mirror of
https://github.com/michaelrsweet/mxml.git
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504 lines
10 KiB
C
504 lines
10 KiB
C
/*
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* "$Id: mxml-index.c,v 1.3 2004/05/16 13:45:56 mike Exp $"
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*
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* Index support code for Mini-XML, a small XML-like file parsing library.
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*
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* Copyright 2003-2004 by Michael Sweet.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* Contents:
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*
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* mxmlIndexDelete() - Delete an index.
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* mxmlIndexEnum() - Return the next node in the index.
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* mxmlIndexFind() - Find the next matching node.
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* mxmlIndexNew() - Create a new index.
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* mxmlIndexReset() - Reset the enumeration/find pointer in the index and
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* return the first node in the index.
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* index_compare() - Compare two nodes.
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* index_find() - Compare a node with index values.
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* index_sort() - Sort the nodes in the index...
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*/
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/*
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* Include necessary headers...
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*/
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#include "config.h"
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#include "mxml.h"
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/*
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* Sort functions...
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*/
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static int index_compare(mxml_index_t *ind, mxml_node_t *first,
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mxml_node_t *second);
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static int index_find(mxml_index_t *ind, const char *element,
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const char *value, mxml_node_t *node);
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static void index_sort(mxml_index_t *ind, int left, int right);
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/*
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* 'mxmlIndexDelete()' - Delete an index.
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*/
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void
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mxmlIndexDelete(mxml_index_t *ind) /* I - Index to delete */
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{
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/*
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* Range check input..
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*/
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if (!ind)
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return;
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/*
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* Free memory...
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*/
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if (ind->attr)
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free(ind->attr);
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if (ind->alloc_nodes)
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free(ind->nodes);
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free(ind);
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}
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/*
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* 'mxmlIndexEnum()' - Return the next node in the index.
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*
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* Nodes are returned in the sorted order of the index.
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*/
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mxml_node_t * /* O - Next node or NULL if there is none */
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mxmlIndexEnum(mxml_index_t *ind) /* I - Index to enumerate */
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{
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/*
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* Range check input...
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*/
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if (!ind)
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return (NULL);
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/*
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* Return the next node...
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*/
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if (ind->cur_node < ind->num_nodes)
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return (ind->nodes[ind->cur_node ++]);
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else
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return (NULL);
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}
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/*
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* 'mxmlIndexFind()' - Find the next matching node.
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*
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* You should call mxmlIndexReset() prior to using this function for
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* the first time with a particular set of "element" and "value"
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* strings. Passing NULL for both "element" and "value" is equivalent
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* to calling mxmlIndexEnum().
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*/
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mxml_node_t * /* O - Node or NULL if none found */
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mxmlIndexFind(mxml_index_t *ind, /* I - Index to search */
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const char *element, /* I - Element name to find, if any */
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const char *value) /* I - Attribute value, if any */
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{
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int diff, /* Difference between names */
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current, /* Current entity in search */
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first, /* First entity in search */
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last; /* Last entity in search */
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/*
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* Range check input...
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*/
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if (!ind || (!ind->attr && value))
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return (NULL);
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/*
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* If both element and value are NULL, just enumerate the nodes in the
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* index...
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*/
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if (!element && !value)
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return (mxmlIndexEnum(ind));
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/*
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* If there are no nodes in the index, return NULL...
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*/
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if (!ind->num_nodes)
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return (NULL);
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/*
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* If cur_node == 0, then find the first matching node...
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*/
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if (ind->cur_node == 0)
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{
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/*
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* Find the first node using a modified binary search algorithm...
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*/
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first = 0;
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last = ind->num_nodes - 1;
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while (last > first)
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{
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current = (first + last) / 2;
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if ((diff = index_find(ind, element, value, ind->nodes[current])) == 0)
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{
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/*
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* Found a match, move back to find the first...
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*/
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while (current > 0 &&
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!index_find(ind, element, value, ind->nodes[current - 1]))
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current --;
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/*
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* Return the first match and save the index to the next...
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*/
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ind->cur_node = current + 1;
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return (ind->nodes[current]);
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}
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else if (diff < 0)
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last = current;
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else
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first = current;
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}
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/*
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* If we get this far, then we found exactly 0 or 1 matches...
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*/
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current = (first + last) / 2;
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ind->cur_node = ind->num_nodes;
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if (!index_find(ind, element, value, ind->nodes[current]))
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{
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/*
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* Found exactly one match...
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*/
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return (ind->nodes[current]);
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}
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else
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{
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/*
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* No matches...
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*/
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return (NULL);
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}
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}
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else if (ind->cur_node < ind->num_nodes &&
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!index_find(ind, element, value, ind->nodes[ind->cur_node]))
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{
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/*
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* Return the next matching node...
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*/
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return (ind->nodes[ind->cur_node ++]);
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}
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/*
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* If we get this far, then we have no matches...
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*/
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ind->cur_node = ind->num_nodes;
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return (NULL);
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}
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/*
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* 'mxmlIndexNew()' - Create a new index.
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*
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* The index will contain all nodes that contain the named element and/or
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* attribute. If both "element" and "attr" are NULL, then the index will
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* contain a sorted list of the elements in the node tree. Nodes are
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* sorted by element name and optionally by attribute value if the "attr"
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* argument is not NULL.
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*/
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mxml_index_t * /* O - New index */
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mxmlIndexNew(mxml_node_t *node, /* I - XML node tree */
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const char *element, /* I - Element to index or NULL for all */
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const char *attr) /* I - Attribute to index or NULL for none */
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{
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mxml_index_t *ind; /* New index */
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mxml_node_t *current, /* Current node in index */
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**temp; /* Temporary node pointer array */
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/*
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* Range check input...
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*/
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if (!node)
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return (NULL);
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/*
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* Create a new index...
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*/
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if ((ind = calloc(1, sizeof(mxml_index_t))) != NULL)
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return (NULL);
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for (current = mxmlFindElement(node, node, element, attr, NULL, MXML_DESCEND);
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current;
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current = mxmlFindElement(current, node, element, attr, NULL, MXML_DESCEND))
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{
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if (ind->num_nodes >= ind->alloc_nodes)
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{
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if (!ind->alloc_nodes)
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temp = malloc(64 * sizeof(mxml_node_t *));
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else
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temp = realloc(ind->nodes, (ind->alloc_nodes + 64) * sizeof(mxml_node_t *));
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if (!temp)
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{
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/*
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* Unable to allocate memory for the index, so abort...
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*/
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mxml_error("Unable to allocate %d bytes for index: %s",
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(ind->alloc_nodes + 64) * sizeof(mxml_node_t *),
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strerror(errno));
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mxmlIndexDelete(ind);
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return (NULL);
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}
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ind->nodes = temp;
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ind->alloc_nodes += 64;
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}
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ind->nodes[ind->num_nodes ++] = current;
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}
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/*
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* Sort nodes based upon the search criteria...
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*/
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if (ind->num_nodes > 1)
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index_sort(ind, 0, ind->num_nodes - 1);
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/*
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* Return the new index...
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*/
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return (ind);
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}
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/*
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* 'mxmlIndexReset()' - Reset the enumeration/find pointer in the index and
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* return the first node in the index.
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*
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* This function should be called prior to using mxmlIndexEnum() or
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* mxmlIndexFind() for the first time.
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*/
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mxml_node_t * /* O - First node or NULL if there is none */
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mxmlIndexReset(mxml_index_t *ind) /* I - Index to reset */
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{
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/*
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* Range check input...
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*/
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if (!ind)
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return (NULL);
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/*
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* Set the index to the first element...
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*/
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ind->cur_node = 0;
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/*
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* Return the first node...
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*/
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if (ind->num_nodes)
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return (ind->nodes[0]);
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else
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return (NULL);
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}
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/*
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* 'index_compare()' - Compare two nodes.
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*/
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static int /* O - Result of comparison */
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index_compare(mxml_index_t *ind, /* I - Index */
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mxml_node_t *first, /* I - First node */
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mxml_node_t *second) /* I - Second node */
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{
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int diff; /* Difference */
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/*
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* Check the element name...
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*/
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if ((diff = strcmp(first->value.element.name,
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second->value.element.name)) != 0)
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return (diff);
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/*
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* Check the attribute value...
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*/
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if (ind->attr)
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{
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if ((diff = strcmp(mxmlElementGetAttr(first, ind->attr),
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mxmlElementGetAttr(second, ind->attr))) != 0)
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return (diff);
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}
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/*
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* No difference, return 0...
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*/
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return (0);
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}
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/*
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* 'index_find()' - Compare a node with index values.
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*/
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static int /* O - Result of comparison */
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index_find(mxml_index_t *ind, /* I - Index */
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const char *element, /* I - Element name or NULL */
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const char *value, /* I - Attribute value or NULL */
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mxml_node_t *node) /* I - Node */
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{
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int diff; /* Difference */
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/*
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* Check the element name...
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*/
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if (element)
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{
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if ((diff = strcmp(element, node->value.element.name)) != 0)
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return (diff);
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}
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/*
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* Check the attribute value...
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*/
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if (value)
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{
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if ((diff = strcmp(value, mxmlElementGetAttr(node, ind->attr))) != 0)
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return (diff);
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}
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/*
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* No difference, return 0...
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*/
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return (0);
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}
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/*
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* 'index_sort()' - Sort the nodes in the index...
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*
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* This function implements the classic quicksort algorithm...
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*/
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static void
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index_sort(mxml_index_t *ind, /* I - Index to sort */
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int left, /* I - Left node in partition */
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int right) /* I - Right node in partition */
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{
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mxml_node_t *pivot, /* Pivot node */
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*temp; /* Swap node */
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int templ, /* Temporary left node */
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tempr; /* Temporary right node */
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/*
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* Sort the pivot in the current partition...
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*/
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pivot = ind->nodes[left];
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for (templ = left, tempr = right; templ < tempr;)
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{
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/*
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* Move left while left node <= pivot node...
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*/
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while ((templ < right) &&
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index_compare(ind, ind->nodes[templ], pivot) <= 0)
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templ ++;
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/*
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* Move right while right node > pivot node...
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*/
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while ((tempr > left) &&
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index_compare(ind, ind->nodes[tempr], pivot) > 0)
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tempr --;
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/*
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* Swap nodes if needed...
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*/
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if (templ < tempr)
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{
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temp = ind->nodes[templ];
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ind->nodes[templ] = ind->nodes[tempr];
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ind->nodes[tempr] = temp;
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}
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}
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/*
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* When we get here, the right (tempr) node is the new position for the
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* pivot node...
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*/
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ind->nodes[left] = ind->nodes[tempr];
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ind->nodes[tempr] = pivot;
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/*
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* Recursively sort the left and right partitions as needed...
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*/
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if (left < (tempr - 1))
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index_sort(ind, left, tempr - 1);
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if (right > (tempr + 1))
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index_sort(ind, tempr + 1, right);
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}
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/*
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* End of "$Id: mxml-index.c,v 1.3 2004/05/16 13:45:56 mike Exp $".
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*/
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