feat: add option counting functions (#396)

Fixes: CLI-350

Author: toxn

src/main/java/org/apache/commons/cli/CommandLine.java

@@ -300,6 +300,45 @@ public Option[] getOptions() {
         return options.toArray(Option.EMPTY_ARRAY);
     }
 
+    /**
+     * Gets the number of times this option appears in the command line.
+     *
+     * @param option the option.
+     * @return Number of times the option is present
+     * @since 1.11.0
+     */
+    public int getOptionCount(final Option option) {
+        int result = 0;
+        for (Option opt : options) {
+            if (Objects.equals(opt, option)) {
+                ++result;
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Gets the number of times this option appears in the command line
+     *
+     * @param optionChar the character name of the option.
+     * @return Number of times the option is present
+     * @since 1.11.0
+     */
+    public int getOptionCount(final char optionChar) {
+        return getOptionCount(String.valueOf(optionChar));
+    }
+
+    /**
+     * Gets the number of times this option appears in the command line
+     *
+     * @param optionName the name of the option.
+     * @return Number of times the option is present
+     * @since 1.11.0
+     */
+    public int getOptionCount(final String optionName) {
+        return getOptionCount(resolveOption(optionName));
+    }
+
     /**
      * Gets the first argument, if any, of this option.
      *

src/test/java/org/apache/commons/cli/OptionCountTest.java

@@ -0,0 +1,59 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one or more
+  contributor license agreements.  See the NOTICE file distributed with
+  this work for additional information regarding copyright ownership.
+  The ASF licenses this file to You under the Apache License, Version 2.0
+  (the "License"); you may not use this file except in compliance with
+  the License.  You may obtain a copy of the License at
+
+      https://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+ */
+
+package org.apache.commons.cli;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class OptionCountTest {
+    private static final Option  VERBOSITY = new Option("v", "verbosity: use multiple times for more");
+    private static final Options OPTIONS   = new Options().addOption(VERBOSITY);
+
+    @Test
+    void testNoSwitch() throws ParseException {
+        final CommandLine cmdLine = new DefaultParser().parse(OPTIONS, new String[]{});
+        assertEquals(0, cmdLine.getOptionCount(VERBOSITY));
+    }
+
+    @Test
+    void testOneSwitch() throws ParseException {
+        final CommandLine cmdLine = new DefaultParser().parse(OPTIONS, new String[]{"-v"});
+        assertEquals(1, cmdLine.getOptionCount(VERBOSITY));
+        assertEquals(1, cmdLine.getOptionCount("v"));
+        assertEquals(1, cmdLine.getOptionCount('v'));
+    }
+
+    @Test
+    void testThreeSwitches() throws ParseException {
+        final CommandLine cmdLine = new DefaultParser().parse(OPTIONS, new String[]{"-v", "-v", "-v"});
+        assertEquals(3, cmdLine.getOptionCount(VERBOSITY));
+    }
+
+    @Test
+    void testThreeSwitchesCompact() throws ParseException {
+        final CommandLine cmdLine = new DefaultParser().parse(OPTIONS, new String[]{"-vvv"});
+        assertEquals(3, cmdLine.getOptionCount(VERBOSITY));
+    }
+
+    @Test
+    void testFiveSwitchesMixed() throws ParseException {
+        final CommandLine cmdLine = new DefaultParser().parse(OPTIONS, new String[]{"-v", "-vvv", "-v"});
+        assertEquals(5, cmdLine.getOptionCount(VERBOSITY));
+    }
+}