-// $Id: CQLNode.java,v 1.10 2002-11-05 17:21:30 mike Exp $
+// $Id: CQLNode.java,v 1.15 2002-11-20 01:15:15 mike Exp $
package org.z3950.zing.cql;
+import java.util.Properties;
+import java.util.Vector;
/**
* Represents a node in a CQL parse-tree.
- * ##
*
- * @version $Id: CQLNode.java,v 1.10 2002-11-05 17:21:30 mike Exp $
+ * @version $Id: CQLNode.java,v 1.15 2002-11-20 01:15:15 mike Exp $
*/
public abstract class CQLNode {
- abstract public String toXCQL(int level);
+ CQLNode() {} // prevent javadoc from documenting this
+
+ /**
+ * Translates a parse-tree into an XCQL document.
+ * <P>
+ * @param level
+ * The number of levels to indent the top element of the XCQL
+ * document. This will typically be 0 when invoked by an
+ * application; it takes higher values when this method is
+ * invoked recursively for nodes further down the tree.
+ * @return
+ * A String containing an XCQL document equivalent to the
+ * parse-tree whose root is this node.
+ */
+ public String toXCQL(int level) {
+ return toXCQL(level, new Vector());
+ }
+
+ abstract public String toXCQL(int level, Vector prefixes);
+
+ protected static String renderPrefixes(int level, Vector prefixes) {
+ if (prefixes.size() == 0)
+ return "";
+ String res = indent(level) + "<prefixes>\n";
+ for (int i = 0; i < prefixes.size(); i++) {
+ CQLPrefix p = (CQLPrefix) prefixes.get(i);
+ res += indent(level+1) + "<prefix>\n";
+ if (p.name != null)
+ res += indent(level+2) + "<name>" + p.name + "</name>\n";
+ res += indent(level+2) +
+ "<identifier>" + p.identifier + "</identifier>\n";
+ res += indent(level+1) + "</prefix>\n";
+ }
+ return res + indent(level) + "</prefixes>\n";
+ }
+
+ /**
+ * Decompiles a parse-tree into a CQL query.
+ * <P>
+ * @return
+ * A String containing a CQL query equivalent to the parse-tree
+ * whose root is this node, so that compiling that query will
+ * yield an identical tree.
+ */
abstract public String toCQL();
- // Utility-function abbreviations for the use of subclasses
+ /**
+ * Renders a parse-tree into a Yaz-style PQF string.
+ * PQF, or Prefix Query Format, is a cryptic but powerful notation
+ * that can be trivially mapped, one-to-one, int Z39.50 Type-1 and
+ * Type-101 queries. A specification for the format can be found
+ * in
+ * <A href="http://indexdata.dk/yaz/doc/tools.php#PQF"
+ * >Chapter 7 (Supporting Tools)</A> of the
+ * <A href="http://indexdata.dk/yaz/">YAZ</A> manual.
+ * <P>
+ * @param config
+ * A <TT>Properties</TT> object containing configuration
+ * information that specifies the mapping from CQL qualifiers,
+ * relations, etc. to Type-1 attributes. The mapping
+ * specification is described in the cql-java distribution's
+ * sample PQF-mapping configuration file,
+ * <TT>etc/pqf.properties</TT>, which see.
+ * @return
+ * A String containing a PQF query equivalent to the parse-tree
+ * whose root is this node. This may be fed into the tool of
+ * your choice to obtain a BER-encoded packet.
+ */
+ abstract public String toPQF(Properties config)
+ throws PQFTranslationException;
+
+ /**
+ * Returns a String of spaces for indenting to the specified level.
+ */
protected static String indent(int level) { return Utils.indent(level); }
- protected static String xq(String str) { return Utils.xq(str); }
- // Test harness
- public static void main (String[] args) {
- CQLNode n1 = new CQLTermNode("dc.author",
- new CQLRelation("="),
- "kernighan");
- CQLNode n2 = new CQLTermNode("dc.title",
- new CQLRelation("all"),
- "elements style");
- CQLNode root = new CQLAndNode(n1, n2);
- System.out.println(root.toXCQL(0));
- }
+ /**
+ * Returns the argument String quoted for XML.
+ * For example, each occurrence of <TT><</TT> is translated to
+ * <TT>&lt;</TT>.
+ */
+ protected static String xq(String str) { return Utils.xq(str); }
}