Mercurial > cgi-bin > hgwebdir.cgi > VMS > C_Libraries > DynArray
view DynArray.h @ 32:958dcb7754ca
PR branch -- added comments about safe usage
| author | Sean Halle <seanhalle@yahoo.com> |
|---|---|
| date | Fri, 08 Mar 2013 05:37:45 -0800 |
| parents | e6b21c2350d1 |
| children | c6e1805505c9 |
line source
1 /*
2 * File: Vector.h
3 * Author: Me
4 *
5 * Created on May 14, 2010, 3:08 PM
6 */
8 #ifndef _DYNARRAY_H
9 #define _DYNARRAY_H
11 #include "PR_impl/PR_primitive_data_types.h"
12 #include "PR_impl/Services_Offered_by_PR/Memory_Handling/vmalloc.h"
16 /*WARNING: Passing a DynArray as a param is dangerous if add to the DynArray
17 * inside the function called! After adding or other operation that might
18 * change the size, must re-read the addr of the chunk of memory that is the
19 * array, via the DynArrayInfo.
20 *Here's why: An array variable is a location, either on the stack
21 * or in a field of a struct, whose contents is an addr. That addr is of the
22 * first location of a chunk of locations. The DynArray works by changing
23 * the chunk of locations, then modifying the contents of the original
24 * array variable. It overwrites the addr of the old chunk of locations
25 * with the addr of the new chunk.
26 *But when the array variable is passed as a parameter, such as
27 * in this: "foo( myDynArray )", then there are now two locations that hold
28 * the addr of the same chunk of locations. So when a call is made that
29 * adds to the DynArray, and inside the DynArray expands, it only updates
30 * the original location with the new addr. Hence, the function will begin
31 * overwriting memory past the end of the old chunk, because it still has
32 * the pointer to the old chunk of locations.
33 *
34 *A dynamic array is accessed same as any other array. However, must use
35 * dyn array calls, defined in here, in order to add or increase the size.
36 * Must re-read the original array variable after any size-changing calls.
37 *To pass a DynArray as a parameter to a function, can only pass the
38 * DynArrayInfo, then inside the function, to read the addr of the first
39 * location in the chunk of locations that is the array, do this:
40 * "localArrayCopy = *(myDynArrayInfo->addrOfPtrToArray). After that, can
41 * treat localArrayCopy as a normal array, as long as don't make any calls
42 * that add or otherwise could increase the size of the array. If do make
43 * such a call, then re-copy the array via the above. Can then use the
44 * copy up until another add to the array.
45 *
46 */
47 typedef struct
48 {
49 void ***addrOfPtrToArray; //addr of var that is array of ptrs == triple *
50 int32 numInArray; //num entries added
51 int32 sizeOfArray; //num elems alloc'd
52 int32 sizeOfElem; //num bytes in one elem of array -- used in 2nd version
53 }
54 PrivDynArrayInfo;
56 PrivDynArrayInfo *
57 makePrivDynArrayInfoFrom( void ***addrOfPtrToArray, int32 sizeOfArray );
59 PrivDynArrayInfo *
60 makePrivDynArrayOfSize( void ***addrOfPtrToArray, int32 sizeOfArray );
62 PrivDynArrayInfo *
63 makePrivDynArrayOfSize_Ext( void ***addrOfPtrToArray, int32 sizeOfArray );
65 int32
66 addToDynArray( void *value, PrivDynArrayInfo *info );
68 void
69 makeHighestDynArrayIndexBe( PrivDynArrayInfo *info, int32 highestIndex );
71 void
72 makeHighestDynArrayIndexBeAtLeast(PrivDynArrayInfo *info,int32 highestIndex);
74 void
75 increaseSizeOfDynArrayTo( PrivDynArrayInfo *info, int32 newSize );
77 typedef void (*FreeFnPtr) ( void * ); //fn has to cast void * to whatever
79 void
80 freeDynArrayDeep( PrivDynArrayInfo *info, FreeFnPtr freeFnPtr );
82 void
83 freeDynArrayFlat( PrivDynArrayInfo *info );
86 typedef void (*DynArrayFnPtr) ( void * ); //fn has to cast void *
88 void
89 forAllInDynArrayDo( PrivDynArrayInfo *info, DynArrayFnPtr fnPtr );
91 #endif /* _DYNARRAY_H */