[HER-1799] H3: expand 'inferred' URI options to optionally include root-page (/)

* ExtractorHTTP.java
    add property inferRootPage; if true (not the default), always consider '/' inferred from all HTTP(S) URIs
* Hop.java, LinkContext.java
    add new hop-type 'I' for inferred URIs; add corresponding LinkContext
* ExtractorImpliedURI.java
    use new 'I'nferred types

modules/src/main/java/org/archive/modules/extractor/ExtractorHTTP.java

@@ -39,6 +39,16 @@ public class ExtractorHTTP extends Extractor {
     public ExtractorHTTP() {
     }
 
+    /** should all HTTP URIs be used to infer a link to the site's root? */
+    boolean inferRootPage = false; 
+    public boolean getInferRootPage() {
+        return inferRootPage;
+    }
+    public void setInferRootPage(boolean inferRootPage) {
+        this.inferRootPage = inferRootPage;
+    }
+
+
     @Override
     protected boolean shouldProcess(CrawlURI uri) {
         if (uri.getFetchStatus() <= 0) {
@@ -57,7 +67,10 @@ public class ExtractorHTTP extends Extractor {
         addHeaderLink(curi, method.getResponseHeader("Content-Location"));
         
         // try /favicon.ico for every HTTP(S) URI
-        addOutlink(curi, "/favicon.ico", LinkContext.EMBED_MISC, Hop.EMBED);
+        addOutlink(curi, "/favicon.ico", LinkContext.INFERRED_MISC, Hop.INFERRED);
+        if(getInferRootPage()) {
+            addOutlink(curi, "/", LinkContext.INFERRED_MISC, Hop.INFERRED);
+        }
     }
 
     protected void addHeaderLink(CrawlURI curi, Header loc) {

modules/src/main/java/org/archive/modules/extractor/ExtractorImpliedURI.java

@@ -132,8 +132,8 @@ public class ExtractorImpliedURI extends Extractor {
                 try {
                     UURI src = curi.getUURI();
                     UURI target = UURIFactory.getInstance(implied);
-                    LinkContext lc = LinkContext.SPECULATIVE_MISC;
-                    Hop hop = Hop.SPECULATIVE;
+                    LinkContext lc = LinkContext.INFERRED_MISC;
+                    Hop hop = Hop.INFERRED;
                     Link out = new Link(src, target, lc, hop);
                     curi.getOutLinks().add(out);
                     numberOfLinksExtracted.incrementAndGet();

modules/src/main/java/org/archive/modules/extractor/Hop.java

@@ -48,8 +48,13 @@ public enum Hop {
     /** 
      * Referral/redirect links, like header 'Location:' on a 301/302 response. 
      */
-    REFER('R');
+    REFER('R'),
 
+    /** 
+     * Inferred/implied links -- not necessarily literally in the source 
+     * material, but deduced by convention.
+     */
+    INFERRED('I');
     
     /** The hop character for logs. */
     private char hopChar;

modules/src/main/java/org/archive/modules/extractor/LinkContext.java

@@ -28,8 +28,9 @@ import java.io.Serializable;
  * @author pjack
  */
 public abstract class LinkContext implements Serializable {
+    private static final long serialVersionUID = 1L;
+
 
-    
     /** Class for representing handy default LinkContext values. */
     private static class SimpleLinkContext extends LinkContext {
 
@@ -65,6 +66,12 @@ public abstract class LinkContext implements Serializable {
     final public static LinkContext SPECULATIVE_MISC
      = new SimpleLinkContext("=SPECULATIVE_MISC");
 
+    /** 
+     * Stand-in value for inferred urls without  other context. 
+     */
+    final public static LinkContext INFERRED_MISC
+        = new SimpleLinkContext("=INFERRED_MISC");
+    
     /** Stand-in value for prerequisite urls without other context. */
     final public static LinkContext PREREQ_MISC
      = new SimpleLinkContext("=PREREQ_MISC");