3.线性表-cursor

fatal.h

#include <stdio.h>
#include <stdlib.h>

#define Error(Str)        FatalError(Str)
#define FatalError(Str)   fprintf(stderr, "%s\n", Str), exit(1)

cursor.h

typedef int ElementType;
#define SpaceSize 100

#ifndef _Cursor_H
#define _Cursor_H

typedef int PtrToNode;
typedef PtrToNode List;
typedef PtrToNode Position;

void InitializeCursorSpace(void);

List MakeEmpty(List L);
int IsEmpty(const List L);
int IsLast(const Position P, const List L);
Position Find(ElementType X, const List L);
void Delete(ElementType X, List L);
Position FindPrevious(ElementType X, const List L);
void Insert(ElementType X, List L, Position P);
void DeleteList(List L);
Position Header(const List L);
Position First(const List L);
Position Advance(const Position P);
ElementType Retrieve(const Position P);

#endif

cursor.c

#include "cursor.h"
#include <stdlib.h>
#include "fatal.h"

/* Place in the interface file */
struct Node
{
    ElementType Element;
    Position    Next;
};

struct Node CursorSpace[SpaceSize];

static Position CursorAlloc(void)
{
    Position P;

    P = CursorSpace[0].Next;
    CursorSpace[0].Next = CursorSpace[P].Next;

    return P;
}

static void CursorFree(Position P)
{
    CursorSpace[P].Next = CursorSpace[0].Next;
    CursorSpace[0].Next = P;
}

void InitializeCursorSpace(void)
{
    int i;

    for (i = 0; i < SpaceSize; i++)
        CursorSpace[i].Next = i + 1;
    CursorSpace[SpaceSize - 1].Next = 0;
}

List MakeEmpty(List L)
{
    if (L != 0)
        DeleteList(L);
    L = CursorAlloc();
    if (L == 0)
        FatalError("Out of memory!");
    CursorSpace[L].Next = 0;
    return L;
}

/* Return true if L is empty */
int IsEmpty(const List L)
{
    return CursorSpace[L].Next == 0;
}

/* Return true if P is the last position in list L */
/* Parameter L is unused in this implementation */
int IsLast(const Position P, const List L)
{
    return CursorSpace[P].Next == 0;
}

/* Return Position of X in L; 0 if not found */
/* Uses a header node */
Position Find(ElementType X, const List L)
{
    Position P;

    P = CursorSpace[L].Next;
    while (P && CursorSpace[P].Element != X)
        P = CursorSpace[P].Next;

    return P;
}

/* Delete from a list */
/* Assume that the position is legal */
/* Assume use of a header node */
void Delete(ElementType X, List L)
{
    Position P, TmpCell;

    P = FindPrevious(X, L);

    if (!IsLast(P, L))  /* Assumption of header use */
    {                      /* X is found; delete it */
        TmpCell = CursorSpace[P].Next;
        CursorSpace[P].Next = CursorSpace[TmpCell].Next;
        CursorFree(TmpCell);
    }
}

/* If X is not found, then Next field of returned value is 0 */
/* Assumes a header */
Position FindPrevious(ElementType X, const List L)
{
    Position P;

    P = L;
    while (CursorSpace[P].Next &&
        CursorSpace[CursorSpace[P].Next].Element != X)
        P = CursorSpace[P].Next;

    return P;
}

/* Insert (after legal position P) */
/* Header implementation assumed */
/* Parameter L is unused in this implementation */
void Insert(ElementType X, List L, Position P)
{
    Position TmpCell;

    TmpCell = CursorAlloc();
    if (TmpCell == 0)
        FatalError("Out of space!!!");

    CursorSpace[TmpCell].Element = X;
    CursorSpace[TmpCell].Next = CursorSpace[P].Next;
    CursorSpace[P].Next = TmpCell;
}


/* Correct DeleteList algorithm */
void DeleteList(List L)
{
    Position P, Tmp;

    P = CursorSpace[L].Next;  /* Header assumed */
    CursorSpace[L].Next = 0;
    while (P != 0)
    {
        Tmp = CursorSpace[P].Next;
        CursorFree(P);
        P = Tmp;
    }
}

Position Header(const List L)
{
    return L;
}

Position First(const List L)
{
    return CursorSpace[L].Next;
}

Position Advance(const Position P)
{
    return CursorSpace[P].Next;
}

ElementType Retrieve(const Position P)
{
    return CursorSpace[P].Element;
}

testcurs.c

#include <stdio.h>
#include "cursor.h"

void PrintList(const List L)
{
    Position P = Header(L);

    if (IsEmpty(L))
        printf("Empty list\n");
    else
    {
        do
        {
            P = Advance(P);
            printf("%d ", Retrieve(P));
        } while (!IsLast(P, L));
        printf("\n");
    }
}

int main()
{
    List L;
    Position P;
    int i;

    InitializeCursorSpace();
    L = MakeEmpty(0);
    P = Header(L);
    PrintList(L);

    for (i = 0; i < 10; i++)
    {
        Insert(i, L, P);
        PrintList(L);
        P = Advance(P);
    }
    for (i = 0; i < 10; i += 2)
        Delete(i, L);

    for (i = 10; i < 15; i++)
    {
        Insert(i, L, P);
        PrintList(L);
        P = Advance(P);
    }
    
    for (i = 0; i < 10; i++)
        if (Find(i, L) == 0)
            printf("Element %d Find fails\n", i);

    printf("Finished deletions\n");

    PrintList(L);

    DeleteList(L);

    return 0;
}

函数调用关系图（Call graph）