bc.y

操作系统源代码

%{
/* bc.y: The grammar for a POSIX compatable bc processor with some
         extensions to the language. */

/*  This file is part of bc written for MINIX.
    Copyright (C) 1991, 1992 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 of the License , 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; see the file COPYING.  If not, write to
    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

    You may contact the author by:
       e-mail:  [e-mail]
      us-mail:  Philip A. Nelson
                Computer Science Department, 9062
                Western Washington University
                Bellingham, WA 98226-9062
       
*************************************************************************/

#include "bcdefs.h"
#include "global.h"
#include "proto.h"
%}

%start program

%union {
	char	 *s_value;
	char	  c_value;
	int	  i_value;
	arg_list *a_value;
       }

/* Extensions over POSIX bc.
   a) NAME was LETTER.  This grammer allows longer names.
      Single letter names will still work.
   b) Relational_expression allowed only one comparison.
      This grammar has added boolean expressions with
      && (and) || (or) and ! (not) and allowed all of them in
      full expressions.
   c) Added an else to the if.
   d) Call by variable array parameters
   e) read() procedure that reads a number under program control from stdin.
   f) halt statement that halts the the program under program control.  It
      is an executed statement.
   g) continue statement for for loops.
   h) optional expressions in the for loop.
   i) print statement to print multiple numbers per line.
   j) warranty statement to print an extended warranty notice.
   j) limits statement to print the processor's limits.
*/

%token <i_value> NEWLINE AND OR NOT
%token <s_value> STRING NAME NUMBER
/*     '-', '+' are tokens themselves		*/
%token <c_value> MUL_OP
/*     '*', '/', '%' 				*/
%token <c_value> ASSIGN_OP
/*     '=', '+=',  '-=', '*=', '/=', '%=', '^=' */
%token <s_value> REL_OP
/*     '==', '<=', '>=', '!=', '<', '>' 	*/
%token <c_value> INCR_DECR
/*     '++', '--' 				*/
%token <i_value> Define    Break    Quit    Length
/*     'define', 'break', 'quit', 'length' 	*/
%token <i_value> Return    For    If    While    Sqrt   Else
/*     'return', 'for', 'if', 'while', 'sqrt', 'else' 	*/
%token <i_value> Scale    Ibase    Obase    Auto  Read
/*     'scale', 'ibase', 'obase', 'auto', 'read' 	*/
%token <i_value> Warranty, Halt, Last, Continue, Print, Limits
/*     'warranty', 'halt', 'last', 'continue', 'print', 'limits'   */

/* Types of all other things. */
%type <i_value> expression return_expression named_expression opt_expression
%type <c_value> '+' '-' 
%type <a_value> opt_parameter_list opt_auto_define_list define_list
%type <a_value> opt_argument_list argument_list
%type <i_value> program input_item semicolon_list statement_list
%type <i_value> statement function   statement_or_error

/* precedence */
%left OR
%left AND
%nonassoc NOT
%left REL_OP
%right ASSIGN_OP
%left '+' '-'
%left MUL_OP
%right '^'
%nonassoc UNARY_MINUS
%nonassoc INCR_DECR

%%
program			: /* empty */
			    {
			      $$ = 0;
			      if (interactive)
				{
				  printf ("%s\n", BC_VERSION);
				  welcome ();
				}
			    }
			| program input_item
			;
input_item		: semicolon_list NEWLINE
			    { run_code (); }
			| function
			    { run_code (); }
			| error NEWLINE
			    {
			      yyerrok;
			      init_gen ();
			    }
			;
semicolon_list		: /* empty */
			    { $$ = 0; }
			| statement_or_error
			| semicolon_list ';' statement_or_error
			| semicolon_list ';'
			;
statement_list		: /* empty */
			    { $$ = 0; }
			| statement_or_error
			| statement_list NEWLINE
			| statement_list NEWLINE statement_or_error
			| statement_list ';'
			| statement_list ';' statement
			;
statement_or_error	: statement
  			| error statement
			    { $$ = $2; }
			;
statement 		: Warranty
			    { warranty (""); }
			| Limits
			    { limits (); }
			| expression
			    {
			      if ($1 & 2)
				warn ("comparison in expression");
			      if ($1 & 1)
				generate ("W");
			      else 
				generate ("p");
			    }
			| STRING
			    {
			      $$ = 0;
			      generate ("w");
			      generate ($1);
			      free ($1);
			    }
			| Break
			    {
			      if (break_label == 0)
				yyerror ("Break outside a for/while");
			      else
				{
				  sprintf (genstr, "J%1d:", break_label);
				  generate (genstr);
				}
			    }
			| Continue
			    {
			      warn ("Continue statement");
			      if (continue_label == 0)
				yyerror ("Continue outside a for");
			      else
				{
				  sprintf (genstr, "J%1d:", continue_label);
				  generate (genstr);
				}
			    }
			| Quit
			    { exit (0); }
			| Halt
			    { generate ("h"); }
			| Return
			    { generate ("0R"); }
			| Return '(' return_expression ')'
			    { generate ("R"); }
			| For 
			    {
			      $1 = break_label; 
			      break_label = next_label++;
			    }
			  '(' opt_expression ';'
			    {
			      if ($4 > 1)
				warn ("Comparison in first for expression");
			      $4 = next_label++;
			      if ($4 < 0)
				sprintf (genstr, "N%1d:", $4);
			      else
				sprintf (genstr, "pN%1d:", $4);
			      generate (genstr);
			    }
			  opt_expression ';'
			    {
			      if ($7 < 0) generate ("1");
			      $7 = next_label++;
			      sprintf (genstr, "B%1d:J%1d:", $7, break_label);
			      generate (genstr);
			      $<i_value>$ = continue_label;
			      continue_label = next_label++;
			      sprintf (genstr, "N%1d:", continue_label);
			      generate (genstr);
			    }
			  opt_expression ')'
			    {
			      if ($10 > 1)
				warn ("Comparison in third for expression");
			      if ($10 < 0)
				sprintf (genstr, "J%1d:N%1d:", $4, $7);
			      else
				sprintf (genstr, "pJ%1d:N%1d:", $4, $7);
			      generate (genstr);
			    }
			  statement
			    {
			      sprintf (genstr, "J%1d:N%1d:",
				       continue_label, break_label);
			      generate (genstr);
			      break_label = $1;
			      continue_label = $<i_value>9;
			    }
			| If '(' expression ')' 
			    {
			      $3 = if_label;
			      if_label = next_label++;
			      sprintf (genstr, "Z%1d:", if_label);
			      generate (genstr);
			    }
			  statement  opt_else
			    {
			      sprintf (genstr, "N%1d:", if_label); 
			      generate (genstr);
			      if_label = $3;
			    }
			| While 
			    {
			      $1 = next_label++;
			      sprintf (genstr, "N%1d:", $1);
			      generate (genstr);
			    }
			'(' expression 
			    {
			      $4 = break_label; 
			      break_label = next_label++;
			      sprintf (genstr, "Z%1d:", break_label);
			      generate (genstr);
			    }
			')' statement
			    {
			      sprintf (genstr, "J%1d:N%1d:", $1, break_label);
			      generate (genstr);
			      break_label = $4;
			    }
			| '{' statement_list '}'
			    { $$ = 0; }
			| Print
			    {  warn ("print statement"); }
			  print_list
			;
print_list		: print_element
 			| print_element ',' print_list
			;
print_element		: STRING
			    {
			      generate ("O");
			      generate ($1);
			      free ($1);
			    }
			| expression
			    { generate ("P"); }
 			;
opt_else		: /* nothing */
			| Else 
			    {
			      warn ("else clause in if statement");
			      $1 = next_label++;
			      sprintf (genstr, "J%d:N%1d:", $1, if_label); 
			      generate (genstr);
			      if_label = $1;
			    }
			  statement
function 		: Define NAME '(' opt_parameter_list ')' '{'
			  NEWLINE opt_auto_define_list 
			    {
			      /* Check auto list against parameter list? */
			      check_params ($4,$8);
			      sprintf (genstr, "F%d,%s.%s[", lookup($2,FUNCT), 
				       arg_str ($4,TRUE), arg_str ($8,TRUE));
			      generate (genstr);
			      free_args ($4);
			      free_args ($8);
			      $1 = next_label;
			      next_label = 0;
			    }
			  statement_list NEWLINE '}'
			    {
			      generate ("0R]");
			      next_label = $1;
			    }
			;
opt_parameter_list	: /* empty */ 
			    { $$ = NULL; }
			| define_list
			;
opt_auto_define_list 	: /* empty */ 
			    { $$ = NULL; }
			| Auto define_list NEWLINE
			    { $$ = $2; } 
			| Auto define_list ';'
			    { $$ = $2; } 
			;
define_list 		: NAME
			    { $$ = nextarg (NULL, lookup ($1,SIMPLE)); }
			| NAME '[' ']'
			    { $$ = nextarg (NULL, lookup ($1,ARRAY)); }
			| define_list ',' NAME
			    { $$ = nextarg ($1, lookup ($3,SIMPLE)); }
			| define_list ',' NAME '[' ']'
			    { $$ = nextarg ($1, lookup ($3,ARRAY)); }
			;
opt_argument_list	: /* empty */
			    { $$ = NULL; }
			| argument_list
			;
argument_list 		: expression
			    {
			      if ($1 > 1) warn ("comparison in argument");
			      $$ = nextarg (NULL,0);
			    }
			| NAME '[' ']'
			    {
			      sprintf (genstr, "K%d:", -lookup ($1,ARRAY));
			      generate (genstr);
			      $$ = nextarg (NULL,1);
			    }
			| argument_list ',' expression
			    {
			      if ($3 > 1) warn ("comparison in argument");
			      $$ = nextarg ($1,0);
			    }
			| argument_list ',' NAME '[' ']'
			    {
			      sprintf (genstr, "K%d:", -lookup ($3,ARRAY));
			      generate (genstr);
			      $$ = nextarg ($1,1);
			    }
			;
opt_expression 		: /* empty */
			    {
			      $$ = -1;
			      warn ("Missing expression in for statement");
			    }
			| expression
			;
return_expression	: /* empty */
			    {
			      $$ = 0;
			      generate ("0");
			    }
			| expression
			    {
			      if ($1 > 1)
				warn ("comparison in return expresion");
			    }
			;
expression		:  named_expression ASSIGN_OP 
			    {
			      if ($2 != '=')
				{
				  if ($1 < 0)
				    sprintf (genstr, "DL%d:", -$1);
				  else
				    sprintf (genstr, "l%d:", $1);
				  generate (genstr);
				}
			    }
			  expression
			    {
			      if ($4 > 1) warn("comparison in assignment");
			      if ($2 != '=')
				{
				  sprintf (genstr, "%c", $2);
				  generate (genstr);
				}
			      if ($1 < 0)
				sprintf (genstr, "S%d:", -$1);
			      else
				sprintf (genstr, "s%d:", $1);
			      generate (genstr);
			      $$ = 0;
			    }
			;
			| expression AND 
			    {
			      warn("&& operator");
			      $2 = next_label++;
			      sprintf (genstr, "DZ%d:p", $2);
			      generate (genstr);
			    }
			  expression
			    {
			      sprintf (genstr, "DZ%d:p1N%d:", $2, $2);
			      generate (genstr);
			      $$ = $1 | $4;
			    }
			| expression OR
			    {
			      warn("|| operator");
			      $2 = next_label++;
			      sprintf (genstr, "B%d:", $2);
			      generate (genstr);
			    }
			  expression
 			    {
			      int tmplab;
			      tmplab = next_label++;
			      sprintf (genstr, "B%d:0J%d:N%d:1N%d:",
				       $2, tmplab, $2, tmplab);
			      generate (genstr);
			      $$ = $1 | $4;
			    }
			| NOT expression
			    {
			      $$ = $2;
			      warn("! operator");
			      generate ("!");
			    }
			| expression REL_OP expression
			    {
			      $$ = 3;
			      switch (*($2))
				{
				case '=':
				  generate ("=");
				  break;

				case '!':
				  generate ("#");
				  break;

				case '<':
				  if ($2[1] == '=')
				    generate ("{");
				  else
				    generate ("<");
				  break;

				case '>':
				  if ($2[1] == '=')
				    generate ("}");
				  else
				    generate (">");
				  break;
				}
			    }
			| expression '+' expression
			    {
			      generate ("+");
			      $$ = $1 | $3;
			    }
			| expression '-' expression
			    {
			      generate ("-");
			      $$ = $1 | $3;
			    }
			| expression MUL_OP expression
			    {
			      genstr[0] = $2;
			      genstr[1] = 0;
			      generate (genstr);
			      $$ = $1 | $3;
			    }
			| expression '^' expression
			    {
			      generate ("^");
			      $$ = $1 | $3;
			    }
			| '-' expression  %prec UNARY_MINUS
			    {
			      generate ("n");
			      $$ = $2;
			    }
			| named_expression
			    {
			      $$ = 1;
			      if ($1 < 0)
				sprintf (genstr, "L%d:", -$1);
			      else
				sprintf (genstr, "l%d:", $1);
			      generate (genstr);
			    }
			| NUMBER
			    {
			      int len = strlen($1);
			      $$ = 1;
			      if (len == 1 && *$1 == '0')
				generate ("0");
			      else if (len == 1 && *$1 == '1')
				generate ("1");
			      else
				{
				  generate ("K");
				  generate ($1);
				  generate (":");
				}
			      free ($1);
			    }
			| '(' expression ')'
			    { $$ = $2 | 1; }
			| NAME '(' opt_argument_list ')'
			    {
			      $$ = 1;
			      if ($3 != NULL)
				{ 
				  sprintf (genstr, "C%d,%s:",
					   lookup ($1,FUNCT),
					   arg_str ($3,FALSE));
				  free_args ($3);
				}
			      else
				{
				  sprintf (genstr, "C%d:", lookup ($1,FUNCT));
				}
			      generate (genstr);
			    }
			| INCR_DECR named_expression
			    {
			      $$ = 1;
			      if ($2 < 0)
				{
				  if ($1 == '+')
				    sprintf (genstr, "DA%d:L%d:", -$2, -$2);
				  else
				    sprintf (genstr, "DM%d:L%d:", -$2, -$2);
				}
			      else
				{
				  if ($1 == '+')
				    sprintf (genstr, "i%d:l%d:", $2, $2);
				  else
				    sprintf (genstr, "d%d:l%d:", $2, $2);
				}
			      generate (genstr);
			    }
			| named_expression INCR_DECR
			    {
			      $$ = 1;
			      if ($1 < 0)
				{
				  sprintf (genstr, "DL%d:x", -$1);
				  generate (genstr); 
				  if ($2 == '+')
				    sprintf (genstr, "A%d:", -$1);
				  else
				      sprintf (genstr, "M%d:", -$1);
				}
			      else
				{
				  sprintf (genstr, "l%d:", $1);
				  generate (genstr);
				  if ($2 == '+')
				    sprintf (genstr, "i%d:", $1);
				  else
				    sprintf (genstr, "d%d:", $1);
				}
			      generate (genstr);
			    }
			| Length '(' expression ')'
			    { generate ("cL"); $$ = 1;}
			| Sqrt '(' expression ')'
			    { generate ("cR"); $$ = 1;}
			| Scale '(' expression ')'
			    { generate ("cS"); $$ = 1;}
			| Read '(' ')'
			    {
			      warn ("read function");
			      generate ("cI"); $$ = 1;
			    }
			;
named_expression	: NAME
			    { $$ = lookup($1,SIMPLE); }
			| NAME '[' expression ']'
			    {
			      if ($3 > 1) warn("comparison in subscript");
			      $$ = lookup($1,ARRAY);
			    }
			| Ibase
			    { $$ = 0; }
			| Obase
			    { $$ = 1; }
			| Scale
			    { $$ = 2; }
			| Last
			    { $$ = 3; }
			;
%%