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parser.y
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parser.y
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/***************************************************************/
/* This module is the YACC_specification of the parser. */
/* All inputs must be terminated by a double simicolon */
/* An input is either a term or a directive. */
/* A term can be a global definition of the kind */
/* - def <identifier> = <expr> in <expr> */
/* or a single expression. */
/* */
/* Expressions are syntactically defined by the following */
/* grammar: */
/* */
/* <expr> ::= <expr0> */
/* | <expr> < <expr> */
/* | <expr> == <expr> */
/* | <expr> > <expr> */
/* | <expr> <= <expr> */
/* | <expr> >= <expr> */
/* | <expr> <> <expr> */
/* | <expr> + <expr> */
/* | <expr> - <expr> */
/* | <expr> * <expr> */
/* | <expr> div <expr> */
/* | <expr> mod <expr> */
/* | - <expr> */
/* | <expr> < <expr> */
/* | <expr> == <expr> */
/* | <expr> > <expr> */
/* | <expr> <= <expr> */
/* | <expr> >= <expr> */
/* | <expr> <> <expr> */
/* | <expr> + <expr> */
/* | <expr> - <expr> */
/* | <expr> * <expr> */
/* | <expr> div <expr> */
/* | <expr> mod <expr> */
/* */
/* <expr0> ::= true */
/* | false */
/* | <num\_const> */
/* | <identifier> */
/* | (<applist>) */
/* | \ <pattern> . <expr> */
/* | let <identifier> = <expr> in <expr> */
/* | letrec <identifier> = <expr> */
/* | if <expr> then <expr> else <expr> */
/* | <expr> and <expr> */
/* | <expr> or <expr> */
/* | not <expr> */
/* | <list> */
/* | cons (<expr>,<expr>) */
/* | head (<expr>) */
/* | tail (<expr>) */
/* | isnil (<expr>) */
/* <list> ::= nil */
/* | [<exprlist>] */
/* <exprlist> ::= (* empty *) */
/* | <expr> */
/* | <expr>,<exprlist> */
/* | <expr>|<expr> */
/* <applist> ::= <expr> */
/* | <applist> <expr0> */
/* | <expr>,<comlist> */
/* <comlist> ::= <expr> */
/* | <expr>,<comlist> */
/* <pattern> ::= <identifier> */
/* | cons(<pattern>,<pattern>) */
/* | (<comlistpat>) */
/* <comlistpat> ::= <pattern> */
/* | <pattern>,<comlistpat> */
/* */
/* The <expr0> nonterminal represents an expression which */
/* cannot start with a minus sign. */
/* (comlist) is represents a tuple; tuples are */
/* currently implemented as non-nil-terminated lists. */
/* */
/* Each directive must be preceded by the symbol "#". */
/* There are seven directives: */
/* - inspect to enter inspection mode (the name of a */
/* globally defined term to inspect can be passed */
/* as a parameter; otherwise, inspection of the */
/* last compiled term is assumed). */
/* - save to save the graph of a term in a file. */
/* The first identifier is the file name, the */
/* second is the term (if the latter does not */
/* exist, the last term is taken). */
/* - quit to exit from the compiler. */
/* - load to load an external file; the file name must */
/* be specified as a normal idenitifier */
/* - garbage to invoke gargabe collection */
/* - option to choose a grabge collection strategy */
/* - info to get general informations on the computation */
/***************************************************************/
/***************************************************************/
/* 1. Inclusion of header files. */
/***************************************************************/
%{
#include "bohm.h"
#include <stdio.h>
#include <stdlib.h>
%}
/***************************************************************/
/* 2. Inclusion of declarations that are being imported. */
/***************************************************************/
%{
int yyerror(const char *msg);
%}
/***************************************************************/
/* 3. Definitions of variables to be exported. */
/***************************************************************/
%{
bool quit,
/* flag indicating quit request */
loading_mode;
/* flag indicating if parsing is */
/* done after a load directive */
char *include_file;
FORM *lastinputterm,
/* pointer to the root of the */
/* term in input */
*current_pos;
/* for inspection mode */
%}
/***************************************************************/
/* 4. Definitions strictly local to the module. */
/***************************************************************/
%{
#define UNBOUND_VARIABLE "scoping error: undefined variable"
int app_nesting_depth;
PATTERN *pattmp;
static bool defined();
%}
/***************************************************************/
/* 5. Definition of grammar symbols attributes. */
/***************************************************************/
%union {
STBUCKET *st_bucket;
/* pointer to a symbol */
/* table bucket */
int num_const;
/* numerical constant */
TERM *term;
/* graph representation */
/* of the term */
FORM *root;
/* root_form */
char *astring;
PATTERN *pattern;
}
/***************************************************************/
/* 6. Definitions of tokens. */
/***************************************************************/
%token EXPRDELIM 257
%token <st_bucket> ID 258
%token <num_const> NUMCONST 259
%token EQUAL 260
%token LEQUAL 261
%token MEQUAL 262
%token NOTEQUAL 263
%token LETKW 400
%token INKW 401
%token INSPECTKW 402
%token QUITKW 403
%token LOADKW 404
%token LETRECKW 405
%token TRUEKW 406
%token FALSEKW 407
%token IFKW 408
%token THENKW 409
%token ELSEKW 410
%token ANDKW 411
%token ORKW 412
%token NOTKW 413
%token DIVKW 414
%token MODKW 415
%token CONSKW 416
%token HEADKW 417
%token TAILKW 418
%token TESTNILKW 419
%token DEFKW 420
%token NILKW 422
%token GARBAGEKW 423
%token OPTIONKW 424
%token INFOKW 425
%token SAVEKW 426
%token TRAVELKW 427
%token <astring> ASTRING 428
/***************************************************************/
/* 7. Association of attributes with nonterminals. */
/***************************************************************/
%type <root> input
%type <root> directive
%type <root> arg
%type <root> term
%type <root> global_decl
%type <term> expr
%type <term> expr0
%type <term> applist
%type <term> comlist
%type <term> exprlist
%type <term> list
%type <pattern> pattern
%type <pattern> comlistpat
%type <astring> optstring
%type <num_const> optint
/***************************************************************/
/* 8. Precedence and associativity of operators. */
/***************************************************************/
%nonassoc ELSEKW INKW '.' '='
%left ANDKW ORKW
%left NOTKW
%left '<' '>' EQUAL LEQUAL MEQUAL NOTEQUAL
%left '+' '-'
%left '*' DIVKW MODKW
%left NEG
/***************************************************************/
/* 9. Definition of the start symbol. */
/***************************************************************/
%start input
/***************************************************************/
/* 10. Grammar rules. */
/***************************************************************/
%%
input : directive
| {
app_nesting_depth = 0;
destroy();
lastinputterm=NULL;
}
term
{
$$ = $2;
}
|
{
printf("no more input");
quit = true;
YYACCEPT;
}
;
directive : '#' INSPECTKW arg EXPRDELIM
{
if ($3 == NULL) $3=lastinputterm;
$$ = $3;
inspect_driver($3);
YYACCEPT;
}
| '#' TRAVELKW arg NUMCONST EXPRDELIM
{
if ($3 == NULL) $3=current_pos;
current_pos = inspect($4,$3);
YYACCEPT;
}
| '#' QUITKW EXPRDELIM
{
quit = true;
YYACCEPT;
}
| '#' LOADKW ASTRING EXPRDELIM
{
include_file = $3;
loading_mode = true;
printf("%s", include_file);
YYACCEPT;
}
| '#' GARBAGEKW EXPRDELIM
{
user();
YYACCEPT;
}
| '#' OPTIONKW optint EXPRDELIM
{
menu($3);
YYACCEPT;
}
| '#' INFOKW optstring EXPRDELIM
{
info($3);
YYACCEPT;
}
| '#' SAVEKW ASTRING EXPRDELIM
{
save($3,lastinputterm,NULL);
free($3);
YYACCEPT;
}
| '#' SAVEKW ASTRING ID EXPRDELIM
{
if (defined($4))
save($3,$4->curr_binding->root,$4->id);
else
{
signal_error(UNBOUND_VARIABLE);
YYACCEPT;
}
free($3);
YYACCEPT;
}
;
arg :
{
$$ = NULL;
}
| ID
{
if (defined($1))
$$ = $1->curr_binding->root;
else
{
signal_error(UNBOUND_VARIABLE);
YYACCEPT;
}
}
;
optstring :
{
$$ = "";
}
| ASTRING
{
$$ = $1;
}
optint :
{
$$ = -1;
}
| NUMCONST
{
$$ = $1;
}
term : expr EXPRDELIM
{
lastinputterm = closeterm(0,$1);
current_pos = lastinputterm;
$$ = lastinputterm;
reduce_term($$);
YYACCEPT;
}
| global_decl EXPRDELIM
{
no_destroy();
YYACCEPT;
}
;
global_decl : DEFKW ID '='
{
app_nesting_depth++;
}
expr
{
app_nesting_depth--;
lastinputterm = closeterm(1,$5);
$$ = lastinputterm;
create_variable_binding($2,$$);
}
;
expr : expr0
{
$$ = $1;
}
| '-' expr %prec NEG
{
$$ = buildminusterm(app_nesting_depth, $2);
}
| expr ANDKW expr
{
$$ = buildandterm(app_nesting_depth,
$1,$3);
}
| expr ORKW expr
{
$$ = buildorterm(app_nesting_depth,
$1,$3);
}
| expr '<' expr
{
$$ = buildrelopterm(app_nesting_depth,
$1,$3,LESS);
}
| expr EQUAL expr
{
$$ = buildrelopterm(app_nesting_depth,
$1,$3,EQ);
}
| expr NOTEQUAL expr
{
$$ = buildrelopterm(app_nesting_depth,
$1,$3,NOTEQ);
}
| expr '>' expr
{
$$ = buildrelopterm(app_nesting_depth,
$1,$3,MORE);
}
| expr LEQUAL expr
{
$$ = buildrelopterm(app_nesting_depth,
$1,$3,LEQ);
}
| expr MEQUAL expr
{
$$ = buildrelopterm(app_nesting_depth,
$1,$3,MEQ);
}
| expr '+' expr
{
$$ = buildmatterm(app_nesting_depth,
$1,$3,ADD);
}
| expr '-' expr
{
$$ = buildmatterm(app_nesting_depth,
$1,$3,SUB);
}
| expr '*' expr
{
$$ = buildmatterm(app_nesting_depth,
$1,$3,PROD);
}
| expr DIVKW expr
{
$$ = buildmatterm(app_nesting_depth,
$1,$3,DIV);
}
| expr MODKW expr
{
$$ = buildmatterm(app_nesting_depth,
$1,$3,MOD);
}
;
expr0 : TRUEKW
{
$$ = buildtrueterm(app_nesting_depth);
}
| FALSEKW
{
$$ = buildfalseterm(app_nesting_depth);
}
| NUMCONST
{
$$ = buildintterm(app_nesting_depth,$1);
}
| ID
{
if (defined($1))
$$ = buildvarterm(app_nesting_depth,$1);
else
{
signal_error(UNBOUND_VARIABLE);
YYERROR;
}
}
| '(' applist ')'
{
$$ = $2;
}
| '\\'
{
push_local_env();
app_nesting_depth++;
}
pattern
{
app_nesting_depth--;
}
'.' expr
{
pattmp=$3;
$$ =
buildplambdaterm(app_nesting_depth,$3,$6);
free_pattern(pattmp);
pop_local_env();
}
| LETKW ID '='
{
app_nesting_depth++;
}
expr INKW
{
app_nesting_depth--;
push_local_env();
create_variable_binding($2, NULL);
}
expr
{
$$ = buildletinterm(app_nesting_depth,
$2,$5,$8);
pop_local_env();
}
| LETRECKW ID '='
{
push_local_env();
create_variable_binding($2, NULL);
app_nesting_depth++;
}
expr
{
$$ = build_mu_term(--app_nesting_depth,
$2,$5);
pop_local_env();
}
| IFKW expr THENKW expr ELSEKW expr
{
$$ = buildifelseterm(app_nesting_depth,
$2,$4,$6);
}
| list
{
$$ = $1;
}
| NOTKW expr
{
$$ = buildnotterm(app_nesting_depth,
$2);
}
| CONSKW '(' expr ',' expr ')'
{
$$ = buildlist(app_nesting_depth,
$3,$5);
}
| HEADKW '(' expr ')'
{
$$ = buildcarterm(app_nesting_depth,
$3);
}
| TAILKW '(' expr ')'
{
$$ = buildcdrterm(app_nesting_depth,
$3);
}
| TESTNILKW '(' expr ')'
{
$$ = buildtestnil(app_nesting_depth,
$3);
}
;
list : NILKW
{
$$ = buildnillist(app_nesting_depth);
}
| '[' ']'
{
$$ = buildnillist(app_nesting_depth);
}
| '[' exprlist
{
$$ = $2;
}
;
exprlist : expr ']'
{
$$ = buildlist(app_nesting_depth,
$1,NULL);
}
| expr ',' exprlist
{
$$ = buildlist(app_nesting_depth,
$1,$3);
}
| expr '|' expr ']'
{
$$ = buildlist(app_nesting_depth,
$1,$3);
}
;
applist : expr
| expr ',' comlist
{
$$ = buildlist(app_nesting_depth,
$1,$3);
}
| applist
{
app_nesting_depth++;
}
expr0
{ app_nesting_depth--;
$$ = buildappterm(app_nesting_depth,$1,$3);
}
;
comlist : expr
{
$$=$1;
}
| expr ',' comlist
{
$$ = buildlist(app_nesting_depth,
$1,$3);
}
comlistpat : pattern
{
$$=$1;
}
| pattern ',' comlistpat
{
pattmp=(PATTERN *)malloc(sizeof(PATTERN));
pattmp->term=
buildlist1(app_nesting_depth,
$1->term,$3->term);
pattmp->var_list=
mergevarlist($1->var_list,$3->var_list);
free($1);
free($3);
$$=pattmp;
}
pattern : CONSKW '(' pattern ',' pattern ')'
{
pattmp=(PATTERN *)malloc(sizeof(PATTERN));
pattmp->term=
buildlist1(app_nesting_depth,
$3->term,$5->term);
pattmp->var_list=
mergevarlist($3->var_list,$5->var_list);
free($3);
free($5);
$$=pattmp;
}
| NILKW
{
pattmp=(PATTERN *)malloc(sizeof(PATTERN));
pattmp->term=buildnillist(app_nesting_depth);
pattmp->var_list=NULL;
$$=pattmp;
}
| '(' comlistpat ')'
{
$$=$2;
}
| ID
{
pattmp=(PATTERN *)malloc(sizeof(PATTERN));
pattmp->term=
buildvoidterm(app_nesting_depth);
create_variable_binding($1, NULL);
pattmp->var_list=
makevarlist($1,pattmp->term);
$$=pattmp;
}
term : error EXPRDELIM
{
error_detected = true;
yyerrok;
YYACCEPT;
}
;
%%
/* The following function checks if an identifier has been */
/* previously declared */
static bool defined(st)
STBUCKET *st;
/* pointer to the bucket for the */
/* identifier */
{
return((st->curr_binding) != NULL);
}