+ * The resulting parse tree may be further processed by hand (see
+ * the individual node-types' documentation for details on the
+ * data structure) or, more often, simply rendered out in the
+ * desired form using one of the back-ends. toCQL()
+ * returns a decompiled CQL query equivalent to the one that was
+ * compiled in the first place; toXCQL() returns an
+ * XML snippet representing the query; and toPQF()
+ * returns the query rendered in Index Data's Prefix Query
+ * Format.
+ *
+ * @param cql The query
+ * @return A CQLNode object which is the root of a parse
+ * tree representing the query. */
public CQLNode parse(String cql)
throws CQLParseException, IOException {
lexer = new CQLLexer(cql, LEXDEBUG);
lexer.nextToken();
- debug("about to parse_query()");
- CQLNode root = parse_query("srw.serverChoice", "=");
+ debug("about to parseQuery()");
+ CQLNode root = parseQuery("srw.serverChoice", new CQLRelation("scr"));
if (lexer.ttype != lexer.TT_EOF)
throw new CQLParseException("junk after end: " + lexer.render());
return root;
}
- private CQLNode parse_query(String qualifier, String relation)
+ private CQLNode parseQuery(String index, CQLRelation relation)
throws CQLParseException, IOException {
- debug("in parse_query()");
-
- CQLNode term = parse_term(qualifier, relation);
- while (lexer.ttype == lexer.TT_WORD) {
- String op = lexer.sval.toLowerCase();
- debug("checking op '" + op + "'");
- if (lexer.sval.equals("and")) {
- match(lexer.TT_WORD);
- CQLNode term2 = parse_term(qualifier, relation);
- term = new CQLAndNode(term, term2);
- } else if (lexer.sval.equals("or")) {
- match(lexer.TT_WORD);
- CQLNode term2 = parse_term(qualifier, relation);
- term = new CQLOrNode(term, term2);
- } else if (lexer.sval.equals("not")) {
- match(lexer.TT_WORD);
- CQLNode term2 = parse_term(qualifier, relation);
- term = new CQLNotNode(term, term2);
- } else if (lexer.sval.equals("prox")) {
- // ### Handle "prox"
+ debug("in parseQuery()");
+
+ CQLNode term = parseTerm(index, relation);
+ while (lexer.ttype != lexer.TT_EOF && lexer.ttype != ')') {
+ if (lexer.ttype == lexer.TT_AND ||
+ lexer.ttype == lexer.TT_OR ||
+ lexer.ttype == lexer.TT_NOT ||
+ lexer.ttype == lexer.TT_PROX) {
+ int type = lexer.ttype;
+ String val = lexer.sval;
+ match(type);
+ ModifierSet ms = gatherModifiers(val);
+ CQLNode term2 = parseTerm(index, relation);
+ term = ((type == lexer.TT_AND) ? new CQLAndNode(term, term2, ms) :
+ (type == lexer.TT_OR) ? new CQLOrNode (term, term2, ms) :
+ (type == lexer.TT_NOT) ? new CQLNotNode(term, term2, ms) :
+ new CQLProxNode(term, term2, ms));
} else {
- throw new CQLParseException("unrecognised boolean: '" +
- lexer.sval + "'");
+ throw new CQLParseException("expected boolean, got " +
+ lexer.render());
}
}
@@ -75,172 +84,290 @@ public class CQLParser {
return term;
}
- private CQLNode parse_term(String qualifier, String relation)
+ private ModifierSet gatherModifiers(String base)
+ throws CQLParseException, IOException {
+ debug("in gatherModifiers()");
+
+ ModifierSet ms = new ModifierSet(base);
+ while (lexer.ttype == '/') {
+ match('/');
+ if (lexer.ttype != lexer.TT_WORD)
+ throw new CQLParseException("expected modifier, "
+ + "got " + lexer.render());
+ String type = lexer.sval.toLowerCase();
+ match(lexer.ttype);
+ if (!isRelation()) {
+ // It's a simple modifier consisting of type only
+ ms.addModifier(type);
+ } else {
+ // It's a complex modifier of the form type=value
+ String comparision = lexer.render(lexer.ttype, false);
+ match(lexer.ttype);
+ String value = matchSymbol("modifier value");
+ ms.addModifier(type, comparision, value);
+ }
+ }
+
+ return ms;
+ }
+
+ private CQLNode parseTerm(String index, CQLRelation relation)
throws CQLParseException, IOException {
- debug("in parse_term()");
+ debug("in parseTerm()");
String word;
while (true) {
if (lexer.ttype == '(') {
debug("parenthesised term");
match('(');
- CQLNode expr = parse_query(qualifier, relation);
+ CQLNode expr = parseQuery(index, relation);
match(')');
return expr;
- } else if (lexer.ttype != lexer.TT_WORD && lexer.ttype != '"') {
- throw new CQLParseException("expected qualifier or term, " +
- "got " + lexer.render());
+ } else if (lexer.ttype == '>') {
+ match('>');
+ return parsePrefix(index, relation);
}
debug("non-parenthesised term");
- word = lexer.sval;
- match(lexer.ttype);
- if (!isRelation())
+ word = matchSymbol("index or term");
+ if (!isRelation() && lexer.ttype != lexer.TT_WORD)
break;
- qualifier = word;
- relation = lexer.render(false);
+ index = word;
+ String relstr = (lexer.ttype == lexer.TT_WORD ?
+ lexer.sval : lexer.render(lexer.ttype, false));
+ relation = new CQLRelation(relstr);
match(lexer.ttype);
- debug("qualifier='" + qualifier + ", relation='" + relation + "'");
+ ModifierSet ms = gatherModifiers(relstr);
+ relation.setModifiers(ms);
+ debug("index='" + index + ", " +
+ "relation='" + relation.toCQL() + "'");
}
- CQLTermNode node = new CQLTermNode(qualifier, relation, word);
- debug("made term node " + node);
+ CQLTermNode node = new CQLTermNode(index, relation, word);
+ debug("made term node " + node.toCQL());
return node;
}
- boolean isRelation() {
- // ### Also need to handle <=, >=, <>
+ private CQLNode parsePrefix(String index, CQLRelation relation)
+ throws CQLParseException, IOException {
+ debug("prefix mapping");
+
+ String name = null;
+ String identifier = matchSymbol("prefix-name");
+ if (lexer.ttype == '=') {
+ match('=');
+ name = identifier;
+ identifier = matchSymbol("prefix-identifer");
+ }
+ CQLNode term = parseQuery(index, relation);
+ return new CQLPrefixNode(name, identifier, term);
+ }
+
+ // Checks for a relation
+ private boolean isRelation() {
+ debug("isRelation: checking ttype=" + lexer.ttype +
+ " (" + lexer.render() + ")");
return (lexer.ttype == '<' ||
lexer.ttype == '>' ||
- lexer.ttype == '=');
+ lexer.ttype == '=' ||
+ lexer.ttype == lexer.TT_LE ||
+ lexer.ttype == lexer.TT_GE ||
+ lexer.ttype == lexer.TT_NE);
}
private void match(int token)
throws CQLParseException, IOException {
- debug("in match(" + lexer.render(token, null, true) + ")");
+ debug("in match(" + lexer.render(token, true) + ")");
if (lexer.ttype != token)
throw new CQLParseException("expected " +
- lexer.render(token, null, true) +
+ lexer.render(token, true) +
", " + "got " + lexer.render());
- lexer.nextToken();
+ int tmp = lexer.nextToken();
+ debug("match() got token=" + lexer.ttype + ", " +
+ "nval=" + lexer.nval + ", sval='" + lexer.sval + "'" +
+ " (tmp=" + tmp + ")");
}
+ private String matchSymbol(String expected)
+ throws CQLParseException, IOException {
+
+ debug("in matchSymbol()");
+ if (lexer.ttype == lexer.TT_WORD ||
+ lexer.ttype == lexer.TT_NUMBER ||
+ lexer.ttype == '"' ||
+ // The following is a complete list of keywords. Because
+ // they're listed here, they can be used unquoted as
+ // indexes, terms, prefix names and prefix identifiers.
+ // ### Instead, we should ask the lexer whether what we
+ // have is a keyword, and let the knowledge reside there.
+ lexer.ttype == lexer.TT_AND ||
+ lexer.ttype == lexer.TT_OR ||
+ lexer.ttype == lexer.TT_NOT ||
+ lexer.ttype == lexer.TT_PROX ||
+ lexer.ttype == lexer.TT_pWORD ||
+ lexer.ttype == lexer.TT_SENTENCE ||
+ lexer.ttype == lexer.TT_PARAGRAPH ||
+ lexer.ttype == lexer.TT_ELEMENT ||
+ lexer.ttype == lexer.TT_ORDERED ||
+ lexer.ttype == lexer.TT_UNORDERED) {
+ String symbol = (lexer.ttype == lexer.TT_NUMBER) ?
+ lexer.render() : lexer.sval;
+ match(lexer.ttype);
+ return symbol;
+ }
+
+ throw new CQLParseException("expected " + expected + ", " +
+ "got " + lexer.render());
+ }
- // Test harness.
- //
- // e.g. echo '(au=Kerninghan or au=Ritchie) and ti=Unix' |
- // java org.z3950.zing.cql.CQLParser
- // yields:
- //
+ * Reads a CQL query either from its command-line argument, if + * there is one, or standard input otherwise. So these two + * invocations are equivalent: + *
+ * CQLParser 'au=(Kerninghan or Ritchie) and ti=Unix' + * echo au=(Kerninghan or Ritchie) and ti=Unix | CQLParser + *+ * The test-harness parses the supplied query and renders is as + * XCQL, so that both of the invocations above produce the + * following output: + *
+ * <triple> + * <boolean> + * <value>and</value> + * </boolean> + * <triple> + * <boolean> + * <value>or</value> + * </boolean> + * <searchClause> + * <index>au</index> + * <relation> + * <value>=</value> + * </relation> + * <term>Kerninghan</term> + * </searchClause> + * <searchClause> + * <index>au</index> + * <relation> + * <value>=</value> + * </relation> + * <term>Ritchie</term> + * </searchClause> + * </triple> + * <searchClause> + * <index>ti</index> + * <relation> + * <value>=</value> + * </relation> + * <term>Unix</term> + * </searchClause> + * </triple> + *+ *
+ * @param -c
+ * Causes the output to be written in CQL rather than XCQL - that
+ * is, a query equivalent to that which was input, is output. In
+ * effect, the test harness acts as a query canonicaliser.
+ * @return
+ * The input query, either as XCQL [default] or CQL [if the
+ * -c option is supplied].
+ */
public static void main (String[] args) {
- if (args.length != 0) {
- System.err.println("Usage: " + args[0]);
+ char mode = 'x'; // x=XCQL, c=CQL, p=PQF
+ String pfile = null;
+
+ Vector