Mini-XML - Tiny XML Parsing Library

Mini-XML is a small XML parsing library that you can use to read XML data files or strings in your application without requiring large non-standard libraries. Mini-XML only requires a "make" program and an ANSI C compatible compiler - GCC works, as do most vendors' ANSI C compilers.

Mini-XML provides the following functionality:

• Reading of UTF-8 and UTF-16 and writing of UTF-8 encoded XML files and strings.
• Data is stored in a linked-list tree structure, preserving the XML data hierarchy.
• SAX (streamed) reading of XML files and strings to minimize memory usage.
• Supports arbitrary element names, attributes, and attribute values with no preset limits, just available memory.
• Supports integer, real, opaque ("cdata"), and text data types in "leaf" nodes.
• Functions for creating and managing trees of data.
• "Find" and "walk" functions for easily locating and navigating trees of data.

Mini-XML doesn't do validation or other types of processing on the data based upon schema files or other sources of definition information.

Note: Version 3.0 hides the definition of the mxml_node_t structure, requiring the use of the various accessor functions that were introduced in version 2.0.

Building Mini-XML

Mini-XML comes with an autoconf-based configure script; just type the following command to get things going:

./configure

The default install prefix is /usr/local, which can be overridden using the --prefix option:

./configure --prefix=/foo

Other configure options can be found using the --help option:

./configure --help

Once you have configured the software, type make to do the build and run the test program to verify that things are working, as follows:

make

If you are using Mini-XML under Microsoft Windows with Visual C++, use the included project files in the vcnet subdirectory to build the library instead. Note: The static library on Windows is NOT thread-safe.

Installing Mini-XML

The install target will install Mini-XML in the lib and include directories:

make install

Once you have installed it, use the -lmxml option to link your application against it.

Documentation

The documentation is available in the doc subdirectory in the files mxml.html (HTML) and mxml.epub (EPUB). You can also look at the testmxml.c source file for examples of using Mini-XML.

Mini-XML provides a single header file which you include:

#include <mxml.h>

Nodes (elements, comments, processing directives, integers, opaque strings, real numbers, and text strings) are represented by mxml_node_t objects. New nodes can be created using the mxmlNewElement(), mxmlNewInteger(), mxmlNewOpaque(), mxmlNewReal(), and mxmlNewText() functions. Only elements can have child nodes, and the top node must be the "?xml" processing directive.

You load an XML file using the mxmlLoadFile() function:

FILE *fp;
mxml_node_t *tree;

fp = fopen("filename.xml", "r");
tree = mxmlLoadFile(NULL, fp, MXML_OPAQUE_CALLBACK);
fclose(fp);

Similarly, you save an XML file using the mxmlSaveFile() function:

FILE *fp;
mxml_node_t *tree;

fp = fopen("filename.xml", "w");
mxmlSaveFile(tree, fp, MXML_NO_CALLBACK);
fclose(fp);

The mxmlLoadString(), mxmlSaveAllocString(), and mxmlSaveString() functions load XML node trees from and save XML node trees to strings:

char buffer[8192];
char *ptr;
mxml_node_t *tree;

...
tree = mxmlLoadString(NULL, buffer, MXML_OPAQUE_CALLBACK);

...
mxmlSaveString(tree, buffer, sizeof(buffer), MXML_NO_CALLBACK);

...
ptr = mxmlSaveAllocString(tree, MXML_NO_CALLBACK);

You can find a named element/node using the mxmlFindElement() function:

mxml_node_t *node = mxmlFindElement(tree, tree, "name", "attr",
				"value", MXML_DESCEND);

The name, attr, and value arguments can be passed as NULL to act as wildcards, e.g.:

/* Find the first "a" element */
node = mxmlFindElement(tree, tree, "a", NULL, NULL, MXML_DESCEND);

/* Find the first "a" element with "href" attribute */
node = mxmlFindElement(tree, tree, "a", "href", NULL, MXML_DESCEND);

/* Find the first "a" element with "href" to a URL */
node = mxmlFindElement(tree, tree, "a", "href",
		   "http://www.minixml.org/",
		   MXML_DESCEND);

/* Find the first element with a "src" attribute*/
node = mxmlFindElement(tree, tree, NULL, "src", NULL, MXML_DESCEND);

/* Find the first element with a "src" = "foo.jpg" */
node = mxmlFindElement(tree, tree, NULL, "src", "foo.jpg",
		   MXML_DESCEND);

You can also iterate with the same function:

mxml_node_t *node;

for (node = mxmlFindElement(tree, tree, "name", NULL, NULL,
			MXML_DESCEND);
 node != NULL;
 node = mxmlFindElement(node, tree, "name", NULL, NULL,
			MXML_DESCEND))
{
  ... do something ...
}

The mxmlFindPath() function finds the (first) value node under a specific element using an XPath:

mxml_node_t *value = mxmlFindPath(tree, "path/to/*/foo/bar");

The mxmlGetInteger(), mxmlGetOpaque(), mxmlGetReal(), and mxmlGetText() functions retrieve the corresponding value from a node:

mxml_node_t *node;

int intvalue = mxmlGetInteger(node);

const char *opaquevalue = mxmlGetOpaque(node);

double realvalue = mxmlGetReal(node);

int whitespacevalue;
const char *textvalue = mxmlGetText(node, &whitespacevalue);

Finally, once you are done with the XML data, use the mxmlDelete() function to recursively free the memory that is used for a particular node or the entire tree:

mxmlDelete(tree);

Getting Help And Reporting Problems

The Mini-XML project page provides access to the current version of this software, documentation, and Github issue tracking page.

Legal Stuff

Copyright © 2003-2022 by Michael R Sweet

The Mini-XML library is licensed under the Apache License Version 2.0 with an optional exception to allow linking against GPL2/LGPL2-only software. See the files "LICENSE" and "NOTICE" for more information.

Note: The exception listed in the NOTICE file only applies when linking against GPL2/LGPL2-only software. Some Apache License purists have objected to linking Apache Licensed code against Mini-XML with these exceptions on the grounds that it makes Mini-XML somehow incompatible with the Apache License. For that reason, people wishing to retain their Apache License purity may omit the exception from their copy of Mini-XML.

Note 2: IANAL, but I am beginning to dislike them!