calc.at

bison 2.0 主要可以用来做语法分析用的

# Simple calculator.                         -*- Autotest -*-
# Copyright (C) 2000, 2001, 2002, 2003, 2004  Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
# 02111-1307, USA.

## ---------------------------------------------------- ##
## Compile the grammar described in the documentation.  ##
## ---------------------------------------------------- ##


# ------------------------- #
# Helping Autotest macros.  #
# ------------------------- #


# _AT_DATA_CALC_Y($1, $2, $3, [BISON-DIRECTIVES])
# -----------------------------------------------
# Produce `calc.y'.  Don't call this macro directly, because it contains
# some occurrences of `$1' etc. which will be interpreted by m4.  So
# you should call it with $1, $2, and $3 as arguments, which is what
# AT_DATA_CALC_Y does.
m4_define([_AT_DATA_CALC_Y],
[m4_if([$1$2$3], $[1]$[2]$[3], [],
       [m4_fatal([$0: Invalid arguments: $@])])dnl
AT_DATA_GRAMMAR([calc.y],
[[/* Infix notation calculator--calc */
]$4[
%{
#include <stdio.h>

#include <stdlib.h>
#include <string.h>
#if HAVE_UNISTD_H
# include <unistd.h>
#else
# undef alarm
# define alarm(seconds) /* empty */
#endif
#include <ctype.h>

/* Exercise pre-prologue dependency to %union.  */
typedef int semantic_value;

static semantic_value global_result = 0;
static int global_count = 0;
%}

/* Exercise %union. */
%union
{
  semantic_value ival;
};

%{
static int power (int base, int exponent);
]AT_LALR1_CC_IF([typedef yy::location YYLTYPE;],
[/* yyerror receives the location if:
   - %location & %pure & %glr
   - %location & %pure & %yacc & %parse-param. */
static void yyerror (AT_YYERROR_ARG_LOC_IF([YYLTYPE *yylloc, ])
                     AT_PARAM_IF([semantic_value *result, int *count, ])
                     const char *s
                     );])[
static int yylex (]AT_LEX_FORMALS[);
static int yygetc (]AT_LEX_FORMALS[);
static void yyungetc (]AT_LEX_PRE_FORMALS[ int c);
%}

/* Bison Declarations */
%token CALC_EOF 0 "end of input"
%token <ival> NUM "number"
%type  <ival> exp

%nonassoc '=' /* comparison	       */
%left '-' '+'
%left '*' '/'
%left NEG     /* negation--unary minus */
%right '^'    /* exponentiation        */

/* Grammar follows */
%%
input:
  line
| input line         { ]AT_PARAM_IF([++*count; ++global_count;])[ }
;

line:
  '\n'
| exp '\n'           { ]AT_PARAM_IF([*result = global_result = $1;])[ }
;

exp:
  NUM                { $$ = $1;             }
| exp '=' exp
  {
    if ($1 != $3)
      fprintf (stderr, "calc: error: %d != %d\n", $1, $3);
    $$ = $1;
  }
| exp '+' exp        { $$ = $1 + $3;        }
| exp '-' exp        { $$ = $1 - $3;        }
| exp '*' exp        { $$ = $1 * $3;        }
| exp '/' exp        { $$ = $1 / $3;        }
| '-' exp  %prec NEG { $$ = -$2;            }
| exp '^' exp        { $$ = power ($1, $3); }
| '(' exp ')'        { $$ = $2;             }
| '(' error ')'      { $$ = 1111;           }
| '!'                { YYERROR;             }
| '-' error          { YYERROR;             }
;
%%
/* The input. */
static FILE *yyin;

]AT_LALR1_CC_IF(
[/* A C++ error reporting function. */
void
yy::parser::error (const location& l, const std::string& m)
{
  (void) l;
  std::cerr << AT_LOCATION_IF([l << ": " << ])m << std::endl;
}

int
yyparse (AT_PARAM_IF([semantic_value *result, int *count]))
{
  yy::parser parser[]AT_PARAM_IF([ (result, count)]);
  parser.set_debug_level (!!YYDEBUG);
  return parser.parse ();
}
],
[static void
yyerror (AT_YYERROR_ARG_LOC_IF([YYLTYPE *yylloc, ])
         AT_PARAM_IF([semantic_value *result, int *count, ])
         const char *s)
{
AT_PARAM_IF([(void) result; (void) count;])
AT_YYERROR_SEES_LOC_IF([
  fprintf (stderr, "%d.%d",
           AT_LOC.first_line, AT_LOC.first_column);
  if (AT_LOC.first_line != AT_LOC.last_line)
    fprintf (stderr, "-%d.%d",
	     AT_LOC.last_line,  AT_LOC.last_column - 1);
  else if (AT_LOC.first_column != AT_LOC.last_column - 1)
    fprintf (stderr, "-%d",
	     AT_LOC.last_column - 1);
  fprintf (stderr, ": ");])
  fprintf (stderr, "%s\n", s);
}])[


]AT_LOCATION_IF([
static YYLTYPE last_yylloc;
])[
static int
yygetc (]AT_LEX_FORMALS[)
{
  int res = getc (yyin);
  ]AT_USE_LEX_ARGS[;
]AT_LOCATION_IF([
  last_yylloc = AT_LOC;
  if (res == '\n')
    {
AT_LALR1_CC_IF(
[     AT_LOC.end.line++;
      AT_LOC.end.column = 0;],
[     AT_LOC.last_line++;
      AT_LOC.last_column = 0;])
    }
  else
AT_LALR1_CC_IF(
[    AT_LOC.end.column++;],
[    AT_LOC.last_column++;])
])[
  return res;
}


static void
yyungetc (]AT_LEX_PRE_FORMALS[ int c)
{
  ]AT_USE_LEX_ARGS[;
]AT_LOCATION_IF([
  /* Wrong when C == `\n'. */
  AT_LOC = last_yylloc;
])[
  ungetc (c, yyin);
}

static int
read_signed_integer (]AT_LEX_FORMALS[)
{
  int c = yygetc (]AT_LEX_ARGS[);
  int sign = 1;
  int n = 0;

  ]AT_USE_LEX_ARGS[;
  if (c == '-')
    {
      c = yygetc (]AT_LEX_ARGS[);
      sign = -1;
    }

  while (isdigit (c))
    {
      n = 10 * n + (c - '0');
      c = yygetc (]AT_LEX_ARGS[);
    }

  yyungetc (]AT_LEX_PRE_ARGS[ c);

  return sign * n;
}



/*---------------------------------------------------------------.
| Lexical analyzer returns an integer on the stack and the token |
| NUM, or the ASCII character read if not a number.  Skips all   |
| blanks and tabs, returns 0 for EOF.                            |
`---------------------------------------------------------------*/

static int
yylex (]AT_LEX_FORMALS[)
{
  static int init = 1;
  int c;

  if (init)
    {
      init = 0;
]AT_LALR1_CC_IF([],
[AT_LOCATION_IF([
      AT_LOC.last_column = 0;
      AT_LOC.last_line = 1;
])])[
    }

]AT_LOCATION_IF([AT_LALR1_CC_IF(
[ AT_LOC.begin = AT_LOC.end;],
[ AT_LOC.first_column = AT_LOC.last_column;
  AT_LOC.first_line   = AT_LOC.last_line;
])])[

  /* Skip white space.  */
  while ((c = yygetc (]AT_LEX_ARGS[)) == ' ' || c == '\t')
    {
]AT_LOCATION_IF([AT_LALR1_CC_IF(
[     AT_LOC.begin = AT_LOC.end;],
[     AT_LOC.first_column = AT_LOC.last_column;
      AT_LOC.first_line   = AT_LOC.last_line;
])])[
    }

  /* process numbers   */
  if (c == '.' || isdigit (c))
    {
      yyungetc (]AT_LEX_PRE_ARGS[ c);
      ]AT_VAL[.ival = read_signed_integer (]AT_LEX_ARGS[);
      return NUM;
    }

  /* Return end-of-file.  */
  if (c == EOF)
    return CALC_EOF;

  /* Return single chars. */
  return c;
}

static int
power (int base, int exponent)
{
  int res = 1;
  if (exponent < 0)
    exit (1);
  for (/* Niente */; exponent; --exponent)
    res *= base;
  return res;
}


int
main (int argc, const char **argv)
{
  semantic_value result = 0;
  int count = 0;
  int status;

  alarm (10);
  if (argc == 2)
    yyin = fopen (argv[1], "r");
  else
    yyin = stdin;

  if (!yyin)
    {
      perror (argv[1]);
      exit (1);
    }