#include <stdio.h>

#include <libxml/parser.h>
#include <libxml/parserInternals.h>

/* Compile with: gcc --std=c99 -o walk walk.c `pkg-config --libs --cflags libxml-2.0` */

static xmlDoc* my_parse_document (const xmlChar *filename) {

	xmlParserCtxt *ctxt = NULL;
	xmlDoc *document = NULL;

	ctxt = xmlCreateFileParserCtxt(filename);
	xmlCtxtUseOptions(ctxt, XML_PARSE_COMPACT | XML_PARSE_RECOVER | XML_PARSE_NOERROR);
	
	if (xmlParseDocument(ctxt) == 0) {
		document = ctxt->myDoc;
		ctxt->myDoc = NULL;
	}

	xmlFreeParserCtxt(ctxt);
	return document;
}


/* Walk the given DOM and show more interrest on <scalar parName="value"> */
void walk (xmlNode *node, int depth) {

	if (node->type == XML_ELEMENT_NODE) {
		int i = 0;
		for (; i < depth; ++i) {
			printf("  ");
		}
		printf("%s ", node->name);
		
		if (xmlStrcmp(node->name, "scalar") == 0) {
			xmlChar *value = xmlGetNoNsProp(node, "parName");
			printf(" parName = %s", value);
			if (value) xmlFree(value);
		}
		
		printf("\n");
	}
	else if (node->type == XML_DOCUMENT_NODE) {
		printf("/\n");
	}

	xmlNode *child = node;
	for (child = node->children; child; child = child->next) {
		walk(child, depth + 1);
	}
}


int
main (int argc, char **argv) {

	xmlDoc *document = NULL;
	xmlNode *root = NULL;
	xmlNode *node = NULL;
	const xmlChar *filename = NULL;
	
	if (argc == 1) {
		printf("Usage: filename\n");
		return 1;
	}
	filename = (const xmlChar *) argv[1];
	
	document = my_parse_document(filename);
	if (document == NULL) {
		printf("Failed to parse %s\n", filename);
		return 1;
	}

	walk((xmlNode *) document, 0);

	xmlFreeDoc(document);
	xmlCleanupParser();

  return 0;
}