gscheme/scheme.y

%{
#import "SchemeTypes.h"

#define YYSTYPE id

YYSTYPE yyresult;
int yyinputitem;

extern int yysofar;
extern NSMutableArray *positions;
%}

%token LPAREN
%token LVECTPAREN
%token RPAREN

%token DEFINE
%token SET
%token LAMBDA

%token BEGINTOK

%token AND
%token OR

%token CASE
%token COND
%token ELSE
%token ARROW

%token CALLCC

%token APPLY

%token IF

%token LET
%token LETSTAR
%token LETREC

%token DOT

%token INTEGER
%token CHAR
%token BOOLEAN
%token DOUBLE
%token SYMBOL
%token STRING

%token QUOTECHAR
%token QUOTE

%% 

top: /* empty */ {
    yyresult = 
        $$ = [NSNull null];
}
| topitem top {
    yyresult = 
        $$ = [Triple newTag:FORM_TOP Arg1:$1 Arg2:$2];
    yyinputitem++;
}
;

topitem: LPAREN DEFINE SYMBOL form RPAREN {
    NSValue *entry = 
        [NSValue valueWithRange:NSMakeRange(yysofar, 0)];

    $$ = [Triple newTag:FORM_DEFINE1 Arg1:$3 Arg2:$4];

    [positions addObject:entry];
}
|  LPAREN DEFINE nonemptysymlist sequence RPAREN { 
    NSValue *entry = 
        [NSValue valueWithRange:NSMakeRange(yysofar, 0)];

    $$ = [Triple newTag:FORM_DEFINE2 Arg1:$3 Arg2:$4];

    [positions addObject:entry];
} 
|  form {
    NSValue *entry = 
        [NSValue valueWithRange:NSMakeRange(yysofar, 0)];

    $$ = $1;

    [positions addObject:entry];
}
;

sequence: form {
    $$ = [Pair newCar:$1 Cdr:[NSNull null]];
}
| form sequence {
    $$ = [Pair newCar:$1 Cdr:$2];
}
;

revsequence: form {
    $$ = [Pair newCar:$1 Cdr:[NSNull null]];
}
| revsequence form {
    $$ = [Pair newCar:$2 Cdr:$1];
}
;

form: INTEGER {
    $$ = $1;
}
| CHAR {
    $$ = $1;
}
| BOOLEAN {
    $$ = $1;
}
| DOUBLE {
    $$ = $1;
}
| SYMBOL {
    $$ = $1;
}
| STRING {
    $$ = $1;
}
| list {
    $$ = $1;
}
| vector {
    $$ = $1;
}
| lambda {
    $$ = $1;
}
| if {
    $$ = $1;
}
| let {
    $$ = $1;
}
| letstar {
    $$ = $1;
}
| letrec {
    $$ = $1;
}
| quote {
    $$ = $1;
}
| apply {
    $$ = $1;
}
| set {
    $$ = $1;
}
| begin {
    $$ = $1;
}
| and {
    $$ = $1;
}
| or {
    $$ = $1;
}
| case {
    $$ = $1;
}
| cond {
    $$ = $1;
}
| callcc {
    $$ = $1;
}

callcc: LPAREN CALLCC form RPAREN {
    $$ = [Triple newTag:FORM_CALLCC Arg1:$3];
}

singlecase: LPAREN LPAREN sequence RPAREN sequence RPAREN {
    $$ = [Pair newCar:$3 Cdr:$5];
}

singlecond: LPAREN form RPAREN {
    $$ = [Triple newTag:FORM_SCOND1 Arg1:$2];
}
| LPAREN form sequence RPAREN {
    $$ = [Triple newTag:FORM_SCOND2 Arg1:$2 Arg2:$3];
}
| LPAREN form ARROW form RPAREN {
    $$ = [Triple newTag:FORM_SCOND3 Arg1:$2 Arg2:$4];
}

elsecasecond:  LPAREN ELSE sequence RPAREN {
    $$ = [Pair newCar:[NSNull null] Cdr:$3];
}

cases: singlecase {
    $$ = [Pair newCar:$1 Cdr:[NSNull null]];
}
| cases singlecase {
    $$ = [Pair newCar:$2 Cdr:$1];
}
;

conditions: singlecond {
    $$ = [Pair newCar:$1 Cdr:[NSNull null]];
}
| conditions singlecond {
    $$ = [Pair newCar:$2 Cdr:$1];
}
;

case: LPAREN CASE form cases RPAREN {
    $$ = [Triple newTag:FORM_CASE Arg1:$3 Arg2:$4];
}
|  LPAREN CASE form cases elsecasecond RPAREN {
    $$ = [Triple newTag:FORM_CASE Arg1:$3 
                 Arg2:[Pair newCar:$5 Cdr:$4]];
}

cond: LPAREN COND conditions RPAREN {
    $$ = [Triple newTag:FORM_COND Arg1:$3];
}
|  LPAREN COND conditions elsecasecond RPAREN {
    $$ = [Triple newTag:FORM_COND Arg1:[Pair newCar:$4 Cdr:$3]];
}

and: LPAREN AND revsequence RPAREN { 
    $$ = [Triple newTag:FORM_AND Arg1:$3];
}
| LPAREN AND RPAREN { 
    $$ = [Triple newTag:FORM_AND Arg1:[NSNull null]];
}

or: LPAREN OR revsequence RPAREN { 
    $$ = [Triple newTag:FORM_OR Arg1:$3];
}
| LPAREN OR RPAREN { 
    $$ = [Triple newTag:FORM_OR Arg1:[NSNull null]];
}

begin: LPAREN BEGINTOK sequence RPAREN { 
    $$ = [Triple newTag:FORM_BEGIN Arg1:$3];
}

set: LPAREN SET SYMBOL form RPAREN { 
    $$ = [Triple newTag:FORM_SET Arg1:$3 Arg2:$4];
}

apply: LPAREN APPLY form form RPAREN {
    $$ = [Triple newTag:FORM_APPLY Arg1:$3 Arg2:$4];
}

if: LPAREN IF form form RPAREN {
    $$ = [Triple newTag:FORM_IF1 Arg1:$3 Arg2:$4];
}
| LPAREN IF form form form RPAREN {
    $$ = [Triple newTag:FORM_IF2 Arg1:$3 Arg2:$4 Arg3:$5];
} 

lambda: LPAREN LAMBDA SYMBOL sequence RPAREN {
    $$ = [Triple newTag:FORM_LAMBDA1 Arg1:$3 Arg2:$4];
}
| LPAREN LAMBDA symlist sequence RPAREN {
    $$ = [Triple newTag:FORM_LAMBDA2 Arg1:$3 Arg2:$4];
} 

quote: QUOTECHAR form {
    $$ = [Triple newTag:FORM_QUOTE Arg1:$2];
}
| LPAREN QUOTE form RPAREN {
    $$ = [Triple newTag:FORM_QUOTE Arg1:$3];
}


singlebinding: LPAREN SYMBOL form RPAREN {
    $$ = [Triple newTag:FORM_BINDING Arg1:$2 Arg2:$3];
}

listofbindings: singlebinding {
    $$ = [Pair newCar:$1 Cdr:[NSNull null]];
}
| singlebinding listofbindings {
    $$ = [Pair newCar:$1 Cdr:$2];
}

let: LPAREN LET LPAREN listofbindings RPAREN sequence RPAREN {
    $$ = [Triple newTag:FORM_LET Arg1:$4 Arg2:$6];
}

letstar: LPAREN LETSTAR LPAREN listofbindings RPAREN sequence RPAREN {
    $$ = [Triple newTag:FORM_LETSTAR Arg1:$4 Arg2:$6];
}

letrec: LPAREN LETREC LPAREN listofbindings RPAREN sequence RPAREN {
    $$ = [Triple newTag:FORM_LETREC Arg1:$4 Arg2:$6];
}

emptylist: LPAREN RPAREN { 
    $$ = [NSNull null];
}
;

nonemptylistdata:  form {
    $$ = [Pair newCar:$1 Cdr:[NSNull null]];
}
| form DOT form {
    $$ = [Pair newCar:$1 Cdr:$3];
}
| form nonemptylistdata {
    $$ = [Pair newCar:$1 Cdr:$2];
}
;

nonemptyvectdata:  form {
    $$ = [Pair newCar:$1 Cdr:[NSNull null]];
}
| form nonemptyvectdata {
    $$ = [Pair newCar:$1 Cdr:$2];
}
;

nonemptylist: LPAREN nonemptylistdata RPAREN {
    $$ = $2;
}
;

list: nonemptylist {
    $$ = $1;
}
| emptylist {
    $$ = $1;
}
;

vector: LVECTPAREN nonemptyvectdata RPAREN {
    $$ = [Vector newFromList:$2];
}
| LVECTPAREN RPAREN {
    $$ = [Vector newFromList:(Pair *)[NSNull null]];
}
;

nonemptysymlistdata: SYMBOL {
    $$ = [Pair newCar:$1 Cdr:[NSNull null]];
}
| SYMBOL DOT SYMBOL {
    $$ = [Pair newCar:$1 Cdr:$3];
}
| SYMBOL nonemptysymlistdata {
    $$ = [Pair newCar:$1 Cdr:$2];
}
;

nonemptysymlist: LPAREN nonemptysymlistdata RPAREN {
    $$ = $2;
}
;

symlist: nonemptysymlist {
    $$ = $1;
}
| emptylist {
    $$ = $1;
}
;

%%