Add prefix matching for policy version

Re-introduced regular expressions to match policy version
so that the policy version found in the metadata, which is just
the major number, can be matched with a policy's version, which
is of the form, major.minor.patch.
Simplified equals() test, as we already know "text!=null".
Added filterPrefixPred() and modified policy filter to use it when
matching versions, as it is simpler to use when matching a version
prefix.
Also added tests to PfObjectFilterTest to test each of the XxxPred()
methods.

Change-Id: I0734873f701a539e883fe25b8eecfdde60cc8b6d
Issue-ID: POLICY-1542
Signed-off-by: Jim Hahn <jrh3@att.com>

1 files changed, 67 insertions, 4 deletions

diff --git a/models-base/src/main/java/org/onap/policy/models/base/PfObjectFilter.java b/models-base/src/main/java/org/onap/policy/models/base/PfObjectFilter.java
index 35319b4fd..f4e457192 100644
--- a/models-base/src/main/java/org/onap/policy/models/base/PfObjectFilter.java
+++ b/models-base/src/main/java/org/onap/policy/models/base/PfObjectFilter.java
@@ -24,6 +24,9 @@ package org.onap.policy.models.base;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.regex.Pattern;
 
 /**
  * Interface for filtering a list of concepts.
@@ -41,14 +44,74 @@ public interface PfObjectFilter<T extends Comparable<T>> {
     public List<T> filter(final List<T> originalList);
 
     /**
-     * Check if a value matches a regular expression.
+     * Check if a value exactly equals some text.
      *
      * @param value the incoming value to check
-     * @param pattern the pattern to check against
+     * @param text the desired text to check against
      * @return match or not
      */
-    public default boolean filterString(final String value, final String pattern) {
-        return value == null || pattern == null || value.equals(pattern);
+    public default boolean filterString(final String value, final String text) {
+        return value == null || text == null || value.equals(text);
+    }
+
+    /**
+     * Gets a predicate used to filter an item in a list by exactly matching an extracted value
+     * with some text.
+     *
+     * @param text the desired text to check against, or {@code null} if to accept everything
+     * @param extractor function to extract the value, to be matched, from a list item
+     * @return a predicate to match a value from a list item
+     */
+    public default Predicate<T> filterStringPred(final String text, Function<T, String> extractor) {
+        // if null text, then everything matches
+        if (text == null) {
+            return item -> true;
+        }
+
+        return item -> text.equals(extractor.apply(item));
+    }
+
+    /**
+     * Gets a predicate used to filter an item in a list by comparing the start of an
+     * extracted value with a prefix.
+     *
+     * @param prefix the desired prefix to check against, or {@code null} if to accept
+     *        everything
+     * @param extractor function to extract the value, to be matched, from a list item
+     * @return a predicate to match a prefix with a value from a list item
+     */
+    public default Predicate<T> filterPrefixPred(final String prefix, Function<T, String> extractor) {
+        // if null prefix, then everything matches
+        if (prefix == null) {
+            return item -> true;
+        }
+
+        return item -> {
+            String value = extractor.apply(item);
+            return (value != null && value.startsWith(prefix));
+        };
+    }
+
+    /**
+     * Gets a predicate used to filter an item in a list by matching an extracted value
+     * with a regular expression.
+     *
+     * @param pattern regular expression to match, or {@code null} if to accept everything
+     * @param extractor function to extract the value, to be matched, from a list item
+     * @return a predicate to match a value from a list item using a regular expression
+     */
+    public default Predicate<T> filterRegexpPred(final String pattern, Function<T, String> extractor) {
+        // if null pattern, then everything matches
+        if (pattern == null) {
+            return item -> true;
+        }
+
+        Pattern pat = Pattern.compile(pattern);
+
+        return item -> {
+            String value = extractor.apply(item);
+            return (value != null && pat.matcher(value).matches());
+        };
     }
 
     /**