itcl_util.c

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/*
 * ------------------------------------------------------------------------
 *      PACKAGE:  [incr Tcl]
 *  DESCRIPTION:  Object-Oriented Extensions to Tcl
 *
 *  [incr Tcl] provides object-oriented extensions to Tcl, much as
 *  C++ provides object-oriented extensions to C.  It provides a means
 *  of encapsulating related procedures together with their shared data
 *  in a local namespace that is hidden from the outside world.  It
 *  promotes code re-use through inheritance.  More than anything else,
 *  it encourages better organization of Tcl applications through the
 *  object-oriented paradigm, leading to code that is easier to
 *  understand and maintain.
 *
 *  This segment provides common utility functions used throughout
 *  the other [incr Tcl] source files.
 *
 * ========================================================================
 *  AUTHOR:  Michael J. McLennan
 *           Bell Labs Innovations for Lucent Technologies
 *           [e-mail]
 *           http://www.tcltk.com/itcl
 *
 *     RCS:  $Id: itcl_util.c 144 2003-02-05 10:56:26Z mdejong $
 * ========================================================================
 *           Copyright (c) 1993-1998  Lucent Technologies, Inc.
 * ------------------------------------------------------------------------
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 */
#include "itclInt.h"
#include "tclCompile.h"

/*
 *  POOL OF LIST ELEMENTS FOR LINKED LIST
 */
static Itcl_ListElem *listPool = NULL;
static int listPoolLen = 0;

#define ITCL_VALID_LIST 0x01face10  /* magic bit pattern for validation */
#define ITCL_LIST_POOL_SIZE 200     /* max number of elements in listPool */


/*
 *  These records are used to keep track of reference-counted data
 *  for Itcl_PreserveData and Itcl_ReleaseData.
 */
typedef struct ItclPreservedData {
    ClientData data;                /* reference to data */
    int usage;                      /* number of active uses */
    Tcl_FreeProc *fproc;            /* procedure used to free data */
} ItclPreservedData;

static Tcl_HashTable *ItclPreservedList = NULL;


/*
 *  This structure is used to take a snapshot of the interpreter
 *  state in Itcl_SaveInterpState.  You can snapshot the state,
 *  execute a command, and then back up to the result or the
 *  error that was previously in progress.
 */
typedef struct InterpState {
    int validate;                   /* validation stamp */
    int status;                     /* return code status */
    Tcl_Obj *objResult;             /* result object */
    char *errorInfo;                /* contents of errorInfo variable */
    char *errorCode;                /* contents of errorCode variable */
} InterpState;

#define TCL_STATE_VALID 0x01233210  /* magic bit pattern for validation */



/*
 * ------------------------------------------------------------------------
 *  Itcl_Assert()
 *
 *  Called whenever an assert() test fails.  Prints a diagnostic
 *  message and abruptly exits.
 * ------------------------------------------------------------------------
 */

void
Itcl_Assert(testExpr, fileName, lineNumber)
    char *testExpr;   /* string representing test expression */
    char *fileName;   /* file name containing this call */
    int lineNumber;   /* line number containing this call */
{
#ifndef NDEBUG
    fprintf(stderr, "Assertion failed: \"%s\" (line %d of %s)",
        testExpr, lineNumber, fileName);
    abort();
#endif
}



/*
 * ------------------------------------------------------------------------
 *  Itcl_InitStack()
 *
 *  Initializes a stack structure, allocating a certain amount of memory
 *  for the stack and setting the stack length to zero.
 * ------------------------------------------------------------------------
 */
void
Itcl_InitStack(stack)
    Itcl_Stack *stack;     /* stack to be initialized */
{
    stack->values = stack->space;
    stack->max = sizeof(stack->space)/sizeof(ClientData);
    stack->len = 0;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_DeleteStack()
 *
 *  Destroys a stack structure, freeing any memory that may have been
 *  allocated to represent it.
 * ------------------------------------------------------------------------
 */
void
Itcl_DeleteStack(stack)
    Itcl_Stack *stack;     /* stack to be deleted */
{
    /*
     *  If memory was explicitly allocated (instead of using the
     *  built-in buffer) then free it.
     */
    if (stack->values != stack->space) {
        ckfree((char*)stack->values);
    }
    stack->values = NULL;
    stack->len = stack->max = 0;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_PushStack()
 *
 *  Pushes a piece of client data onto the top of the given stack.
 *  If the stack is not large enough, it is automatically resized.
 * ------------------------------------------------------------------------
 */
void
Itcl_PushStack(cdata,stack)
    ClientData cdata;      /* data to be pushed onto stack */
    Itcl_Stack *stack;     /* stack */
{
    ClientData *newStack;

    if (stack->len+1 >= stack->max) {
        stack->max = 2*stack->max;
        newStack = (ClientData*)
            ckalloc((unsigned)(stack->max*sizeof(ClientData)));

        if (stack->values) {
            memcpy((char*)newStack, (char*)stack->values,
                (size_t)(stack->len*sizeof(ClientData)));

            if (stack->values != stack->space)
                ckfree((char*)stack->values);
        }
        stack->values = newStack;
    }
    stack->values[stack->len++] = cdata;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_PopStack()
 *
 *  Pops a bit of client data from the top of the given stack.
 * ------------------------------------------------------------------------
 */
ClientData
Itcl_PopStack(stack)
    Itcl_Stack *stack;  /* stack to be manipulated */
{
    if (stack->values && (stack->len > 0)) {
        stack->len--;
        return stack->values[stack->len];
    }
    return (ClientData)NULL;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_PeekStack()
 *
 *  Gets the current value from the top of the given stack.
 * ------------------------------------------------------------------------
 */
ClientData
Itcl_PeekStack(stack)
    Itcl_Stack *stack;  /* stack to be examined */
{
    if (stack->values && (stack->len > 0)) {
        return stack->values[stack->len-1];
    }
    return (ClientData)NULL;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_GetStackValue()
 *
 *  Gets a value at some index within the stack.  Index "0" is the
 *  first value pushed onto the stack.
 * ------------------------------------------------------------------------
 */
ClientData
Itcl_GetStackValue(stack,pos)
    Itcl_Stack *stack;  /* stack to be examined */
    int pos;            /* get value at this index */
{
    if (stack->values && (stack->len > 0)) {
        assert(pos < stack->len);
        return stack->values[pos];
    }
    return (ClientData)NULL;
}


/*
 * ------------------------------------------------------------------------
 *  Itcl_InitList()
 *
 *  Initializes a linked list structure, setting the list to the empty
 *  state.
 * ------------------------------------------------------------------------
 */
void
Itcl_InitList(listPtr)
    Itcl_List *listPtr;     /* list to be initialized */
{
    listPtr->validate = ITCL_VALID_LIST;
    listPtr->num      = 0;
    listPtr->head     = NULL;
    listPtr->tail     = NULL;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_DeleteList()
 *
 *  Destroys a linked list structure, deleting all of its elements and
 *  setting it to an empty state.  If the elements have memory associated
 *  with them, this memory must be freed before deleting the list or it
 *  will be lost.
 * ------------------------------------------------------------------------
 */
void
Itcl_DeleteList(listPtr)
    Itcl_List *listPtr;     /* list to be deleted */
{
    Itcl_ListElem *elemPtr;

    assert(listPtr->validate == ITCL_VALID_LIST);

    elemPtr = listPtr->head;
    while (elemPtr) {
        elemPtr = Itcl_DeleteListElem(elemPtr);
    }
    listPtr->validate = 0;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_CreateListElem()
 *
 *  Low-level routined used by procedures like Itcl_InsertList() and
 *  Itcl_AppendList() to create new list elements.  If elements are
 *  available, one is taken from the list element pool.  Otherwise,
 *  a new one is allocated.
 * ------------------------------------------------------------------------
 */
Itcl_ListElem*
Itcl_CreateListElem(listPtr)
    Itcl_List *listPtr;     /* list that will contain this new element */
{
    Itcl_ListElem *elemPtr;

    if (listPoolLen > 0) {
        elemPtr = listPool;
        listPool = elemPtr->next;
        --listPoolLen;
    }
    else {
        elemPtr = (Itcl_ListElem*)ckalloc((unsigned)sizeof(Itcl_ListElem));
    }
    elemPtr->owner = listPtr;
    elemPtr->value = NULL;
    elemPtr->next  = NULL;
    elemPtr->prev  = NULL;

    return elemPtr;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_DeleteListElem()
 *
 *  Destroys a single element in a linked list, returning it to a pool of
 *  elements that can be later reused.  Returns a pointer to the next
 *  element in the list.
 * ------------------------------------------------------------------------
 */
Itcl_ListElem*
Itcl_DeleteListElem(elemPtr)
    Itcl_ListElem *elemPtr;     /* list element to be deleted */
{
    Itcl_List *listPtr;
    Itcl_ListElem *nextPtr;

    nextPtr = elemPtr->next;

    if (elemPtr->prev) {
        elemPtr->prev->next = elemPtr->next;
    }
    if (elemPtr->next) {
        elemPtr->next->prev = elemPtr->prev;
    }

    listPtr = elemPtr->owner;
    if (elemPtr == listPtr->head)
        listPtr->head = elemPtr->next;
    if (elemPtr == listPtr->tail)
        listPtr->tail = elemPtr->prev;
    --listPtr->num;

    if (listPoolLen < ITCL_LIST_POOL_SIZE) {
        elemPtr->next = listPool;
        listPool = elemPtr;
        ++listPoolLen;
    }
    else {
        ckfree((char*)elemPtr);
    }
    return nextPtr;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_InsertList()
 *
 *  Creates a new list element containing the given value and returns
 *  a pointer to it.  The element is inserted at the beginning of the
 *  specified list.
 * ------------------------------------------------------------------------
 */
Itcl_ListElem*
Itcl_InsertList(listPtr,val)
    Itcl_List *listPtr;     /* list being modified */
    ClientData val;         /* value associated with new element */
{
    Itcl_ListElem *elemPtr;
    assert(listPtr->validate == ITCL_VALID_LIST);

    elemPtr = Itcl_CreateListElem(listPtr);

    elemPtr->value = val;
    elemPtr->next  = listPtr->head;
    elemPtr->prev  = NULL;
    if (listPtr->head) {
        listPtr->head->prev = elemPtr;
    }
    listPtr->head  = elemPtr;
    if (listPtr->tail == NULL) {
        listPtr->tail = elemPtr;
    }
    ++listPtr->num;

    return elemPtr;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_InsertListElem()
 *
 *  Creates a new list element containing the given value and returns
 *  a pointer to it.  The element is inserted in the list just before
 *  the specified element.
 * ------------------------------------------------------------------------
 */
Itcl_ListElem*
Itcl_InsertListElem(pos,val)
    Itcl_ListElem *pos;     /* insert just before this element */
    ClientData val;         /* value associated with new element */
{
    Itcl_List *listPtr;
    Itcl_ListElem *elemPtr;

    listPtr = pos->owner;
    assert(listPtr->validate == ITCL_VALID_LIST);
    assert(pos != NULL);

    elemPtr = Itcl_CreateListElem(listPtr);
    elemPtr->value = val;

    elemPtr->prev = pos->prev;
    if (elemPtr->prev) {
        elemPtr->prev->next = elemPtr;
    }
    elemPtr->next = pos;
    pos->prev     = elemPtr;

    if (listPtr->head == pos) {
        listPtr->head = elemPtr;
    }
    if (listPtr->tail == NULL) {
        listPtr->tail = elemPtr;
    }
    ++listPtr->num;

    return elemPtr;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_AppendList()
 *
 *  Creates a new list element containing the given value and returns
 *  a pointer to it.  The element is appended at the end of the
 *  specified list.
 * ------------------------------------------------------------------------
 */
Itcl_ListElem*
Itcl_AppendList(listPtr,val)
    Itcl_List *listPtr;     /* list being modified */
    ClientData val;         /* value associated with new element */
{
    Itcl_ListElem *elemPtr;
    assert(listPtr->validate == ITCL_VALID_LIST);

    elemPtr = Itcl_CreateListElem(listPtr);

    elemPtr->value = val;
    elemPtr->prev  = listPtr->tail;
    elemPtr->next  = NULL;
    if (listPtr->tail) {
        listPtr->tail->next = elemPtr;
    }
    listPtr->tail  = elemPtr;
    if (listPtr->head == NULL) {
        listPtr->head = elemPtr;
    }
    ++listPtr->num;

    return elemPtr;
}

/*
 * ------------------------------------------------------------------------
 *  Itcl_AppendListElem()
 *
 *  Creates a new list element containing the given value and returns
 *  a pointer to it.  The element is inserted in the list just after
 *  the specified element.
 * ------------------------------------------------------------------------