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[micropolis] / src / tk / tktxbtre.c

/* 
 * tkTextBTree.c --
 *
 *      This file contains code that manages the B-tree representation
 *      of text for Tk's text widget.  The B-tree holds both the text
 *      and tag information related to the text.
 *
 * Copyright 1992 Regents of the University of California
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that this copyright
 * notice appears in all copies.  The University of California
 * makes no representations about the suitability of this
 * software for any purpose.  It is provided "as is" without
 * express or implied warranty.
 */

#ifndef lint
static char rcsid[] = "$Header: /user6/ouster/wish/RCS/tkTextBTree.c,v 1.16 92/08/17 09:13:58 ouster Exp $ SPRITE (Berkeley)";
#endif /* not lint */

#include "tkint.h"
#include "tkconfig.h"
#include "tktext.h"


/*
 * The data structure below keeps summary information about one tag as part
 * of the tag information in a node.
 */

typedef struct Summary {
    TkTextTag *tagPtr;                  /* Handle for tag. */
    int toggleCount;                    /* Number of transitions into or
                                         * out of this tag that occur in
                                         * the subtree rooted at this node. */
    struct Summary *nextPtr;            /* Next in list of all tags for same
                                         * node, or NULL if at end of list. */
} Summary;

/*
 * The data structure below defines a node in the B-tree representing
 * all of the lines in a text widget.
 */

typedef struct Node {
    struct Node *parentPtr;             /* Pointer to parent node, or NULL if
                                         * this is the root. */
    struct Node *nextPtr;               /* Next in list of children of the
                                         * same parent node, or NULL for end
                                         * of list. */
    Summary *summaryPtr;                /* First in malloc-ed list of info
                                         * about tags in this subtree (NULL if
                                         * no tag info in the subtree). */
    int level;                          /* Level of this node in the B-tree.
                                         * 0 refers to the bottom of the tree
                                         * (children are lines, not nodes). */
    union {                             /* First in linked list of children. */
        struct Node *nodePtr;           /* Used if level > 0. */
        TkTextLine *linePtr;            /* Used if level == 0. */
    } children;
    int numChildren;                    /* Number of children of this node. */
    int numLines;                       /* Total number of lines (leaves) in
                                         * the subtree rooted here. */
} Node;

/*
 * Upper and lower bounds on how many children a node may have:
 * rebalance when either of these limits is exceeded.  MAX_CHILDREN
 * should be twice MIN_CHILDREN and MIN_CHILDREN must be >= 2.
 */

#define MAX_CHILDREN 12
#define MIN_CHILDREN 6

/*
 * The data structure below defines an entire B-tree.
 */

typedef struct BTree {
    Node *rootPtr;                      /* Pointer to root of B-tree. */
} BTree;

/*
 * The structure below is used to pass information between
 * TkBTreeGetTags and IncCount:
 */

typedef struct TagInfo {
    int numTags;                        /* Number of tags for which there
                                         * is currently information in
                                         * tags and counts. */
    int arraySize;                      /* Number of entries allocated for
                                         * tags and counts. */
    TkTextTag **tagPtrs;                /* Array of tags seen so far.
                                         * Malloc-ed. */
    int *counts;                        /* Toggle count (so far) for each
                                         * entry in tags.  Malloc-ed. */
} TagInfo;

/*
 * Macro to compute the space needed for a line that holds n non-null
 * characters:
 */

#define LINE_SIZE(n) ((unsigned) (sizeof(TkTextLine) - 3 + (n)))

/*
 * Variable that indicates whether to enable consistency checks for
 * debugging.
 */

int tkBTreeDebug = 0;

/*
 * Forward declarations for procedures defined in this file:
 */

static void             AddToggleToLine _ANSI_ARGS_((TkTextLine *linePtr,
                            int index, TkTextTag *tagPtr));
static void             ChangeNodeToggleCount _ANSI_ARGS_((Node *nodePtr,
                            TkTextTag *tagPtr, int delta));
static void             CheckNodeConsistency _ANSI_ARGS_((Node *nodePtr));
static void             DeleteSummaries _ANSI_ARGS_((Summary *tagPtr));
static void             DestroyNode _ANSI_ARGS_((Node *nodePtr));
static void             IncCount _ANSI_ARGS_((TkTextTag *tagPtr, int inc,
                            TagInfo *tagInfoPtr));
static void             Rebalance _ANSI_ARGS_((BTree *treePtr, Node *nodePtr));
static void             RecomputeNodeCounts _ANSI_ARGS_((Node *nodePtr));
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeCreate --
 *
 *      This procedure is called to create a new text B-tree.
 *
 * Results:
 *      The return value is a pointer to a new B-tree containing
 *      one line with nothing but a newline character.
 *
 * Side effects:
 *      Memory is allocated and initialized.
 *
 *----------------------------------------------------------------------
 */

TkTextBTree
TkBTreeCreate()
{
    register BTree *treePtr;
    register Node *rootPtr;
    register TkTextLine *linePtr;

    rootPtr = (Node *) ckalloc(sizeof(Node));
    linePtr = (TkTextLine *) ckalloc(LINE_SIZE(1));
    rootPtr->parentPtr = NULL;
    rootPtr->nextPtr = NULL;
    rootPtr->summaryPtr = NULL;
    rootPtr->level = 0;
    rootPtr->children.linePtr = linePtr;
    rootPtr->numChildren = 1;
    rootPtr->numLines = 1;

    linePtr->parentPtr = rootPtr;
    linePtr->nextPtr = NULL;
    linePtr->annotPtr = NULL;
    linePtr->numBytes = 1;
    linePtr->bytes[0] = '\n';
    linePtr->bytes[1] = 0;

    treePtr = (BTree *) ckalloc(sizeof(BTree));
    treePtr->rootPtr = rootPtr;

    return (TkTextBTree) treePtr;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeDestroy --
 *
 *      Delete a B-tree, recycling all of the storage it contains.
 *
 * Results:
 *      The tree given by treePtr is deleted.  TreePtr should never
 *      again be used.
 *
 * Side effects:
 *      Memory is freed.
 *
 *----------------------------------------------------------------------
 */

void
TkBTreeDestroy(tree)
    TkTextBTree tree;                   /* Pointer to tree to delete. */ 
{
    BTree *treePtr = (BTree *) tree;

    DestroyNode(treePtr->rootPtr);
    ckfree((char *) treePtr);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * DestroyNode --
 *
 *      This is a recursive utility procedure used during the deletion
 *      of a B-tree.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      All the storage for nodePtr and its descendants is freed.
 *
 *----------------------------------------------------------------------
 */

static void
DestroyNode(nodePtr)
    register Node *nodePtr;
{
    if (nodePtr->level == 0) {
        register TkTextLine *curPtr, *nextLinePtr;
        register TkAnnotation *annotPtr, *nextAnnotPtr;

        for (curPtr = nodePtr->children.linePtr; curPtr != NULL; ) {
            nextLinePtr = curPtr->nextPtr;
            for (annotPtr = curPtr->annotPtr; annotPtr != NULL; ) {
                nextAnnotPtr = annotPtr->nextPtr;
                if (annotPtr->type == TK_ANNOT_TOGGLE) {
                    ckfree((char *) annotPtr);
                }
                annotPtr = nextAnnotPtr;
            }
            ckfree((char *) curPtr);
            curPtr = nextLinePtr;
        }
    } else {
        register Node *curPtr, *nextPtr;

        for (curPtr = nodePtr->children.nodePtr; curPtr != NULL; ) {
            nextPtr = curPtr->nextPtr;
            DestroyNode(curPtr);
            curPtr = nextPtr;
        }
    }
    DeleteSummaries(nodePtr->summaryPtr);
    ckfree((char *) nodePtr);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * DeleteSummaries --
 *
 *      Free up all of the memory in a list of tag summaries associated
 *      with a node.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Storage is released.
 *
 *----------------------------------------------------------------------
 */

static void
DeleteSummaries(summaryPtr)
    register Summary *summaryPtr;       /* First in list of node's tag
                                         * summaries. */
{
    register Summary *nextPtr;
    while (summaryPtr != NULL) {
        nextPtr = summaryPtr->nextPtr;
        ckfree((char *) summaryPtr);
        summaryPtr = nextPtr;
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeInsertChars --
 *
 *      Insert characters at a given position in a B-tree.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      NumBytes characters are added to the B-tree at the given
 *      character position.  This can cause the structure of the
 *      B-tree to change.
 *
 *----------------------------------------------------------------------
 */

void
TkBTreeInsertChars(tree, linePtr, ch, string)
    TkTextBTree tree;                   /* B-tree in which to insert. */
    register TkTextLine *linePtr;       /* Pointer to line in which to
                                         * insert. */
    int ch;                             /* Index of character before which
                                         * to insert.  Must not be after
                                         * last character in line.*/
    char *string;                       /* Pointer to bytes to insert (may
                                         * contain newlines, must be null-
                                         * terminated). */
{
    BTree *treePtr = (BTree *) tree;
    register Node *nodePtr;
    register TkAnnotation *annotPtr;
    TkTextLine *prevPtr;
    int newChunkLength;                 /* # chars in current line being
                                         * inserted. */
    register char *eol;                 /* Pointer to last character in
                                         * current line being inserted. */
    int changeToLineCount;              /* Counts change to total number of
                                         * lines in file. */
    TkAnnotation *afterPtr;             /* List of annotations that occur
                                         * at or after the insertion point
                                         * in the line of the insertion. */
    int prefixLength, suffixLength, totalLength;
    register TkTextLine *newPtr;

    /*
     * Find the line just before the one where the insertion will occur
     * but with the same parent node (if there is one).  This is needed
     * so we can replace the insertion line with a new one.  Remove this
     * line from the list for its parent, since it's going to be discarded
     * when we're all done).
     */

    nodePtr = linePtr->parentPtr;
    prevPtr = nodePtr->children.linePtr;
    if (prevPtr == linePtr) {
        prevPtr = NULL;
        nodePtr->children.linePtr = linePtr->nextPtr;
    } else {
        for ( ; prevPtr->nextPtr != linePtr;  prevPtr = prevPtr->nextPtr) {
            /* Empty loop body. */
        }
        prevPtr->nextPtr = linePtr->nextPtr;
    }

    /*
     * Break up the annotations for the insertion line into two pieces:
     * those before the insertion point, and those at or after the insertion
     * point.
     */

    afterPtr = NULL;
    if ((linePtr->annotPtr != NULL) && (linePtr->annotPtr->ch >= ch)) {
        afterPtr = linePtr->annotPtr;
        linePtr->annotPtr = NULL;
    } else {
        for (annotPtr = linePtr->annotPtr; annotPtr != NULL;
                annotPtr = annotPtr->nextPtr) {
            if ((annotPtr->nextPtr != NULL)
                    && (annotPtr->nextPtr->ch >= ch)) {
                afterPtr = annotPtr->nextPtr;
                annotPtr->nextPtr = NULL;
                break;
            }
        }
    }

    /*
     * Chop the string up into lines and insert each line individually.
     */

    changeToLineCount = -1;
    prefixLength = ch;
    while (1) {
        for (newChunkLength = 0, eol = string; *eol != 0; eol++) {
            newChunkLength++;
            if (*eol == '\n') {
                break;
            }
        }

        /*
         * Create a new line consisting of up to three parts: a prefix
         * from linePtr, some material from string, and a suffix from
         * linePtr.
         */

        if ((newChunkLength == 0) || (*eol != '\n')) {
            suffixLength = linePtr->numBytes - ch;
        } else {
            suffixLength = 0;
        }
        totalLength = prefixLength + newChunkLength + suffixLength;
        newPtr = (TkTextLine *) ckalloc(LINE_SIZE(totalLength));
        newPtr->parentPtr = nodePtr;
        if (prevPtr == NULL) {
            newPtr->nextPtr = nodePtr->children.linePtr;
            nodePtr->children.linePtr = newPtr;
        } else {
            newPtr->nextPtr = prevPtr->nextPtr;
            prevPtr->nextPtr = newPtr;
        }
        if (linePtr->annotPtr != NULL) {
            newPtr->annotPtr = linePtr->annotPtr;
            for (annotPtr = newPtr->annotPtr; annotPtr != NULL;
                    annotPtr = annotPtr->nextPtr) {
                annotPtr->linePtr = newPtr;
            }
            linePtr->annotPtr = NULL;
        } else {
            newPtr->annotPtr = NULL;
        }
        newPtr->numBytes = totalLength;
        if (prefixLength != 0) {
            memcpy((VOID *) newPtr->bytes, (VOID *) linePtr->bytes,
                    prefixLength);
        }
        if (newChunkLength != 0) {
            memcpy((VOID *) (newPtr->bytes + prefixLength), (VOID *) string,
                    newChunkLength);
        }
        if (suffixLength != 0) {
            memcpy((VOID *) (newPtr->bytes + prefixLength + newChunkLength),
                    (VOID *) (linePtr->bytes + ch), suffixLength);
        }
        newPtr->bytes[totalLength] = 0;
        changeToLineCount += 1;

        /*
         * Quit after the suffix has been output (there is always at least
         * one character of suffix: the newline).  Before jumping out of the
         * loop, put back the annotations that pertain to the suffix.
         * Careful!  If no newlines were inserted, there could already be
         * annotations at the beginning of the line;  add back to the end.
         */

        if (suffixLength != 0) {
            if (newPtr->annotPtr == NULL) {
                newPtr->annotPtr = afterPtr;
            } else {
                for (annotPtr = newPtr->annotPtr; annotPtr->nextPtr != NULL;
                        annotPtr = annotPtr->nextPtr) {
                    /* Empty loop body. */
                }
                annotPtr->nextPtr = afterPtr;
            }
            for (annotPtr = afterPtr; annotPtr != NULL;
                    annotPtr = annotPtr->nextPtr) {
                annotPtr->linePtr = newPtr;
                annotPtr->ch += prefixLength+newChunkLength-ch;
            }
            break;
        }

        /*
         * Advance to insert the next line chunk.
         */

        string += newChunkLength;
        prefixLength = 0;
        prevPtr = newPtr;
    }

    /*
     * Increment the line counts in all the parent nodes of the insertion
     * point, then rebalance the tree if necessary.
     */

    for ( ; nodePtr != NULL; nodePtr = nodePtr->parentPtr) {
        nodePtr->numLines += changeToLineCount;
    }
    nodePtr = linePtr->parentPtr;
    nodePtr->numChildren += changeToLineCount;
    if (nodePtr->numChildren > MAX_CHILDREN) {
        Rebalance(treePtr, nodePtr);
    }

    ckfree((char *) linePtr);
    if (tkBTreeDebug) {
        TkBTreeCheck(tree);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeDeleteChars --
 *
 *      Delete a range of characters from a B-tree.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Information is deleted from the B-tree.  This can cause the
 *      internal structure of the B-tree to change.  Note: the two
 *      lines given by line1Ptr and line2Ptr will be replaced with
 *      a single line containing the undeleted parts of the original
 *      lines.  This could potentially result in an empty line;
 *      normally the caller should adjust the deletion range to prevent
 *      this sort of behavior.
 *
 *----------------------------------------------------------------------
 */

void
TkBTreeDeleteChars(tree, line1Ptr, ch1, line2Ptr, ch2)
    TkTextBTree tree;                   /* B-tree in which to delete. */
    register TkTextLine *line1Ptr;      /* Line containing first character
                                         * to delete. */
    int ch1;                            /* Index within linePtr1 of first
                                         * character to delete. */
    register TkTextLine *line2Ptr;      /* Line containing character just
                                         * after last one to delete. */
    int ch2;                            /* Index within linePtr2 of character
                                         * just after last one to delete. */
{
    BTree *treePtr = (BTree *) tree;
    TkTextLine *linePtr, *nextPtr, *prevLinePtr;
    Node *nodePtr, *parentPtr, *nextNodePtr;
    TkAnnotation *annotPtr, *annotPtr2;
    int ch;
    int linesDeleted;                   /* Counts lines deleted from current
                                         * level-0 node. */

    /*
     * Work through the tree deleting all of the lines between line1Ptr
     * and line2Ptr (but don't delete line1Ptr or line2Ptr yet).  Also
     * delete any nodes in the B-tree that become empty because of
     * this process.
     */

    linePtr = line1Ptr->nextPtr;
    nodePtr = line1Ptr->parentPtr;
    if (line1Ptr == line2Ptr) {
        goto middleLinesDeleted;
    }
    while (1) {

        /*
         * Delete all relevant lines within the same level-0 node.
         */

        linesDeleted = 0;
        while ((linePtr != line2Ptr) && (linePtr != NULL)) {
            /*
             * Move any annotations in this line to the end of the
             * deletion range.  If both the starting and ending toggle
             * for a tagged range get moved, they'll cancel each other
             * automatically and be dropped, which is the right behavior.
             */

            for (annotPtr = linePtr->annotPtr; annotPtr != NULL;
                    annotPtr = annotPtr2) {
                if (annotPtr->type == TK_ANNOT_TOGGLE) {
                    AddToggleToLine(line2Ptr, ch2, annotPtr->info.tagPtr);
                    ChangeNodeToggleCount(nodePtr, annotPtr->info.tagPtr, -1);
                    annotPtr2 = annotPtr->nextPtr;
                    ckfree((char *) annotPtr);
                } else {
                    annotPtr2 = annotPtr->nextPtr;
                    TkBTreeRemoveAnnotation(annotPtr);
                    annotPtr->linePtr = line2Ptr;
                    annotPtr->ch = ch2;
                    TkBTreeAddAnnotation(annotPtr);
                }
            }
            nextPtr = linePtr->nextPtr;
            ckfree((char *) linePtr);
            linesDeleted++;
            linePtr = nextPtr;
        }
        if (nodePtr == line1Ptr->parentPtr) {
            line1Ptr->nextPtr = linePtr;
        } else {
            nodePtr->children.linePtr = linePtr;
        }
        for (parentPtr = nodePtr; parentPtr != NULL;
                parentPtr = parentPtr->parentPtr) {
            parentPtr->numLines -= linesDeleted;
        }
        nodePtr->numChildren -= linesDeleted;
        if (linePtr == line2Ptr) {
            break;
        }

        /*
         * Find the next level-0 node to visit, and its first line (but
         * remember the current node so we can come back to delete it if
         * it's empty).
         */

        nextNodePtr = nodePtr;
        while (nextNodePtr->nextPtr == NULL) {
            nextNodePtr = nextNodePtr->parentPtr;
        }
        nextNodePtr = nextNodePtr->nextPtr;
        while (nextNodePtr->level > 0) {
            nextNodePtr = nextNodePtr->children.nodePtr;
        }
        linePtr = nextNodePtr->children.linePtr;

        /*
         * Now go back to the node we just left and delete it if
         * it's empty, along with any of its ancestors that are
         * empty.  It may seem funny to go back like this, but it's
         * simpler to find the next place to visit before modifying
         * the tree structure.
         */

        while (nodePtr->numChildren == 0) {
            parentPtr = nodePtr->parentPtr;
            if (parentPtr->children.nodePtr == nodePtr) {
                parentPtr->children.nodePtr = nodePtr->nextPtr;
            } else {
                Node *prevPtr;

                for (prevPtr = parentPtr->children.nodePtr;
                        prevPtr->nextPtr != nodePtr;
                        prevPtr = prevPtr->nextPtr) {
                }
                prevPtr->nextPtr = nodePtr->nextPtr;
            }
            parentPtr->numChildren--;
            DeleteSummaries(nodePtr->summaryPtr);
            ckfree((char *) nodePtr);
            nodePtr = parentPtr;
        }
        nodePtr = nextNodePtr;
    }

    /*
     * Make a new line that consists of the first part of the first
     * line of the deletion range and the last part of the last line
     * of the deletion range.
     */

    middleLinesDeleted:
    nodePtr = line1Ptr->parentPtr;
    linePtr = (TkTextLine *) ckalloc(LINE_SIZE(ch1 + line2Ptr->numBytes - ch2));
    linePtr->parentPtr = nodePtr;
    linePtr->nextPtr = line1Ptr->nextPtr;
    linePtr->annotPtr = NULL;
    linePtr->numBytes = ch1 + line2Ptr->numBytes - ch2;
    if (ch1 != 0) {
        memcpy((VOID *) linePtr->bytes, (VOID *) line1Ptr->bytes, ch1);
    }
    strcpy(linePtr->bytes + ch1, line2Ptr->bytes + ch2);

    /*
     * Process the annotations for the starting and ending lines.  Enter
     * a new annotation on linePtr (the joined line) for each of these
     * annotations, then delete the originals.  The code below is a little
     * tricky (e.g. the "break" in the first loop) to handle the case where
     * the starting and ending lines are the same.
     */

    for (annotPtr = line1Ptr->annotPtr; annotPtr != NULL;
            annotPtr = line1Ptr->annotPtr) {
        if (annotPtr->ch <= ch1) {
            ch = annotPtr->ch;
        } else {
            if (line1Ptr == line2Ptr) {
                break;
            }
            ch = ch1;
        }
        line1Ptr->annotPtr = annotPtr->nextPtr;
        if (annotPtr->type == TK_ANNOT_TOGGLE) {
            AddToggleToLine(linePtr, ch, annotPtr->info.tagPtr);
            ChangeNodeToggleCount(line1Ptr->parentPtr, annotPtr->info.tagPtr,
                    -1);
            ckfree((char *) annotPtr);
        } else {
            annotPtr->linePtr = linePtr;
            annotPtr->ch = ch;
            TkBTreeAddAnnotation(annotPtr);
        }
    }
    for (annotPtr = line2Ptr->annotPtr; annotPtr != NULL;
            annotPtr = line2Ptr->annotPtr) {
        if (annotPtr->ch >= ch2) {
            ch = annotPtr->ch - ch2 + ch1;
        } else {
            ch = ch1;
        }
        line2Ptr->annotPtr = annotPtr->nextPtr;
        if (annotPtr->type == TK_ANNOT_TOGGLE) {
            AddToggleToLine(linePtr, ch, annotPtr->info.tagPtr);
            ChangeNodeToggleCount(line2Ptr->parentPtr, annotPtr->info.tagPtr,
                    -1);
            ckfree((char *) annotPtr);
        } else {
            annotPtr->linePtr = linePtr;
            annotPtr->ch = ch;
            TkBTreeAddAnnotation(annotPtr);
        }
    }

    /*
     * Delete the original starting and stopping lines (don't forget
     * that the annotations have already been deleted) and insert the
     * new line in place of line1Ptr.
     */

    nodePtr = line1Ptr->parentPtr;
    if (nodePtr->children.linePtr == line1Ptr) {
        nodePtr->children.linePtr = linePtr;
    } else {
        for (prevLinePtr = nodePtr->children.linePtr;
                prevLinePtr->nextPtr != line1Ptr;
                prevLinePtr = prevLinePtr->nextPtr) {
            /* Empty loop body. */
        }
        prevLinePtr->nextPtr = linePtr;
    }
    ckfree((char *) line1Ptr);
    nodePtr = line2Ptr->parentPtr;
    if (line2Ptr != line1Ptr) {
        if (nodePtr->children.linePtr == line2Ptr) {
            nodePtr->children.linePtr = line2Ptr->nextPtr;
        } else {
            for (prevLinePtr = nodePtr->children.linePtr;
                    prevLinePtr->nextPtr != line2Ptr;
                    prevLinePtr = prevLinePtr->nextPtr) {
                /* Empty loop body. */
            }
            prevLinePtr->nextPtr = line2Ptr->nextPtr;
        }
        ckfree((char *) line2Ptr);
        for (parentPtr = nodePtr; parentPtr != NULL;
                parentPtr = parentPtr->parentPtr) {
            parentPtr->numLines--;
        }
        nodePtr->numChildren--;
    }

    /*
     * Rebalance the tree, starting from each of the endpoints of the
     * deletion range.  This code is a tricky, because the act of
     * rebalancing the parent of one endpoint can cause the parent of
     * the other endpoint to be reallocated.  The only thing it's safe
     * to hold onto is a pointer to a line.  Thus, rebalance line2Ptr's
     * parent first, then use linePtr find the second parent to rebalance
     * second.  
     */

    if (nodePtr != linePtr->parentPtr) {
        Rebalance(treePtr, nodePtr);
    }
    Rebalance(treePtr, linePtr->parentPtr);
    if (tkBTreeDebug) {
        TkBTreeCheck(tree);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeTag --
 *
 *      Turn a given tag on or off for a given range of characters in
 *      a B-tree of text.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The given tag is added to the given range of characters
 *      in the tree or removed from all those characters, depending
 *      on the "add" argument.
 *
 *----------------------------------------------------------------------
 */

void
TkBTreeTag(tree, line1, ch1, line2, ch2, tagPtr, add)
    TkTextBTree tree;                   /* B-tree in which to add tag
                                         * information. */
    int line1, ch1;                     /* Position of first character to
                                         * tag. */
    int line2, ch2;                     /* Position of character just after
                                         * last one to tag. */
    TkTextTag *tagPtr;                  /* Tag to associate with the range
                                         * of characters. */
    int add;                            /* One means add tag to the given
                                         * range of characters;  zero means
                                         * remove the tag from the range. */
{
    BTree *treePtr = (BTree *) tree;
    register TkTextLine *line1Ptr, *line2Ptr;
    TkTextSearch search;
    int oldState;

    /*
     * Find the lines containing the first and last characters to be tagged,
     * and adjust the starting and stopping locations if they don't already
     * point within lines.  If the range would have started or stopped at the
     * end of a line, round it up to the beginning of the next line (right
     * now this restriction keeps the final newline from being tagged).
     */

    if (line1 < 0) {
        line1 = 0;
        ch1 = 0;
    }
    line1Ptr = TkBTreeFindLine(tree, line1);
    if (line1Ptr == NULL) {
        return;
    }
    if (ch1 >= line1Ptr->numBytes) {
        TkTextLine *nextLinePtr;

        nextLinePtr = TkBTreeNextLine(line1Ptr);
        if (nextLinePtr == NULL) {
            return;
        } else {
            line1Ptr = nextLinePtr;
            line1++;
            ch1 = 0;
        }
    }
    if (line2 < 0) {
        return;
    }
    line2Ptr = TkBTreeFindLine(tree, line2);
    if (line2Ptr == NULL) {
        line2Ptr = TkBTreeFindLine(tree, treePtr->rootPtr->numLines-1);
        ch2 = line2Ptr->numBytes-1;
    }
    if (ch2 >= line2Ptr->numBytes) {
        TkTextLine *nextLinePtr;

        nextLinePtr = TkBTreeNextLine(line2Ptr);
        if (nextLinePtr == NULL) {
            ch2 = line2Ptr->numBytes-1;
        } else {
            line2Ptr = nextLinePtr;
            line2++;
            ch2 = 0;
        }
    }

    /*
     * See if the tag is already present or absent at the start of the
     * range.  If the state doesn't already match what we want then add
     * a toggle there.
     */

    oldState = TkBTreeCharTagged(line1Ptr, ch1, tagPtr);
    if ((add != 0) ^ oldState) {
        AddToggleToLine(line1Ptr, ch1, tagPtr);
    }

    /*
     * Scan the range of characters covered by the change and delete
     * any existing tag transitions except those on the first and
     * last characters.  Keep track of whether the old state just before
     * the last character (not including any tags on it) is what we
     * want now;  if not, then add a tag toggle there.
     */

    TkBTreeStartSearch(tree, line1, ch1+1, line2, ch2, tagPtr, &search);
    while (TkBTreeNextTag(&search)) {
        if ((search.linePtr == line2Ptr) && (search.ch1 == ch2)) {
            break;
        }
        oldState ^= 1;
        AddToggleToLine(search.linePtr, search.ch1, tagPtr);
    }
    if ((add != 0) ^ oldState) {
        AddToggleToLine(line2Ptr, ch2, tagPtr);
    }

    if (tkBTreeDebug) {
        TkBTreeCheck(tree);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeAddAnnotation --
 *
 *      Given a filled in annotation, this procedure links it into
 *      a B-tree structure so that it will track changes to the B-tree.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      AnnotPtr will be linked into its tree.  Note:  the storage for
 *      annotPtr is assumed to have been malloc'ed by the caller.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
void
TkBTreeAddAnnotation(annotPtr)
    TkAnnotation *annotPtr;     /* Pointer to annotation.  The caller must
                                 * have filled in all the fields except the
                                 * "nextPtr" field.  The type should NOT be
                                 * TK_ANNOT_TOGGLE;  these annotations are
                                 * managed by the TkBTreeTag procedure. */
{
    register TkAnnotation *annotPtr2, *prevPtr;

    for (prevPtr = NULL, annotPtr2 = annotPtr->linePtr->annotPtr;
            annotPtr2 != NULL;
            prevPtr = annotPtr2, annotPtr2 = annotPtr2->nextPtr) {
        if (annotPtr2->ch > annotPtr->ch) {
            break;
        }
    }
    if (prevPtr == NULL) {
        annotPtr->nextPtr = annotPtr->linePtr->annotPtr;
        annotPtr->linePtr->annotPtr = annotPtr;
    } else {
        annotPtr->nextPtr = prevPtr->nextPtr;
        prevPtr->nextPtr = annotPtr;
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeRemoveAnnotation --
 *
 *      This procedure unlinks an annotation from a B-tree so that
 *      the annotation will no longer be managed by the B-tree code.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      AnnotPtr will be unlinked from its tree.  Note:  it is up to the
 *      caller to free the storage for annotPtr, if that is desired.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
void
TkBTreeRemoveAnnotation(annotPtr)
    TkAnnotation *annotPtr;     /* Pointer to annotation, which must
                                 * have been linked into tree by a previous
                                 * call to TkBTreeAddAnnotation. */
{
    register TkAnnotation *prevPtr;

    if (annotPtr->linePtr->annotPtr == annotPtr) {
        annotPtr->linePtr->annotPtr = annotPtr->nextPtr;
    } else {
        for (prevPtr = annotPtr->linePtr->annotPtr;
/* BUG: fixed by dhopkins, prevPtr was null!
                prevPtr->nextPtr != annotPtr;
*/
                (prevPtr != NULL) && (prevPtr->nextPtr != annotPtr);
                prevPtr = prevPtr->nextPtr) {
            /* Empty loop body. */
        }
        if (prevPtr != NULL) { /* Bullet proofing by dhopkins */
            prevPtr->nextPtr = annotPtr->nextPtr;
        }
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeFindLine --
 *
 *      Find a particular line in a B-tree based on its line number.
 *
 * Results:
 *      The return value is a pointer to the line structure for the
 *      line whose index is "line", or NULL if no such line exists.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

TkTextLine *
TkBTreeFindLine(tree, line)
    TkTextBTree tree;                   /* B-tree in which to find line. */
    int line;                           /* Index of desired line. */
{
    BTree *treePtr = (BTree *) tree;
    register Node *nodePtr;
    register TkTextLine *linePtr;
    int linesLeft;

    nodePtr = treePtr->rootPtr;
    linesLeft = line;
    if ((line < 0) || (line >= nodePtr->numLines)) {
        return NULL;
    }

    /*
     * Work down through levels of the tree until a node is found at
     * level 0.
     */

    while (nodePtr->level != 0) {
        for (nodePtr = nodePtr->children.nodePtr;
                nodePtr->numLines <= linesLeft;
                nodePtr = nodePtr->nextPtr) {
            if (nodePtr == NULL) {
                panic("TkBTreeFindLine ran out of nodes");
            }
            linesLeft -= nodePtr->numLines;
        }
    }

    /*
     * Work through the lines attached to the level-0 node.
     */

    for (linePtr = nodePtr->children.linePtr; linesLeft > 0;
            linePtr = linePtr->nextPtr) {
        if (linePtr == NULL) {
            panic("TkBTreeFindLine ran out of lines");
        }
        linesLeft -= 1;
    }
    return linePtr;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeNextLine --
 *
 *      Given an existing line in a B-tree, this procedure locates the
 *      next line in the B-tree.  This procedure is used for scanning
 *      through the B-tree.
 *
 * Results:
 *      The return value is a pointer to the line that immediately
 *      follows linePtr, or NULL if there is no such line.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

TkTextLine *
TkBTreeNextLine(linePtr)
    register TkTextLine *linePtr;       /* Pointer to existing line in
                                         * B-tree. */
{
    register Node *nodePtr;

    if (linePtr->nextPtr != NULL) {
        return linePtr->nextPtr;
    }

    /*
     * This was the last line associated with the particular parent node.
     * Search up the tree for the next node, then search down from that
     * node to find the first line,
     */

    for (nodePtr = linePtr->parentPtr; ; nodePtr = nodePtr->parentPtr) {
        if (nodePtr->nextPtr != NULL) {
            nodePtr = nodePtr->nextPtr;
            break;
        }
        if (nodePtr->parentPtr == NULL) {
            return (TkTextLine *) NULL;
        }
    }
    while (nodePtr->level > 0) {
        nodePtr = nodePtr->children.nodePtr;
    }
    return nodePtr->children.linePtr;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeLineIndex --
 *
 *      Given a pointer to a line in a B-tree, return the numerical
 *      index of that line.
 *
 * Results:
 *      The result is the index of linePtr within the tree, where 0
 *      corresponds to the first line in the tree.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
TkBTreeLineIndex(linePtr)
    TkTextLine *linePtr;                /* Pointer to existing line in
                                         * B-tree. */
{
    register TkTextLine *linePtr2;
    register Node *nodePtr, *parentPtr, *nodePtr2;
    int index;

    /*
     * First count how many lines precede this one in its level-0
     * node.
     */

    nodePtr = linePtr->parentPtr;
    index = 0;
    for (linePtr2 = nodePtr->children.linePtr; linePtr2 != linePtr;
            linePtr2 = linePtr2->nextPtr) {
        if (linePtr2 == NULL) {
            panic("TkBTreeLineIndex couldn't find line");
        }
        index += 1;
    }

    /*
     * Now work up through the levels of the tree one at a time,
     * counting how many lines are in nodes preceding the current
     * node.
     */

    for (parentPtr = nodePtr->parentPtr ; parentPtr != NULL;
            nodePtr = parentPtr, parentPtr = parentPtr->parentPtr) {
        for (nodePtr2 = parentPtr->children.nodePtr; nodePtr2 != nodePtr;
                nodePtr2 = nodePtr2->nextPtr) {
            if (nodePtr2 == NULL) {
                panic("TkBTreeLineIndex couldn't find node");
            }
            index += nodePtr2->numLines;
        }
    }
    return index;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeStartSearch --
 *
 *      This procedure sets up a search for tag transitions involving
 *      a given tag (or all tags) in a given range of the text.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The information at *searchPtr is set up so that subsequent calls
 *      to TkBTreeNextTag will return information about the locations of
 *      tag transitions.  Note that TkBTreeNextTag must be called to get
 *      the first transition.
 *
 *----------------------------------------------------------------------
 */

void
TkBTreeStartSearch(tree, line1, ch1, line2, ch2, tagPtr, searchPtr)
    TkTextBTree tree;                   /* Tree to search. */
    int line1, ch1;                     /* Character position at which to                                                * start search (tags at this position
                                         * will be returned). */
    int line2, ch2;                     /* Character position at which to                                                * stop search (tags at this position
                                         * will be returned). */
    TkTextTag *tagPtr;                  /* Tag to search for.  NULL means
                                         * search for any tag. */
    register TkTextSearch *searchPtr;   /* Where to store information about
                                         * search's progress. */
{
    register TkAnnotation *annotPtr;

    searchPtr->tree = tree;
    if (line1 < 0) {
        searchPtr->line1 = 0;
        searchPtr->ch1 = 0;
    } else {
        searchPtr->line1 = line1;
        searchPtr->ch1 = ch1;
    }
    searchPtr->line2 = line2;
    searchPtr->ch2 = ch2;
    searchPtr->tagPtr = tagPtr;
    searchPtr->allTags = (tagPtr == NULL);

    searchPtr->linePtr = TkBTreeFindLine(searchPtr->tree, searchPtr->line1);
    if (searchPtr->linePtr == NULL) {
        searchPtr->line1 = searchPtr->line2;
        searchPtr->ch1 = searchPtr->ch2;
        searchPtr->annotPtr = NULL;
    } else {
        for (annotPtr = searchPtr->linePtr->annotPtr;
                (annotPtr != NULL) && (annotPtr->ch < ch1);
                annotPtr = annotPtr->nextPtr) {
            /* Empty loop body. */
        }
        searchPtr->annotPtr = annotPtr;
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeNextTag --
 *
 *      Once a tag search has begun, successive calls to this procedure
 *      return successive tag toggles.  Note:  it is NOT SAFE to call this
 *      procedure if characters have been inserted into or deleted from
 *      the B-tree since the call to TkBTreeStartSearch.
 *
 * Results:
 *      The return value is 1 if another toggle was found that met the
 *      criteria specified in the call to TkBTreeStartSearch.  0 is
 *      returned if no more matching tag transitions were found.
 *
 * Side effects:
 *      Information in *searchPtr is modified to update the state of the
 *      search and indicate where the next tag toggle is located.
 *
 *----------------------------------------------------------------------
 */

int
TkBTreeNextTag(searchPtr)
    register TkTextSearch *searchPtr;   /* Information about search in
                                         * progress;  must have been set up by
                                         * call to TkBTreeStartSearch. */
{
    register TkAnnotation *annotPtr;
    register Node *nodePtr;
    register Summary *summaryPtr;

    if (searchPtr->linePtr == NULL) {
        return 0;
    }

    /*
     * The outermost loop iterates over lines that may potentially contain
     * a relevant tag transition, starting from the current line and tag.
     */

    while (1) {
        /*
         * See if there are more tags on the current line that are relevant.
         */
    
        for (annotPtr = searchPtr->annotPtr; annotPtr != NULL;
                annotPtr = annotPtr->nextPtr) {
            if ((annotPtr->type == TK_ANNOT_TOGGLE)
                    && (searchPtr->allTags
                    || (annotPtr->info.tagPtr == searchPtr->tagPtr))) {
                if ((searchPtr->line1 == searchPtr->line2)
                        && (annotPtr->ch > searchPtr->ch2)) {
                    goto searchOver;
                }
                searchPtr->tagPtr = annotPtr->info.tagPtr;
                searchPtr->ch1 = annotPtr->ch;
                searchPtr->annotPtr = annotPtr->nextPtr;
                return 1;
            }
        }
    
        /*
         * See if there are more lines associated with the current parent
         * node.  If so, go back to the top of the loop to search the next
         * one of them.
         */
    
        if (searchPtr->line1 >= searchPtr->line2) {
            goto searchOver;
        }
        searchPtr->line1++;
        if (searchPtr->linePtr->nextPtr != NULL) {
            searchPtr->linePtr = searchPtr->linePtr->nextPtr;
            searchPtr->annotPtr = searchPtr->linePtr->annotPtr;
            continue;
        }
    
        /*
         * Search across and up through the B-tree's node hierarchy looking
         * for the next node that has a relevant tag transition somewhere in
         * its subtree.  Be sure to update the current line number as we
         * skip over large chunks of lines.
         */
    
        nodePtr = searchPtr->linePtr->parentPtr;
        while (1) {
            while (nodePtr->nextPtr == NULL) {
                if (nodePtr->parentPtr == NULL) {
                    goto searchOver;
                }
                nodePtr = nodePtr->parentPtr;
            }
            nodePtr = nodePtr->nextPtr;
            for (summaryPtr = nodePtr->summaryPtr; summaryPtr != NULL;
                    summaryPtr = summaryPtr->nextPtr) {
                if ((searchPtr->allTags) ||
                        (summaryPtr->tagPtr == searchPtr->tagPtr)) {
                    goto gotNodeWithTag;
                }
            }
            searchPtr->line1 += nodePtr->numLines;
        }
    
        /*
         * At this point we've found a subtree that has a relevant tag
         * transition.  Now search down (and across) through that subtree
         * to find the first level-0 node that has a relevant tag transition.
         */
    
        gotNodeWithTag:
        while (nodePtr->level > 0) {
            for (nodePtr = nodePtr->children.nodePtr; ;
                    nodePtr = nodePtr->nextPtr) {
                for (summaryPtr = nodePtr->summaryPtr; summaryPtr != NULL;
                        summaryPtr = summaryPtr->nextPtr) {
                    if ((searchPtr->allTags)
                            || (summaryPtr->tagPtr == searchPtr->tagPtr)) {
                        goto nextChild;
                    }
                }
                searchPtr->line1 += nodePtr->numLines;
                if (nodePtr->nextPtr == NULL) {
                    panic("TkBTreeNextTag found incorrect tag summary info.");
                }
            }
            nextChild:
            continue;
        }
    
        /*
         * Now we're down to a level-0 node that contains a line that contains
         * a relevant tag transition.  Set up line information and go back to
         * the beginning of the loop to search through lines.
         */

        searchPtr->linePtr = nodePtr->children.linePtr;
        searchPtr->annotPtr = searchPtr->linePtr->annotPtr;
        if (searchPtr->line1 > searchPtr->line2) {
            goto searchOver;
        }
        continue;
    }

    searchOver:
    searchPtr->line1 = searchPtr->line2;
    searchPtr->ch1 = searchPtr->ch2;
    searchPtr->annotPtr = NULL;
    searchPtr->linePtr = NULL;
    return 0;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeCheck --
 *
 *      This procedure runs a set of consistency checks over a B-tree
 *      and panics if any inconsistencies are found.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If a structural defect is found, the procedure panics with an
 *      error message.
 *
 *----------------------------------------------------------------------
 */

void
TkBTreeCheck(tree)
    TkTextBTree tree;           /* Tree to check. */
{
    BTree *treePtr = (BTree *) tree;
    register Summary *summaryPtr;

    /*
     * Make sure that overall there is an even count of tag transitions
     * for the whole text.
     */

    for (summaryPtr = treePtr->rootPtr->summaryPtr; summaryPtr != NULL;
            summaryPtr = summaryPtr->nextPtr) {
        if (summaryPtr->toggleCount & 1) {
            panic("TkBTreeCheck found odd toggle count for \"%s\" (%d)",
                    summaryPtr->tagPtr->name, summaryPtr->toggleCount);
        }
    }

    /*
     * Call a recursive procedure to do all of the rest of the checks.
     */

    CheckNodeConsistency(treePtr->rootPtr);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * Rebalance --
 *
 *      This procedure is called when a node of a B-tree appears to be
 *      out of balance (too many children, or too few).  It rebalances
 *      that node and all of its ancestors in the tree.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The internal structure of treePtr may change.
 *
 *----------------------------------------------------------------------
 */

static void
Rebalance(treePtr, nodePtr)
    BTree *treePtr;                     /* Tree that is being rebalanced. */
    register Node *nodePtr;             /* Node that may be out of balance. */
{
    /*
     * Loop over the entire ancestral chain of the node, working up
     * through the tree one node at a time until the root node has
     * been processed.
     */

    for ( ; nodePtr != NULL; nodePtr = nodePtr->parentPtr) {
        register Node *newPtr, *childPtr;
        register TkTextLine *linePtr;
        int i;

        /*
         * Check to see if the node has too many children.  If it does,
         * then split off all but the first MIN_CHILDREN into a separate
         * node following the original one.  Then repeat until the
         * node has a decent size.
         */

        if (nodePtr->numChildren > MAX_CHILDREN) {
            while (1) {
                /*
                 * If the node being split is the root node, then make a
                 * new root node above it first.
                 */
    
                if (nodePtr->parentPtr == NULL) {
                    newPtr = (Node *) ckalloc(sizeof(Node));
                    newPtr->parentPtr = NULL;
                    newPtr->nextPtr = NULL;
                    newPtr->summaryPtr = NULL;
                    newPtr->level = nodePtr->level + 1;
                    newPtr->children.nodePtr = nodePtr;
                    newPtr->numChildren = 1;
                    newPtr->numLines = nodePtr->numLines;
                    RecomputeNodeCounts(newPtr);
                    treePtr->rootPtr = newPtr;
                }
                newPtr = (Node *) ckalloc(sizeof(Node));
                newPtr->parentPtr = nodePtr->parentPtr;
                newPtr->nextPtr = nodePtr->nextPtr;
                nodePtr->nextPtr = newPtr;
                newPtr->summaryPtr = NULL;
                newPtr->level = nodePtr->level;
                newPtr->numChildren = nodePtr->numChildren - MIN_CHILDREN;
                if (nodePtr->level == 0) {
                    for (i = MIN_CHILDREN-1,
                            linePtr = nodePtr->children.linePtr;
                            i > 0; i--, linePtr = linePtr->nextPtr) {
                        /* Empty loop body. */
                    }
                    newPtr->children.linePtr = linePtr->nextPtr;
                    linePtr->nextPtr = NULL;
                } else {
                    for (i = MIN_CHILDREN-1,
                            childPtr = nodePtr->children.nodePtr;
                            i > 0; i--, childPtr = childPtr->nextPtr) {
                        /* Empty loop body. */
                    }
                    newPtr->children.nodePtr = childPtr->nextPtr;
                    childPtr->nextPtr = NULL;
                }
                RecomputeNodeCounts(nodePtr);
                nodePtr->parentPtr->numChildren++;
                nodePtr = newPtr;
                if (nodePtr->numChildren <= MAX_CHILDREN) {
                    RecomputeNodeCounts(nodePtr);
                    break;
                }
            }
        }

        while (nodePtr->numChildren < MIN_CHILDREN) {
            register Node *otherPtr;
            Node *halfwayNodePtr = NULL;        /* Initialization needed only */
            TkTextLine *halfwayLinePtr = NULL;  /* to prevent cc warnings. */
            int totalChildren, firstChildren, i;

            /*
             * Too few children for this node.  If this is the root,
             * it's OK for it to have less than MIN_CHILDREN children
             * as long as it's got at least two.  If it has only one
             * (and isn't at level 0), then chop the root node out of
             * the tree and use its child as the new root.
             */

            if (nodePtr->parentPtr == NULL) {
                if ((nodePtr->numChildren == 1) && (nodePtr->level > 0)) {
                    treePtr->rootPtr = nodePtr->children.nodePtr;
                    treePtr->rootPtr->parentPtr = NULL;
                    DeleteSummaries(nodePtr->summaryPtr);
                    ckfree((char *) nodePtr);
                }
                return;
            }

            /*
             * Not the root.  Make sure that there are siblings to
             * balance with.
             */

            if (nodePtr->parentPtr->numChildren < 2) {
                Rebalance(treePtr, nodePtr->parentPtr);
                continue;
            }

            /*
             * Find a sibling to borrow from, and arrange for nodePtr to
             * be the earlier of the pair.
             */

            if (nodePtr->nextPtr == NULL) {
                for (otherPtr = nodePtr->parentPtr->children.nodePtr;
                        otherPtr->nextPtr != nodePtr;
                        otherPtr = otherPtr->nextPtr) {
                    /* Empty loop body. */
                }
                nodePtr = otherPtr;
            }
            otherPtr = nodePtr->nextPtr;

            /*
             * We're going to either merge the two siblings together
             * into one node or redivide the children among them to
             * balance their loads.  As preparation, join their two
             * child lists into a single list and remember the half-way
             * point in the list.
             */

            totalChildren = nodePtr->numChildren + otherPtr->numChildren;
            firstChildren = totalChildren/2;
            if (nodePtr->children.nodePtr == NULL) {
                nodePtr->children = otherPtr->children;
            } else if (nodePtr->level == 0) {
                register TkTextLine *linePtr;

                for (linePtr = nodePtr->children.linePtr, i = 1;
                        linePtr->nextPtr != NULL;
                        linePtr = linePtr->nextPtr, i++) {
                    if (i == firstChildren) {
                        halfwayLinePtr = linePtr;
                    }
                }
                linePtr->nextPtr = otherPtr->children.linePtr;
                while (i <= firstChildren) {
                    halfwayLinePtr = linePtr;
                    linePtr = linePtr->nextPtr;
                    i++;
                }
            } else {
                register Node *childPtr;

                for (childPtr = nodePtr->children.nodePtr, i = 1;
                        childPtr->nextPtr != NULL;
                        childPtr = childPtr->nextPtr, i++) {
                    if (i <= firstChildren) {
                        if (i == firstChildren) {
                            halfwayNodePtr = childPtr;
                        }
                    }
                }
                childPtr->nextPtr = otherPtr->children.nodePtr;
                while (i <= firstChildren) {
                    halfwayNodePtr = childPtr;
                    childPtr = childPtr->nextPtr;
                    i++;
                }
            }

            /*
             * If the two siblings can simply be merged together, do it.
             */

            if (totalChildren < MAX_CHILDREN) {
                RecomputeNodeCounts(nodePtr);
                nodePtr->nextPtr = otherPtr->nextPtr;
                nodePtr->parentPtr->numChildren--;
                DeleteSummaries(otherPtr->summaryPtr);
                ckfree((char *) otherPtr);
                continue;
            }

            /*
             * The siblings can't be merged, so just divide their
             * children evenly between them.
             */

            if (nodePtr->level == 0) {
                otherPtr->children.linePtr = halfwayLinePtr->nextPtr;
                halfwayLinePtr->nextPtr = NULL;
            } else {
                otherPtr->children.nodePtr = halfwayNodePtr->nextPtr;
                halfwayNodePtr->nextPtr = NULL;
            }
            RecomputeNodeCounts(nodePtr);
            RecomputeNodeCounts(otherPtr);
        }
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * RecomputeNodeCounts --
 *
 *      This procedure is called to recompute all the counts in a node
 *      (tags, child information, etc.) by scaning the information in
 *      its descendants.  This procedure is called during rebalancing
 *      when a node's child structure has changed.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The tag counts for nodePtr are modified to reflect its current
 *      child structure, as are its numChildren and numLines fields.
 *      Also, all of the children's parentPtr fields are made to point
 *      to nodePtr.
 *
 *----------------------------------------------------------------------
 */

static void
RecomputeNodeCounts(nodePtr)
    register Node *nodePtr;             /* Node whose tag summary information
                                         * must be recomputed. */
{
    register Summary *summaryPtr, *summaryPtr2;
    register Node *childPtr;
    register TkTextLine *linePtr;
    register TkAnnotation *annotPtr;

    /*
     * Zero out all the existing counts for the node, but don't delete
     * the existing Summary records (most of them will probably be reused).
     */

    for (summaryPtr = nodePtr->summaryPtr; summaryPtr != NULL;
            summaryPtr = summaryPtr->nextPtr) {
        summaryPtr->toggleCount = 0;
    }
    nodePtr->numChildren = 0;
    nodePtr->numLines = 0;

    /*
     * Scan through the children, adding the childrens' tag counts into
     * the node's tag counts and adding new Summarys to the node if
     * necessary.
     */

    if (nodePtr->level == 0) {
        for (linePtr = nodePtr->children.linePtr; linePtr != NULL;
                linePtr = linePtr->nextPtr) {
            nodePtr->numChildren++;
            nodePtr->numLines++;
            linePtr->parentPtr = nodePtr;
            for (annotPtr = linePtr->annotPtr; annotPtr != NULL;
                    annotPtr = annotPtr->nextPtr) {
                if (annotPtr->type != TK_ANNOT_TOGGLE) {
                    continue;
                }
                for (summaryPtr = nodePtr->summaryPtr; ;
                        summaryPtr = summaryPtr->nextPtr) {
                    if (summaryPtr == NULL) {
                        summaryPtr = (Summary *) ckalloc(sizeof(Summary));
                        summaryPtr->tagPtr = annotPtr->info.tagPtr;
                        summaryPtr->toggleCount = 1;
                        summaryPtr->nextPtr = nodePtr->summaryPtr;
                        nodePtr->summaryPtr = summaryPtr;
                        break;
                    }
                    if (summaryPtr->tagPtr == annotPtr->info.tagPtr) {
                        summaryPtr->toggleCount++;
                        break;
                    }
                }
            }
        }
    } else {
        for (childPtr = nodePtr->children.nodePtr; childPtr != NULL;
                childPtr = childPtr->nextPtr) {
            nodePtr->numChildren++;
            nodePtr->numLines += childPtr->numLines;
            childPtr->parentPtr = nodePtr;
            for (summaryPtr2 = childPtr->summaryPtr; summaryPtr2 != NULL;
                    summaryPtr2 = summaryPtr2->nextPtr) {
                for (summaryPtr = nodePtr->summaryPtr; ;
                        summaryPtr = summaryPtr->nextPtr) {
                    if (summaryPtr == NULL) {
                        summaryPtr = (Summary *) ckalloc(sizeof(Summary));
                        summaryPtr->tagPtr = summaryPtr2->tagPtr;
                        summaryPtr->toggleCount = summaryPtr2->toggleCount;
                        summaryPtr->nextPtr = nodePtr->summaryPtr;
                        nodePtr->summaryPtr = summaryPtr;
                        break;
                    }
                    if (summaryPtr->tagPtr == summaryPtr2->tagPtr) {
                        summaryPtr->toggleCount += summaryPtr2->toggleCount;
                        break;
                    }
                }
            }
        }
    }

    /*
     * Scan through the node's tag records again and delete any Summary
     * records that still have a zero count.
     */

    summaryPtr2 = NULL;
    for (summaryPtr = nodePtr->summaryPtr; summaryPtr != NULL; ) {
        if (summaryPtr->toggleCount > 0) {
            summaryPtr2 = summaryPtr;
            summaryPtr = summaryPtr->nextPtr;
            continue;
        }
        if (summaryPtr2 != NULL) {
            summaryPtr2->nextPtr = summaryPtr->nextPtr;
            ckfree((char *) summaryPtr);
            summaryPtr = summaryPtr2->nextPtr;
        } else {
            nodePtr->summaryPtr = summaryPtr->nextPtr;
            ckfree((char *) summaryPtr);
            summaryPtr = nodePtr->summaryPtr;
        }
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * AddToggleToLine --
 *
 *      Insert a tag transition at a particular point in a particular
 *      line.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      LinePtr and all its ancestors in the B-tree stucture are modified
 *      to indicate the presence of a transition (either on or off) on
 *      tag at the given place in the given line.
 *
 *----------------------------------------------------------------------
 */

static void
AddToggleToLine(linePtr, index, tagPtr)
    TkTextLine *linePtr;                /* Line within which to add
                                         * transition. */
    int index;                          /* Character before which to
                                         * add transition. */
    TkTextTag *tagPtr;                  /* Information about tag. */
{
    register TkAnnotation *annotPtr, *prevPtr;
    int delta = 1;

    /*
     * Find the position where the toggle should be inserted into
     * the array (just after prevPtr), and see if there is already
     * a toggle at exactly the point where we're going to insert a
     * new toggle.  If so then the two toggles cancel;  just delete
     * the existing toggle.
     */

    for (prevPtr = NULL, annotPtr = linePtr->annotPtr; annotPtr != NULL;
            prevPtr = annotPtr, annotPtr = annotPtr->nextPtr) {
        if (annotPtr->ch > index) {
            break;
        }
        if ((annotPtr->type == TK_ANNOT_TOGGLE)
                && (annotPtr->ch == index)
                && (annotPtr->info.tagPtr == tagPtr)) {
            if (prevPtr == NULL) {
                linePtr->annotPtr = annotPtr->nextPtr;
            } else {
                prevPtr->nextPtr = annotPtr->nextPtr;
            }
            ckfree((char *) annotPtr);
            delta = -1;
            goto updateNodes;
        }
    }

    /*
     * Create a new toggle and insert it into the list.
     */

    annotPtr = (TkAnnotation *) ckalloc(sizeof(TkAnnotation));
    annotPtr->type = TK_ANNOT_TOGGLE;
    annotPtr->linePtr = linePtr;
    annotPtr->ch = index;
    annotPtr->info.tagPtr = tagPtr;
    if (prevPtr == NULL) {
        annotPtr->nextPtr = linePtr->annotPtr;
        linePtr->annotPtr = annotPtr;
    } else {
        annotPtr->nextPtr = prevPtr->nextPtr;
        prevPtr->nextPtr = annotPtr;
    }

    /*
     * Update all the nodes above this line to reflect the change in
     * toggle structure.
     */

    updateNodes:
    ChangeNodeToggleCount(linePtr->parentPtr, tagPtr, delta);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * ChangeNodeToggleCount --
 *
 *      This procedure increments or decrements the toggle count for
 *      a particular tag in a particular node and all its ancestors.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The toggle count for tag is adjusted up or down by "delta" in
 *      nodePtr.
 *
 *----------------------------------------------------------------------
 */

static void
ChangeNodeToggleCount(nodePtr, tagPtr, delta)
    register Node *nodePtr;             /* Node whose toggle count for a tag
                                         * must be changed. */
    TkTextTag *tagPtr;                  /* Information about tag. */
    int delta;                          /* Amount to add to current toggle
                                         * count for tag (may be negative). */
{
    register Summary *summaryPtr, *prevPtr;

    /*
     * Iterate over the node and all of its ancestors.
     */

    for ( ; nodePtr != NULL; nodePtr = nodePtr->parentPtr) {
        /*
         * See if there's already an entry for this tag for this node.  If so,
         * perhaps all we have to do is adjust its count.
         */
    
        for (prevPtr = NULL, summaryPtr = nodePtr->summaryPtr;
                summaryPtr != NULL;
                prevPtr = summaryPtr, summaryPtr = summaryPtr->nextPtr) {
            if (summaryPtr->tagPtr != tagPtr) {
                continue;
            }
            summaryPtr->toggleCount += delta;
            if (summaryPtr->toggleCount > 0) {
                goto nextAncestor;
            }
            if (summaryPtr->toggleCount < 0) {
                panic("ChangeNodeToggleCount: negative toggle count");
            }
    
            /*
             * Zero count;  must remove this tag from the list.
             */
    
            if (prevPtr == NULL) {
                nodePtr->summaryPtr = summaryPtr->nextPtr;
            } else {
                prevPtr->nextPtr = summaryPtr->nextPtr;
            }
            ckfree((char *) summaryPtr);
            goto nextAncestor;
        }
    
        /*
         * This tag isn't in the list.  Add a new entry to the list.
         */
    
        if (delta < 0) {
            panic("ChangeNodeToggleCount: negative delta, no tag entry");
        }
        summaryPtr = (Summary *) ckalloc(sizeof(Summary));
        summaryPtr->tagPtr = tagPtr;
        summaryPtr->toggleCount = delta;
        summaryPtr->nextPtr = nodePtr->summaryPtr;
        nodePtr->summaryPtr = summaryPtr;

        nextAncestor:
        continue;
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeCharTagged --
 *
 *      Determine whether a particular character has a particular tag.
 *
 * Results:
 *      The return value is 1 if the given tag is in effect at the
 *      character given by linePtr and ch, and 0 otherwise.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
TkBTreeCharTagged(linePtr, ch, tagPtr)
    TkTextLine *linePtr;                /* Line containing character of
                                         * interest. */
    int ch;                             /* Index of character in linePtr. */
    TkTextTag *tagPtr;                  /* Tag of interest. */
{
    register Node *nodePtr;
    register TkTextLine *siblingLinePtr;
    int toggles;

    /*
     * Count the number of toggles for the tag at the line level (i.e.
     * in all the sibling lines that precede this one, plus in this line
     * up to the character of interest.
     */

    toggles = 0;
    for (siblingLinePtr = linePtr->parentPtr->children.linePtr; ;
            siblingLinePtr = siblingLinePtr->nextPtr) {
        register TkAnnotation *annotPtr;

        for (annotPtr = siblingLinePtr->annotPtr;
                (annotPtr != NULL) && ((siblingLinePtr != linePtr)
                    || (annotPtr->ch <= ch));
                annotPtr = annotPtr->nextPtr) {
            if ((annotPtr->type == TK_ANNOT_TOGGLE)
                    && (annotPtr->info.tagPtr == tagPtr)) {
                toggles++;
            }
        }
        if (siblingLinePtr == linePtr) {
            break;
        }
    }

    /*
     * For each node in the ancestry of this line, count the number of
     * toggles of the given tag in siblings that precede that node.
     */

    for (nodePtr = linePtr->parentPtr; nodePtr->parentPtr != NULL;
            nodePtr = nodePtr->parentPtr) {
        register Node *siblingPtr;
        register Summary *summaryPtr;

        for (siblingPtr = nodePtr->parentPtr->children.nodePtr; 
                siblingPtr != nodePtr; siblingPtr = siblingPtr->nextPtr) {
            for (summaryPtr = siblingPtr->summaryPtr; summaryPtr != NULL;
                    summaryPtr = summaryPtr->nextPtr) {
                if (summaryPtr->tagPtr == tagPtr) {
                    toggles += summaryPtr->toggleCount;
                }
            }
        }
    }

    /*
     * An odd number of toggles means that the tag is present at the
     * given point.
     */

    return toggles & 1;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeGetTags --
 *
 *      Return information about all of the tags that are associated
 *      with a particular character in a B-tree of text.
 *
 * Results:
 *      The return value is a malloc-ed array containing pointers to
 *      information for each of the tags that is associated with
 *      the character at the position given by linePtr and ch.  The
 *      word at *numTagsPtr is filled in with the number of pointers
 *      in the array.  It is up to the caller to free the array by
 *      passing it to free.  If there are no tags at the given character
 *      then a NULL pointer is returned and *numTagsPtr will be set to 0.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
TkTextTag **
TkBTreeGetTags(tree, linePtr, ch, numTagsPtr)
    TkTextBTree tree;           /* Tree to check. */
    TkTextLine *linePtr;        /* Line containing character of interest. */
    int ch;                     /* Index within linePtr of character for
                                 * which tag information is wanted. */
    int *numTagsPtr;            /* Store number of tags found at this
                                 * location. */
{
    register Node *nodePtr;
    register TkTextLine *siblingLinePtr;
    int src, dst;
    TagInfo tagInfo;
#define NUM_TAG_INFOS 10

    tagInfo.numTags = 0;
    tagInfo.arraySize = NUM_TAG_INFOS;
    tagInfo.tagPtrs = (TkTextTag **) ckalloc((unsigned)
            NUM_TAG_INFOS*sizeof(TkTextTag *));
    tagInfo.counts = (int *) ckalloc((unsigned)
            NUM_TAG_INFOS*sizeof(int));

    /*
     * Record tag toggles at the line level (i.e. in all the sibling
     * lines that precede this one, plus in this line up to the character
     * of interest.
     */

    for (siblingLinePtr = linePtr->parentPtr->children.linePtr; ;
            siblingLinePtr = siblingLinePtr->nextPtr) {
        register TkAnnotation *annotPtr;

        for (annotPtr = siblingLinePtr->annotPtr;
                (annotPtr != NULL) && ((siblingLinePtr != linePtr)
                    || (annotPtr->ch <= ch));
                annotPtr = annotPtr->nextPtr) {
            if (annotPtr->type == TK_ANNOT_TOGGLE) {
                IncCount(annotPtr->info.tagPtr, 1, &tagInfo);
            }
        }
        if (siblingLinePtr == linePtr) {
            break;
        }
    }

    /*
     * For each node in the ancestry of this line, record tag toggles
     * for all siblings that precede that node.
     */

    for (nodePtr = linePtr->parentPtr; nodePtr->parentPtr != NULL;
            nodePtr = nodePtr->parentPtr) {
        register Node *siblingPtr;
        register Summary *summaryPtr;

        for (siblingPtr = nodePtr->parentPtr->children.nodePtr; 
                siblingPtr != nodePtr; siblingPtr = siblingPtr->nextPtr) {
            for (summaryPtr = siblingPtr->summaryPtr; summaryPtr != NULL;
                    summaryPtr = summaryPtr->nextPtr) {
                IncCount(summaryPtr->tagPtr, summaryPtr->toggleCount, &tagInfo);
            }
        }
    }

    /*
     * Go through the tag information and squash out all of the tags
     * that have even toggle counts (these tags exist before the point
     * of interest, but not at the desired character itself).
     */

    for (src = 0, dst = 0; src < tagInfo.numTags; src++) {
        if (tagInfo.counts[src] & 1) {
            tagInfo.tagPtrs[dst] = tagInfo.tagPtrs[src];
            dst++;
        }
    }
    *numTagsPtr = dst;
    ckfree((char *) tagInfo.counts);
    if (dst == 0) {
        ckfree((char *) tagInfo.tagPtrs);
        return NULL;
    }
    return tagInfo.tagPtrs;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * IncCount --
 *
 *      This is a utility procedure used by TkBTreeGetTags.  It
 *      increments the count for a particular tag, adding a new
 *      entry for that tag if there wasn't one previously.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The information at *tagInfoPtr may be modified, and the arrays
 *      may be reallocated to make them larger.
 *
 *----------------------------------------------------------------------
 */

static void
IncCount(tagPtr, inc, tagInfoPtr)
    TkTextTag *tagPtr;          /* Handle for tag. */
    int inc;                    /* Amount by which to increment tag count. */
    TagInfo *tagInfoPtr;        /* Holds cumulative information about tags;
                                 * increment count here. */
{
    register TkTextTag **tagPtrPtr;
    int count;

    for (tagPtrPtr = tagInfoPtr->tagPtrs, count = tagInfoPtr->numTags;
            count > 0; tagPtrPtr++, count--) {
        if (*tagPtrPtr == tagPtr) {
            tagInfoPtr->counts[tagInfoPtr->numTags-count] += inc;
            return;
        }
    }

    /*
     * There isn't currently an entry for this tag, so we have to
     * make a new one.  If the arrays are full, then enlarge the
     * arrays first.
     */

    if (tagInfoPtr->numTags == tagInfoPtr->arraySize) {
        TkTextTag **newTags;
        int *newCounts, newSize;

        newSize = 2*tagInfoPtr->arraySize;
        newTags = (TkTextTag **) ckalloc((unsigned)
                (newSize*sizeof(TkTextTag *)));
        memcpy((VOID *) newTags, (VOID *) tagInfoPtr->tagPtrs,
                tagInfoPtr->arraySize * sizeof(TkTextTag *));
        ckfree((char *) tagInfoPtr->tagPtrs);
        tagInfoPtr->tagPtrs = newTags;
        newCounts = (int *) ckalloc((unsigned) (newSize*sizeof(int)));
        memcpy((VOID *) newCounts, (VOID *) tagInfoPtr->counts,
                tagInfoPtr->arraySize * sizeof(int));
        ckfree((char *) tagInfoPtr->counts);
        tagInfoPtr->counts = newCounts;
        tagInfoPtr->arraySize = newSize;
    }

    tagInfoPtr->tagPtrs[tagInfoPtr->numTags] = tagPtr;
    tagInfoPtr->counts[tagInfoPtr->numTags] = inc;
    tagInfoPtr->numTags++;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * CheckNodeConsistency --
 *
 *      This procedure is called as part of consistency checking for
 *      B-trees:  it checks several aspects of a node and also runs
 *      checks recursively on the node's children.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If anything suspicious is found in the tree structure, the
 *      procedure panics.
 *
 *----------------------------------------------------------------------
 */

static void
CheckNodeConsistency(nodePtr)
    register Node *nodePtr;             /* Node whose subtree should be
                                         * checked. */
{
    register Node *childNodePtr;
    register Summary *summaryPtr, *summaryPtr2;
    register TkAnnotation *annotPtr;
    register TkTextLine *linePtr;
    register char *p;
    int numChildren, numLines, toggleCount, minChildren, index, numBytes;

    if (nodePtr->parentPtr != NULL) {
        minChildren = MIN_CHILDREN;
    } else if (nodePtr->level > 0) {
        minChildren = 2;
    } else  {
        minChildren = 1;
    }
    if ((nodePtr->numChildren < minChildren)
            || (nodePtr->numChildren > MAX_CHILDREN)) {
        panic("CheckNodeConsistency found bad child count (%d)",
                nodePtr->numChildren);
    }

    numChildren = 0;
    numLines = 0;
    if (nodePtr->level == 0) {
        for (linePtr = nodePtr->children.linePtr; linePtr != NULL;
                linePtr = linePtr->nextPtr) {
            if (linePtr->parentPtr != nodePtr) {
                panic("CheckNodeConsistency found line that %s",
                        "didn't point to parent");
            }
            for (p = linePtr->bytes, numBytes = 0; *p != 0; p++, numBytes++) {
                if ((*p == '\n') && (numBytes != linePtr->numBytes-1)) {
                    panic("CheckNodeConsistency found line with extra newline");
                }
            }
            if (numBytes != linePtr->numBytes) {
                panic("CheckNodeConsistency found line with bad numBytes");
            }
            if (linePtr->bytes[numBytes-1] != '\n') {
                panic("CheckNodeConsistency found line with no newline");
            }
            index = 0;
            for (annotPtr = linePtr->annotPtr; annotPtr != NULL;
                        annotPtr = annotPtr->nextPtr) {
                if (annotPtr->ch < index) {
                    panic("CheckNodeConsistency found %s (%d %d)",
                            "out-of-order tag indices", index,
                            annotPtr->ch);
                }
                index = annotPtr->ch;
                if (annotPtr->type == TK_ANNOT_TOGGLE) {
                    for (summaryPtr = nodePtr->summaryPtr; ;
                            summaryPtr = summaryPtr->nextPtr) {
                        if (summaryPtr == NULL) {
                            panic("CheckNodeConsistency found line %s",
                                    "tag with no node tag: %s",
                                    summaryPtr->tagPtr->name);
                        }
                        if (summaryPtr->tagPtr == annotPtr->info.tagPtr) {
                            break;
                        }
                    }
                }
            }
            numChildren++;
            numLines++;
        }
    } else {
        for (childNodePtr = nodePtr->children.nodePtr; childNodePtr != NULL;
                childNodePtr = childNodePtr->nextPtr) {
            CheckNodeConsistency(childNodePtr);
            for (summaryPtr = childNodePtr->summaryPtr; summaryPtr != NULL;
                        summaryPtr = summaryPtr->nextPtr) {
                for (summaryPtr2 = nodePtr->summaryPtr; ;
                        summaryPtr2 = summaryPtr2->nextPtr) {
                    if (summaryPtr2 == NULL) {
                        panic("CheckNodeConsistency found %s (%s)",
                                "node tag with no parent tag",
                                summaryPtr->tagPtr->name);
                    }
                    if (summaryPtr->tagPtr == summaryPtr2->tagPtr) {
                        break;
                    }
                }
            }
            numChildren++;
            numLines += childNodePtr->numLines;
            if (childNodePtr->parentPtr != nodePtr) {
                panic("CheckNodeConsistency found node that %s",
                        "didn't point to parent");
            }
            if (childNodePtr->level != (nodePtr->level-1)) {
                panic("CheckNodeConsistency found level mismatch (%d %d)",
                        nodePtr->level, childNodePtr->level);
            }
        }
    }
    if (numChildren != nodePtr->numChildren) {
        panic("CheckNodeConsistency found mismatch in numChildren (%d %d)",
                numChildren, nodePtr->numChildren);
    }
    if (numLines != nodePtr->numLines) {
        panic("CheckNodeConsistency found mismatch in numLines (%d %d)",
                numLines, nodePtr->numLines);
    }

    for (summaryPtr = nodePtr->summaryPtr; summaryPtr != NULL;
            summaryPtr = summaryPtr->nextPtr) {
        toggleCount = 0;
        if (nodePtr->level == 0) {
            for (linePtr = nodePtr->children.linePtr; linePtr != NULL;
                    linePtr = linePtr->nextPtr) {
                for (annotPtr = linePtr->annotPtr; annotPtr != NULL;
                        annotPtr = annotPtr->nextPtr) {
                    if (annotPtr->info.tagPtr == summaryPtr->tagPtr) {
                        toggleCount++;
                    }
                }
            }
        } else {
            for (childNodePtr = nodePtr->children.nodePtr;
                    childNodePtr != NULL;
                    childNodePtr = childNodePtr->nextPtr) {
                for (summaryPtr2 = childNodePtr->summaryPtr;
                        summaryPtr2 != NULL;
                        summaryPtr2 = summaryPtr2->nextPtr) {
                    if (summaryPtr2->tagPtr == summaryPtr->tagPtr) {
                        toggleCount += summaryPtr2->toggleCount;
                    }
                }
            }
        }
        if (toggleCount != summaryPtr->toggleCount) {
            panic("CheckNodeConsistency found mismatch in toggleCount (%d %d)",
                    toggleCount, summaryPtr->toggleCount);
        }
        for (summaryPtr2 = summaryPtr->nextPtr; summaryPtr2 != NULL;
                summaryPtr2 = summaryPtr2->nextPtr) {
            if (summaryPtr2->tagPtr == summaryPtr->tagPtr) {
                panic("CheckNodeConsistency found duplicated node tag: %s",
                        summaryPtr->tagPtr->name);
            }
        }
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkBTreeNumLines --
 *
 *      This procedure returns a count of the number of lines of
 *      text present in a given B-tree.
 *
 * Results:
 *      The return value is a count of the number of lines in tree.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
TkBTreeNumLines(tree)
    TkTextBTree tree;                   /* Information about tree. */
{
    BTree *treePtr = (BTree *) tree;
    return treePtr->rootPtr->numLines;
}