[xml] Text node merging is inconsistent when using addPrevSibling vs. addNextSibling

[John Shahid <jvshahid gmail com>]

Given the following document,

<root>a<b>c</b></root>

reparenting the 'c' text node using addPrevSibling(b_node, c_node) cause the document to end up with two text nodes 'a' and 'c', in other words root will have 3 nodes 'a', 'c' text nodes and the empty b node. On the other hand if addNextSibling(a_node, c_node) was used, the text nodes will be merged correctly and the root node will have 2 nodes 'ac' text node and the empty b node. Below is a test program that outputs the contents of the nodes in both cases.

This was tested with version 2.7.8 on ubuntu as well as master (commit 8fc913fcc9d2c3fd5c76694cb4e631ca1242de37)

#include <stdio.h>

#include <libxml/parser.h>

#include <libxml/tree.h>

int main() {

  /*

   * this initialize the library and check potential ABI mismatches

   * between the version it was compiled for and the actual shared

   * library used.

   */

  LIBXML_TEST_VERSION;

  xmlDocPtr doc1, doc2; /* the resulting document tree */

  const char doc_content [] = "<root>a<b>c</b></root>";

  doc1 = xmlReadMemory(doc_content, sizeof(doc_content), NULL, NULL, 1);

  doc2 = xmlReadMemory(doc_content, sizeof(doc_content), NULL, NULL, 1);

  if (!doc1 || !doc2) {

    fprintf(stderr, "Failed to parse %s\n", doc_content);

    return 1;

  }

  xmlNodePtr b_node = doc1->children->last;

  xmlNodePtr c_node = b_node->last;

  xmlAddPrevSibling(b_node, c_node);

  b_node = doc2->children->last;

  c_node = b_node->last;

  xmlAddNextSibling(doc2->children->children, c_node);

  for (xmlNodePtr node = doc1->children->children; node; node = node->next)

    printf("contents: %s\n", node->content);

  for (xmlNodePtr node = doc2->children->children; node; node = node->next)

    printf("contents: %s\n", node->content);

  return 0;

}