+ * 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 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 parseQuery(String qualifier, CQLRelation relation) + throws CQLParseException, IOException { + debug("in parseQuery()"); + + CQLNode term = parseTerm(qualifier, relation); + while (lexer.ttype != lexer.TT_EOF && + lexer.ttype != ')') { + if (lexer.ttype == lexer.TT_AND) { + match(lexer.TT_AND); + CQLNode term2 = parseTerm(qualifier, relation); + term = new CQLAndNode(term, term2); + } else if (lexer.ttype == lexer.TT_OR) { + match(lexer.TT_OR); + CQLNode term2 = parseTerm(qualifier, relation); + term = new CQLOrNode(term, term2); + } else if (lexer.ttype == lexer.TT_NOT) { + match(lexer.TT_NOT); + CQLNode term2 = parseTerm(qualifier, relation); + term = new CQLNotNode(term, term2); + } else if (lexer.ttype == lexer.TT_PROX) { + match(lexer.TT_PROX); + CQLProxNode proxnode = new CQLProxNode(term); + gatherProxParameters(proxnode); + CQLNode term2 = parseTerm(qualifier, relation); + proxnode.addSecondSubterm(term2); + term = (CQLNode) proxnode; + } else { + throw new CQLParseException("expected boolean, got " + + lexer.render()); + } + } + + debug("no more ops"); + return term; + } + + private CQLNode parseTerm(String qualifier, CQLRelation relation) + throws CQLParseException, IOException { + debug("in parseTerm()"); + + String word; + while (true) { + if (lexer.ttype == '(') { + debug("parenthesised term"); + match('('); + CQLNode expr = parseQuery(qualifier, relation); + match(')'); + return expr; + } else if (lexer.ttype == '>') { + match('>'); + return parsePrefix(qualifier, relation); + } + + debug("non-parenthesised term"); + word = matchSymbol("qualifier or term"); + if (!isBaseRelation()) + break; + + qualifier = word; + relation = new CQLRelation(lexer.render(lexer.ttype, false)); + match(lexer.ttype); + + while (lexer.ttype == '/') { + match('/'); + if (lexer.ttype != lexer.TT_RELEVANT && + lexer.ttype != lexer.TT_FUZZY && + lexer.ttype != lexer.TT_STEM && + lexer.ttype != lexer.TT_PHONETIC) + throw new CQLParseException("expected relation modifier, " + + "got " + lexer.render()); + relation.addModifier(lexer.sval.toLowerCase()); + match(lexer.ttype); + } + + debug("qualifier='" + qualifier + ", " + + "relation='" + relation.toCQL() + "'"); + } + + CQLTermNode node = new CQLTermNode(qualifier, relation, word); + debug("made term node " + node.toCQL()); + return node; + } + + private CQLNode parsePrefix(String qualifier, 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(qualifier, relation); + return new CQLPrefixNode(name, identifier, term); + } + + private void gatherProxParameters(CQLProxNode node) + throws CQLParseException, IOException { + for (int i = 0; i < 4; i++) { + if (lexer.ttype != '/') + return; // end of proximity parameters + + match('/'); + if (lexer.ttype != '/') { + // not an omitted default + switch (i) { + // Order should be: relation/distance/unit/ordering + // For now, use MA's: unit/relation/distance/ordering + case 0: gatherProxRelation(node); break; + case 1: gatherProxDistance(node); break; + case 2: gatherProxUnit(node); break; + case 3: gatherProxOrdering(node); break; + } + } + } + } + + private void gatherProxRelation(CQLProxNode node) + throws CQLParseException, IOException { + if (!isProxRelation()) + throw new CQLParseException("expected proximity relation, got " + + lexer.render()); + node.addModifier("relation", lexer.render(lexer.ttype, false)); + match(lexer.ttype); + debug("gPR matched " + lexer.render(lexer.ttype, false)); + } + + private void gatherProxDistance(CQLProxNode node) + throws CQLParseException, IOException { + if (lexer.ttype != lexer.TT_NUMBER) + throw new CQLParseException("expected proximity distance, got " + + lexer.render()); + node.addModifier("distance", lexer.render(lexer.ttype, false)); + match(lexer.ttype); + debug("gPD matched " + lexer.render(lexer.ttype, false)); + } + + private void gatherProxUnit(CQLProxNode node) + throws CQLParseException, IOException { + if (lexer.ttype != lexer.TT_pWORD && + lexer.ttype != lexer.TT_SENTENCE && + lexer.ttype != lexer.TT_PARAGRAPH && + lexer.ttype != lexer.TT_ELEMENT) + throw new CQLParseException("expected proximity unit, got " + + lexer.render()); + node.addModifier("unit", lexer.render()); + match(lexer.ttype); + } + + private void gatherProxOrdering(CQLProxNode node) + throws CQLParseException, IOException { + if (lexer.ttype != lexer.TT_ORDERED && + lexer.ttype != lexer.TT_UNORDERED) + throw new CQLParseException("expected proximity ordering, got " + + lexer.render()); + node.addModifier("ordering", lexer.render()); + match(lexer.ttype); + } + + private boolean isBaseRelation() { + debug("isBaseRelation: checking ttype=" + lexer.ttype + + " (" + lexer.render() + ")"); + return (isProxRelation() || + lexer.ttype == lexer.TT_ANY || + lexer.ttype == lexer.TT_ALL || + lexer.ttype == lexer.TT_EXACT || + lexer.ttype == lexer.TT_SCR); + } + + // Checks for a relation that may be used inside a prox operator + private boolean isProxRelation() { + debug("isProxRelation: checking ttype=" + lexer.ttype + + " (" + lexer.render() + ")"); + return (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, true) + ")"); + if (lexer.ttype != token) + throw new CQLParseException("expected " + + lexer.render(token, true) + + ", " + "got " + lexer.render()); + 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 + // qualifiers, 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_ANY || + lexer.ttype == lexer.TT_ALL || + lexer.ttype == lexer.TT_EXACT || + 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 || + lexer.ttype == lexer.TT_RELEVANT || + lexer.ttype == lexer.TT_FUZZY || + lexer.ttype == lexer.TT_STEM || + lexer.ttype == lexer.TT_SCR || + lexer.ttype == lexer.TT_PHONETIC) { + String symbol = (lexer.ttype == lexer.TT_NUMBER) ? + lexer.render() : lexer.sval; + match(lexer.ttype); + return symbol; + } + + throw new CQLParseException("expected " + expected + ", " + + "got " + lexer.render()); + } + + + /** + * Simple test-harness for the CQLParser class. + *
+ * 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) {
+ char mode = 'x'; // x=XCQL, c=CQL, p=PQF
+ String pfile = null;
+
+ Vector argv = new Vector();
+ for (int i = 0; i < args.length; i++) {
+ argv.add(args[i]);
+ }
+
+ if (argv.size() > 0 && argv.get(0).equals("-c")) {
+ mode = 'c';
+ argv.remove(0);
+ } else if (argv.size() > 1 && argv.get(0).equals("-p")) {
+ mode = 'p';
+ argv.remove(0);
+ pfile = (String) argv.get(0);
+ argv.remove(0);
+ }
+
+ if (argv.size() > 1) {
+ System.err.println(
+ "Usage: CQLParser [-c] [-p