examples/Extensions.cpp File Reference

example: register use of extended element names More...

Include dependency graph for Extensions.cpp:

Functions
int	main (int, char **)
	Example use of E57 extension functions.

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Detailed Description

example: register use of extended element names

Also see listing at end of this page for source without line numbers (to cut&paste from).

/*** Extensions.cpp example: register use of extended element names */
#include <iostream>
#include "E57Foundation.h"
using namespace e57;
using namespace std;

int main(int /*argc*/, char** /*argv*/) {
    try {
        ImageFile imf("temp._e57", "w");

        imf.extensionsAdd("ext1", "http://www.example.com/MyExtension1");

        ustring uri;
        if (!imf.extensionsLookupPrefix("ext1", uri))
            cout << "Oops, ext1 should have been defined" << endl;
        else
            cout << "ext1 is prefix for uri=" << uri << endl;

        ustring prefix;
        if (!imf.extensionsLookupUri("http://www.example.com/MyExtension1", prefix))
            cout << "Oops, URI http://www.example.com/MyExtension1 should have been defined" << endl;
        else
            cout << "URI http://www.example.com/MyExtension1 has prefix=" << prefix << endl;

        cout << "Defined extensions:" << endl;
        for (int i = 0; i < imf.extensionsCount(); i++)
            cout << "  prefix:" << imf.extensionsPrefix(i) << " URI:" << imf.extensionsUri(i) << endl;

        imf.root().set("ext1:greeting", StringNode(imf, "Hello world."));

        imf.close(); // don't forget to explicitly close the ImageFile
    } catch(E57Exception& ex) {
        ex.report(__FILE__, __LINE__, __FUNCTION__);
        return(-1);
    }
    return(0);
}

This example program shows how to declare an E57 extension prefix and URI in an ImageFile. See the HelloWorld.cpp example for discussion of the use of include files, constructing an ImageFile, and the try/catch block to handle exceptions.

In source line 12 an write-mode ImageFile is created. In source line 14 an E57 extension is declared in the ImageFile, with prefix "ext1" and a given URI. The extension must be declared before the prefix is used in any element names. Source lines 17 and 23 show that given a prefix, the corresponding URI can be found (and vice versa). Source lines 28-30 show how to iterate over all extensions defined in the file. Note that the standardized default ASTM URI does not qualify as an "extension" and is not printed in the output. Finally, a StringNode is added to the ImageFile root on source line 32, using the "ext1" extension in the element name. If some unknown extension had been given instead in the element name on source line 32 (e.g. "ext2"), then the StructureNode::set function would have thrown an E57_ERROR_BAD_PATH_NAME exception.

In the XML listing below, the "ext1" prefix is declared in XML line 3, and is used in the element name in XML line 5.

The following console output is produced:

The XML section of the temp._e57 E57 file produced by this example program is as follows:

Here is the source code without line numbers to cut&paste from:

/*** Extensions.cpp example: register use of extended element names */
#include <iostream>
#include "E57Foundation.h"
using namespace e57;
using namespace std;

int main(int /*argc*/, char** /*argv*/) {
    try {
        ImageFile imf("temp._e57", "w");

        imf.extensionsAdd("ext1", "http://www.example.com/MyExtension1");

        ustring uri;
        if (!imf.extensionsLookupPrefix("ext1", uri))
            cout << "Oops, ext1 should have been defined" << endl;
        else
            cout << "ext1 is prefix for uri=" << uri << endl;

        ustring prefix;
        if (!imf.extensionsLookupUri("http://www.example.com/MyExtension1", prefix))
            cout << "Oops, URI http://www.example.com/MyExtension1 should have been defined" << endl;
        else
            cout << "URI http://www.example.com/MyExtension1 has prefix=" << prefix << endl;

        cout << "Defined extensions:" << endl;
        for (int i = 0; i < imf.extensionsCount(); i++)
            cout << "  prefix:" << imf.extensionsPrefix(i) << " URI:" << imf.extensionsUri(i) << endl;

        imf.root().set("ext1:greeting", StringNode(imf, "Hello world."));

        imf.close(); // don't forget to explicitly close the ImageFile
    } catch(E57Exception& ex) {
        ex.report(__FILE__, __LINE__, __FUNCTION__);
        return(-1);
    }
    return(0);
}