[LIB-9] Set of entities for PGN parsing and formatting

[chesshog.git] / chesshog-format / src / main / java / org / hedgecode / chess / pgn / token / EmptyToken.java

diff --git a/chesshog-format/src/main/java/org/hedgecode/chess/pgn/token/EmptyToken.java b/chesshog-format/src/main/java/org/hedgecode/chess/pgn/token/EmptyToken.java
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+/*
+ * Copyright (c) 2018-2020. Developed by Hedgecode.
+ *
+ * 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.
+ */
+
+package org.hedgecode.chess.pgn.token;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.hedgecode.chess.pgn.PGNConstants;
+import org.hedgecode.chess.pgn.entity.Game;
+import org.hedgecode.chess.position.ParseException;
+
+/**
+ * EmptyToken
+ *
+ * @author Dmitry Samoshin aka gotty
+ */
+public class EmptyToken implements Token<Game> {
+
+    private static final String EMPTY_REGEX = "^\\s*$";
+    private static final Pattern EMPTY_PATTERN = Pattern.compile(EMPTY_REGEX, Pattern.MULTILINE);
+
+    @Override
+    public int token(Game game, String pgn) throws ParseException {
+        Matcher matcher = EMPTY_PATTERN.matcher(pgn);
+        if (!matcher.find()) {
+            throw new ParseException("parse.pgn.incorrect.empty", pgn);
+        }
+        return pgn.indexOf(PGNConstants.PGN_CRLF) + 1;
+    }
+
+}