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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.document.predicate;
import com.yahoo.document.predicate.parser.PredicateLexer;
import com.yahoo.document.predicate.parser.PredicateParser;
import com.yahoo.text.Ascii;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import java.nio.charset.StandardCharsets;
/**
* @author <a href="mailto:simon@yahoo-inc.com">Simon Thoresen Hult</a>
*/
public abstract class Predicate implements Cloneable {
private final static char QUOTE_CHAR = '\'';
private final static Ascii.Encoder ASCII_ENCODER = Ascii.newEncoder(StandardCharsets.UTF_8, QUOTE_CHAR);
private final static Ascii.Decoder ASCII_DECODER = Ascii.newDecoder(StandardCharsets.UTF_8);
@Override
public Predicate clone() throws CloneNotSupportedException {
return (Predicate)super.clone();
}
@Override
public final String toString() {
StringBuilder out = new StringBuilder();
appendTo(out);
return out.toString();
}
protected abstract void appendTo(StringBuilder out);
protected static void appendQuotedTo(String str, StringBuilder out) {
String encoded = asciiEncode(str);
if (requiresQuote(encoded)) {
out.append(QUOTE_CHAR).append(encoded).append(QUOTE_CHAR);
} else {
out.append(str);
}
}
private static boolean requiresQuote(String str) {
for (int i = 0, len = str.length(); i < len; i = str.offsetByCodePoints(i, 1)) {
int c = str.codePointAt(i);
if (c == Ascii.ESCAPE_CHAR || !Character.isLetterOrDigit(c)) {
return true;
}
}
return false;
}
public static String asciiEncode(String str) {
return ASCII_ENCODER.encode(str);
}
public static String asciiDecode(String str) {
return ASCII_DECODER.decode(str);
}
public static Predicate fromBinary(byte[] buf) {
return BinaryFormat.decode(buf);
}
public static Predicate fromString(String str) {
ANTLRStringStream input = new ANTLRStringStream(str);
PredicateLexer lexer = new PredicateLexer(input);
CommonTokenStream tokens = new CommonTokenStream(lexer);
PredicateParser parser = new PredicateParser(tokens);
try {
return parser.predicate();
} catch (RecognitionException e) {
throw new IllegalArgumentException(e);
}
}
}
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