Share the ECI string builder of the data matrix decoder with the PDF417 decoder (#1508)

* Shared the ECI string builder of the datamatrix decoder with the PDF417 decoder

core/src/main/java/com/google/zxing/common/ECIStringBuilder.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright 2022 ZXing authors
+ *
+ * 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 com.google.zxing.common;
+
+import com.google.zxing.FormatException;
+
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Class that converts a sequence of ECIs and bytes into a string
+ *
+ * @author Alex Geller
+ */
+public final class ECIStringBuilder {
+  private StringBuilder currentBytes;
+  private StringBuilder result;
+  private Charset currentCharset = StandardCharsets.ISO_8859_1;
+
+  public ECIStringBuilder() {
+    currentBytes = new StringBuilder();
+  }
+  public ECIStringBuilder(int initialCapacity) {
+    currentBytes = new StringBuilder(initialCapacity);
+  }
+
+  /**
+   * Appends {@code value} as a byte value
+   */
+  public void append(char value) {
+    currentBytes.append((char) (value & 0xff));
+  }
+
+  /**
+   * Appends {@code value} as a byte value (not its string representation)
+   */
+  public void append(byte value) {
+    currentBytes.append((char) (value & 0xff));
+  }
+
+  /**
+   * Appends the characters in {@code value} as bytes values
+   */
+  public void append(String value) {
+    currentBytes.append(value);
+  }
+
+  /**
+   * Append the string repesentation of {@code value} (short for {@code append(String.valueOf(value))})
+   */
+  public void append(int value) {
+    append(String.valueOf(value));
+  }
+
+  public void appendECI(int value) throws FormatException {
+    encodeCurrentBytesIfAny();
+    CharacterSetECI characterSetECI = CharacterSetECI.getCharacterSetECIByValue(value);
+    if (characterSetECI == null) {
+      throw FormatException.getFormatInstance();
+    }
+    currentCharset = characterSetECI.getCharset();
+  }
+
+  private void encodeCurrentBytesIfAny() {
+    if (currentCharset.equals(StandardCharsets.ISO_8859_1)) {
+      if (currentBytes.length() > 0) {
+        if (result == null) {
+          result = currentBytes;
+          currentBytes = new StringBuilder();
+        } else {
+          result.append(currentBytes);
+          currentBytes = new StringBuilder();
+        }
+      }
+    } else if (currentBytes.length() > 0) {
+      byte[] bytes = currentBytes.toString().getBytes(StandardCharsets.ISO_8859_1);
+      currentBytes = new StringBuilder();
+      if (result == null) {
+        result = new StringBuilder(new String(bytes, currentCharset));
+      } else {
+        result.append(new String(bytes, currentCharset));
+      }
+    }
+  }
+
+  /**
+   * Appends the characters from {@code value} (unlike all other append methods of this class who append bytes)
+   */
+  public void appendCharacters(StringBuilder value) {
+    encodeCurrentBytesIfAny();
+    result.append(value);
+  }
+
+  /**
+   * Short for {@code toString().length()} (if possible, use {@link #isEmpty()} instead)
+   */
+  public int length() {
+    return toString().length();
+  }
+
+  public boolean isEmpty() {
+    return currentBytes.length() == 0 && (result == null || result.length() == 0);
+  }
+
+  @Override
+  public String toString() {
+    encodeCurrentBytesIfAny();
+    return result == null ? "" : result.toString();
+  }
+}

core/src/main/java/com/google/zxing/datamatrix/decoder/DecodedBitStreamParser.java

@@ -19,10 +19,9 @@ package com.google.zxing.datamatrix.decoder;
 import com.google.zxing.FormatException;
 import com.google.zxing.common.BitSource;
 import com.google.zxing.common.DecoderResult;
-import com.google.zxing.common.CharacterSetECI;
+import com.google.zxing.common.ECIStringBuilder;
 
 import java.nio.charset.StandardCharsets;
-import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
@@ -128,7 +127,7 @@ final class DecodedBitStreamParser {
       }
     } while (mode != Mode.PAD_ENCODE && bits.available() > 0);
     if (resultTrailer.length() > 0) {
-      result.append(resultTrailer);
+      result.appendCharacters(resultTrailer);
     }
     if (isECIencoded) {
       // Examples for this numbers can be found in this documentation of a hardware barcode scanner:
@@ -588,70 +587,4 @@ final class DecodedBitStreamParser {
     return tempVariable >= 0 ? tempVariable : tempVariable + 256;
   }
 
-  private static final class ECIStringBuilder {
-    private StringBuilder currentBytes;
-    private StringBuilder currentChars;
-    private Charset currentCharset = StandardCharsets.ISO_8859_1;
-    private String result = null;
-    private boolean hadECI = false;
-
-    private ECIStringBuilder(int initialCapacity) {
-      currentBytes = new StringBuilder(initialCapacity);
-    }
-
-    private void append(char value) {
-      currentBytes.append(value);
-    }
-
-    private void append(String value) {
-      currentBytes.append(value);
-    }
-
-    private void append(int value) {
-      currentBytes.append(value);
-    }
-
-    private void appendECI(int value) throws FormatException {
-      encodeCurrentBytesIfAny();
-      CharacterSetECI characterSetECI = CharacterSetECI.getCharacterSetECIByValue(value);
-      if (characterSetECI == null) {
-        throw FormatException.getFormatInstance(new RuntimeException("Unsupported ECI value " + value));
-      }
-      currentCharset = characterSetECI.getCharset();
-    }
-
-    private void encodeCurrentBytesIfAny() {
-      if (!hadECI) {
-        currentChars = currentBytes;
-        currentBytes = new StringBuilder();
-        hadECI = true;
-      } else if (currentBytes.length() > 0) {
-        byte[] bytes = new byte[currentBytes.length()];
-        for (int i = 0; i < bytes.length; i++) {
-          bytes[i] = (byte) (currentBytes.charAt(i) & 0xff);
-        }
-        currentChars.append(new String(bytes, currentCharset));
-        currentBytes.setLength(0);
-      }
-    }
-
-    private void append(StringBuilder value) {
-      encodeCurrentBytesIfAny();
-      currentChars.append(value);
-    }
-
-    /**
-     * returns the length of toString()
-     */
-    public int length() {
-      return toString().length();
-    }
-
-    public String toString() {
-      encodeCurrentBytesIfAny();
-      result = result == null ? currentChars.toString() : result + currentChars.toString();
-      currentChars.setLength(0);
-      return result;
-    }
-  }
 }

core/src/main/java/com/google/zxing/pdf417/decoder/DecodedBitStreamParser.java

@@ -17,14 +17,12 @@
 package com.google.zxing.pdf417.decoder;
 
 import com.google.zxing.FormatException;
-import com.google.zxing.common.CharacterSetECI;
+import com.google.zxing.common.ECIStringBuilder;
 import com.google.zxing.common.DecoderResult;
 import com.google.zxing.pdf417.PDF417ResultMetadata;
 
-import java.io.ByteArrayOutputStream;
 import java.math.BigInteger;
 import java.util.Arrays;
-import java.io.UnsupportedEncodingException;
 
 /**
  * <p>This class contains the methods for decoding the PDF417 codewords.</p>
@@ -100,7 +98,7 @@ final class DecodedBitStreamParser {
   }
 
   static DecoderResult decode(int[] codewords, String ecLevel) throws FormatException {
-    ECIOutput result = new ECIOutput(codewords.length * 2);
+    ECIStringBuilder result = new ECIStringBuilder(codewords.length * 2);
     int codeIndex = textCompaction(codewords, 1, result);
     PDF417ResultMetadata resultMetadata = new PDF417ResultMetadata();
     while (codeIndex < codewords[0]) {
@@ -205,37 +203,37 @@ final class DecodedBitStreamParser {
           codeIndex++;
           switch (codewords[codeIndex]) {
             case MACRO_PDF417_OPTIONAL_FIELD_FILE_NAME:
-              ECIOutput fileName = new ECIOutput();
+              ECIStringBuilder fileName = new ECIStringBuilder();
               codeIndex = textCompaction(codewords, codeIndex + 1, fileName);
               resultMetadata.setFileName(fileName.toString());
               break;
             case MACRO_PDF417_OPTIONAL_FIELD_SENDER:
-              ECIOutput sender = new ECIOutput();
+              ECIStringBuilder sender = new ECIStringBuilder();
               codeIndex = textCompaction(codewords, codeIndex + 1, sender);
               resultMetadata.setSender(sender.toString());
               break;
             case MACRO_PDF417_OPTIONAL_FIELD_ADDRESSEE:
-              ECIOutput addressee = new ECIOutput();
+              ECIStringBuilder addressee = new ECIStringBuilder();
               codeIndex = textCompaction(codewords, codeIndex + 1, addressee);
               resultMetadata.setAddressee(addressee.toString());
               break;
             case MACRO_PDF417_OPTIONAL_FIELD_SEGMENT_COUNT:
-              ECIOutput segmentCount = new ECIOutput();
+              ECIStringBuilder segmentCount = new ECIStringBuilder();
               codeIndex = numericCompaction(codewords, codeIndex + 1, segmentCount);
               resultMetadata.setSegmentCount(Integer.parseInt(segmentCount.toString()));
               break;
             case MACRO_PDF417_OPTIONAL_FIELD_TIME_STAMP:
-              ECIOutput timestamp = new ECIOutput();
+              ECIStringBuilder timestamp = new ECIStringBuilder();
               codeIndex = numericCompaction(codewords, codeIndex + 1, timestamp);
               resultMetadata.setTimestamp(Long.parseLong(timestamp.toString()));
               break;
             case MACRO_PDF417_OPTIONAL_FIELD_CHECKSUM:
-              ECIOutput checksum = new ECIOutput();
+              ECIStringBuilder checksum = new ECIStringBuilder();
               codeIndex = numericCompaction(codewords, codeIndex + 1, checksum);
               resultMetadata.setChecksum(Integer.parseInt(checksum.toString()));
               break;
             case MACRO_PDF417_OPTIONAL_FIELD_FILE_SIZE:
-              ECIOutput fileSize = new ECIOutput();
+              ECIStringBuilder fileSize = new ECIStringBuilder();
               codeIndex = numericCompaction(codewords, codeIndex + 1, fileSize);
               resultMetadata.setFileSize(Long.parseLong(fileSize.toString()));
               break;
@@ -276,7 +274,7 @@ final class DecodedBitStreamParser {
    * @param result    The decoded data is appended to the result.
    * @return The next index into the codeword array.
    */
-  private static int textCompaction(int[] codewords, int codeIndex, ECIOutput result) throws FormatException {
+  private static int textCompaction(int[] codewords, int codeIndex, ECIStringBuilder result) throws FormatException {
     // 2 character per codeword
     int[] textCompactionData = new int[(codewords[0] - codeIndex) * 2];
     // Used to hold the byte compaction value if there is a mode shift
@@ -353,7 +351,7 @@ final class DecodedBitStreamParser {
   private static Mode decodeTextCompaction(int[] textCompactionData,
                                            int[] byteCompactionData,
                                            int length,
-                                           ECIOutput result,
+                                           ECIStringBuilder result,
                                            Mode startMode) {
     // Beginning from an initial state
     // The default compaction mode for PDF417 in effect at the start of each symbol shall always be Text
@@ -547,7 +545,7 @@ final class DecodedBitStreamParser {
   private static int byteCompaction(int mode,
                                     int[] codewords,
                                     int codeIndex,
-                                    ECIOutput result) throws FormatException {
+                                    ECIStringBuilder result) throws FormatException {
     boolean end = false;
     
     while (codeIndex < codewords[0] && !end) {
@@ -602,7 +600,7 @@ final class DecodedBitStreamParser {
    * @param result    The decoded data is appended to the result.
    * @return The next index into the codeword array.
    */
-  private static int numericCompaction(int[] codewords, int codeIndex, ECIOutput result) throws FormatException {
+  private static int numericCompaction(int[] codewords, int codeIndex, ECIStringBuilder result) throws FormatException {
     int count = 0;
     boolean end = false;
 
@@ -697,67 +695,4 @@ final class DecodedBitStreamParser {
     return resultString.substring(1);
   }
 
-  private static final class ECIOutput {
-    private boolean needFlush = false;
-    private String encodingName = "ISO-8859-1";
-    private ByteArrayOutputStream bytes = new ByteArrayOutputStream();
-    private StringBuilder result;
-
-    private ECIOutput() {
-      result = new StringBuilder();
-    }
-
-    private ECIOutput(int size) {
-      result = new StringBuilder(size);
-    }
-
-    private void append(byte value) {
-      bytes.write(value);
-      needFlush = true;
-    }
-
-    private void append(char value) {
-      bytes.write(value & 0xff);
-      needFlush = true;
-    }
-
-    private void append(String s) {
-      for (int i = 0; i < s.length(); i++) {
-        append(s.charAt(i));
-      }
-    }
-
-    private void appendECI(int value) throws FormatException {
-      flush();
-      bytes = new ByteArrayOutputStream();
-      CharacterSetECI charsetECI = CharacterSetECI.getCharacterSetECIByValue(value);
-      if (charsetECI == null) {
-        throw FormatException.getFormatInstance();
-      }
-      encodingName = charsetECI.name();
-    }
-
-    private void flush() {
-      if (needFlush) {
-        needFlush = false;
-        try {
-          result.append(bytes.toString(encodingName));
-        } catch (UnsupportedEncodingException uee) {
-          // can't happen
-          throw new IllegalStateException(uee);
-        }
-      }
-    }
-
-    private boolean isEmpty() {
-      return !needFlush && result.length() == 0;
-    }
-
-    @Override
-    public String toString() {
-      flush();
-      return result.toString();
-    }
-  }
-
 }