--- /dev/null
+/*
+Copyright (c) 2019 James Ahlborn
+
+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.healthmarketscience.jackcess.impl;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+import static com.healthmarketscience.jackcess.impl.ByteUtil.ByteStream;
+
+/**
+ * Various constants used for creating "general" (access 1997) sort order
+ * text index entries.
+ *
+ * @author James Ahlborn
+ */
+public class General97IndexCodes extends GeneralLegacyIndexCodes
+{
+ // stash the codes in some resource files
+ private static final String CODES_FILE =
+ DatabaseImpl.RESOURCE_PATH + "index_codes_gen_97.txt";
+ private static final String EXT_MAPPINGS_FILE =
+ DatabaseImpl.RESOURCE_PATH + "index_mappings_ext_gen_97.txt";
+
+ private static final class Codes
+ {
+ /** handlers for the first 256 chars. use nested class to lazy load the
+ handlers */
+ private static final CharHandler[] _values = loadCodes(
+ CODES_FILE, FIRST_CHAR, LAST_CHAR);
+ }
+
+ private static final class ExtMappings
+ {
+ /** mappings for the rest of the chars in BMP 0. use nested class to lazy
+ load the handlers. since these codes are for single byte encodings,
+ you would think you wou;dn't need any ext codes. however, some chars
+ in the extended range have corollaries in the single byte range. this
+ array holds the mappings from the ext range to the single byte range.
+ chars without mappings go to 0. */
+ private static final short[] _values = loadMappings(
+ EXT_MAPPINGS_FILE, FIRST_EXT_CHAR, LAST_EXT_CHAR);
+ }
+
+ static final General97IndexCodes GEN_97_INSTANCE = new General97IndexCodes();
+
+ General97IndexCodes() {}
+
+ /**
+ * Returns the CharHandler for the given character.
+ */
+ @Override
+ CharHandler getCharHandler(char c)
+ {
+ if(c <= LAST_CHAR) {
+ return Codes._values[c];
+ }
+
+ // some ext chars are equivalent to single byte chars. most chars have no
+ // equivalent, and they map to 0 (which is an "ignored" char, so it all
+ // works out)
+ int extOffset = asUnsignedChar(c) - asUnsignedChar(FIRST_EXT_CHAR);
+ return Codes._values[ExtMappings._values[extOffset]];
+ }
+
+ @Override
+ void writeNonNullIndexTextValue(
+ Object value, ByteStream bout, boolean isAscending)
+ throws IOException
+ {
+ // use simplified format for 97 encoding
+ writeNonNull97IndexTextValue(value, bout, isAscending);
+ }
+
+ static short[] loadMappings(String mappingsFilePath,
+ char firstChar, char lastChar)
+ {
+ int firstCharCode = asUnsignedChar(firstChar);
+ int numMappings = (asUnsignedChar(lastChar) - firstCharCode) + 1;
+ short[] values = new short[numMappings];
+
+ BufferedReader reader = null;
+ try {
+
+ reader = new BufferedReader(
+ new InputStreamReader(
+ DatabaseImpl.getResourceAsStream(mappingsFilePath), "US-ASCII"));
+
+ // this is a sparse file with entries like <fromCode>,<toCode>
+ String mappingLine = null;
+ while((mappingLine = reader.readLine()) != null) {
+ mappingLine = mappingLine.trim();
+ if(mappingLine.length() == 0) {
+ continue;
+ }
+
+ String[] mappings = mappingLine.split(",");
+ int fromCode = Integer.parseInt(mappings[0]);
+ int toCode = Integer.parseInt(mappings[1]);
+
+ values[fromCode - firstCharCode] = (short)toCode;
+ }
+
+ } catch(IOException e) {
+ throw new RuntimeException("failed loading index mappings file " +
+ mappingsFilePath, e);
+ } finally {
+ ByteUtil.closeQuietly(reader);
+ }
+
+ return values;
+ }
+}
projects / jackcess.git / commitdiff