Switch to enum for PicaConstants

Avoid reassignment to static fields, keep switch in parser

See #296

Author: fsteeg

metafacture-biblio/src/main/java/org/metafacture/biblio/pica/PicaConstants.java

@@ -1,4 +1,4 @@
-/* Copyright 2016,2019 Christoph Böhme and hbz
+/* Copyright 2016,2019 Christoph Böhme and others
  *
  * Licensed under the Apache License, Version 2.0 the "License";
  * you may not use this file except in compliance with the License.
@@ -13,40 +13,44 @@
  * limitations under the License.
  */
 
+package org.metafacture.biblio.pica;
+
 /**
  * Useful constants for PICA+.
  * PICA+ comes with two possible serializations:
  * a normalized one and a non-normalized.
  *
- * @author Christoph Böhme
- * @author Pascal Christoph (dr0i)
+ * @author Christoph Böhme (initial implementation)
+ * @author Pascal Christoph (dr0i) (add support for non-normalized pica+)
+ * @author Fabian Steeg (fsteeg) (switch to enum)
  *
  */
+enum PicaConstants {
+	// We use '\0' for null/empty
+	RECORD_MARKER('\u001d', '\n'), //
+	FIELD_MARKER('\u001e', '\0'), //
+	SUBFIELD_MARKER('\u001f', '$'), //
+	FIELD_END_MARKER('\n', '\n'), //
+	NO_MARKER('\0', '\0');
 
-package org.metafacture.biblio.pica;
-
-final class PicaConstants{
-    public static char RECORD_MARKER = '\u001d';
-    public static char FIELD_MARKER = '\u001e';
-    public static char SUBFIELD_MARKER = '\u001f';
-    public static char FIELD_END_MARKER = '\n';
-
-    public static void setNormalizedSerialization() {
-        RECORD_MARKER = '\u001d';
-        FIELD_MARKER = '\u001e';
-        SUBFIELD_MARKER = '\u001f';
-        FIELD_END_MARKER = '\n';
-    }
+	char normalized;
+	char nonNormalized;
 
-    public static void setNonNormalizedSerialization() {
-        RECORD_MARKER = '\n';
-        FIELD_MARKER = '\n'; //this is a dummy
-        SUBFIELD_MARKER = '$';
-        FIELD_END_MARKER = '\n';
-    }
+	PicaConstants(char normalized, char nonNormalized) {
+		this.normalized = normalized;
+		this.nonNormalized = nonNormalized;
+	}
 
-    private PicaConstants() {
-        // No instances allowed
-    }
+	public char get(boolean isNormalized) {
+		return isNormalized ? normalized : nonNormalized;
+	}
 
-}
+	public static PicaConstants from(boolean isNormalized, char ch) {
+		for (PicaConstants value : values()) {
+			if (ch == (isNormalized ? value.normalized : value.nonNormalized)) {
+				return value;
+			}
+		}
+		return NO_MARKER;
+	}
+}

metafacture-biblio/src/main/java/org/metafacture/biblio/pica/PicaDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016, 2019 Christoph Böhme and hbz
+ * Copyright 2016, 2019 Christoph Böhme and others
  *
  * Licensed under the Apache License, Version 2.0 the "License";
  * you may not use this file except in compliance with the License.
@@ -143,7 +143,8 @@
  * support other pica encodings.
  *
  * @author Christoph Böhme
- * @author Pascal Christoph (dr0i)
+ * @author Pascal Christoph (dr0i) (add support for non-normalized pica+)
+ * @author Fabian Steeg (fsteeg) (switch to enum)
  *
  */
 @Description("Parses pica+ records. The parser only parses single records. " +
@@ -167,37 +168,36 @@ public final class PicaDecoder
     private int recordLen;
 
     private boolean ignoreMissingIdn;
+    private boolean isNormalized;
 
     public PicaDecoder() {
-        makeConstants();
+        this(true);
     }
 
     public PicaDecoder(boolean normalized) {
         setNormalizedSerialization(normalized);
-        makeConstants();
     }
+
     /**
-     * Controls wether the input is serialzed as normalized or non-normalized
+     * Controls whether the input is read as normalized or non-normalized
      * pica+. As the default "normalized" is assumed.
      *
-     * @param normalized if true, the input is treated as "normalized" pica+ ;
-     *                   if false, it's treated as non-normalized serialized.
+     * @param normalized if true, the input is treated as normalized pica+ ;
+     *                   if false, it's treated as non-normalized.
      */
     public void setNormalizedSerialization(boolean normalized) {
-        if (normalized)
-            PicaConstants.setNormalizedSerialization();
-        else
-            PicaConstants.setNonNormalizedSerialization();
+        this.isNormalized = normalized;
         makeConstants();
     }
+
     private void makeConstants() {
-        START_MARKERS = "(?:^|" + PicaConstants.FIELD_MARKER + "|"
-                + PicaConstants.FIELD_END_MARKER + "|"
-                + PicaConstants.RECORD_MARKER + "|.*\n" + ")";
+        START_MARKERS = "(?:^|" + PicaConstants.FIELD_MARKER.get(isNormalized) + "|"
+                + PicaConstants.FIELD_END_MARKER.get(isNormalized) + "|"
+                + PicaConstants.RECORD_MARKER.get(isNormalized) + "|.*\n" + ")";
         ID_FIELDS_PATTERN = Pattern
                 .compile(START_MARKERS + "(?:003@|203@(?:/..+)?|107F) "
-                        + " ?(\\" + PicaConstants.SUBFIELD_MARKER + "|"
-                        + PicaConstants.SUBFIELD_MARKER + ")0");
+                        + " ?(\\" + PicaConstants.SUBFIELD_MARKER.get(isNormalized) + "|"
+                        + PicaConstants.SUBFIELD_MARKER.get(isNormalized) + ")0");
         idFieldMatcher = ID_FIELDS_PATTERN.matcher("");
     }
     /**
@@ -303,7 +303,7 @@ public void process(final String record) {
 
         PicaParserState state = PicaParserState.FIELD_NAME;
         for (int i = 0; i < recordLen; ++i) {
-            state = state.parseChar(buffer[i], parserContext);
+            state = state.parseChar(buffer[i], parserContext, isNormalized);
         }
         state.endOfInput(parserContext);
 
@@ -337,7 +337,7 @@ private String extractRecordId() {
         idBuilder.setLength(0);
         for (int i = idFromIndex; i < recordLen; ++i) {
             final char ch = buffer[i];
-            if (isSubfieldDelimiter(ch)) {
+            if (isMarker(ch)) {
                 break;
             }
             idBuilder.append(ch);
@@ -353,11 +353,8 @@ private int findRecordId() {
         return idFieldMatcher.end();
     }
 
-    private static boolean isSubfieldDelimiter(final char ch) {
-        return ch == PicaConstants.RECORD_MARKER
-                || ch == PicaConstants.FIELD_MARKER
-                || ch == PicaConstants.FIELD_END_MARKER
-                || ch == PicaConstants.SUBFIELD_MARKER;
+    private boolean isMarker(final char ch) {
+        return PicaConstants.from(isNormalized, ch) != PicaConstants.NO_MARKER;
     }
 
 }

metafacture-biblio/src/main/java/org/metafacture/biblio/pica/PicaParserState.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016,2019 Christoph Böhme and hbz
+ * Copyright 2016,2019 Christoph Böhme and others
  *
  * Licensed under the Apache License, Version 2.0 the "License";
  * you may not use this file except in compliance with the License.
@@ -25,30 +25,33 @@
  * The parser ignores spaces in field names. They are not included in the
  * field name.
  *
- * Empty subfields are skipped. For instance, parsing the following normalized 
- * pica+ would NOT produce an empty literal: 003@ \u001f\u001e. The parser also
+ * Empty subfields are skipped. For instance, parsing the following input
+ * would NOT produce an empty literal: 003@ \u001f\u001e. The parser also
  * skips unnamed fields without any subfields.
  *
  * @author Christoph Böhme
- * @author Pascal Christoph (dr0i)
- * 
+ * @author Pascal Christoph (dr0i) (add support for non-normalized pica+)
+ * @author Fabian Steeg (fsteeg) (switch to enum)
  */
 enum PicaParserState {
 
     FIELD_NAME {
         @Override
-        protected PicaParserState parseChar(final char ch, final PicaParserContext ctx) {
+        protected PicaParserState parseChar(final char ch, final PicaParserContext ctx, boolean normalized) {
             final PicaParserState next;
-            if(ch==PicaConstants.RECORD_MARKER ||
-               ch==PicaConstants.FIELD_MARKER ||
-               ch==PicaConstants.FIELD_END_MARKER){
+            switch (PicaConstants.from(normalized, ch)) {
+            case RECORD_MARKER:
+            case FIELD_MARKER:
+            case FIELD_END_MARKER:
                 ctx.emitStartEntity();
                 ctx.emitEndEntity();
                 next = FIELD_NAME;
-            }else if(ch==PicaConstants.SUBFIELD_MARKER){
+                break;
+            case SUBFIELD_MARKER:
                 ctx.emitStartEntity();
                 next = SUBFIELD_NAME;
-            }else{
+                break;
+            default:
                 ctx.appendText(ch);
                 next = this;
             }
@@ -63,16 +66,19 @@ protected void endOfInput(final PicaParserContext ctx) {
     },
     SUBFIELD_NAME {
         @Override
-        protected PicaParserState parseChar(final char ch, final PicaParserContext ctx) {
+        protected PicaParserState parseChar(final char ch, final PicaParserContext ctx, boolean normalized) {
             final PicaParserState next;
-            if(ch==PicaConstants.RECORD_MARKER ||
-               ch==PicaConstants.FIELD_MARKER ||
-               ch==PicaConstants.FIELD_END_MARKER){
+            switch (PicaConstants.from(normalized, ch)) {
+            case RECORD_MARKER:
+            case FIELD_MARKER:
+            case FIELD_END_MARKER:
                 ctx.emitEndEntity();
                 next = FIELD_NAME;
-            }else if(ch==PicaConstants.SUBFIELD_MARKER)
+                break;
+            case SUBFIELD_MARKER:
                 next = this;
-            else{
+                break;
+            default:
                 ctx.setSubfieldName(ch);
                 next = SUBFIELD_VALUE;
             }
@@ -86,18 +92,21 @@ protected void endOfInput(final PicaParserContext ctx) {
     },
     SUBFIELD_VALUE {
         @Override
-        protected PicaParserState parseChar(final char ch, final PicaParserContext ctx) {
+        protected PicaParserState parseChar(final char ch, final PicaParserContext ctx, boolean normalized) {
             final PicaParserState next;
-            if(ch==PicaConstants.RECORD_MARKER ||
-               ch==PicaConstants.FIELD_MARKER ||
-               ch==PicaConstants.FIELD_END_MARKER){
+            switch (PicaConstants.from(normalized, ch)) {
+            case RECORD_MARKER:
+            case FIELD_MARKER:
+            case FIELD_END_MARKER:
                 ctx.emitLiteral();
                 ctx.emitEndEntity();
                 next = FIELD_NAME;
-            }else if(ch==PicaConstants.SUBFIELD_MARKER){
+                break;
+            case SUBFIELD_MARKER:
                 ctx.emitLiteral();
                 next = SUBFIELD_NAME;
-            }else{
+                break;
+            default:
                 ctx.appendText(ch);
                 next = this;
             }
@@ -111,7 +120,8 @@ protected void endOfInput(final PicaParserContext ctx) {
         }
     };
 
-    protected abstract PicaParserState parseChar(final char ch, final PicaParserContext ctx);
+    protected abstract PicaParserState parseChar(final char ch, final PicaParserContext ctx, final boolean normalized);
 
     protected abstract void endOfInput(final PicaParserContext ctx);
+
 }