* src/reader.c (symbols_output): New, extracted from...

[bison.git] / doc / bison.texinfo

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index 5b930a45594005e7eb65eb54d6460c54cfe146b2..bf0f790b371cd38698d5802c67e3904ecfa1c8bb 100644 (file)
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -447,16 +447,26 @@ lexicography, not grammar.)
 
 Here is a simple C function subdivided into tokens:
 
 
 Here is a simple C function subdivided into tokens:
 

+@ifinfo

 @example
 int             /* @r{keyword `int'} */
 @example
 int             /* @r{keyword `int'} */

-square (x)      /* @r{identifier, open-paren,} */
-                /* @r{identifier, close-paren} */
-     int x;     /* @r{keyword `int', identifier, semicolon} */
+square (int x)  /* @r{identifier, open-paren, identifier,}
+                   @r{identifier, close-paren} */

 @{               /* @r{open-brace} */
 @{               /* @r{open-brace} */

-  return x * x; /* @r{keyword `return', identifier,} */
-                /* @r{asterisk, identifier, semicolon} */
+  return x * x; /* @r{keyword `return', identifier, asterisk,
+                   identifier, semicolon} */

 @}               /* @r{close-brace} */
 @end example
 @}               /* @r{close-brace} */
 @end example

+@end ifinfo
+@ifnotinfo
+@example
+int             /* @r{keyword `int'} */
+square (int x)  /* @r{identifier, open-paren, identifier, identifier, close-paren} */
+@{               /* @r{open-brace} */
+  return x * x; /* @r{keyword `return', identifier, asterisk, identifier, semicolon} */
+@}               /* @r{close-brace} */
+@end example
+@end ifnotinfo

 
 The syntactic groupings of C include the expression, the statement, the
 declaration, and the function definition.  These are represented in the
 
 The syntactic groupings of C include the expression, the statement, the
 declaration, and the function definition.  These are represented in the


@@ -855,11 +865,12 @@ The declarations section (@pxref{Prologue, , The prologue}) contains two
 preprocessor directives.
 
 The @code{#define} directive defines the macro @code{YYSTYPE}, thus
 preprocessor directives.
 
 The @code{#define} directive defines the macro @code{YYSTYPE}, thus

-specifying the C data type for semantic values of both tokens and groupings
-(@pxref{Value Type, ,Data Types of Semantic Values}).  The Bison parser will use whatever type
-@code{YYSTYPE} is defined as; if you don't define it, @code{int} is the
-default.  Because we specify @code{double}, each token and each expression
-has an associated value, which is a floating point number.
+specifying the C data type for semantic values of both tokens and
+groupings (@pxref{Value Type, ,Data Types of Semantic Values}).  The
+Bison parser will use whatever type @code{YYSTYPE} is defined as; if you
+don't define it, @code{int} is the default.  Because we specify
+@code{double}, each token and each expression has an associated value,
+which is a floating point number.

 
 The @code{#include} directive is used to declare the exponentiation
 function @code{pow}.
 
 The @code{#include} directive is used to declare the exponentiation
 function @code{pow}.


@@ -1066,10 +1077,11 @@ token type is an identifier, that identifier is defined by Bison as a C
 macro whose definition is the appropriate number.  In this example,
 therefore, @code{NUM} becomes a macro for @code{yylex} to use.
 
 macro whose definition is the appropriate number.  In this example,
 therefore, @code{NUM} becomes a macro for @code{yylex} to use.
 

-The semantic value of the token (if it has one) is stored into the global
-variable @code{yylval}, which is where the Bison parser will look for it.
-(The C data type of @code{yylval} is @code{YYSTYPE}, which was defined
-at the beginning of the grammar; @pxref{Rpcalc Decls, ,Declarations for @code{rpcalc}}.)
+The semantic value of the token (if it has one) is stored into the
+global variable @code{yylval}, which is where the Bison parser will look
+for it.  (The C data type of @code{yylval} is @code{YYSTYPE}, which was
+defined at the beginning of the grammar; @pxref{Rpcalc Decls,
+,Declarations for @code{rpcalc}}.)

 
 A token type code of zero is returned if the end-of-file is encountered.
 (Bison recognizes any nonpositive value as indicating the end of the
 
 A token type code of zero is returned if the end-of-file is encountered.
 (Bison recognizes any nonpositive value as indicating the end of the


@@ -1202,19 +1214,19 @@ Here is how to compile and run the parser file:
 @example
 @group
 # @r{List files in current directory.}
 @example
 @group
 # @r{List files in current directory.}

-% ls
+$ @kbd{ls}

 rpcalc.tab.c  rpcalc.y
 @end group
 
 @group
 # @r{Compile the Bison parser.}
 # @r{@samp{-lm} tells compiler to search math library for @code{pow}.}
 rpcalc.tab.c  rpcalc.y
 @end group
 
 @group
 # @r{Compile the Bison parser.}
 # @r{@samp{-lm} tells compiler to search math library for @code{pow}.}

-% cc rpcalc.tab.c -lm -o rpcalc
+$ @kbd{cc rpcalc.tab.c -lm -o rpcalc}

 @end group
 
 @group
 # @r{List files again.}
 @end group
 
 @group
 # @r{List files again.}

-% ls
+$ @kbd{ls}

 rpcalc  rpcalc.tab.c  rpcalc.y
 @end group
 @end example
 rpcalc  rpcalc.tab.c  rpcalc.y
 @end group
 @end example


@@ -1223,19 +1235,19 @@ The file @file{rpcalc} now contains the executable code.  Here is an
 example session using @code{rpcalc}.
 
 @example
 example session using @code{rpcalc}.
 
 @example

-% rpcalc
-4 9 +
+$ @kbd{rpcalc}
+@kbd{4 9 +}

 13
 13

-3 7 + 3 4 5 *+-
+@kbd{3 7 + 3 4 5 *+-}

 -13
 -13

-3 7 + 3 4 5 * + - n              @r{Note the unary minus, @samp{n}}
+@kbd{3 7 + 3 4 5 * + - n}              @r{Note the unary minus, @samp{n}}

 13
 13

-5 6 / 4 n +
+@kbd{5 6 / 4 n +}

 -3.166666667
 -3.166666667

-3 4 ^                            @r{Exponentiation}
+@kbd{3 4 ^}                            @r{Exponentiation}

 81
 81

-^D                               @r{End-of-file indicator}
-%
+@kbd{^D}                               @r{End-of-file indicator}
+$

 @end example
 
 @node Infix Calc
 @end example
 
 @node Infix Calc


@@ -1315,12 +1327,12 @@ Here is a sample run of @file{calc.y}:
 
 @need 500
 @example
 
 @need 500
 @example

-% calc
-4 + 4.5 - (34/(8*3+-3))
+$ @kbd{calc}
+@kbd{4 + 4.5 - (34/(8*3+-3))}

 6.880952381
 6.880952381

--56 + 2
+@kbd{-56 + 2}

 -54
 -54

-3 ^ 2
+@kbd{3 ^ 2}

 9
 @end example
 
 9
 @end example
 


@@ -1372,13 +1384,11 @@ Bison programs.
 @cindex @code{ltcalc}
 @cindex calculator, location tracking
 
 @cindex @code{ltcalc}
 @cindex calculator, location tracking
 

-This example extends the infix notation calculator with location tracking.
-This feature will be used to improve error reporting, and provide better
-error messages.
-
-For the sake of clarity, we will switch for this example to an integer
-calculator, since most of the work needed to use locations will be done
-in the lexical analyser.
+This example extends the infix notation calculator with location
+tracking.  This feature will be used to improve the error messages.  For
+the sake of clarity, this example is a simple integer calculator, since
+most of the work needed to use locations will be done in the lexical
+analyser.

 
 @menu
 * Decls: Ltcalc Decls.  Bison and C declarations for ltcalc.
 
 @menu
 * Decls: Ltcalc Decls.  Bison and C declarations for ltcalc.


@@ -1389,8 +1399,8 @@ in the lexical analyser.
 @node Ltcalc Decls
 @subsection Declarations for @code{ltcalc}
 
 @node Ltcalc Decls
 @subsection Declarations for @code{ltcalc}
 

-The C and Bison declarations for the location tracking calculator are the same
-as the declarations for the infix notation calculator.
+The C and Bison declarations for the location tracking calculator are
+the same as the declarations for the infix notation calculator.

 
 @example
 /* Location tracking calculator.  */
 
 @example
 /* Location tracking calculator.  */


@@ -1411,22 +1421,24 @@ as the declarations for the infix notation calculator.
 %% /* Grammar follows */
 @end example
 
 %% /* Grammar follows */
 @end example
 

-In the code above, there are no declarations specific to locations.  Defining
-a data type for storing locations is not needed: we will use the type provided
-by default (@pxref{Location Type, ,Data Types of Locations}), which is a four
-member structure with the following integer fields: @code{first_line},
-@code{first_column}, @code{last_line} and @code{last_column}.
+@noindent
+Note there are no declarations specific to locations.  Defining a data
+type for storing locations is not needed: we will use the type provided
+by default (@pxref{Location Type, ,Data Types of Locations}), which is a
+four member structure with the following integer fields:
+@code{first_line}, @code{first_column}, @code{last_line} and
+@code{last_column}.

 
 @node Ltcalc Rules
 @subsection Grammar Rules for @code{ltcalc}
 
 
 @node Ltcalc Rules
 @subsection Grammar Rules for @code{ltcalc}
 

-Whether you choose to handle locations or not has no effect on the syntax of
-your language.  Therefore, grammar rules for this example will be very close to
-those of the previous example: we will only modify them to benefit from the new
-informations we will have.
+Whether handling locations or not has no effect on the syntax of your
+language.  Therefore, grammar rules for this example will be very close
+to those of the previous example: we will only modify them to benefit
+from the new information.

 
 

-Here, we will use locations to report divisions by zero, and locate the wrong
-expressions or subexpressions.
+Here, we will use locations to report divisions by zero, and locate the
+wrong expressions or subexpressions.

 
 @example
 @group
 
 @example
 @group


@@ -1447,17 +1459,17 @@ exp     : NUM           @{ $$ = $1; @}
         | exp '-' exp   @{ $$ = $1 - $3; @}
         | exp '*' exp   @{ $$ = $1 * $3; @}
 @end group
         | exp '-' exp   @{ $$ = $1 - $3; @}
         | exp '*' exp   @{ $$ = $1 * $3; @}
 @end group

-        | exp '/' exp

 @group
 @group

+        | exp '/' exp

             @{
               if ($3)
                 $$ = $1 / $3;
               else
                 @{
                   $$ = 1;
             @{
               if ($3)
                 $$ = $1 / $3;
               else
                 @{
                   $$ = 1;

-                  printf("Division by zero, l%d,c%d-l%d,c%d",
-                         @@3.first_line, @@3.first_column,
-                         @@3.last_line, @@3.last_column);
+                  fprintf (stderr, "%d.%d-%d.%d: division by zero",
+                           @@3.first_line, @@3.first_column,
+                           @@3.last_line, @@3.last_column);

                 @}
             @}
 @end group
                 @}
             @}
 @end group


@@ -1472,25 +1484,24 @@ This code shows how to reach locations inside of semantic actions, by
 using the pseudo-variables @code{@@@var{n}} for rule components, and the
 pseudo-variable @code{@@$} for groupings.
 
 using the pseudo-variables @code{@@@var{n}} for rule components, and the
 pseudo-variable @code{@@$} for groupings.
 

-In this example, we never assign a value to @code{@@$}, because the
-output parser can do this automatically.  By default, before executing
-the C code of each action, @code{@@$} is set to range from the beginning
-of @code{@@1} to the end of @code{@@@var{n}}, for a rule with @var{n}
-components.
-
-Of course, this behavior can be redefined (@pxref{Location Default
-Action, , Default Action for Locations}), and for very specific rules,
-@code{@@$} can be computed by hand.
+We don't need to assign a value to @code{@@$}: the output parser does it
+automatically.  By default, before executing the C code of each action,
+@code{@@$} is set to range from the beginning of @code{@@1} to the end
+of @code{@@@var{n}}, for a rule with @var{n} components.  This behavior
+can be redefined (@pxref{Location Default Action, , Default Action for
+Locations}), and for very specific rules, @code{@@$} can be computed by
+hand.

 
 @node Ltcalc Lexer
 @subsection The @code{ltcalc} Lexical Analyzer.
 
 
 @node Ltcalc Lexer
 @subsection The @code{ltcalc} Lexical Analyzer.
 

-Until now, we relied on Bison's defaults to enable location tracking. The next
-step is to rewrite the lexical analyser, and make it able to feed the parser
-with locations of tokens, as he already does for semantic values.
+Until now, we relied on Bison's defaults to enable location
+tracking. The next step is to rewrite the lexical analyser, and make it
+able to feed the parser with the token locations, as it already does for
+semantic values.

 
 

-To do so, we must take into account every single character of the input text,
-to avoid the computed locations of being fuzzy or wrong:
+To this end, we must take into account every single character of the
+input text, to avoid the computed locations of being fuzzy or wrong:

 
 @example
 @group
 
 @example
 @group


@@ -1540,17 +1551,18 @@ yylex (void)
 @}
 @end example
 
 @}
 @end example
 

-Basically, the lexical analyzer does the same processing as before: it skips
-blanks and tabs, and reads numbers or single-character tokens.  In addition
-to this, it updates the @code{yylloc} global variable (of type @code{YYLTYPE}),
-where the location of tokens is stored.
+Basically, the lexical analyzer performs the same processing as before:
+it skips blanks and tabs, and reads numbers or single-character tokens.
+In addition, it updates @code{yylloc}, the global variable (of type
+@code{YYLTYPE}) containing the token's location.

 
 

-Now, each time this function returns a token, the parser has it's number as
-well as it's semantic value, and it's position in the text. The last needed
-change is to initialize @code{yylloc}, for example in the controlling
-function:
+Now, each time this function returns a token, the parser has its number
+as well as its semantic value, and its location in the text. The last
+needed change is to initialize @code{yylloc}, for example in the
+controlling function:

 
 @example
 
 @example

+@group

 int
 main (void)
 @{
 int
 main (void)
 @{


@@ -1558,11 +1570,12 @@ main (void)
   yylloc.first_column = yylloc.last_column = 0;
   return yyparse ();
 @}
   yylloc.first_column = yylloc.last_column = 0;
   return yyparse ();
 @}

+@end group

 @end example
 
 @end example
 

-Remember that computing locations is not a matter of syntax.  Every character
-must be associated to a location update, whether it is in valid input, in
-comments, in literal strings, and so on...
+Remember that computing locations is not a matter of syntax.  Every
+character must be associated to a location update, whether it is in
+valid input, in comments, in literal strings, and so on.

 
 @node Multi-function Calc
 @section Multi-Function Calculator: @code{mfcalc}
 
 @node Multi-function Calc
 @section Multi-Function Calculator: @code{mfcalc}


@@ -1592,20 +1605,20 @@ to create named variables, store values in them, and use them later.
 Here is a sample session with the multi-function calculator:
 
 @example
 Here is a sample session with the multi-function calculator:
 
 @example

-% mfcalc
-pi = 3.141592653589
+$ @kbd{mfcalc}
+@kbd{pi = 3.141592653589}

 3.1415926536
 3.1415926536

-sin(pi)
+@kbd{sin(pi)}

 0.0000000000
 0.0000000000

-alpha = beta1 = 2.3
+@kbd{alpha = beta1 = 2.3}

 2.3000000000
 2.3000000000

-alpha
+@kbd{alpha}

 2.3000000000
 2.3000000000

-ln(alpha)
+@kbd{ln(alpha)}

 0.8329091229
 0.8329091229

-exp(ln(beta1))
+@kbd{exp(ln(beta1))}

 2.3000000000
 2.3000000000

-%
+$

 @end example
 
 Note that multiple assignment and nested function calls are permitted.
 @end example
 
 Note that multiple assignment and nested function calls are permitted.


@@ -2375,7 +2388,8 @@ the numbers associated with @var{x} and @var{y}.
 
 In a simple program it may be sufficient to use the same data type for
 the semantic values of all language constructs.  This was true in the
 
 In a simple program it may be sufficient to use the same data type for
 the semantic values of all language constructs.  This was true in the

-RPN and infix calculator examples (@pxref{RPN Calc, ,Reverse Polish Notation Calculator}).
+RPN and infix calculator examples (@pxref{RPN Calc, ,Reverse Polish
+Notation Calculator}).

 
 Bison's default is to use type @code{int} for all semantic values.  To
 specify some other type, define @code{YYSTYPE} as a macro, like this:
 
 Bison's default is to use type @code{int} for all semantic values.  To
 specify some other type, define @code{YYSTYPE} as a macro, like this:


@@ -3068,11 +3082,11 @@ terminal symbol.  All kinds of token declarations allow
 @findex %expect
 
 Bison normally warns if there are any conflicts in the grammar
 @findex %expect
 
 Bison normally warns if there are any conflicts in the grammar

-(@pxref{Shift/Reduce, ,Shift/Reduce Conflicts}), but most real grammars have harmless shift/reduce
-conflicts which are resolved in a predictable way and would be difficult to
-eliminate.  It is desirable to suppress the warning about these conflicts
-unless the number of conflicts changes.  You can do this with the
-@code{%expect} declaration.
+(@pxref{Shift/Reduce, ,Shift/Reduce Conflicts}), but most real grammars
+have harmless shift/reduce conflicts which are resolved in a predictable
+way and would be difficult to eliminate.  It is desirable to suppress
+the warning about these conflicts unless the number of conflicts
+changes.  You can do this with the @code{%expect} declaration.

 
 The declaration looks like this:
 
 
 The declaration looks like this:
 


@@ -3080,10 +3094,11 @@ The declaration looks like this:
 %expect @var{n}
 @end example
 
 %expect @var{n}
 @end example
 

-Here @var{n} is a decimal integer.  The declaration says there should be no
-warning if there are @var{n} shift/reduce conflicts and no reduce/reduce
-conflicts.  The usual warning is given if there are either more or fewer
-conflicts, or if there are any reduce/reduce conflicts.
+Here @var{n} is a decimal integer.  The declaration says there should be
+no warning if there are @var{n} shift/reduce conflicts and no
+reduce/reduce conflicts.  An error, instead of the usual warning, is
+given if there are either more or fewer conflicts, or if there are any
+reduce/reduce conflicts.

 
 In general, using @code{%expect} involves these steps:
 
 
 In general, using @code{%expect} involves these steps: