io.quarkus.vertx.http.runtime.attribute.ExchangeAttributeParser Maven / Gradle / Ivy
package io.quarkus.vertx.http.runtime.attribute;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.ServiceLoader;
import org.jboss.logging.Logger;
/**
* Attribute parser for exchange attributes. This builds an attribute from a string definition.
*
* This uses a service loader mechanism to allow additional token types to be loaded. Token definitions are loaded
* from the provided class loader.
*
*/
public class ExchangeAttributeParser {
private static final Logger log = Logger.getLogger(ExchangeAttributeParser.class);
private final List builders;
private final List wrappers;
public ExchangeAttributeParser(List wrappers) {
this(ExchangeAttributeParser.class.getClassLoader(), wrappers);
}
public ExchangeAttributeParser(final ClassLoader classLoader, List wrappers) {
this.wrappers = wrappers;
ServiceLoader loader = ServiceLoader.load(ExchangeAttributeBuilder.class, classLoader);
final List builders = new ArrayList<>();
for (ExchangeAttributeBuilder instance : loader) {
builders.add(instance);
}
//sort with the highest priority first
builders.sort(new Comparator() {
@Override
public int compare(ExchangeAttributeBuilder o1, ExchangeAttributeBuilder o2) {
return Integer.compare(o2.priority(), o1.priority());
}
});
this.builders = Collections.unmodifiableList(builders);
}
/**
* Parses the provided value string, and turns it into a list of exchange attributes.
*
* Tokens are created according to the following rules:
*
* % attributes = new ArrayList<>();
int pos = 0;
int state = 0; //0 = literal, 1 = %, 2 = %{, 3 = $, 4 = ${, 5 = %<
for (int i = 0; i < valueString.length(); ++i) {
char c = valueString.charAt(i);
switch (state) {
case 0: {
if (c == '%' || c == '$') {
if (pos != i) {
attributes.add(wrap(parseSingleToken(valueString.substring(pos, i))));
pos = i;
}
if (c == '%') {
state = 1;
} else {
state = 3;
}
}
break;
}
case 1: {
if (c == '{') {
state = 2;
} else if (c == '<') {
state = 5;
} else if (c == '%') {
//literal percent
attributes.add(wrap(new ConstantExchangeAttribute("%")));
pos = i + 1;
state = 0;
} else {
attributes.add(wrap(parseSingleToken(valueString.substring(pos, i + 1))));
pos = i + 1;
state = 0;
}
break;
}
case 2: {
if (c == '}') {
attributes.add(wrap(parseSingleToken(valueString.substring(pos, i + 1))));
pos = i + 1;
state = 0;
}
break;
}
case 3: {
if (c == '{') {
state = 4;
} else if (c == '$') {
//literal dollars
attributes.add(wrap(new ConstantExchangeAttribute("$")));
pos = i + 1;
state = 0;
} else {
attributes.add(wrap(parseSingleToken(valueString.substring(pos, i + 1))));
pos = i + 1;
state = 0;
}
break;
}
case 4: {
if (c == '}') {
attributes.add(wrap(parseSingleToken(valueString.substring(pos, i + 1))));
pos = i + 1;
state = 0;
}
break;
}
case 5: {
attributes.add(wrap(parseSingleToken(valueString.substring(pos, i + 1))));
pos = i + 1;
state = 0;
break;
}
}
}
switch (state) {
case 0:
case 1:
case 3:
case 5: {
if (pos != valueString.length()) {
attributes.add(wrap(parseSingleToken(valueString.substring(pos))));
}
break;
}
case 2:
case 4: {
throw new RuntimeException("Mismatched braces: " + valueString);
}
}
if (attributes.size() == 1) {
return attributes.get(0);
}
return new CompositeExchangeAttribute(attributes.toArray(new ExchangeAttribute[attributes.size()]));
}
public ExchangeAttribute parseSingleToken(final String token) {
for (final ExchangeAttributeBuilder builder : builders) {
ExchangeAttribute res = builder.build(token);
if (res != null) {
return res;
}
}
if (token.startsWith("%")) {
log.errorf("Unknown token %s", token);
}
return new ConstantExchangeAttribute(token);
}
private ExchangeAttribute wrap(ExchangeAttribute attribute) {
ExchangeAttribute res = attribute;
for (ExchangeAttributeWrapper w : wrappers) {
res = w.wrap(res);
}
return res;
}
}