* Makefile.in (SUBDIRS): Add chillrt.

[deliverable/binutils-gdb.git] / gdb / ch-exp.y

/* YACC grammar for Chill expressions, for GDB.
   Copyright (C) 1992 Free Software Foundation, Inc.

This file is part of GDB.

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; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* Parse a Chill expression from text in a string,
   and return the result as a  struct expression  pointer.
   That structure contains arithmetic operations in reverse polish,
   with constants represented by operations that are followed by special data.
   See expression.h for the details of the format.
   What is important here is that it can be built up sequentially
   during the process of parsing; the lower levels of the tree always
   come first in the result.

   Note that malloc's and realloc's in this file are transformed to
   xmalloc and xrealloc respectively by the same sed command in the
   makefile that remaps any other malloc/realloc inserted by the parser
   generator.  Doing this with #defines and trying to control the interaction
   with include files (<malloc.h> and <stdlib.h> for example) just became
   too messy, particularly when such includes can be inserted at random
   times by the parser generator.

   Also note that the language accepted by this parser is more liberal
   than the one accepted by an actual Chill compiler.  For example, the
   language rule that a simple name string can not be one of the reserved
   simple name strings is not enforced (e.g "case" is not treated as a
   reserved name).  Another example is that Chill is a strongly typed
   language, and certain expressions that violate the type constraints
   may still be evaluated if gdb can do so in a meaningful manner, while
   such expressions would be rejected by the compiler.  The reason for
   this more liberal behavior is the philosophy that the debugger
   is intended to be a tool that is used by the programmer when things
   go wrong, and as such, it should provide as few artificial barriers
   to it's use as possible.  If it can do something meaningful, even
   something that violates language contraints that are enforced by the
   compiler, it should do so without complaint.

 */
   
%{

#include "defs.h"
#include "expression.h"
#include "language.h"
#include "value.h"
#include "parser-defs.h"
#include "ch-lang.h"

/* Remap normal yacc parser interface names (yyparse, yylex, yyerror, etc),
   as well as gratuitiously global symbol names, so we can have multiple
   yacc generated parsers in gdb.  Note that these are only the variables
   produced by yacc.  If other parser generators (bison, byacc, etc) produce
   additional global names that conflict at link time, then those parser
   generators need to be fixed instead of adding those names to this list. */

#define	yymaxdepth chill_maxdepth
#define	yyparse	chill_parse
#define	yylex	chill_lex
#define	yyerror	chill_error
#define	yylval	chill_lval
#define	yychar	chill_char
#define	yydebug	chill_debug
#define	yypact	chill_pact
#define	yyr1	chill_r1
#define	yyr2	chill_r2
#define	yydef	chill_def
#define	yychk	chill_chk
#define	yypgo	chill_pgo
#define	yyact	chill_act
#define	yyexca	chill_exca
#define yyerrflag chill_errflag
#define yynerrs	chill_nerrs
#define	yyps	chill_ps
#define	yypv	chill_pv
#define	yys	chill_s
#define	yy_yys	chill_yys
#define	yystate	chill_state
#define	yytmp	chill_tmp
#define	yyv	chill_v
#define	yy_yyv	chill_yyv
#define	yyval	chill_val
#define	yylloc	chill_lloc
#define yyreds	chill_reds		/* With YYDEBUG defined */
#define yytoks	chill_toks		/* With YYDEBUG defined */

#ifndef YYDEBUG
#define	YYDEBUG	0		/* Default to no yydebug support */
#endif

int
yyparse PARAMS ((void));

static int
yylex PARAMS ((void));

void
yyerror PARAMS ((char *));

%}

/* Although the yacc "value" of an expression is not used,
   since the result is stored in the structure being created,
   other node types do have values.  */

%union
  {
    LONGEST lval;
    unsigned LONGEST ulval;
    struct {
      LONGEST val;
      struct type *type;
    } typed_val;
    double dval;
    struct symbol *sym;
    struct type *tval;
    struct stoken sval;
    struct ttype tsym;
    struct symtoken ssym;
    int voidval;
    struct block *bval;
    enum exp_opcode opcode;
    struct internalvar *ivar;

    struct type **tvec;
    int *ivec;
  }

%token <voidval> FIXME

%token <typed_val>	INTEGER_LITERAL
%token <ulval>		BOOLEAN_LITERAL
%token <typed_val>	CHARACTER_LITERAL
%token <dval>		FLOAT_LITERAL
%token <ssym>		GENERAL_PROCEDURE_NAME
%token <ssym>		LOCATION_NAME
%token <voidval>	SET_LITERAL
%token <voidval>	EMPTINESS_LITERAL
%token <voidval>	CHARACTER_STRING_LITERAL
%token <voidval>	BIT_STRING_LITERAL

%token <voidval>	STRING
%token <voidval>	CONSTANT
%token <voidval>	'.'
%token <voidval>	';'
%token <voidval>	':'
%token <voidval>	CASE
%token <voidval>	OF
%token <voidval>	ESAC
%token <voidval>	LOGIOR
%token <voidval>	ORIF
%token <voidval>	LOGXOR
%token <voidval>	LOGAND
%token <voidval>	ANDIF
%token <voidval>	'='
%token <voidval>	NOTEQUAL
%token <voidval>	'>'
%token <voidval>	GTR
%token <voidval>	'<'
%token <voidval>	LEQ
%token <voidval>	IN
%token <voidval>	'+'
%token <voidval>	'-'
%token <voidval>	'*'
%token <voidval>	'/'
%token <voidval>	SLASH_SLASH
%token <voidval>	MOD
%token <voidval>	REM
%token <voidval>	NOT
%token <voidval>	POINTER
%token <voidval>	RECEIVE
%token <voidval>	SC
%token <voidval>	'['
%token <voidval>	']'
%token <voidval>	'('
%token <voidval>	')'
%token <voidval>	UP
%token <voidval>	IF
%token <voidval>	THEN
%token <voidval>	ELSE
%token <voidval>	FI
%token <voidval>	ELSIF
%token <voidval>	ILLEGAL_TOKEN

/* Tokens which are not Chill tokens used in expressions, but rather GDB
   specific things that we recognize in the same context as Chill tokens
   (register names for example). */

%token <lval>		GDB_REGNAME	/* Machine register name */
%token <lval>		GDB_LAST	/* Value history */
%token <ivar>		GDB_VARIABLE	/* Convenience variable */
%token <voidval>	GDB_ASSIGNMENT	/* Assign value to somewhere */

%type <voidval>		location
%type <voidval>		access_name
%type <voidval>		primitive_value
%type <voidval>		location_contents
%type <voidval>		value_name
%type <voidval>		literal
%type <voidval>		tuple
%type <voidval>		value_string_element
%type <voidval>		value_string_slice
%type <voidval>		value_array_element
%type <voidval>		value_array_slice
%type <voidval>		value_structure_field
%type <voidval>		expression_conversion
%type <voidval>		value_procedure_call
%type <voidval>		value_built_in_routine_call
%type <voidval>		start_expression
%type <voidval>		zero_adic_operator
%type <voidval>		parenthesised_expression
%type <voidval>		value
%type <voidval>		undefined_value
%type <voidval>		expression
%type <voidval>		conditional_expression
%type <voidval>		then_alternative
%type <voidval>		else_alternative
%type <voidval>		sub_expression
%type <voidval>		value_case_alternative
%type <voidval>		operand_0
%type <voidval>		operand_1
%type <voidval>		operand_2
%type <voidval>		operand_3
%type <voidval>		operand_4
%type <voidval>		operand_5
%type <voidval>		operand_6
%type <voidval>		integer_literal_expression
%type <voidval>		synonym_name
%type <voidval>		value_enumeration_name
%type <voidval>		value_do_with_name
%type <voidval>		value_receive_name
%type <voidval>		string_primitive_value
%type <voidval>		start_element
%type <voidval>		left_element
%type <voidval>		right_element
%type <voidval>		slice_size
%type <voidval>		array_primitive_value
%type <voidval>		expression_list
%type <voidval>		lower_element
%type <voidval>		upper_element
%type <voidval>		first_element
%type <voidval>		structure_primitive_value
%type <voidval>		field_name
%type <voidval>		mode_name
%type <voidval>		boolean_expression
%type <voidval>		case_selector_list
%type <voidval>		subexpression
%type <voidval>		case_label_specification
%type <voidval>		buffer_location

%type <voidval>		single_assignment_action

%%

/* Z.200, 5.3.1 */

value		:	expression
			{
			  $$ = 0;	/* FIXME */
			}
		|	undefined_value
			{
			  $$ = 0;	/* FIXME */
			}
		;

undefined_value	:	FIXME
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 4.2.1 */

location	:	access_name
			{
			  $$ = 0;	/* FIXME */
			}
  		|	FIXME
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 4.2.2 */

access_name	:	LOCATION_NAME
			{
			  write_exp_elt_opcode (OP_VAR_VALUE);
			  write_exp_elt_sym ($1.sym);
			  write_exp_elt_opcode (OP_VAR_VALUE);
			}
		|	GDB_LAST		/* gdb specific */
			{
			  write_exp_elt_opcode (OP_LAST);
			  write_exp_elt_longcst ($1);
			  write_exp_elt_opcode (OP_LAST); 
			}
		|	GDB_REGNAME		/* gdb specific */
			{
			  write_exp_elt_opcode (OP_REGISTER);
			  write_exp_elt_longcst ($1);
			  write_exp_elt_opcode (OP_REGISTER); 
			}
		|	GDB_VARIABLE	/* gdb specific */
			{
			  write_exp_elt_opcode (OP_INTERNALVAR);
			  write_exp_elt_intern ($1);
			  write_exp_elt_opcode (OP_INTERNALVAR); 
			}
  		|	FIXME
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 4.2.8 */

expression_list	:	expression
			{
			  arglist_len = 1;
			}
		|	expression_list ',' expression
			{
			  arglist_len++;
			}

/* Z.200, 5.2.1 */

primitive_value	:	location_contents
			{
			  $$ = 0;	/* FIXME */
			}
                |	value_name
			{
			  $$ = 0;	/* FIXME */
			}
                |	literal
			{
			  $$ = 0;	/* FIXME */
			}
                |	tuple
			{
			  $$ = 0;	/* FIXME */
			}
                |	value_string_element
			{
			  $$ = 0;	/* FIXME */
			}
                |	value_string_slice
			{
			  $$ = 0;	/* FIXME */
			}
                |	value_array_element
			{
			  $$ = 0;	/* FIXME */
			}
                |	value_array_slice
			{
			  $$ = 0;	/* FIXME */
			}
                |	value_structure_field
			{
			  $$ = 0;	/* FIXME */
			}
                |	expression_conversion
			{
			  $$ = 0;	/* FIXME */
			}
                |	value_procedure_call
			{
			  $$ = 0;	/* FIXME */
			}
                |	value_built_in_routine_call
			{
			  $$ = 0;	/* FIXME */
			}
                |	start_expression
			{
			  $$ = 0;	/* FIXME */
			}
                |	zero_adic_operator
			{
			  $$ = 0;	/* FIXME */
			}
                |	parenthesised_expression
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.2 */

location_contents:	location
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.3 */

value_name	:	synonym_name
			{
			  $$ = 0;	/* FIXME */
			}
		|	value_enumeration_name
			{
			  $$ = 0;	/* FIXME */
			}
		|	value_do_with_name
			{
			  $$ = 0;	/* FIXME */
			}
		|	value_receive_name
			{
			  $$ = 0;	/* FIXME */
			}
		|	GENERAL_PROCEDURE_NAME
			{
			  write_exp_elt_opcode (OP_VAR_VALUE);
			  write_exp_elt_sym ($1.sym);
			  write_exp_elt_opcode (OP_VAR_VALUE);
			}
		;

/* Z.200, 5.2.4.1 */

literal		:	INTEGER_LITERAL
			{
			  write_exp_elt_opcode (OP_LONG);
			  write_exp_elt_type ($1.type);
			  write_exp_elt_longcst ((LONGEST) ($1.val));
			  write_exp_elt_opcode (OP_LONG);
			}
		|	BOOLEAN_LITERAL
			{
			  write_exp_elt_opcode (OP_BOOL);
			  write_exp_elt_longcst ((LONGEST) $1);
			  write_exp_elt_opcode (OP_BOOL);
			}
		|	CHARACTER_LITERAL
			{
			  write_exp_elt_opcode (OP_LONG);
			  write_exp_elt_type ($1.type);
			  write_exp_elt_longcst ((LONGEST) ($1.val));
			  write_exp_elt_opcode (OP_LONG);
			}
		|	FLOAT_LITERAL
			{
			  write_exp_elt_opcode (OP_DOUBLE);
			  write_exp_elt_type (builtin_type_double);
			  write_exp_elt_dblcst ($1);
			  write_exp_elt_opcode (OP_DOUBLE);
			}
		|	SET_LITERAL
			{
			  $$ = 0;	/* FIXME */
			}
		|	EMPTINESS_LITERAL
			{
			  $$ = 0;	/* FIXME */
			}
		|	CHARACTER_STRING_LITERAL
			{
			  $$ = 0;	/* FIXME */
			}
		|	BIT_STRING_LITERAL
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.5 */

tuple		:	FIXME
			{
			  $$ = 0;	/* FIXME */
			}
		;


/* Z.200, 5.2.6 */

value_string_element:	string_primitive_value '(' start_element ')'
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.7 */

value_string_slice:	string_primitive_value '(' left_element ':' right_element ')'
			{
			  $$ = 0;	/* FIXME */
			}
		|	string_primitive_value '(' start_element UP slice_size ')'
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.8 */

value_array_element:	array_primitive_value '('
				/* This is to save the value of arglist_len
				   being accumulated for each dimension. */
				{ start_arglist (); }
			expression_list ')'
			{
			  write_exp_elt_opcode (MULTI_SUBSCRIPT);
			  write_exp_elt_longcst ((LONGEST) end_arglist ());
			  write_exp_elt_opcode (MULTI_SUBSCRIPT);
			}
		;

/* Z.200, 5.2.9 */

value_array_slice:	array_primitive_value '(' lower_element ':' upper_element ')'
			{
			  $$ = 0;	/* FIXME */
			}
		|	array_primitive_value '(' first_element UP slice_size ')'
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.10 */

value_structure_field:	structure_primitive_value '.' field_name
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.11 */

expression_conversion:	mode_name '(' expression ')'
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.12 */

value_procedure_call:	FIXME
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.13 */

value_built_in_routine_call:	FIXME
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.14 */

start_expression:	FIXME
			{
			  $$ = 0;	/* FIXME */
			}	/* Not in GNU-Chill */
		;

/* Z.200, 5.2.15 */

zero_adic_operator:	FIXME
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.2.16 */

parenthesised_expression:	'(' expression ')'
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.3.2 */

expression	:	operand_0
			{
			  $$ = 0;	/* FIXME */
			}
		|	conditional_expression
			{
			  $$ = 0;	/* FIXME */
			}
		;

conditional_expression : IF boolean_expression then_alternative else_alternative FI
			{
			  $$ = 0;	/* FIXME */
			}
		|	CASE case_selector_list OF value_case_alternative '[' ELSE sub_expression ']' ESAC
			{
			  $$ = 0;	/* FIXME */
			}
		;

then_alternative:	THEN subexpression
			{
			  $$ = 0;	/* FIXME */
			}
		;

else_alternative:	ELSE subexpression
			{
			  $$ = 0;	/* FIXME */
			}
		|	ELSIF boolean_expression then_alternative else_alternative
			{
			  $$ = 0;	/* FIXME */
			}
		;

sub_expression	:	expression
			{
			  $$ = 0;	/* FIXME */
			}
		;

value_case_alternative:	case_label_specification ':' sub_expression ';'
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.3.3 */

operand_0	:	operand_1
			{
			  $$ = 0;	/* FIXME */
			}
		|	operand_0 LOGIOR operand_1
			{
			  write_exp_elt_opcode (BINOP_BITWISE_IOR);
			}
		|	operand_0 ORIF operand_1
			{
			  $$ = 0;	/* FIXME */
			}
		|	operand_0 LOGXOR operand_1
			{
			  write_exp_elt_opcode (BINOP_BITWISE_XOR);
			}
		|	single_assignment_action
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.3.4 */

operand_1	:	operand_2
			{
			  $$ = 0;	/* FIXME */
			}
		|	operand_1 LOGAND operand_2
			{
			  write_exp_elt_opcode (BINOP_BITWISE_AND);
			}
		|	operand_1 ANDIF operand_2
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.3.5 */

operand_2	:	operand_3
			{
			  $$ = 0;	/* FIXME */
			}
		|	operand_2 '=' operand_3
			{
			  write_exp_elt_opcode (BINOP_EQUAL);
			}
		|	operand_2 NOTEQUAL operand_3
			{
			  write_exp_elt_opcode (BINOP_NOTEQUAL);
			}
		|	operand_2 '>' operand_3
			{
			  write_exp_elt_opcode (BINOP_GTR);
			}
		|	operand_2 GTR operand_3
			{
			  write_exp_elt_opcode (BINOP_GEQ);
			}
		|	operand_2 '<' operand_3
			{
			  write_exp_elt_opcode (BINOP_LESS);
			}
		|	operand_2 LEQ operand_3
			{
			  write_exp_elt_opcode (BINOP_LEQ);
			}
		|	operand_2 IN operand_3
			{
			  $$ = 0;	/* FIXME */
			}
		;


/* Z.200, 5.3.6 */

operand_3	:	operand_4
			{
			  $$ = 0;	/* FIXME */
			}
		|	operand_3 '+' operand_4
			{
			  write_exp_elt_opcode (BINOP_ADD);
			}
		|	operand_3 '-' operand_4
			{
			  write_exp_elt_opcode (BINOP_SUB);
			}
		|	operand_3 SLASH_SLASH operand_4
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.3.7 */

operand_4	:	operand_5
			{
			  $$ = 0;	/* FIXME */
			}
		|	operand_4 '*' operand_5
			{
			  write_exp_elt_opcode (BINOP_MUL);
			}
		|	operand_4 '/' operand_5
			{
			  write_exp_elt_opcode (BINOP_DIV);
			}
		|	operand_4 MOD operand_5
			{
			  write_exp_elt_opcode (BINOP_MOD);
			}
		|	operand_4 REM operand_5
			{
			  write_exp_elt_opcode (BINOP_REM);
			}
		;

/* Z.200, 5.3.8 */

operand_5	:	operand_6
			{
			  $$ = 0;	/* FIXME */
			}
		|	'-' operand_6
			{
			  write_exp_elt_opcode (UNOP_NEG);
			}
		|	NOT operand_6
			{
			  write_exp_elt_opcode (UNOP_LOGICAL_NOT);
			}
		|	'(' integer_literal_expression ')' operand_6
			{
			  $$ = 0;	/* FIXME */
			}
		;

/* Z.200, 5.3.9 */

operand_6	:	POINTER location
			{
			  $$ = 0;	/* FIXME */
			}
		|	RECEIVE buffer_location
			{
			  $$ = 0;	/* FIXME */
			}
		|	primitive_value
			{
			  $$ = 0;	/* FIXME */
			}
		;


/* Z.200, 6.2 */

single_assignment_action :	location GDB_ASSIGNMENT value
			{
			  write_exp_elt_opcode (BINOP_ASSIGN);
			}

/* Z.200, 12.4.3 */
/* FIXME:  For now we just accept only a single integer literal. */

integer_literal_expression:
			INTEGER_LITERAL
			{
			  $$ = 0;
			}

/* Z.200, 12.4.3 */

array_primitive_value :	primitive_value
			{
			  $$ = 0;
			}


/* Things which still need productions... */

synonym_name	 	:	FIXME { $$ = 0; }
value_enumeration_name 	:	FIXME { $$ = 0; }
value_do_with_name 	:	FIXME { $$ = 0; }
value_receive_name 	:	FIXME { $$ = 0; }
string_primitive_value 	:	FIXME { $$ = 0; }
start_element 		:	FIXME { $$ = 0; }
left_element 		:	FIXME { $$ = 0; }
right_element 		:	FIXME { $$ = 0; }
slice_size 		:	FIXME { $$ = 0; }
lower_element 		:	FIXME { $$ = 0; }
upper_element 		:	FIXME { $$ = 0; }
first_element 		:	FIXME { $$ = 0; }
structure_primitive_value:	FIXME { $$ = 0; }
field_name 		:	FIXME { $$ = 0; }
mode_name 		:	FIXME { $$ = 0; }
boolean_expression 	:	FIXME { $$ = 0; }
case_selector_list 	:	FIXME { $$ = 0; }
subexpression 		:	FIXME { $$ = 0; }
case_label_specification:	FIXME { $$ = 0; }
buffer_location 	:	FIXME { $$ = 0; }

%%

/* Try to consume a simple name string token.  If successful, returns
   a pointer to a nullbyte terminated copy of the name that can be used
   in symbol table lookups.  If not successful, returns NULL. */

static char *
match_simple_name_string ()
{
  char *tokptr = lexptr;

  if (isalpha (*tokptr))
    {
      do {
	tokptr++;
      } while (isalpha (*tokptr) || isdigit (*tokptr) || (*tokptr == '_'));
      yylval.sval.ptr = lexptr;
      yylval.sval.length = tokptr - lexptr;
      lexptr = tokptr;
      return (copy_name (yylval.sval));
    }
  return (NULL);
}

/* Start looking for a value composed of valid digits as set by the base
   in use.  Note that '_' characters are valid anywhere, in any quantity,
   and are simply ignored.  Since we must find at least one valid digit,
   or reject this token as an integer literal, we keep track of how many
   digits we have encountered. */
  
static int
decode_integer_value (base, tokptrptr, ivalptr)
  int base;
  char **tokptrptr;
  int *ivalptr;
{
  char *tokptr = *tokptrptr;
  int temp;
  int digits = 0;

  while (*tokptr != '\0')
    {
      temp = tolower (*tokptr);
      tokptr++;
      switch (temp)
	{
	case '_':
	  continue;
	case '0':  case '1':  case '2':  case '3':  case '4':
	case '5':  case '6':  case '7':  case '8':  case '9':
	  temp -= '0';
	  break;
	case 'a':  case 'b':  case 'c':  case 'd':  case 'e': case 'f':
	  temp -= 'a';
	  temp += 10;
	  break;
	default:
	  temp = base;
	  break;
	}
      if (temp < base)
	{
	  digits++;
	  *ivalptr *= base;
	  *ivalptr += temp;
	}
      else
	{
	  /* Found something not in domain for current base. */
	  tokptr--;	/* Unconsume what gave us indigestion. */
	  break;
	}
    }
  
  /* If we didn't find any digits, then we don't have a valid integer
     value, so reject the entire token.  Otherwise, update the lexical
     scan pointer, and return non-zero for success. */
  
  if (digits == 0)
    {
      return (0);
    }
  else
    {
      *tokptrptr = tokptr;
      return (1);
    }
}

static int
decode_integer_literal (valptr, tokptrptr)
  int *valptr;
  char **tokptrptr;
{
  char *tokptr = *tokptrptr;
  int base = 0;
  int ival = 0;
  int explicit_base = 0;
  
  /* Look for an explicit base specifier, which is optional. */
  
  switch (*tokptr)
    {
    case 'd':
    case 'D':
      explicit_base++;
      base = 10;
      tokptr++;
      break;
    case 'b':
    case 'B':
      explicit_base++;
      base = 2;
      tokptr++;
      break;
    case 'h':
    case 'H':
      explicit_base++;
      base = 16;
      tokptr++;
      break;
    case 'o':
    case 'O':
      explicit_base++;
      base = 8;
      tokptr++;
      break;
    default:
      base = 10;
      break;
    }
  
  /* If we found an explicit base ensure that the character after the
     explicit base is a single quote. */
  
  if (explicit_base && (*tokptr++ != '\''))
    {
      return (0);
    }
  
  /* Attempt to decode whatever follows as an integer value in the
     indicated base, updating the token pointer in the process and
     computing the value into ival.  Also, if we have an explicit
     base, then the next character must not be a single quote, or we
     have a bitstring literal, so reject the entire token in this case.
     Otherwise, update the lexical scan pointer, and return non-zero
     for success. */

  if (!decode_integer_value (base, &tokptr, &ival))
    {
      return (0);
    }
  else if (explicit_base && (*tokptr == '\''))
    {
      return (0);
    }
  else
    {
      *valptr = ival;
      *tokptrptr = tokptr;
      return (1);
    }
}

/*  If it wasn't for the fact that floating point values can contain '_'
    characters, we could just let strtod do all the hard work by letting it
    try to consume as much of the current token buffer as possible and
    find a legal conversion.  Unfortunately we need to filter out the '_'
    characters before calling strtod, which we do by copying the other
    legal chars to a local buffer to be converted.  However since we also
    need to keep track of where the last unconsumed character in the input
    buffer is, we have transfer only as many characters as may compose a
    legal floating point value. */
    
static int
match_float_literal ()
{
  char *tokptr = lexptr;
  char *buf;
  char *copy;
  char ch;
  double dval;
  extern double strtod ();
  
  /* Make local buffer in which to build the string to convert.  This is
     required because underscores are valid in chill floating point numbers
     but not in the string passed to strtod to convert.  The string will be
     no longer than our input string. */
     
  copy = buf = (char *) alloca (strlen (tokptr) + 1);

  /* Transfer all leading digits to the conversion buffer, discarding any
     underscores. */

  while (isdigit (*tokptr) || *tokptr == '_')
    {
      if (*tokptr != '_')
	{
	  *copy++ = *tokptr;
	}
      tokptr++;
    }

  /* Now accept either a '.', or one of [eEdD].  Dot is legal regardless
     of whether we found any leading digits, and we simply accept it and
     continue on to look for the fractional part and/or exponent.  One of
     [eEdD] is legal only if we have seen digits, and means that there
     is no fractional part.  If we find neither of these, then this is
     not a floating point number, so return failure. */

  switch (*tokptr++)
    {
      case '.':
        /* Accept and then look for fractional part and/or exponent. */
	*copy++ = '.';
	break;

      case 'e':
      case 'E':
      case 'd':
      case 'D':
	if (copy == buf)
	  {
	    return (0);
	  }
	*copy++ = 'e';
	goto collect_exponent;
	break;

      default:
	return (0);
        break;
    }

  /* We found a '.', copy any fractional digits to the conversion buffer, up
     to the first nondigit, non-underscore character. */

  while (isdigit (*tokptr) || *tokptr == '_')
    {
      if (*tokptr != '_')
	{
	  *copy++ = *tokptr;
	}
      tokptr++;
    }

  /* Look for an exponent, which must start with one of [eEdD].  If none
     is found, jump directly to trying to convert what we have collected
     so far. */

  switch (*tokptr)
    {
      case 'e':
      case 'E':
      case 'd':
      case 'D':
	*copy++ = 'e';
	tokptr++;
	break;
      default:
	goto convert_float;
	break;
    }

  /* Accept an optional '-' or '+' following one of [eEdD]. */

  collect_exponent:
  if (*tokptr == '+' || *tokptr == '-')
    {
      *copy++ = *tokptr++;
    }

  /* Now copy an exponent into the conversion buffer.  Note that at the 
     moment underscores are *not* allowed in exponents. */

  while (isdigit (*tokptr))
    {
      *copy++ = *tokptr++;
    }

  /* If we transfered any chars to the conversion buffer, try to interpret its
     contents as a floating point value.  If any characters remain, then we
     must not have a valid floating point string. */

  convert_float:
  *copy = '\0';
  if (copy != buf)
      {
        dval = strtod (buf, &copy);
        if (*copy == '\0')
	  {
	    yylval.dval = dval;
	    lexptr = tokptr;
	    return (FLOAT_LITERAL);
	  }
      }
  return (0);
}

/* Recognize a character literal.  A character literal is single character
   or a control sequence, enclosed in single quotes.  A control sequence
   is a comma separated list of one or more integer literals, enclosed
   in parenthesis and introduced with a circumflex character.

   EX:  'a'  '^(7)'  '^(7,8)'

   As a GNU chill extension, the syntax C'xx' is also recognized as a 
   character literal, where xx is a hex value for the character.

   Returns CHARACTER_LITERAL if a match is found.
   */

static int
match_character_literal ()
{
  char *tokptr = lexptr;
  int ival = 0;
  
  if ((tolower (*tokptr) == 'c') && (*(tokptr + 1) == '\''))
    {
      /* We have a GNU chill extension form, so skip the leading "C'",
	 decode the hex value, and then ensure that we have a trailing
	 single quote character. */
      tokptr += 2;
      if (!decode_integer_value (16, &tokptr, &ival) || (*tokptr != '\''))
	{
	  return (0);
	}
      tokptr++;
    }
  else if (*tokptr == '\'')
    {
      tokptr++;

      /* Determine which form we have, either a control sequence or the
	 single character form. */
      
      if ((*tokptr == '^') && (*(tokptr + 1) == '('))
	{
	  /* Match and decode a control sequence.  Return zero if we don't
	     find a valid integer literal, or if the next unconsumed character
	     after the integer literal is not the trailing ')'.
	     FIXME:  We currently don't handle the multiple integer literal
	     form. */
	  tokptr += 2;
	  if (!decode_integer_literal (&ival, &tokptr) || (*tokptr++ != ')'))
	    {
	      return (0);
	    }
	}
      else
	{
	  ival = *tokptr++;
	}
      
      /* The trailing quote has not yet been consumed.  If we don't find
	 it, then we have no match. */
      
      if (*tokptr++ != '\'')
	{
	  return (0);
	}
    }
  else
    {
      /* Not a character literal. */
      return (0);
    }
  yylval.typed_val.val = ival;
  yylval.typed_val.type = builtin_type_chill_char;
  lexptr = tokptr;
  return (CHARACTER_LITERAL);
}

/* Recognize an integer literal, as specified in Z.200 sec 5.2.4.2.
   Note that according to 5.2.4.2, a single "_" is also a valid integer
   literal, however GNU-chill requires there to be at least one "digit"
   in any integer literal. */

static int
match_integer_literal ()
{
  char *tokptr = lexptr;
  int ival;
  
  if (!decode_integer_literal (&ival, &tokptr))
    {
      return (0);
    }
  else 
    {
      yylval.typed_val.val = ival;
      yylval.typed_val.type = builtin_type_int;
      lexptr = tokptr;
      return (INTEGER_LITERAL);
    }
}

/* Recognize tokens that start with '$'.  These include:

	$regname	A native register name or a "standard
			register name".
			Return token GDB_REGNAME.

	$variable	A convenience variable with a name chosen
			by the user.
			Return token GDB_VARIABLE.

	$digits		Value history with index <digits>, starting
			from the first value which has index 1.
			Return GDB_LAST.

	$$digits	Value history with index <digits> relative
			to the last value.  I.E. $$0 is the last
			value, $$1 is the one previous to that, $$2
			is the one previous to $$1, etc.
			Return token GDB_LAST.

	$ | $0 | $$0	The last value in the value history.
			Return token GDB_LAST.

	$$		An abbreviation for the second to the last
			value in the value history, I.E. $$1
			Return token GDB_LAST.

    Note that we currently assume that register names and convenience
    variables follow the convention of starting with a letter or '_'.

   */

static int
match_dollar_tokens ()
{
  char *tokptr;
  int regno;
  int namelength;
  int negate;
  int ival;

  /* We will always have a successful match, even if it is just for
     a single '$', the abbreviation for $$0.  So advance lexptr. */

  tokptr = ++lexptr;

  if (*tokptr == '_' || isalpha (*tokptr))
    {
      /* Look for a match with a native register name, usually something
	 like "r0" for example. */

      for (regno = 0; regno < NUM_REGS; regno++)
	{
	  namelength = strlen (reg_names[regno]);
	  if (STREQN (tokptr, reg_names[regno], namelength)
	      && !isalnum (tokptr[namelength]))
	    {
	      yylval.lval = regno;
	      lexptr += namelength + 1;
	      return (GDB_REGNAME);
	    }
	}

      /* Look for a match with a standard register name, usually something
	 like "pc", which gdb always recognizes as the program counter
	 regardless of what the native register name is. */

      for (regno = 0; regno < num_std_regs; regno++)
	{
	  namelength = strlen (std_regs[regno].name);
	  if (STREQN (tokptr, std_regs[regno].name, namelength)
	      && !isalnum (tokptr[namelength]))
	    {
	      yylval.lval = std_regs[regno].regnum;
	      lexptr += namelength;
	      return (GDB_REGNAME);
	    }
	}

      /* Attempt to match against a convenience variable.  Note that
	 this will always succeed, because if no variable of that name
	 already exists, the lookup_internalvar will create one for us.
	 Also note that both lexptr and tokptr currently point to the
	 start of the input string we are trying to match, and that we
	 have already tested the first character for non-numeric, so we
	 don't have to treat it specially. */

      while (*tokptr == '_' || isalnum (*tokptr))
	{
	  tokptr++;
	}
      yylval.sval.ptr = lexptr;
      yylval.sval.length = tokptr - lexptr;
      yylval.ivar = lookup_internalvar (copy_name (yylval.sval));
      lexptr = tokptr;
      return (GDB_VARIABLE);
    }

  /* Since we didn't match against a register name or convenience
     variable, our only choice left is a history value. */

  if (*tokptr == '$')
    {
      negate = 1;
      ival = 1;
      tokptr++;
    }
  else
    {
      negate = 0;
      ival = 0;
    }

  /* Attempt to decode more characters as an integer value giving
     the index in the history list.  If successful, the value will
     overwrite ival (currently 0 or 1), and if not, ival will be
     left alone, which is good since it is currently correct for
     the '$' or '$$' case. */

  decode_integer_literal (&ival, &tokptr);
  yylval.lval = negate ? -ival : ival;
  lexptr = tokptr;
  return (GDB_LAST);
}

struct token
{
  char *operator;
  int token;
};

static const struct token tokentab5[] =
{
    { "ANDIF", ANDIF }
};

static const struct token tokentab4[] =
{
    { "ORIF", ORIF }
};

static const struct token tokentab3[] =
{
    { "MOD", MOD },
    { "REM", REM },
    { "NOT", NOT },
    { "XOR", LOGXOR },
    { "AND", LOGAND }
};

static const struct token tokentab2[] =
{
    { ":=", GDB_ASSIGNMENT },
    { "//", SLASH_SLASH },
    { "/=", NOTEQUAL },
    { "<=", LEQ },
    { ">=", GTR },
    { "IN", IN },
    { "OR", LOGIOR }
};

/* Read one token, getting characters through lexptr.  */
/* This is where we will check to make sure that the language and the
   operators used are compatible.  */

static int
yylex ()
{
    unsigned int i;
    int token;
    char *simplename;
    struct symbol *sym;

    /* Skip over any leading whitespace. */
    while (isspace (*lexptr))
	{
	    lexptr++;
	}
    /* Look for special single character cases which can't be the first
       character of some other multicharacter token. */
    switch (*lexptr)
	{
	    case '\0':
	        return (0);
	    case ',':
	    case '=':
	    case ';':
	    case '!':
	    case '+':
	    case '-':
	    case '*':
	    case '/':
	    case '(':
	    case ')':
	    case '[':
	    case ']':
		return (*lexptr++);
	}
    /* Look for characters which start a particular kind of multicharacter
       token, such as a character literal, register name, convenience
       variable name, etc. */
    switch (*lexptr)
      {
        case 'C':
        case 'c':
	case '\'':
	  token = match_character_literal ();
	  if (token != 0)
	    {
	      return (token);
	    }
	  break;
	case '$':
	  token = match_dollar_tokens ();
	  if (token != 0)
	    {
	      return (token);
	    }
	  break;
      }
    /* See if it is a special token of length 5.  */
    for (i = 0; i < sizeof (tokentab5) / sizeof (tokentab5[0]); i++)
	{
	    if (STREQN (lexptr, tokentab5[i].operator, 5))
		{
		    lexptr += 5;
		    return (tokentab5[i].token);
		}
	}
    /* See if it is a special token of length 4.  */
    for (i = 0; i < sizeof (tokentab4) / sizeof (tokentab4[0]); i++)
	{
	    if (STREQN (lexptr, tokentab4[i].operator, 4))
		{
		    lexptr += 4;
		    return (tokentab4[i].token);
		}
	}
    /* See if it is a special token of length 3.  */
    for (i = 0; i < sizeof (tokentab3) / sizeof (tokentab3[0]); i++)
	{
	    if (STREQN (lexptr, tokentab3[i].operator, 3))
		{
		    lexptr += 3;
		    return (tokentab3[i].token);
		}
	}
    /* See if it is a special token of length 2.  */
    for (i = 0; i < sizeof (tokentab2) / sizeof (tokentab2[0]); i++)
	{
	    if (STREQN (lexptr, tokentab2[i].operator, 2))
		{
		    lexptr += 2;
		    return (tokentab2[i].token);
		}
	}
    /* Look for single character cases which which could be the first
       character of some other multicharacter token, but aren't, or we
       would already have found it. */
    switch (*lexptr)
	{
	    case ':':
	    case '/':
	    case '<':
	    case '>':
		return (*lexptr++);
	}
    /* Look for other special tokens. */
    if (STREQN (lexptr, "TRUE", 4)) /* FIXME:  What about lowercase? */
	{
	    yylval.ulval = 1;
	    lexptr += 4;
	    return (BOOLEAN_LITERAL);
	}
    if (STREQN (lexptr, "FALSE", 5)) /* FIXME:  What about lowercase? */
	{
	    yylval.ulval = 0;
	    lexptr += 5;
	    return (BOOLEAN_LITERAL);
	}
    /* Look for a float literal before looking for an integer literal, so
       we match as much of the input stream as possible. */
    token = match_float_literal ();
    if (token != 0)
	{
	    return (token);
	}
    token = match_integer_literal ();
    if (token != 0)
	{
	    return (token);
	}

    /* Try to match a simple name string, and if a match is found, then
       further classify what sort of name it is and return an appropriate
       token.  Note that attempting to match a simple name string consumes
       the token from lexptr, so we can't back out if we later find that
       we can't classify what sort of name it is. */

    simplename = match_simple_name_string ();
    if (simplename != NULL)
      {
	sym = lookup_symbol (simplename, expression_context_block,
			     VAR_NAMESPACE, (int *) NULL,
			     (struct symtab **) NULL);
	if (sym != NULL)
	  {
	    yylval.ssym.stoken.ptr = NULL;
	    yylval.ssym.stoken.length = 0;
	    yylval.ssym.sym = sym;
	    yylval.ssym.is_a_field_of_this = 0;	/* FIXME, C++'ism */
	    switch (SYMBOL_CLASS (sym))
	      {
	      case LOC_BLOCK:
		/* Found a procedure name. */
		return (GENERAL_PROCEDURE_NAME);
	      case LOC_STATIC:
		/* Found a global or local static variable. */
		return (LOCATION_NAME);
	      case LOC_REGISTER:
	      case LOC_ARG:
	      case LOC_REF_ARG:
	      case LOC_REGPARM:
	      case LOC_LOCAL:
	      case LOC_LOCAL_ARG:
		if (innermost_block == NULL
		    || contained_in (block_found, innermost_block))
		  {
		    innermost_block = block_found;
		  }
		return (LOCATION_NAME);
		break;
	      case LOC_CONST:
	      case LOC_LABEL:
		return (LOCATION_NAME);
		break;
	      case LOC_UNDEF:
	      case LOC_TYPEDEF:
	      case LOC_CONST_BYTES:
		error ("Symbol \"%s\" names no location.", simplename);
		break;
	      }
	  }
	else if (!have_full_symbols () && !have_partial_symbols ())
	  {
	    error ("No symbol table is loaded.  Use the \"file\" command.");
	  }
	else
	  {
	    error ("No symbol \"%s\" in current context.", simplename);
	  }
      }

    /* Catch single character tokens which are not part of some
       longer token. */

    switch (*lexptr)
      {
	case '.':			/* Not float for example. */
	  return (*lexptr++);
      }

    return (ILLEGAL_TOKEN);
}

void
yyerror (msg)
     char *msg;	/* unused */
{
  printf ("Parsing:  %s\n", lexptr);
  if (yychar < 256)
    {
      error ("Invalid syntax in expression near character '%c'.", yychar);
    }
  else
    {
      error ("Invalid syntax in expression");
    }
}