1 files changed, 151 insertions, 0 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/query/rewrite/rewriters/MisspellRewriter.java b/container-search/src/main/java/com/yahoo/search/query/rewrite/rewriters/MisspellRewriter.java
new file mode 100644
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+++ b/container-search/src/main/java/com/yahoo/search/query/rewrite/rewriters/MisspellRewriter.java
@@ -0,0 +1,151 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.query.rewrite.rewriters;
+
+import java.io.*;
+import java.util.*;
+import java.util.logging.Logger;
+
+import com.google.inject.Inject;
+import com.yahoo.component.chain.dependencies.After;
+import com.yahoo.component.chain.dependencies.Provides;
+import com.yahoo.search.query.rewrite.*;
+import com.yahoo.search.*;
+import com.yahoo.component.ComponentId;
+import com.yahoo.filedistribution.fileacquirer.FileAcquirer;
+import com.yahoo.search.query.rewrite.RewritesConfig;
+
+/**
+ * This rewriter would retrieve spell corrected query from QLAS and
+ * add it to the original query tree as equiv<br>
+ * - Features:<br>
+ *   RewritesAsEquiv flag: add rewrites to original query as equiv
+ *
+ * @author Karen Sze Wing Lee
+ */
+@After("QLAS")
+@Provides("MisspellRewriter")
+public class MisspellRewriter extends QueryRewriteSearcher {
+
+    // Flag for skipping this rewriter if the query has been rewritten
+    private final boolean SKIP_REWRITER_IF_REWRITTEN = false;
+
+    // Name of the rewriter
+    public static final String REWRITER_NAME = "MisspellRewriter";
+
+    private Logger logger = Logger.getLogger(MisspellRewriter.class.getName());
+
+    /**
+     * Constructor for MisspellRewriter
+     */
+    @Inject
+    public MisspellRewriter(ComponentId id) {
+        super(id);
+    }
+
+    /**
+     * Constructor for MisspellRewriter unit test
+     */
+    public MisspellRewriter() {
+        super();
+    }
+
+    /**
+     * Instance creation time config loading besides FSA.
+     * Empty for this rewriter
+     */
+    public boolean configure(FileAcquirer fileAcquirer,
+                             RewritesConfig config,
+                             HashMap<String, File> fileList) {
+        return true;
+    }
+
+    /**
+     * Main logic of rewriter<br>
+     * - Retrieve spell corrected query from QLAS<br>
+     * - Add spell corrected query as equiv
+     */
+    public HashMap<String, Object> rewrite(Query query,
+                                           String dictKey) throws RuntimeException {
+
+        Boolean rewritten = false;
+
+        HashMap<String, Object> result = new HashMap<>();
+        result.put(RewriterConstants.REWRITTEN, rewritten);
+        result.put(RewriterConstants.DICT_KEY, dictKey);
+
+        RewriterUtils.log(logger, query,
+                         "In MisspellRewriter");
+
+        // Retrieve flags for enabling the features
+        String qssRw = getQPConfig(query, RewriterConstants.QSS_RW);
+        String qssSugg = getQPConfig(query, RewriterConstants.QSS_SUGG);
+
+        boolean isQSSRw = false;
+        boolean isQSSSugg = false;
+
+        if(qssRw!=null) {
+            isQSSRw = qssRw.equalsIgnoreCase("true");
+        }
+        if(qssSugg!=null) {
+            isQSSSugg = qssSugg.equalsIgnoreCase("true");
+        }
+
+        // Rewrite is not enabled
+        if(!isQSSRw && !isQSSSugg) {
+            return result;
+        }
+
+        // Retrieve spell corrected query from QLAS
+        String rewrites = RewriterUtils.getSpellCorrected(query, isQSSRw, isQSSSugg);
+
+        // No rewrites
+        if(rewrites==null) {
+            RewriterUtils.log(logger, query, "No rewrite is retrieved");
+            return result;
+        } else {
+            RewriterUtils.log(logger, query, "Retrieved spell corrected query: " +
+                              rewrites);
+        }
+
+        // Adding rewrite to the query tree
+        query = RewriterFeatures.addRewritesAsEquiv(query, dictKey, rewrites, false, 0);
+
+        rewritten = true;
+        RewriterUtils.log(logger, query, "MisspellRewriter final query: " +
+                          query.toDetailString());
+
+        result.put(RewriterConstants.REWRITTEN, rewritten);
+        result.put(RewriterConstants.DICT_KEY, rewrites);
+
+        return result;
+    }
+
+    /**
+     * Get the flag which specifies whether this rewriter
+     * should be skipped if the query has been rewritten
+     *
+     * @return true if rewriter should be skipped, false
+     *         otherwise
+     */
+    public boolean getSkipRewriterIfRewritten() {
+        return SKIP_REWRITER_IF_REWRITTEN;
+    }
+
+   /**
+    * Get the name of the rewriter
+    *
+    * @return Name of the rewriter
+    */
+   public String getRewriterName() {
+       return REWRITER_NAME;
+   }
+
+   /**
+    * Get default FSA dictionary names
+    *
+    * @return Pair of FSA dictionary name and filename
+    */
+   public HashMap<String, String> getDefaultFSAs() {
+       return null;
+   }
+}