* Why is that useful? Mainly to produce test-cases for CQL parsers * (including the CQLParser class in this package): you can * generate a random search tree, render it to XCQL and remember the * result. Then decompile the tree to CQL, feed the generated CQL to * the parser of your choice, and check that the XCQL it comes up with * is the same what you got from your initial rendering. *
* This code is based on the same grammar as the CQLParser class in * this distribution - there is a generate_x() method * for each grammar element X. * * @version $Id: CQLGenerator.java 5239 2008-03-17 09:00:00Z icmdriver $ * @see http://zing.z3950.org/cql/index.html */ public class CQLGenerator { Properties params; Random rnd; static private boolean DEBUG = false; /** * Creates a new CQL generator with the specified parameters. *
* @param params * A Properties table containing configuration * parameters for the queries to be generated by this generator. * Recognised parameters are: *
*
*
*
*
*
*
*
* Uses the parameters that were associated with the generator * when it was created. You are free to create as many random * queries as you wish from a single generator; each of them will * use the same parameters. *
* @return
* A CQLNode that is the root of the generated tree.
* That tree may be rendered in XCQL using its toXCQL()
* method, or decompiled into CQL using its toCQL
* method.
*/
public CQLNode generate() throws MissingParameterException {
return generate_cql_query();
}
private CQLNode generate_cql_query() throws MissingParameterException {
if (!maybe("complexQuery")) {
return generate_search_clause();
}
CQLNode node1 = generate_cql_query();
CQLNode node2 = generate_search_clause();
// ### should generate prefix-mapping nodes
if (maybe("proxOp")) {
// ### generate proximity nodes
} else {
switch (rnd.nextInt(3)) {
case 0: return new CQLAndNode(node1, node2, new ModifierSet("and"));
case 1: return new CQLOrNode (node1, node2, new ModifierSet("or"));
case 2: return new CQLNotNode(node1, node2, new ModifierSet("not"));
}
}
return generate_search_clause();
}
private CQLNode generate_search_clause() throws MissingParameterException {
if (maybe("complexClause")) {
return generate_cql_query();
}
// ### Should sometimes generate index/relation-free terms
String index = generate_index();
CQLRelation relation = generate_relation();
String term = generate_term();
return new CQLTermNode(index, relation, term);
}
// ### Should probably be more configurable
private String generate_index() {
String index = ""; // shut up compiler warning
if (rnd.nextInt(2) == 0) {
switch (rnd.nextInt(3)) {
case 0: index = "dc.author"; break;
case 1: index = "dc.title"; break;
case 2: index = "dc.subject"; break;
}
} else {
switch (rnd.nextInt(4)) {
case 0: index = "bath.author"; break;
case 1: index = "bath.title"; break;
case 2: index = "bath.subject"; break;
case 3: index = "foo>bar"; break;
}
}
return index;
}
private CQLRelation generate_relation() throws MissingParameterException {
String base = generate_base_relation();
CQLRelation rel = new CQLRelation(base);
// ### should generate modifiers too
return rel;
}
private String generate_base_relation() throws MissingParameterException {
if (maybe("equalsRelation")) {
return "=";
} else if (maybe("numericRelation")) {
return generate_numeric_relation();
} else {
switch (rnd.nextInt(3)) {
case 0: return "exact";
case 1: return "all";
case 2: return "any";
}
}
// NOTREACHED
return ""; // shut up compiler warning
}
// ### could read candidate terms from /usr/dict/words
// ### should introduce wildcard characters
// ### should generate multi-word terms
private String generate_term() {
switch (rnd.nextInt(10)) {
case 0: return "cat";
case 1: return "\"cat\"";
case 2: return "comp.os.linux";
case 3: return "xml:element";
case 4: return "
* It generates a single random query using the parameters
* specified in a nominated properties file, plus any additional
* name value pairs provided on the command-line, and
* decompiles it into CQL which is written to standard output.
*
* For example,
* java org.z3950.zing.cql.CQLGenerator
* etc/generate.properties seed 18398,
* where the file generate.properties contains:
* @param configFile
* The name of a properties file from which to read the
* configuration parameters (see above).
* @param name
* The name of a configuration parameter.
* @param value
* The value to assign to the configuration parameter named in
* the immediately preceding command-line argument.
* @return
* A CQL query expressed in a form that should be comprehensible
* to all conformant CQL compilers.
*/
public static void main (String[] args) throws Exception {
if (args.length % 2 != 1) {
System.err.println("Usage: CQLGenerator
* complexQuery=0.4
* complexClause=0.4
* equalsRelation=0.5
* numericRelation=0.7
* proxOp=0.0
*
* yields:
* ((dc.author = "<xml.element>") or (bath.title = cat)) and
* (dc.subject >= "the complete dinosaur")
*
*