Make it possible to build a parser by tokens

src/main/java/com/ethlo/time/Field.java

@@ -40,7 +40,8 @@ public enum Field
     HOUR(13),
     MINUTE(16),
     SECOND(19),
-    NANO(20);
+    NANO(20),
+    ZONE_OFFSET(17);
 
     private final int requiredLength;
 

src/main/java/com/ethlo/time/TimezoneOffset.java

@@ -29,6 +29,9 @@
 public class TimezoneOffset
 {
     public static final TimezoneOffset UTC = new TimezoneOffset(0, 0);
+    private static final int SECONDS_PER_HOUR = 3600;
+    private static final int SECONDS_PER_MINUTE = 60;
+    private static final int MINUTES_PER_HOUR = 60;
     private final int hours;
     private final int minutes;
 
@@ -43,6 +46,13 @@ public static TimezoneOffset ofHoursMinutes(int hours, int minutes)
         return new TimezoneOffset(hours, minutes);
     }
 
+    public static TimezoneOffset ofTotalSeconds(int seconds)
+    {
+        final int absHours = seconds / SECONDS_PER_HOUR;
+        int absMinutes = (seconds / SECONDS_PER_MINUTE) % MINUTES_PER_HOUR;
+        return ofHoursMinutes(absHours, absMinutes);
+    }
+
     public static TimezoneOffset of(ZoneOffset offset)
     {
         final int seconds = offset.getTotalSeconds();

src/main/java/com/ethlo/time/internal/LimitedCharArrayIntegerUtil.java

@@ -52,15 +52,14 @@ public static int parsePositiveInt(final String strNum, int startInclusive, int
         int result = 0;
         try
         {
-
             for (int i = startInclusive; i < endExclusive; i++)
             {
                 final char c = strNum.charAt(i);
                 if (c < ZERO || c > DIGIT_9)
                 {
                     ErrorUtil.raiseUnexpectedCharacter(strNum, i);
                 }
-                result = result * 10 + (c - ZERO);
+                result = (result * 10) + (c - ZERO);
             }
         }
         catch (StringIndexOutOfBoundsException exc)

src/main/java/com/ethlo/time/token/ConfigurableDateTimeParser.java

@@ -0,0 +1,102 @@
+package com.ethlo.time.token;
+
+/*-
+ * #%L
+ * Internet Time Utility
+ * %%
+ * Copyright (C) 2017 - 2024 Morten Haraldsen (ethlo)
+ * %%
+ * Licensed 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
+ *
+ *      http://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.
+ * #L%
+ */
+
+import static com.ethlo.time.Field.NANO;
+import static com.ethlo.time.Field.YEAR;
+
+import java.text.ParsePosition;
+
+import com.ethlo.time.DateTime;
+import com.ethlo.time.Field;
+import com.ethlo.time.TimezoneOffset;
+
+public class ConfigurableDateTimeParser implements DateTimeParser
+{
+    private final DateTimeToken[] tokens;
+
+    public ConfigurableDateTimeParser(DateTimeToken... tokens)
+    {
+        this.tokens = tokens;
+    }
+
+    public ConfigurableDateTimeParser combine(DateTimeToken... tokens)
+    {
+        return new ConfigurableDateTimeParser(combine(this.tokens, tokens));
+    }
+
+    private DateTimeToken[] combine(DateTimeToken[] a, DateTimeToken[] b)
+    {
+        final DateTimeToken[] result = new DateTimeToken[a.length + b.length];
+        System.arraycopy(a, 0, result, 0, a.length);
+        System.arraycopy(b, 0, result, a.length, b.length);
+        return result;
+    }
+
+    @Override
+    public DateTime parse(String text, ParsePosition parsePosition)
+    {
+        int fractionsLength = 0;
+        int highestOrdinal = YEAR.ordinal();
+        final int[] values = new int[]{0, 1, 1, 0, 0, 0, 0, -1};
+        for (DateTimeToken token : tokens)
+        {
+            final int index = parsePosition.getIndex();
+            final int value = token.read(text, parsePosition);
+            final Field field = token.getField();
+            if (field != null)
+            {
+                final int ordinal = field.ordinal();
+                values[ordinal] = value;
+                highestOrdinal = Math.max(ordinal, highestOrdinal);
+                if (token instanceof FractionsToken)
+                {
+                    fractionsLength = parsePosition.getIndex() - index;
+                    values[ordinal] = scale(value, fractionsLength);
+                }
+            }
+        }
+
+        return new DateTime(
+                Field.values()[Math.min(highestOrdinal, NANO.ordinal())],
+                values[Field.YEAR.ordinal()],
+                values[Field.MONTH.ordinal()],
+                values[Field.DAY.ordinal()],
+                values[Field.HOUR.ordinal()],
+                values[Field.MINUTE.ordinal()],
+                values[Field.SECOND.ordinal()],
+                values[Field.NANO.ordinal()],
+                values[Field.ZONE_OFFSET.ordinal()] != -1 ? TimezoneOffset.ofTotalSeconds(values[Field.ZONE_OFFSET.ordinal()]) : null,
+                fractionsLength
+        );
+    }
+
+    private int scale(int value, int length)
+    {
+        int pos = length;
+        while (pos < 9)
+        {
+            value *= 10;
+            pos++;
+        }
+        return value;
+    }
+}

src/main/java/com/ethlo/time/token/DateTimeParser.java

@@ -0,0 +1,30 @@
+package com.ethlo.time.token;
+
+/*-
+ * #%L
+ * Internet Time Utility
+ * %%
+ * Copyright (C) 2017 - 2024 Morten Haraldsen (ethlo)
+ * %%
+ * Licensed 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
+ *
+ *      http://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.
+ * #L%
+ */
+
+import java.text.ParsePosition;
+
+import com.ethlo.time.DateTime;
+
+public interface DateTimeParser
+{
+    DateTime parse(String text, ParsePosition parsePosition);
+}

src/main/java/com/ethlo/time/token/DateTimeToken.java

@@ -0,0 +1,32 @@
+package com.ethlo.time.token;
+
+/*-
+ * #%L
+ * Internet Time Utility
+ * %%
+ * Copyright (C) 2017 - 2024 Morten Haraldsen (ethlo)
+ * %%
+ * Licensed 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
+ * 
+ *      http://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.
+ * #L%
+ */
+
+import java.text.ParsePosition;
+
+import com.ethlo.time.Field;
+
+public interface DateTimeToken
+{
+    int read(String text, ParsePosition parsePosition);
+
+    Field getField();
+}

src/main/java/com/ethlo/time/token/DigitsToken.java

@@ -0,0 +1,53 @@
+package com.ethlo.time.token;
+
+/*-
+ * #%L
+ * Internet Time Utility
+ * %%
+ * Copyright (C) 2017 - 2024 Morten Haraldsen (ethlo)
+ * %%
+ * Licensed 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
+ * 
+ *      http://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.
+ * #L%
+ */
+
+import com.ethlo.time.Field;
+import com.ethlo.time.internal.LimitedCharArrayIntegerUtil;
+
+import java.text.ParsePosition;
+
+public class DigitsToken implements DateTimeToken
+{
+    private final Field field;
+    private final int length;
+
+    public DigitsToken(Field field, int length)
+    {
+        this.field = field;
+        this.length = length;
+    }
+
+    @Override
+    public int read(String text, ParsePosition parsePosition)
+    {
+        final int offset = parsePosition.getIndex();
+        final int end = offset + length;
+        final int value = LimitedCharArrayIntegerUtil.parsePositiveInt(text, offset, end);
+        parsePosition.setIndex(end);
+        return value;
+    }
+
+    public Field getField()
+    {
+        return field;
+    }
+}

src/main/java/com/ethlo/time/token/FourDigitToken.java

@@ -0,0 +1,31 @@
+package com.ethlo.time.token;
+
+/*-
+ * #%L
+ * Internet Time Utility
+ * %%
+ * Copyright (C) 2017 - 2024 Morten Haraldsen (ethlo)
+ * %%
+ * Licensed 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
+ *
+ *      http://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.
+ * #L%
+ */
+
+import com.ethlo.time.Field;
+
+public class FourDigitToken extends DigitsToken
+{
+    public FourDigitToken(Field field)
+    {
+        super(field, 4);
+    }
+}

src/main/java/com/ethlo/time/token/FractionsToken.java

@@ -0,0 +1,60 @@
+package com.ethlo.time.token;
+
+/*-
+ * #%L
+ * Internet Time Utility
+ * %%
+ * Copyright (C) 2017 - 2024 Morten Haraldsen (ethlo)
+ * %%
+ * Licensed 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
+ * 
+ *      http://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.
+ * #L%
+ */
+
+import static com.ethlo.time.internal.LimitedCharArrayIntegerUtil.DIGIT_9;
+import static com.ethlo.time.internal.LimitedCharArrayIntegerUtil.ZERO;
+
+import java.text.ParsePosition;
+
+import com.ethlo.time.Field;
+
+public class FractionsToken implements DateTimeToken
+{
+    @Override
+    public int read(final String text, final ParsePosition parsePosition)
+    {
+        int idx = parsePosition.getIndex();
+        final int length = text.length();
+        int value = 0;
+        while (idx < length)
+        {
+            final char c = text.charAt(idx);
+            if (c < ZERO || c > DIGIT_9)
+            {
+                break;
+            }
+            else
+            {
+                value = value * 10 + (c - ZERO);
+                idx++;
+            }
+        }
+        parsePosition.setIndex(idx);
+        return value;
+    }
+
+    @Override
+    public Field getField()
+    {
+        return Field.NANO;
+    }
+}