/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.script.expression;
import org.apache.lucene.expressions.Expression;
import org.apache.lucene.expressions.SimpleBindings;
import org.apache.lucene.expressions.js.JavascriptCompiler;
import org.apache.lucene.expressions.js.VariableContext;
import org.apache.lucene.queries.function.ValueSource;
import org.apache.lucene.queries.function.valuesource.DoubleConstValueSource;
import org.apache.lucene.search.SortField;
import org.elasticsearch.SpecialPermission;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.index.fielddata.IndexFieldData;
import org.elasticsearch.index.fielddata.IndexNumericFieldData;
import org.elasticsearch.index.mapper.GeoPointFieldMapper.GeoPointFieldType;
import org.elasticsearch.index.mapper.DateFieldMapper;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.mapper.MapperService;
import org.elasticsearch.script.ClassPermission;
import org.elasticsearch.script.CompiledScript;
import org.elasticsearch.script.ExecutableScript;
import org.elasticsearch.script.ScriptEngine;
import org.elasticsearch.script.ScriptException;
import org.elasticsearch.script.SearchScript;
import org.elasticsearch.search.lookup.SearchLookup;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* Provides the infrastructure for Lucene expressions as a scripting language for Elasticsearch. Only
* {@link SearchScript}s are supported.
*/
public class ExpressionScriptEngine extends AbstractComponent implements ScriptEngine {
public static final String NAME = "expression";
public ExpressionScriptEngine(Settings settings) {
super(settings);
}
@Override
public String getType() {
return NAME;
}
@Override
public String getExtension() {
return NAME;
}
@Override
public Object compile(String scriptName, String scriptSource, Map<String, String> params) {
// classloader created here
final SecurityManager sm = System.getSecurityManager();
SpecialPermission.check();
return AccessController.doPrivileged(new PrivilegedAction<Expression>() {
@Override
public Expression run() {
try {
// snapshot our context here, we check on behalf of the expression
AccessControlContext engineContext = AccessController.getContext();
ClassLoader loader = getClass().getClassLoader();
if (sm != null) {
loader = new ClassLoader(loader) {
@Override
protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
try {
engineContext.checkPermission(new ClassPermission(name));
} catch (SecurityException e) {
throw new ClassNotFoundException(name, e);
}
return super.loadClass(name, resolve);
}
};
}
// NOTE: validation is delayed to allow runtime vars, and we don't have access to per index stuff here
return JavascriptCompiler.compile(scriptSource, JavascriptCompiler.DEFAULT_FUNCTIONS, loader);
} catch (ParseException e) {
throw convertToScriptException("compile error", scriptSource, scriptSource, e);
}
}
});
}
@Override
public SearchScript search(CompiledScript compiledScript, SearchLookup lookup, @Nullable Map<String, Object> vars) {
Expression expr = (Expression)compiledScript.compiled();
MapperService mapper = lookup.doc().mapperService();
// NOTE: if we need to do anything complicated with bindings in the future, we can just extend Bindings,
// instead of complicating SimpleBindings (which should stay simple)
SimpleBindings bindings = new SimpleBindings();
ReplaceableConstDoubleValueSource specialValue = null;
boolean needsScores = false;
for (String variable : expr.variables) {
try {
if (variable.equals("_score")) {
bindings.add(new SortField("_score", SortField.Type.SCORE));
needsScores = true;
} else if (variable.equals("_value")) {
specialValue = new ReplaceableConstDoubleValueSource();
bindings.add("_value", specialValue);
// noop: _value is special for aggregations, and is handled in ExpressionScriptBindings
// TODO: if some uses it in a scoring expression, they will get a nasty failure when evaluating...need a
// way to know this is for aggregations and so _value is ok to have...
} else if (vars != null && vars.containsKey(variable)) {
// TODO: document and/or error if vars contains _score?
// NOTE: by checking for the variable in vars first, it allows masking document fields with a global constant,
// but if we were to reverse it, we could provide a way to supply dynamic defaults for documents missing the field?
Object value = vars.get(variable);
if (value instanceof Number) {
bindings.add(variable, new DoubleConstValueSource(((Number) value).doubleValue()).asDoubleValuesSource());
} else {
throw new ParseException("Parameter [" + variable + "] must be a numeric type", 0);
}
} else {
String fieldname = null;
String methodname = null;
String variablename = "value"; // .value is the default for doc['field'], its optional.
boolean dateAccessor = false; // true if the variable is of type doc['field'].date.xxx
VariableContext[] parts = VariableContext.parse(variable);
if (parts[0].text.equals("doc") == false) {
throw new ParseException("Unknown variable [" + parts[0].text + "]", 0);
}
if (parts.length < 2 || parts[1].type != VariableContext.Type.STR_INDEX) {
throw new ParseException("Variable 'doc' must be used with a specific field like: doc['myfield']", 3);
} else {
fieldname = parts[1].text;
}
if (parts.length == 3) {
if (parts[2].type == VariableContext.Type.METHOD) {
methodname = parts[2].text;
} else if (parts[2].type == VariableContext.Type.MEMBER) {
variablename = parts[2].text;
} else {
throw new IllegalArgumentException("Only member variables or member methods may be accessed on a field when not accessing the field directly");
}
}
if (parts.length > 3) {
// access to the .date "object" within the field
if (parts.length == 4 && ("date".equals(parts[2].text) || "getDate".equals(parts[2].text))) {
if (parts[3].type == VariableContext.Type.METHOD) {
methodname = parts[3].text;
dateAccessor = true;
} else if (parts[3].type == VariableContext.Type.MEMBER) {
variablename = parts[3].text;
dateAccessor = true;
}
}
if (!dateAccessor) {
throw new IllegalArgumentException("Variable [" + variable + "] does not follow an allowed format of either doc['field'] or doc['field'].method()");
}
}
MappedFieldType fieldType = mapper.fullName(fieldname);
if (fieldType == null) {
throw new ParseException("Field [" + fieldname + "] does not exist in mappings", 5);
}
IndexFieldData<?> fieldData = lookup.doc().fieldDataService().getForField(fieldType);
// delegate valuesource creation based on field's type
// there are three types of "fields" to expressions, and each one has a different "api" of variables and methods.
final ValueSource valueSource;
if (fieldType instanceof GeoPointFieldType) {
// geo
if (methodname == null) {
valueSource = GeoField.getVariable(fieldData, fieldname, variablename);
} else {
valueSource = GeoField.getMethod(fieldData, fieldname, methodname);
}
} else if (fieldType instanceof DateFieldMapper.DateFieldType) {
if (dateAccessor) {
// date object
if (methodname == null) {
valueSource = DateObject.getVariable(fieldData, fieldname, variablename);
} else {
valueSource = DateObject.getMethod(fieldData, fieldname, methodname);
}
} else {
// date field itself
if (methodname == null) {
valueSource = DateField.getVariable(fieldData, fieldname, variablename);
} else {
valueSource = DateField.getMethod(fieldData, fieldname, methodname);
}
}
} else if (fieldData instanceof IndexNumericFieldData) {
// number
if (methodname == null) {
valueSource = NumericField.getVariable(fieldData, fieldname, variablename);
} else {
valueSource = NumericField.getMethod(fieldData, fieldname, methodname);
}
} else {
throw new ParseException("Field [" + fieldname + "] must be numeric, date, or geopoint", 5);
}
needsScores |= valueSource.getSortField(false).needsScores();
bindings.add(variable, valueSource.asDoubleValuesSource());
}
} catch (Exception e) {
// we defer "binding" of variables until here: give context for that variable
throw convertToScriptException("link error", expr.sourceText, variable, e);
}
}
return new ExpressionSearchScript(compiledScript, bindings, specialValue, needsScores);
}
/**
* converts a ParseException at compile-time or link-time to a ScriptException
*/
private ScriptException convertToScriptException(String message, String source, String portion, Throwable cause) {
List<String> stack = new ArrayList<>();
stack.add(portion);
StringBuilder pointer = new StringBuilder();
if (cause instanceof ParseException) {
int offset = ((ParseException) cause).getErrorOffset();
for (int i = 0; i < offset; i++) {
pointer.append(' ');
}
}
pointer.append("^---- HERE");
stack.add(pointer.toString());
throw new ScriptException(message, cause, stack, source, NAME);
}
@Override
public ExecutableScript executable(CompiledScript compiledScript, Map<String, Object> vars) {
return new ExpressionExecutableScript(compiledScript, vars);
}
@Override
public void close() {}
@Override
public boolean isInlineScriptEnabled() {
return true;
}
}