1

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Stack

ADT Stack

Implementazione in Linguaggio C

Corso di Linguaggi e Traduttori 1AA 2004-05

2

2

Stack

StackLIFO : Last Input First Output

IN OUT

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Stack

Specifica Algebrica dell’ADTSTACK

type Stack [Item] uses Item, Booleansyntax

NEWSTACK : → Stack

PUSH : Item x Stack → StackISEMPTY : Stack → BooleanPOP : Stack → Stack

TOP : Stack → ItemREPLACE : Item x Stack → Stack

semantics...

end Stack.

4

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Stack

Specifica Algebrica dell’ADTSTACKsemanticsfor all stk in Stack; el, elm in Item;ISEMPTY(NEWSTACK) = true

ISEMPTY(PUSH(elm,stk)) = falsePOP(NEWSTACK) = errorPOP(PUSH(elm, stk)) = stk

TOP(NEWSTACK) = errorTOP(PUSH(elm, stk)) = elmREPLACE(elm,NEWSTACK) = errorREPLACE(el,PUSH(elm, stk)) = PUSH(el,stk)

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Stack

STACK: NEWSTACK

Vista Grafica

STACK newSTACK( ) ;Interfaccia C

NEWSTACK : → StackSintassi

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Stack

STACK: PUSH

Vista Grafica

STACK push(Item , Stack ) ;Interfaccia C

PUSH : Item x Stack → StackSintassi

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Stack

STACK: ISEMPTY

Vista Grafica

Boolean isempty(Stack ) ;Interfaccia C

ISEMPTY : Stack → BooleanSintassi

False True

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Stack

STACK: POP

Vista Grafica

STACK pop(Stack ) ;Interfaccia C

POP : Stack → StackSintassi

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9

Stack

STACK: TOP

Vista Grafica

STACK top(Stack ) ;Interfaccia C

TOP : Stack → ItemSintassi

value

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Stack

STACK: REPLACE

Vista Grafica

STACK replace(Item , Stack ) ;Interfaccia C

REPLACE : Item x Stack → StackSintassi

1

2

11

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Stack

Stack – Interfacce C (file stack.h)#ifndef __STACK

#define __STACK

#include "utils.h"

STACK newSTACK() ; // instance creation (for dynamic allocation)

STACK push(Item, STACK) ; // push an Item into a STACK

STACK replace(Item, STACK) ; // replace the top of a STACK

Boolean isEmpty(STACK) ; // check whether the STACK is empty or not

Item top(STACK) ; // return the top of a STACK

STACK pop(STACK) ; // pop the top from a STACK

STACK initSTACK(STACK) ; // instance initialization (for static alloc.)

void deleteSTACK(STACK) ; // instance deletion

void displaySTACK(char *, STACK) ; // display the contents of a STACK

#endif

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Stack

ADT Stack

Implementazionestruttura statica

Corso di Linguaggi e Traduttori 1AA 2004-05

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Stack

…

Stack – Implementazione Statica

struct stack{

int index ; Item buffer[MAXSTK];

} ;} index=i

MAXSTK-1

0

1

…

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Stack

…

Stack – Implementazione Statica

index=i

MAXSTK-1

typedef struct stack * STACK;

0

1

…

15

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Stack

Stack – Implementazione statica#ifndef __STATIC_STACK#define __STATIC_STACK

/* TYPES AND CONSTANTS */

#define MAXSTK 100#include "stack_item.h“

/* STATIC STACK: STRUCTURE */

struct stack {int index ; /* current top */Item buffer[MAXSTK] ; /* data storage */

} ;typedef struct stack * STACK ;

#include “stack.h“ /* STACK INTERFACE */#endif

16

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Stack

Stack – Implementazione dinewSTACKSTACK newSTACK() { // no need for instance creation, here }

STACK initSTACK(STACK S) {S->index = -1 ; return S ;

}

MAXSTK-1

0

1

…

index = -1

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Stack

i2

Stack – Implementazione di pushSTACK push(Item item, STACK S) {if ( (S->index) >= MAXSTK - 1 )

ERROR("Stack is full!");else{S->index)++ ; S->buffer[S->index] = item ;

}return S ;

}

index=i

MAXSTK-1

i1

…0

…

index=i+1

MAXSTK-1

…0

…push(Itemi2, STACK s)

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Stack

Stack – Implementazione diisEmptyBoolean isEmpty(STACK S) {ALERT("Executing isEmpty");return (Boolean) ( S->index < 0 );

}

MAXSTK-1

0

1

…

index = -1

index≠0

MAXSTK-1

i1

…0

…

False True

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Stack

Stack – Implementazione di topItem top(STACK S) {ALERT("Executing top: index = %d",S->index);if ( S->index < 0 ) {ERROR("Stack is empty!"); return 0.0;

}else return S->buffer[S->index] ;}

index=i

MAXSTK-1

i1

…0

…top(STACK s) i1

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Stack

Stack – Implementazione di popSTACK pop(STACK S) {ALERT("Executing pop: index = %d",S->index);if ( S->index < 0 )

ERROR("Stack is empty!");else S->index-- ;return S ;

}

index=i

MAXSTK-1

i1

…0

…

pop(STACK s)

MAXSTK-1

0

…

i3index=i-1

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Stack

Stack – Implementazione direplaceSTACK replace(Item item, STACK S) {if ( S->index < 0 )

ERROR("Stack is empty!“);else S->buffer[S->index] = item ;return S ;

}

index=i

MAXSTK-1

i1

…0

…replace(Item i2, STACK s)

index=i

MAXSTK-1

i2

…0

…

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Stack

Stack – Verifica Semantica delle Primitive#include <stdio.h>#include "auto_stack.h"/* STACK TESTING */// automatic allocation for STACK instances// no need for instance creation and deletion#include "test_stack_suite_1.c“

int main() {Item item ;struct stack myStack ;STACK s ;s = initSTACK(&myStack) ;// instead of NewSTACKtest_suite_1(s) ;

return 0 ;

}

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Stack

Stack – Verifica Semantica delle Primitivevoid test_suite_1(STACK s) {

int i ; Item item ;/* isEmpty(newStack) = true */printf("isEmpty(newStack) = true ? ");(isEmpty(s)) ? printf("OK\n") : printf("NO\n");/* isEmpty(push(anItem,S)) = false */printf("isEmpty(push(anItem,S)) = false ? ");push( 0.0, s);(!isEmpty(s)) ? printf("OK\n") : printf("NO\n");/* pop(push(anItem,S)) = S */ printf("pop(push(anItem,S)) = S ? ") ;push(1.0, s); push((2.0, s);pop(s) ;(top(s) == 1.0) ? printf("OK\n") : printf("NO\n");

}

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Stack

ADT Stack

Implementazionestruttura dinamica

Corso di Linguaggi e Traduttori 1AA 2004-05

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Stack

Stack – ImplementazioneDinamicatypedef struct node {

Item item ;struct node * next ;

} Node ; } item

next

typedef typedef Node * STACK ; item

next

item

next

item

next

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Stack

Stack – Implementazionedinamica

#ifndef __DYN_STACK#define __DYN_STACK

/* DYNAMIC STACK: STRUCTURE */#include "stack_item.h"

typedef struct node {Item item ;struct node * next ;

} Node ;

typedef Node * STACK ;

/* --- STACK INTERFACE --- */#include "stack.h"

#endif

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Stack

Stack – Implementazione dinewSTACKSTACK newSTACK(void){return NULL ;

}

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Stack

Stack – Implementazione di pushSTACK push(Item item, STACK S){Node * ptr ;ptr = (Node *) malloc(sizeof(struct node)) ;if ( ptr == NULL ) goto push_exception;ptr->item = item ; ptr->next = S ;return (STACK) ptr ;

push_exception:exit(-1) ; // unrecoverable error

}

i1

next

next

push(Itemi2, STACK s) i1

next

next

i2

next

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Stack

Stack – Implementazione diisEmptyBoolean isEmpty(STACK S){return (Boolean) ( S == NULL ) ;

}

False

i1

next

next

i2

next

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Stack

Stack – Implementazione di topItem top(STACK S) {if ( S == NULL ) goto top_exception ;return S->item ;

top_exception:ERROR("Stack is Empty!") ;return theDummyItem ;

}

top(STACK s) i1i1

next

next

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Stack

Stack – Implementazione di popSTACK pop(STACK S) {Node * next ;if ( S == NULL ) goto pop_exception ;next = S->next ; free(S) ;return next ;

pop_exception:ERROR("Stack is Empty!") ;return S ;

}

pop(STACK s)i1

next

next

i2

next i1

next

next

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Stack

Stack – Implementazione direplaceSTACK replace(Item item, STACK S) {if ( S == NULL ) goto replace_exception ;S->item = item ;return S;

replace_exception:ERROR("Stack is Empty!") ;return S ;

}

replace(Item i2, STACK s)

i1

next

next

i2

next

next

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Stack

Stack – Verifica Semantica delle Primitive#include <stdio.h>#include "dyn_stack.h"#include "test_stack_suite_1.c"

/* DYNAMIC STACK: TESTING */int main(int argc, char ** argv) {int i ; Item item ;STACK s = newSTACK() ;test_suite_1(s) ;deleteSTACK(s) ;return 0 ;

}/* end main */

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Stack

Stack – Verifica Semantica delle Primitive/* STACK TESTING: TEST SUITE #1 */void test_suite_1(STACK s) {int i ; Item item ;/* isEmpty(newStack) = true */printf("isEmpty(newStack) = true ? ") ;( isEmpty(s) ) ? printf("OK\n") : printf("NO\n") ;/* isEmpty(push(anItem,S)) = false */printf("isEmpty(push(anItem,S)) = false ? ") ;s = push((double) 0, s) ;( ! isEmpty(s) ) ? printf("OK\n") : printf("NO\n") ;/* pop(newStack) = error */s = pop(s) ;printf("pop(newStack) = error ? ") ;s = pop(s) ;/* pop(push(anItem,S)) = S */printf("pop(push(anItem,S)) = S ? ") ;…

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Stack

Stack – Verifica Semantica delle Primitive

…s = push((double) 1, s) ;s = push((double) 2, s) ; s = pop(s) ;( top(s) == 1.0 ) ? printf("OK\n") : printf("NO\n");/* top(newStack) = error */s = pop(s) ;printf("top(newStack) = error ? ") ;item = top(s) ;/* top(push(anItem,S)) = anItem */printf("top(push(anItem,S)) = anItem ? ") ;s = push((double) 11, s) ;s = push((double) 22, s);( top(s) == 22.0 ) ? printf("OK\n"): printf("NO\n");…

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Stack

Stack – Verifica Semantica delle Primitive

…/*replace(anItem1,push(anItem,S))=push(anItem1,S)*/printf("replace(anItem1,push(anItem,S)) =

push(anItem1,S) ? ") ;s = push((double) 1, s) ;s = push((double) 2, s) ;replace((double) 3, s) ; item = top(s) ;s = pop(s);( ( top(s) == 1.0 ) && ( item == 3.0 ) ) ? printf("OK\n") : printf("NO\n") ;

}/* end main */