mxml/mxml-search.c

//
// Search/navigation functions for Mini-XML, a small XML file parsing library.
//
// https://www.msweet.org/mxml
//
// Copyright © 2003-2024 by Michael R Sweet.
//
// Licensed under Apache License v2.0.  See the file "LICENSE" for more
// information.
//

#include "mxml-private.h"


//
// 'mxmlFindElement()' - Find the named element.
//
// The search is constrained by the name, attribute name, and value; any
// `NULL` names or values are treated as wildcards, so different kinds of
// searches can be implemented by looking for all elements of a given name
// or all elements with a specific attribute. The descend argument determines
// whether the search descends into child nodes; normally you will use
// `MXML_DESCEND_FIRST` for the initial search and `MXML_NO_DESCEND`
// to find additional direct descendents of the node. The top node argument
// constrains the search to a particular node's children.
//

mxml_node_t *				// O - Element node or `NULL`
mxmlFindElement(mxml_node_t *node,	// I - Current node
                mxml_node_t *top,	// I - Top node
                const char  *element,	// I - Element name or `NULL` for any
		const char  *attr,	// I - Attribute name, or `NULL` for none
		const char  *value,	// I - Attribute value, or `NULL` for any
		int         descend)	// I - Descend into tree - `MXML_DESCEND`, `MXML_NO_DESCEND`, or `MXML_DESCEND_FIRST`
{
  const char	*temp;			// Current attribute value


  // Range check input...
  if (!node || !top || (!attr && value))
    return (NULL);

  // Start with the next node...
  node = mxmlWalkNext(node, top, descend);

  // Loop until we find a matching element...
  while (node != NULL)
  {
    // See if this node matches...
    if (node->type == MXML_TYPE_ELEMENT && node->value.element.name && (!element || !strcmp(node->value.element.name, element)))
    {
      // See if we need to check for an attribute...
      if (!attr)
        return (node);			// No attribute search, return it...

      // Check for the attribute...
      if ((temp = mxmlElementGetAttr(node, attr)) != NULL)
      {
        // OK, we have the attribute, does it match?
	if (!value || !strcmp(value, temp))
	  return (node);		// Yes, return it...
      }
    }

    // No match, move on to the next node...
    if (descend == MXML_DESCEND)
      node = mxmlWalkNext(node, top, MXML_DESCEND);
    else
      node = node->next;
  }

  return (NULL);
}


//
// 'mxmlFindPath()' - Find a node with the given path.
//
// The "path" is a slash-separated list of element names. The name "*" is
// considered a wildcard for one or more levels of elements.  For example,
// "foo/one/two", "bar/two/one", "*\/one", and so forth.
//
// The first child node of the found node is returned if the given node has
// children and the first child is a value node.
//

mxml_node_t *				// O - Found node or `NULL`
mxmlFindPath(mxml_node_t *top,		// I - Top node
	     const char  *path)		// I - Path to element
{
  mxml_node_t	*node;			// Current node
  char		element[256];		// Current element name
  const char	*pathsep;		// Separator in path
  int		descend;		// mxmlFindElement option


  // Range check input...
  if (!top || !path || !*path)
    return (NULL);

  // Search each element in the path...
  node = top;
  while (*path)
  {
    // Handle wildcards...
    if (!strncmp(path, "*/", 2))
    {
      path += 2;
      descend = MXML_DESCEND;
    }
    else
    {
      descend = MXML_DESCEND_FIRST;
    }

    // Get the next element in the path...
    if ((pathsep = strchr(path, '/')) == NULL)
      pathsep = path + strlen(path);

    if (pathsep == path || (pathsep - path) >= sizeof(element))
      return (NULL);

    memcpy(element, path, pathsep - path);
    element[pathsep - path] = '\0';

    if (*pathsep)
      path = pathsep + 1;
    else
      path = pathsep;

    // Search for the element...
    if ((node = mxmlFindElement(node, node, element, NULL, NULL, descend)) == NULL)
      return (NULL);
  }

  // If we get this far, return the node or its first child...
  if (node->child && node->child->type != MXML_TYPE_ELEMENT)
    return (node->child);
  else
    return (node);
}


//
// 'mxmlWalkNext()' - Walk to the next logical node in the tree.
//
// The descend argument controls whether the first child is considered
// to be the next node.  The top node argument constrains the walk to
// the node's children.
//

mxml_node_t *				// O - Next node or `NULL`
mxmlWalkNext(mxml_node_t *node,		// I - Current node
             mxml_node_t *top,		// I - Top node
             int         descend)	// I - Descend into tree - `MXML_DESCEND`, `MXML_NO_DESCEND`, or `MXML_DESCEND_FIRST`
{
  if (!node)
  {
    return (NULL);
  }
  else if (node->child && descend)
  {
    return (node->child);
  }
  else if (node == top)
  {
    return (NULL);
  }
  else if (node->next)
  {
    return (node->next);
  }
  else if (node->parent && node->parent != top)
  {
    node = node->parent;

    while (!node->next)
    {
      if (node->parent == top || !node->parent)
        return (NULL);
      else
        node = node->parent;
    }

    return (node->next);
  }
  else
  {
    return (NULL);
  }
}


//
// 'mxmlWalkPrev()' - Walk to the previous logical node in the tree.
//
// The descend argument controls whether the previous node's last child
// is considered to be the previous node.  The top node argument constrains
// the walk to the node's children.
//

mxml_node_t *				// O - Previous node or `NULL`
mxmlWalkPrev(mxml_node_t *node,		// I - Current node
             mxml_node_t *top,		// I - Top node
             int         descend)	// I - Descend into tree - `MXML_DESCEND`, `MXML_NO_DESCEND`, or `MXML_DESCEND_FIRST`
{
  if (!node || node == top)
  {
    return (NULL);
  }
  else if (node->prev)
  {
    if (node->prev->last_child && descend)
    {
      // Find the last child under the previous node...
      node = node->prev->last_child;

      while (node->last_child)
        node = node->last_child;

      return (node);
    }
    else
    {
      return (node->prev);
    }
  }
  else if (node->parent != top)
  {
    return (node->parent);
  }
  else
  {
    return (NULL);
  }
}