[Mulgara-svn] r599 - branches/mgr-61-sparql/src/jar/sparql/java/org/mulgara/sparql

[pag at mulgara.org]

Author: pag
Date: 2007-12-04 15:41:42 -0600 (Tue, 04 Dec 2007)
New Revision: 599

Added:
   branches/mgr-61-sparql/src/jar/sparql/java/org/mulgara/sparql/SparqlInterpreter.java
Log:
Adding an interpreter class to convert strings into CSTs and then ASTs

Added: branches/mgr-61-sparql/src/jar/sparql/java/org/mulgara/sparql/SparqlInterpreter.java
===================================================================
--- branches/mgr-61-sparql/src/jar/sparql/java/org/mulgara/sparql/SparqlInterpreter.java	2007-12-04 21:40:59 UTC (rev 598)
+++ branches/mgr-61-sparql/src/jar/sparql/java/org/mulgara/sparql/SparqlInterpreter.java	2007-12-04 21:41:42 UTC (rev 599)
@@ -0,0 +1,86 @@
+/**
+ * The contents of this file are subject to the Open Software License
+ * Version 3.0 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.opensource.org/licenses/osl-3.0.txt
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ */
+package org.mulgara.sparql;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.mulgara.parser.Interpreter;
+import org.mulgara.parser.MulgaraLexerException;
+import org.mulgara.parser.MulgaraParserException;
+import org.mulgara.query.Query;
+import org.mulgara.query.operation.Command;
+import org.mulgara.sparql.compiler.ExpressionParser;
+import org.mulgara.sparql.compiler.ExpressionScanner;
+import org.mulgara.sparql.cst.SelectQuery;
+import org.mulgara.sparql.cst.SparqlQuery;
+
+import beaver.Parser;
+
+/**
+ * Interpreter for SPARQL queries.
+ * 
+ * @created December 4, 2007
+ * @author Paul Gearon
+ * @copyright &copy; 2007 <a href="mailto:pgearon at users.sourceforge.net">Paul Gearon</a>
+ * @licence <a href="{@docRoot}/../../LICENCE.txt">Open Software License v3.0</a>
+ */
+public class SparqlInterpreter implements Interpreter {
+
+  /**
+   * @see org.mulgara.parser.Interpreter#parseCommand(java.lang.String)
+   */
+  public Command parseCommand(String command) throws MulgaraParserException, MulgaraLexerException, IllegalArgumentException, IOException {
+    ExpressionParser parser = new ExpressionParser();
+    ExpressionScanner input = new ExpressionScanner(new StringReader(command));
+    SparqlQuery cmdNode; 
+    try {
+      cmdNode = (SparqlQuery)parser.parse(input);
+    } catch (Parser.Exception e) {
+      throw new MulgaraParserException("Error parsing: " + e.getMessage(), e);
+    }
+    // double-dispatch into this command so that it invokes the correct method in this class
+    return cmdNode.accept(this);
+  }
+
+  /**
+   * Only handles a single query
+   * @see org.mulgara.parser.Interpreter#parseCommands(java.lang.String)
+   */
+  public List<Command> parseCommands(String command) throws MulgaraParserException, MulgaraLexerException, IOException, IllegalArgumentException {
+    List<Command> result = new ArrayList<Command>();
+    result.add(parseCommand(command));
+    return result;
+  }
+
+  /**
+   * Parses a query.  Throws an exception if the string results in some other type of command.
+   * @see org.mulgara.parser.Interpreter#parseQuery(java.lang.String)
+   */
+  public Query parseQuery(String queryString) throws IOException, MulgaraLexerException, MulgaraParserException {
+    Command cmd = parseCommand(queryString);
+    if (!cmd.isAnswerable()) throw new MulgaraParserException("Not a valid query [" + cmd.getClass().getSimpleName() + "]: " + queryString);
+    return (Query)cmd;
+  }
+
+  public Command visit(SelectQuery select) {
+    // TODO:
+    return null;
+  }
+
+// TODO  
+//  public void visit(DescribeQuery describe) {
+// 
+//  }
+}