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general components and objects to use the Sling API
package com.composum.sling.core.util;
import org.apache.commons.lang3.StringUtils;
import org.apache.sling.api.resource.ValueMap;
import org.apache.sling.api.wrappers.ValueMapDecorator;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.nio.charset.StandardCharsets;
import java.util.Formatter;
import java.util.Locale;
import java.util.Map;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
/**
* replace all '${key}' elements in the stream by their values from the value map;
* escape '$' and '\' with a prepended '\'
* - a key '${resource:/a/path/to/resource} is replaced by the content of the resource loaded by the class loader
* - if a value is a Reader the content of the reader is copied as value; caution a reader object can be read only once
* - a key can contain a format string (${name;format}); in this case the embedded value is formatted (@see #java.util.Formatter)
*/
public class ValueEmbeddingReader extends Reader {
private static final Logger LOG = LoggerFactory.getLogger(ValueEmbeddingReader.class);
public static final String TYPE_RESOURCE = "resource";
public static final char PATH_SEPARATOR = '/';
public static final char MEMBER_SEPARATOR = '.';
public static final char TYPE_SEPARATOR = ':';
public static final char FORMAT_SEPARATOR = ';';
public static final int BUFSIZE = 1024;
public static class Key {
public String type = null;
public final String name;
public final String format;
public final String pattern;
public Key(String key) {
pattern = key;
int typeSep = key.indexOf(TYPE_SEPARATOR);
if (typeSep > 0) {
int pathSep = key.indexOf(PATH_SEPARATOR);
if (pathSep < 0 || pathSep > typeSep) {
int memberSep = key.indexOf(MEMBER_SEPARATOR);
if (memberSep < 0 || memberSep > typeSep) {
type = key.substring(0, typeSep);
key = key.substring(typeSep + 1);
}
}
}
int formatSep = key.indexOf(FORMAT_SEPARATOR);
if (formatSep > 0) {
name = key.substring(0, formatSep);
format = key.substring(formatSep + 1);
} else {
name = key;
format = null;
}
}
@Override
public String toString() {
return pattern;
}
}
protected final Reader reader;
protected final ValueMap values;
protected final Locale locale;
protected final Class resourceContext;
protected final ResourceBundle resourceBundle;
protected boolean keepUnresolvable = false;
protected boolean eof = false;
protected char[] buf = new char[BUFSIZE * 2]; // reserve place for values (max length: BUFSIZE)
protected int off = 0;
protected int len = 0;
private transient Reader embed;
/**
* @param reader the text to read - probably with embedded value placeholders
* @param values the set of available placeholders
*/
public ValueEmbeddingReader(@NotNull Reader reader, @NotNull Map values) {
this(reader, values, null, null, null);
}
/**
* @param reader the text to read - probably with embedded value placeholders
* @param values the set of available placeholders
* @param locale the locale to use for value formatting
* @param resourceContext the context class for resource loading
*/
public ValueEmbeddingReader(@NotNull Reader reader, @NotNull Map values,
@Nullable Locale locale, @Nullable Class resourceContext) {
this(reader, values, locale, resourceContext, null);
}
/**
* @param reader the text to read - probably with embedded value placeholders
* @param values the set of available placeholders
* @param locale the locale to use for value formatting
* @param resourceContext the context class for resource loading
* @param resourceBundle the translations bundle (switches translation on)
*/
public ValueEmbeddingReader(@NotNull Reader reader, @NotNull Map values,
@Nullable Locale locale, @Nullable Class resourceContext,
@Nullable ResourceBundle resourceBundle) {
this.reader = reader;
this.values = values instanceof ValueMap ? ((ValueMap) values) : new ValueMapDecorator(values);
this.locale = locale != null ? locale : Locale.getDefault();
this.resourceContext = resourceContext != null ? resourceContext : values.getClass();
this.resourceBundle = resourceBundle;
}
public boolean isKeepUnresolvable(final boolean... decision) {
return decision.length > 0 ? (keepUnresolvable = decision[0]) : keepUnresolvable;
}
protected void embedKey(Key key) {
embed = new StringReader(keepUnresolvable ? ("${" + key + "}") : "");
}
@Override
public void close() throws IOException {
reader.close();
}
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
if (embed != null) {
if (this.len > 0) { // flush buffer before embedding a reader
return copy(cbuf, off, len);
}
int count = embed.read(cbuf, off, len); // embed a readers content
if (count >= 0) {
return count;
}
embed.close(); // stop embedding on readers EOF
embed = null;
}
if (this.len < len && !eof) {
load();
}
if (this.len < 1) {
return -1;
}
return copy(cbuf, off, len);
}
protected int copy(char[] cbuf, int off, int len) {
int count = Math.min(this.len, len);
if (count > 0) {
System.arraycopy(this.buf, this.off, cbuf, off, count);
this.off += count;
this.len -= count;
}
return count;
}
protected void load() throws IOException {
if (off > 0) {
System.arraycopy(buf, off, buf, 0, len);
off = 0;
}
while (!eof && len < BUFSIZE) {
int token = reader.read();
if (token < 0) {
eof = true;
} else if (token == '\\') { // escaped '$' or '\'?
int next = reader.read();
if (next < 0) {
buf[len++] = '\\';
eof = true;
} else {
if (next != '\\' && next != '$') {
buf[len++] = '\\';
}
buf[len++] = (char) next;
}
} else if (token == '$') { // '${...} ?
int next = reader.read();
if (next < 0) {
buf[len++] = '$';
eof = true;
} else {
if (next == '{') {
StringBuilder keyBuffer = new StringBuilder();
while (!eof && (next = reader.read()) != '}') {
if (next < 0) {
eof = true;
} else {
keyBuffer.append((char) next);
}
}
if (!eof) {
Key key = new Key(keyBuffer.toString().trim());
if (TYPE_RESOURCE.equals(key.type)) {
if (resourceContext != null) {
InputStream stream = resourceContext.getResourceAsStream(key.name);
if (stream != null) {
// recursive embedding of a resource file with the given value set
embed = new ValueEmbeddingReader(
new InputStreamReader(stream, StandardCharsets.UTF_8),
values, locale, resourceContext, resourceBundle);
return; // stop buffering up to the end of the embedded reader
} else {
LOG.warn("resource '{}' not available; probably invalid context ({})", key.name, resourceContext.getName());
}
}
embedKey(key);
return; // stop buffering up to the end of the embedded reader
} else {
Object value = values.get(key.name);
if (value == null && resourceBundle != null) {
try {
value = resourceBundle.getString(key.name);
} catch (MissingResourceException mrex) {
value = key.name;
}
}
if (value instanceof Reader) {
// recursive embedding of a reader object with the given value set
embed = new ValueEmbeddingReader((Reader) value, values,
locale, resourceContext, resourceBundle);
return; // stop buffering up to the end of the embedded reader
} else if (value != null) {
String string;
if (StringUtils.isNotBlank(key.format)) {
StringBuilder builder = new StringBuilder();
Formatter formatter = new Formatter(builder);
formatter.format(locale, key.format, value);
string = builder.toString();
} else {
string = value.toString();
}
string.getChars(0, string.length(), buf, len);
len += string.length();
} else {
embedKey(key);
return; // stop buffering up to the end of the embedded reader
}
}
} else {
buf[len++] = '$';
buf[len++] = '{';
keyBuffer.getChars(0, keyBuffer.length(), buf, len);
len += keyBuffer.length();
}
} else {
buf[len++] = '$';
buf[len++] = (char) next;
}
}
} else {
buf[len++] = (char) token;
}
}
}
}
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