CSC 466 Spring 2017 Assignment:: A6 Basic Type System ---------------------------------------------------------------

Your assignment: Build the basic type system - type set at declaration - consult sym-tab on var usage - build type of expression based on parts - LHS = RHS types should match ** Also make sure vars are declared of course

Note:: we started this in class -- start with the project you already have from /tmp/466T/ic0315.tar.gz that we worked on in class on Wed 3/15

************************************************************* Kinds of changes you may need to make..... - scanner for new symbols/keywords -- regular expressions - parser for expression operators, ... -- grammar rules - symbol table entries -- calling functions - type table for new types -- calling functions - symbol & type table look-up -- the code

*************************************************************

Additions: (make these enhancements to the language/project) floating point literals ** must have . and exactly 2 digits to right -- such as: 7.23 123.45

Error message for double-declared variables

type system rules assignment operator: may only assign int into int bool into bool may assign float into float int into float

math operators: int + int -> int float + float -> float float + int -> float int + float -> float same for * Add - with same rules Add / but result of any division using int and/or float is float

Add ( ) to expressions

Submission: In your CS directory by 8:00am on Tuesday 3/28

* create Type2Lastname as the directory containing your solution - clearly, replace "Lastname" by your name * be sure your makefile works * create a README file explaining - how to run your solution - sample programs to illustrate correctness - clean programs; program with errors; ... * clean the generated files * tar your solution % tar -cf type2lastname.tar Type2Lastname * make sure your tar file is in your home directory and not some other subdirectory - don't make me look for it

Here is the makefile:

go: lex.yy.c w.tab.c gcc w.tab.c lex.yy.c -lfl -ly -o go

lex.yy.c: w.l flex w.l

w.tab.c: w.y bison -dv w.y

clean: rm -f lex.yy.c rm -f w.output rm -f w.tab.h rm -f w.tab.c rm -f go

Here is the lex code:

%{

typedef struct { char thestr[25]; int ival; int ttype; }tstruct ;

#define YYSTYPE tstruct

#include "w.tab.h"

%}

DIGIT [0-9] UC [A-Z] LC [a-z] L [A-Za-z]

%%

START { return tstart;} FINISH { return tfinish;} BEGIN { return tbegin;} END { return tend;} INT { return tint;} FLOAT { return tfloat;} BOOL { return tbool;} PRINT { return tprint;} PRINTLN { return tprintln;} IF { return tif;} WHILE { return twhile;} LT { return tlt;} GT { return tgt;} EQ { return teq;} ":(" { return tfalse;} ":)" { return ttrue;} ":=" { return tassign;}

\"([^"]*)\" { return tstrlit;} {L}+ { return tid; } {DIGIT}+ { return tnum; }

@@.* {} /* comments */

[ \t] /* ignore whitespace */

{}

<> yyterminate(); /* signal end of dialogue */

. return yytext[0];

%%

Here is the yacc code:

%{

#include #include #include

typedef struct { char thestr[25]; int ival; int ttype; }tstruct ;

#define YYSTYPE tstruct

int yylex(); void yyerror( char *s );

#include "symtab.c"

%}

%token tstart %token tfinish %token tbegin %token tend %token tint %token tfloat %token tbool %token tprint %token tprintln %token tif %token twhile %token tlt %token tgt %token teq %token tfalse %token ttrue %token tassign %token tstrlit %token tid %token tnum

%%

p : prog ;

prog : tstart tfinish | tstart DL SL tfinish {printf("Prog ");} ;

DL : DL D {printf("declst ");} | D {printf("declst ");} ;

D : tid Dtail { addtab($1.thestr); addtype($1.thestr, $2.ttype); } ;

Dtail : ',' tid Dtail { addtab($2.thestr); addtype($2.thestr, $3.ttype); $$.ttype = $3.ttype; } | ':' type ';' {$$.ttype = $2.ttype;} ;

type: tint {$$.ttype = 10;} | tfloat {$$.ttype = 20;} | tbool {$$.ttype = 30;} ;

SL : SL S {printf("stmtlst ");} | S {printf("stmtlst ");} ;

S : tprint tstrlit ';' {printf("print lit "); } | tprint tid ';' { printf("print id "); if ( intab($2.thestr) ) printf("%s is declared %d ", $2.thestr, @2.first_line); else printf("UNDECLARED:: %s ", $2.thestr); } | tprintln ';' | tid tassign expr ';' { printf("assign "); if ( intab($1.thestr) ) printf("%s is declared ", $1.thestr); else printf("UNDECLARED:: %s ", $1.thestr);

$1.ttype = gettype($1.thestr); if ($1.ttype > 0 ) { if ($1.ttype == $3.ttype) ; else { printf("Incompatible ASSIGN types %d %d ", $1.ttype, $3.ttype); } } else yyerror("Type Error :::");

} | error ';' {printf("error in statement ");} ;

expr : expr '+' term { if ($1.ttype == 10 && $3.ttype == 10) $$.ttype = 10; else if ($1.ttype == 20 && $3.ttype == 20) $$.ttype = 20; else $$.ttype = -1; } | term { $$.ttype = $1.ttype; } ;

term : term '*' factor { if ($1.ttype == 10 && $3.ttype == 10) $$.ttype = 10; else if ($1.ttype == 20 && $3.ttype == 20) $$.ttype = 20; else $$.ttype = -1; } | factor { $$.ttype = $1.ttype; } ;

factor : tid { if ( intab($1.thestr) ) printf("%s is declared ", $1.thestr); else printf("UNDECLARED:: %s ", $1.thestr); $$.ttype = gettype($1.thestr); if ($$.ttype > 0 ) ; else yyerror("Type Error :::"); } | tnum {$$.ttype = 10;} | ttrue {$$.ttype = 30;} | tfalse {$$.ttype = 30;} ;

%%

int main() { yyparse (); printf("--------------------- "); showtab(); }

void yyerror(char *s) /* Called by yyparse on error */ { printf ("\terror: %s ", s); printf ("ERROR: %s at line %d ", s, 123); }

Here is the sym.c code

struct stelem { char sname[25]; int stype; }; typedef struct stelem entry;

entry symtab[100]; int nsym;

void addtab( char *s) { nsym++; strcpy( symtab[nsym].sname, s); symtab[nsym].stype = -1; }

void showtab() { int i; for (i = 1; i <= nsym; ++i) printf("%d: %s %d ", i, symtab[i].sname, symtab[i].stype); }

int intab( char *s) { int i; for ( i = 1; i <= nsym; ++i) { if ( strcmp(symtab[i].sname, s) == 0) return 1; } return 0;

}

int addtype( char *s, int t) { int i, loc = -1; for ( i = 1; i <= nsym; ++i) { if ( strcmp(symtab[i].sname, s) == 0) loc = i; } if (loc > 0) { printf("Set type %s to %d ", s, t); symtab[loc].stype = t; } else { printf("Unable to set type %s to %d ", s, t); } }

int gettype( char *s) { int t = -1; int i, loc = -1; for ( i = 1; i <= nsym; ++i) { if ( strcmp(symtab[i].sname, s) == 0) loc = i; } if (loc > 0) { t = symtab[loc].stype; printf("Get type for %s to %d ", s, t); } if (loc <= 0) printf("gettype var %s not found ", s); else if (t < 0) printf("gettype var %s has bad type %d ", s, t); else printf("gettype var %s has type %d ", s, t);

return t; }