Add a SourceRoot.matcher(boolean) method.

The matcher returned by that method combines the effects of all includes and excludes.

Author: desruisseaux

api/maven-api-core/src/main/java/org/apache/maven/api/SourceRoot.java

@@ -19,6 +19,7 @@
 package org.apache.maven.api;
 
 import java.nio.file.Path;
+import java.nio.file.PathMatcher;
 import java.util.List;
 import java.util.Optional;
 
@@ -45,10 +46,11 @@ default Path directory() {
     }
 
     /**
-     * {@return the list of pattern matchers for the files to include}.
+     * {@return the list of patterns for the files to include}.
      * The path separator is {@code /} on all platforms, including Windows.
-     * If the pattern does not start with {@code regex:} or {@code glob:}, the default variation of
-     * the {@code glob} pattern will be used.
+     * The prefix before the {@code :} character, if present and longer than 1 character, is the syntax.
+     * If no syntax is specified, or if its length is 1 character (interpreted as a Windows drive),
+     * the default is a Maven-specific variation of the {@code "glob"} pattern.
      *
      * <p>
      * The default implementation returns an empty list, which means to apply a language-dependent pattern.
@@ -59,14 +61,24 @@ default List<String> includes() {
     }
 
     /**
-     * {@return the list of pattern matchers for the files to exclude}.
+     * {@return the list of patterns for the files to exclude}.
      * The exclusions are applied after the inclusions.
      * The default implementation returns an empty list.
      */
     default List<String> excludes() {
         return List.of();
     }
 
+    /**
+     * {@return a matcher combining the include and exclude patterns}.
+     * The matcher is absent if the includes/excludes lists are empty
+     * and {@code useDefaultExcludes} is {@code false}.
+     *
+     * @param useDefaultExcludes whether to add the default set of patterns to exclude
+     *        (mostly <abbr>SCM</abbr> files)
+     */
+    Optional<PathMatcher> matcher(boolean useDefaultExcludes);
+
     /**
      * {@return in which context the source files will be used}.
      * Not to be confused with dependency scope.

impl/maven-impl/src/main/java/org/apache/maven/impl/DefaultSourceRoot.java

@@ -19,6 +19,7 @@
 package org.apache.maven.impl;
 
 import java.nio.file.Path;
+import java.nio.file.PathMatcher;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
@@ -41,6 +42,8 @@ public final class DefaultSourceRoot implements SourceRoot {
 
     private final List<String> excludes;
 
+    private transient PathMatcher matcher, matcherWithDefaults;
+
     private final ProjectScope scope;
 
     private final Language language;
@@ -142,7 +145,7 @@ public DefaultSourceRoot(final ProjectScope scope, final Language language, fina
      * @param directory directory of the source code
      * @param includes list of patterns for the files to include, or {@code null} if unspecified
      * @param excludes list of patterns for the files to exclude, or {@code null} if unspecified
-     * */
+     */
     public DefaultSourceRoot(
             final ProjectScope scope,
             final Language language,
@@ -183,7 +186,7 @@ public Path directory() {
     }
 
     /**
-     * {@return the list of pattern matchers for the files to include}.
+     * {@return the list of patterns for the files to include}.
      */
     @Override
     @SuppressWarnings("ReturnOfCollectionOrArrayField") // Safe because unmodifiable
@@ -192,14 +195,36 @@ public List<String> includes() {
     }
 
     /**
-     * {@return the list of pattern matchers for the files to exclude}.
+     * {@return the list of patterns for the files to exclude}.
      */
     @Override
     @SuppressWarnings("ReturnOfCollectionOrArrayField") // Safe because unmodifiable
     public List<String> excludes() {
         return excludes;
     }
 
+    /**
+     * {@return a matcher combining the include and exclude patterns}.
+     *
+     * @param useDefaultExcludes whether to add <abbr>SCM</abbr> files to set of exclude patterns
+     */
+    @Override
+    public Optional<PathMatcher> matcher(boolean useDefaultExcludes) {
+        PathMatcher cached = useDefaultExcludes ? matcherWithDefaults : matcher;
+        if (cached != null) {
+            return Optional.of(cached);
+        }
+        Optional<PathMatcher> selector =
+                new PathSelector(directory(), includes(), excludes(), useDefaultExcludes).simplify();
+        cached = selector.orElse(null);
+        if (useDefaultExcludes) {
+            matcherWithDefaults = cached;
+        } else {
+            matcher = cached;
+        }
+        return selector;
+    }
+
     /**
      * {@return in which context the source files will be used}.
      */