context ();
- declare_variable ($3); @}
- ;
+let:
+ LET '(' var ')'
+ @{
+ $$ = push_context ();
+ declare_variable ($3);
+ @};
@end group
@end example
@@ -4045,9 +4077,10 @@ declaration or not:
@example
@group
-compound: '@{' declarations statements '@}'
- | '@{' statements '@}'
- ;
+compound:
+ '@{' declarations statements '@}'
+| '@{' statements '@}'
+;
@end group
@end example
@@ -4056,12 +4089,13 @@ But when we add a mid-rule action as follows, the rules
become nonfunctional:
@example
@group
-compound: @{ prepare_for_local_variables (); @}
- '@{' declarations statements '@}'
+compound:
+ @{ prepare_for_local_variables (); @}
+ '@{' declarations statements '@}'
@end group
@group
- | '@{' statements '@}'
- ;
+| '@{' statements '@}'
+;
@end group
@end example
@@ -4078,11 +4112,12 @@ actions into the two rules, like this:
@example
@group
-compound: @{ prepare_for_local_variables (); @}
- '@{' declarations statements '@}'
- | @{ prepare_for_local_variables (); @}
- '@{' statements '@}'
- ;
+compound:
+ @{ prepare_for_local_variables (); @}
+ '@{' declarations statements '@}'
+| @{ prepare_for_local_variables (); @}
+ '@{' statements '@}'
+;
@end group
@end example
@@ -4096,10 +4131,11 @@ does work is to put the action after the open-brace,
like this:
@example
@group
-compound: '@{' @{ prepare_for_local_variables (); @}
- declarations statements '@}'
- | '@{' statements '@}'
- ;
+compound:
+ '@{' @{ prepare_for_local_variables (); @}
+ declarations statements '@}'
+| '@{' statements '@}'
+;
@end group
@end example
@@ -4112,18 +4148,16 @@ serves as a subroutine:
@example
@group
-subroutine: /* empty */
- @{ prepare_for_local_variables (); @}
- ;
-
+subroutine:
+ /* empty */ @{ prepare_for_local_variables (); @}
+;
@end group
@group
-compound: subroutine
- '@{' declarations statements '@}'
- | subroutine
- '@{' statements '@}'
- ;
+compound:
+ subroutine '@{' declarations statements '@}'
+| subroutine '@{' statements '@}'
+;
@end group
@end example
@@ -4208,24 +4242,25 @@ Here is a basic example using the default data type for
locations:
@example
@group
-exp: @dots{}
- | exp '/' exp
- @{
- @@$.first_column = @@1.first_column;
- @@$.first_line = @@1.first_line;
- @@$.last_column = @@3.last_column;
- @@$.last_line = @@3.last_line;
- if ($3)
- $$ = $1 / $3;
- else
- @{
- $$ = 1;
- fprintf (stderr,
- "Division by zero, l%d,c%d-l%d,c%d",
- @@3.first_line, @@3.first_column,
- @@3.last_line, @@3.last_column);
- @}
- @}
+exp:
+ @dots{}
+| exp '/' exp
+ @{
+ @@$.first_column = @@1.first_column;
+ @@$.first_line = @@1.first_line;
+ @@$.last_column = @@3.last_column;
+ @@$.last_line = @@3.last_line;
+ if ($3)
+ $$ = $1 / $3;
+ else
+ @{
+ $$ = 1;
+ fprintf (stderr,
+ "Division by zero, l%d,c%d-l%d,c%d",
+ @@3.first_line, @@3.first_column,
+ @@3.last_line, @@3.last_column);
+ @}
+ @}
@end group
@end example
@@ -4239,20 +4274,21 @@ example above simply rewrites this way:
@example
@group
-exp: @dots{}
- | exp '/' exp
- @{
- if ($3)
- $$ = $1 / $3;
- else
- @{
- $$ = 1;
- fprintf (stderr,
- "Division by zero, l%d,c%d-l%d,c%d",
- @@3.first_line, @@3.first_column,
- @@3.last_line, @@3.last_column);
- @}
- @}
+exp:
+ @dots{}
+| exp '/' exp
+ @{
+ if ($3)
+ $$ = $1 / $3;
+ else
+ @{
+ $$ = 1;
+ fprintf (stderr,
+ "Division by zero, l%d,c%d-l%d,c%d",
+ @@3.first_line, @@3.first_column,
+ @@3.last_line, @@3.last_column);
+ @}
+ @}
@end group
@end example
@@ -6804,16 +6840,18 @@ factorial operators (@samp{!}), and allow parentheses
for grouping.
@example
@group
-expr: term '+' expr
- | term
- ;
+expr:
+ term '+' expr
+| term
+;
@end group
@group
-term: '(' expr ')'
- | term '!'
- | NUMBER
- ;
+term:
+ '(' expr ')'
+| term '!'
+| NUMBER
+;
@end group
@end example
@@ -6851,9 +6889,9 @@ statements, with a pair of rules like this:
@example
@group
if_stmt:
- IF expr THEN stmt
- | IF expr THEN stmt ELSE stmt
- ;
+ IF expr THEN stmt
+| IF expr THEN stmt ELSE stmt
+;
@end group
@end example
@@ -6920,20 +6958,22 @@ the conflict:
%%
@end group
@group
-stmt: expr
- | if_stmt
- ;
+stmt:
+ expr
+| if_stmt
+;
@end group
@group
if_stmt:
- IF expr THEN stmt
- | IF expr THEN stmt ELSE stmt
- ;
+ IF expr THEN stmt
+| IF expr THEN stmt ELSE stmt
+;
@end group
-expr: variable
- ;
+expr:
+ variable
+;
@end example
@node Precedence
@@ -6962,12 +7002,13 @@ input @address@hidden - 2 * 3}} can be parsed in two
different ways):
@example
@group
-expr: expr '-' expr
- | expr '*' expr
- | expr '<' expr
- | '(' expr ')'
- @dots{}
- ;
+expr:
+ expr '-' expr
+| expr '*' expr
+| expr '<' expr
+| '(' expr ')'
address@hidden
+;
@end group
@end example
@@ -7172,10 +7213,11 @@ Now the precedence of @code{UMINUS} can be used in
specific rules:
@example
@group
-exp: @dots{}
- | exp '-' exp
- @dots{}
- | '-' exp %prec UMINUS
+exp:
+ @dots{}
+| exp '-' exp
+ @dots{}
+| '-' exp %prec UMINUS
@end group
@end example
@@ -7241,20 +7283,18 @@ of zero or more @code{word} groupings.
@example
@group
-sequence: /* empty */
- @{ printf ("empty sequence\n"); @}
- | maybeword
- | sequence word
- @{ printf ("added word %s\n", $2); @}
- ;
+sequence:
+ /* empty */ @{ printf ("empty sequence\n"); @}
+| maybeword
+| sequence word @{ printf ("added word %s\n", $2); @}
+;
@end group
@group
-maybeword: /* empty */
- @{ printf ("empty maybeword\n"); @}
- | word
- @{ printf ("single word %s\n", $1); @}
- ;
+maybeword:
+ /* empty */ @{ printf ("empty maybeword\n"); @}
+| word @{ printf ("single word %s\n", $1); @}
+;
@end group
@end example
@@ -7282,28 +7322,30 @@ reduce/reduce conflict must be studied and usually
eliminated. Here is the
proper way to define @code{sequence}:
@example
-sequence: /* empty */
- @{ printf ("empty sequence\n"); @}
- | sequence word
- @{ printf ("added word %s\n", $2); @}
- ;
+sequence:
+ /* empty */ @{ printf ("empty sequence\n"); @}
+| sequence word @{ printf ("added word %s\n", $2); @}
+;
@end example
Here is another common error that yields a reduce/reduce conflict:
@example
-sequence: /* empty */
- | sequence words
- | sequence redirects
- ;
+sequence:
+ /* empty */
+| sequence words
+| sequence redirects
+;
-words: /* empty */
- | words word
- ;
+words:
+ /* empty */
+| words word
+;
-redirects:/* empty */
- | redirects redirect
- ;
+redirects:
+ /* empty */
+| redirects redirect
+;
@end example
@noindent
@@ -7322,10 +7364,11 @@ Here are two ways to correct these rules. First, to
make it a single level
of sequence:
@example
-sequence: /* empty */
- | sequence word
- | sequence redirect
- ;
+sequence:
+ /* empty */
+| sequence word
+| sequence redirect
+;
@end example
Second, to prevent either a @code{words} or a @code{redirects}
@@ -7333,22 +7376,25 @@ from being empty:
@example
@group
-sequence: /* empty */
- | sequence words
- | sequence redirects
- ;
+sequence:
+ /* empty */
+| sequence words
+| sequence redirects
+;
@end group
@group
-words: word
- | words word
- ;
+words:
+ word
+| words word
+;
@end group
@group
-redirects:redirect
- | redirects redirect
- ;
+redirects:
+ redirect
+| redirects redirect
+;
@end group
@end example
@@ -7364,30 +7410,27 @@ Here is an example:
%token ID
%%
-def: param_spec return_spec ','
- ;
+def: param_spec return_spec ',';
param_spec:
- type
- | name_list ':' type
- ;
+ type
+| name_list ':' type
+;
@end group
@group
return_spec:
- type
- | name ':' type
- ;
+ type
+| name ':' type
+;
@end group
@group
-type: ID
- ;
+type: ID;
@end group
@group
-name: ID
- ;
+name: ID;
name_list:
- name
- | name ',' name_list
- ;
+ name
+| name ',' name_list
+;
@end group
@end example
@@ -7436,11 +7479,10 @@ distinct. In the above example, adding one rule to
%%
@dots{}
return_spec:
- type
- | name ':' type
- /* This rule is never used. */
- | ID BOGUS
- ;
+ type
+| name ':' type
+| ID BOGUS /* This rule is never used. */
+;
@end group
@end example
@@ -7460,13 +7502,13 @@ rather than the one for @code{name}.
@example
param_spec:
- type
- | name_list ':' type
- ;
+ type
+| name_list ':' type
+;
return_spec:
- type
- | ID ':' type
- ;
+ type
+| ID ':' type
+;
@end example
For a more detailed exposition of LALR(1) parsers and parser
@@ -8043,10 +8085,11 @@ in the current context, the parse can continue.
For example:
@example
-stmnts: /* empty string */
- | stmnts '\n'
- | stmnts exp '\n'
- | stmnts error '\n'
+stmnts:
+ /* empty string */
+| stmnts '\n'
+| stmnts exp '\n'
+| stmnts error '\n'
@end example
The fourth rule in this example says that an error followed by a newline
@@ -8087,10 +8130,11 @@ close-delimiter will probably appear to be unmatched,
and generate another,
spurious error message:
@example
-primary: '(' expr ')'
- | '(' error ')'
- @dots{}
- ;
+primary:
+ '(' expr ')'
+| '(' error ')'
address@hidden
+;
@end example
Error recovery strategies are necessarily guesses. When they guess wrong,
@@ -8212,18 +8256,16 @@ duplication, with actions omitted for brevity:
@example
@group
initdcl:
- declarator maybeasm '='
- init
- | declarator maybeasm
- ;
+ declarator maybeasm '=' init
+| declarator maybeasm
+;
@end group
@group
notype_initdcl:
- notype_declarator maybeasm '='
- init
- | notype_declarator maybeasm
- ;
+ notype_declarator maybeasm '=' init
+| notype_declarator maybeasm
+;
@end group
@end example
@@ -8264,24 +8306,21 @@ as an identifier if it appears in that context. Here
is how you can do it:
@dots{}
@end group
@group
-expr: IDENTIFIER
- | constant
- | HEX '('
- @{ hexflag = 1; @}
- expr ')'
- @{ hexflag = 0;
- $$ = $4; @}
- | expr '+' expr
- @{ $$ = make_sum ($1, $3); @}
- @dots{}
- ;
+expr:
+ IDENTIFIER
+| constant
+| HEX '(' @{ hexflag = 1; @}
+ expr ')' @{ hexflag = 0; $$ = $4; @}
+| expr '+' expr @{ $$ = make_sum ($1, $3); @}
address@hidden
+;
@end group
@group
constant:
- INTEGER
- | STRING
- ;
+ INTEGER
+| STRING
+;
@end group
@end example
@@ -8307,12 +8346,12 @@ For example, in C-like languages, a typical error
recovery rule is to skip
tokens until the next semicolon, and then start a new statement, like this:
@example
-stmt: expr ';'
- | IF '(' expr ')' stmt @{ @dots{} @}
- @dots{}
- error ';'
- @{ hexflag = 0; @}
- ;
+stmt:
+ expr ';'
+| IF '(' expr ')' stmt @{ @dots{} @}
address@hidden
+| error ';' @{ hexflag = 0; @}
+;
@end example
If there is a syntax error in the middle of a @samp{hex (@var{expr})}
@@ -8329,11 +8368,11 @@ and skips to the close-parenthesis:
@example
@group
-expr: @dots{}
- | '(' expr ')'
- @{ $$ = $2; @}
- | '(' error ')'
- @dots{}
+expr:
+ @dots{}
+| '(' expr ')' @{ $$ = $2; @}
+| '(' error ')'
address@hidden
@end group
@end example
@@ -8391,12 +8430,13 @@ The following grammar file, @file{calc.y}, will be used
in the sequel:
%left '+' '-'
%left '*'
%%
-exp: exp '+' exp
- | exp '-' exp
- | exp '*' exp
- | exp '/' exp
- | NUM
- ;
+exp:
+ exp '+' exp
+| exp '-' exp
+| exp '*' exp
+| exp '/' exp
+| NUM
+;
useless: STR;
%%
@end example
@@ -9022,7 +9062,7 @@ Also warn about mid-rule values that are used but not set.
For example, warn about unset @code{$$} in the mid-rule action in:
@example
- exp: '1' @{ $1 = 1; @} '+' exp @{ $$ = $2 + $4; @};
+exp: '1' @{ $1 = 1; @} '+' exp @{ $$ = $2 + $4; @};
@end example
These warnings are not enabled by default since they sometimes prove to
@@ -10078,8 +10118,8 @@ Location Tracking Calculator: @code{ltcalc}}).
unit: assignments exp @{ driver.result = $2; @};
assignments:
- assignments assignment @address@hidden
-| /* Nothing. */ @address@hidden;
+ /* Nothing. */ @address@hidden
+| assignments assignment @address@hidden;
assignment:
"identifier" ":=" exp @{ driver.variables[$1] = $3; @};
@@ -11149,8 +11189,9 @@ real start-symbol:
@example
%token START_FOO START_BAR;
%start start;
-start: START_FOO foo
- | START_BAR bar;
+start:
+ START_FOO foo
+| START_BAR bar;
@end example
These tokens prevents the introduction of new conflicts. As far as the
--
1.7.9.2
- RFC: doc: use only @example, not @smallexample, Akim Demaille, 2012/03/15
- Re: RFC: doc: use only @example, not @smallexample, Paul Eggert, 2012/03/15
- Re: RFC: doc: use only @example, not @smallexample, Akim Demaille, 2012/03/16
- Re: RFC: doc: use only @example, not @smallexample, Paul Eggert, 2012/03/16
- Re: RFC: doc: use only @example, not @smallexample,
Akim Demaille <=
- Re: RFC: doc: use only @example, not @smallexample, Akim Demaille, 2012/03/19
- Re: RFC: doc: use only @example, not @smallexample, Akim Demaille, 2012/03/19
Re: RFC: doc: use only @example, not @smallexample, Akim Demaille, 2012/03/16