google-cloud-core: Optimize Date.parseDate(String)

google-cloud-clients/google-cloud-core/src/main/java/com/google/cloud/Date.java

@@ -21,15 +21,12 @@
 import java.io.Serializable;
 import java.util.Calendar;
 import java.util.Objects;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 /** Represents a Date without time, such as 2017-03-17. Date is timezone independent. */
 @BetaApi("This is going to be replaced with LocalDate from threetenbp")
 public final class Date implements Comparable<Date>, Serializable {
 
   // Date format "yyyy-mm-dd"
-  private static final Pattern FORMAT_REGEXP = Pattern.compile("(\\d\\d\\d\\d)-(\\d\\d)-(\\d\\d)");
   private static final long serialVersionUID = 8067099123096783929L;
   private final int year;
   private final int month;
@@ -57,13 +54,14 @@ public static Date fromYearMonthDay(int year, int month, int dayOfMonth) {
 
   /** @param date Data in RFC 3339 date format (yyyy-mm-dd). */
   public static Date parseDate(String date) {
-    Matcher matcher = FORMAT_REGEXP.matcher(date);
-    if (!matcher.matches()) {
-      throw new IllegalArgumentException("Invalid date: " + date);
-    }
-    int year = Integer.parseInt(matcher.group(1));
-    int month = Integer.parseInt(matcher.group(2));
-    int dayOfMonth = Integer.parseInt(matcher.group(3));
+    Preconditions.checkNotNull(date);
+    final String invalidDate = "Invalid date: " + date;
+    Preconditions.checkArgument(date.length() == 10, invalidDate);
+    Preconditions.checkArgument(date.charAt(4) == '-', invalidDate);
+    Preconditions.checkArgument(date.charAt(7) == '-', invalidDate);
+    int year = Integer.parseInt(date.substring(0, 4));
+    int month = Integer.parseInt(date.substring(5, 7));
+    int dayOfMonth = Integer.parseInt(date.substring(8, 10));
     return new Date(year, month, dayOfMonth);
   }
 

google-cloud-clients/google-cloud-core/src/test/java/com/google/cloud/DateTest.java

@@ -18,6 +18,7 @@
 
 import static com.google.common.testing.SerializableTester.reserializeAndAssert;
 import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.fail;
 
 import com.google.common.testing.EqualsTester;
 import java.text.ParseException;
@@ -34,10 +35,51 @@ public class DateTest {
 
   @Test
   public void parseDate() {
-    Date date = Date.parseDate("2016-09-18");
-    assertThat(date.getYear()).isEqualTo(2016);
-    assertThat(date.getMonth()).isEqualTo(9);
-    assertThat(date.getDayOfMonth()).isEqualTo(18);
+    verifyDate("2016-09-18", 2016, 9, 18);
+    verifyDate("2000-01-01", 2000, 1, 1);
+    verifyDate("9999-12-31", 9999, 12, 31);
+    verifyDate("0001-01-01", 1, 1, 1);
+    verifyDate("2000-02-29", 2000, 2, 29); // This is a valid leap year.
+    verifyDate("1900-02-29", 1900, 2, 29); // This is NOT a valid leap year.
+    verifyDate("2001-02-29", 2001, 2, 29); // Also not a valid leap year.
+    verifyDate("2000-04-31", 2000, 4, 31); // Not a valid date.
+  }
+
+  private void verifyDate(String input, int year, int month, int day) {
+    Date date = Date.parseDate(input);
+    assertThat(date.getYear()).isEqualTo(year);
+    assertThat(date.getMonth()).isEqualTo(month);
+    assertThat(date.getDayOfMonth()).isEqualTo(day);
+  }
+
+  @Test
+  public void parseInvalidDates() {
+    parseInvalidDate("2016/09/18");
+    parseInvalidDate("2016 09 18");
+    parseInvalidDate("2016-9-18");
+    parseInvalidDate("2016-09-18T10:00");
+    parseInvalidDate("");
+    parseInvalidDate("test");
+    parseInvalidDate("aaaa-bb-cc");
+    parseInvalidDate("aaaa-01-01");
+    parseInvalidDate("2019-bb-01");
+    parseInvalidDate("2019-01-cc");
+    parseInvalidDate("2000-13-01");
+    parseInvalidDate("2000-12-32");
+    parseInvalidDate("10000-01-01");
+    parseInvalidDate("0000-01-01");
+    parseInvalidDate("-001-01-01");
+    parseInvalidDate("0001--1-01");
+    parseInvalidDate("0001-01--1");
+  }
+
+  private void parseInvalidDate(String input) {
+    try {
+      Date.parseDate(input);
+      fail("Expected exception");
+    } catch (IllegalArgumentException e) {
+      // Ignore, this is the expected exception.
+    }
   }
 
   @Test