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NIFI-3206: Add ifElse function to Expression Language 

This closes #1333

Signed-off-by: jpercivall <JPercivall@apache.org>
This commit is contained in:
Matt Burgess 2016-12-15 13:12:55 -05:00 committed by jpercivall
parent 34627f78b7
commit 21ed556691
6 changed files with 112 additions and 6 deletions
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1
nifi-commons/nifi-expression-language/src/main/antlr3/org/apache/nifi/attribute/expression/language/antlr/AttributeExpressionLexer.g
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@ -182,6 +182,7 @@ SUBSTRING : 'substring';
REPLACE : 'replace';
REPLACE_FIRST : 'replaceFirst';
REPLACE_ALL : 'replaceAll';
IF_ELSE : 'ifElse';
// 4 arg functions
GET_DELIMITED_FIELD : 'getDelimitedField';

2
nifi-commons/nifi-expression-language/src/main/antlr3/org/apache/nifi/attribute/expression/language/antlr/AttributeExpressionParser.g
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@ -77,7 +77,7 @@ zeroArgString : (TO_UPPER | TO_LOWER | TRIM | TO_STRING | URL_ENCODE | URL_DECOD
oneArgString : ((SUBSTRING_BEFORE | SUBSTRING_BEFORE_LAST | SUBSTRING_AFTER | SUBSTRING_AFTER_LAST | REPLACE_NULL | REPLACE_EMPTY |
PREPEND | APPEND | FORMAT | STARTS_WITH | ENDS_WITH | CONTAINS | JOIN | JSON_PATH | FROM_RADIX) LPAREN! anyArg RPAREN!) |
(TO_RADIX LPAREN! anyArg (COMMA! anyArg)? RPAREN!);
twoArgString : ((REPLACE | REPLACE_FIRST | REPLACE_ALL) LPAREN! anyArg COMMA! anyArg RPAREN!) |
twoArgString : ((REPLACE | REPLACE_FIRST | REPLACE_ALL | IF_ELSE) LPAREN! anyArg COMMA! anyArg RPAREN!) |
(SUBSTRING LPAREN! anyArg (COMMA! anyArg)? RPAREN!);
fiveArgString : GET_DELIMITED_FIELD LPAREN! anyArg (COMMA! anyArg (COMMA! anyArg (COMMA! anyArg (COMMA! anyArg)?)?)?)? RPAREN!;

8
nifi-commons/nifi-expression-language/src/main/java/org/apache/nifi/attribute/expression/language/Query.java
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@ -54,6 +54,7 @@ import org.apache.nifi.attribute.expression.language.evaluation.functions.Greate
import org.apache.nifi.attribute.expression.language.evaluation.functions.GreaterThanOrEqualEvaluator;
import org.apache.nifi.attribute.expression.language.evaluation.functions.HostnameEvaluator;
import org.apache.nifi.attribute.expression.language.evaluation.functions.IPEvaluator;
import org.apache.nifi.attribute.expression.language.evaluation.functions.IfElseEvaluator;
import org.apache.nifi.attribute.expression.language.evaluation.functions.InEvaluator;
import org.apache.nifi.attribute.expression.language.evaluation.functions.IndexOfEvaluator;
import org.apache.nifi.attribute.expression.language.evaluation.functions.IsEmptyEvaluator;
@ -126,6 +127,7 @@ import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.tree.Tree;
import static org.apache.nifi.attribute.expression.language.antlr.AttributeExpressionParser.FROM_RADIX;
import static org.apache.nifi.attribute.expression.language.antlr.AttributeExpressionParser.IF_ELSE;
import static org.apache.nifi.attribute.expression.language.antlr.AttributeExpressionParser.MATH;
import static org.apache.nifi.attribute.expression.language.antlr.AttributeExpressionParser.ALL_ATTRIBUTES;
import static org.apache.nifi.attribute.expression.language.antlr.AttributeExpressionParser.ALL_DELINEATED_VALUES;
@ -1361,6 +1363,12 @@ public class Query {
return addToken(new JsonPathEvaluator(toStringEvaluator(subjectEvaluator),
toStringEvaluator(argEvaluators.get(0), "first argument to jsonPath")), "jsonPath");
}
case IF_ELSE: {
verifyArgCount(argEvaluators, 2, "ifElse");
return addToken(new IfElseEvaluator(toBooleanEvaluator(subjectEvaluator),
toStringEvaluator(argEvaluators.get(0), "argument to return if true"),
toStringEvaluator(argEvaluators.get(1), "argument to return if false")), "ifElse");
}
default:
throw new AttributeExpressionLanguageParsingException("Expected a Function-type expression but got " + tree.toString());
}

53
nifi-commons/nifi-expression-language/src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/IfElseEvaluator.java Normal file
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@ -0,0 +1,53 @@
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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.apache.nifi.attribute.expression.language.evaluation.functions;
import org.apache.nifi.attribute.expression.language.evaluation.Evaluator;
import org.apache.nifi.attribute.expression.language.evaluation.QueryResult;
import org.apache.nifi.attribute.expression.language.evaluation.StringEvaluator;
import org.apache.nifi.attribute.expression.language.evaluation.StringQueryResult;
import java.util.Map;
public class IfElseEvaluator extends StringEvaluator {
private final Evaluator<Boolean> subject;
private final Evaluator<String> trueEvaluator;
private final Evaluator<String> falseEvaluator;
public IfElseEvaluator(final Evaluator<Boolean> subject, final Evaluator<String> trueEvaluator, final Evaluator<String> falseEvaluator) {
this.subject = subject;
this.trueEvaluator = trueEvaluator;
this.falseEvaluator = falseEvaluator;
}
@Override
public QueryResult<String> evaluate(final Map<String, String> attributes) {
final QueryResult<Boolean> subjectValue = subject.evaluate(attributes);
if (subjectValue == null) {
return new StringQueryResult(null);
}
final String ifElseValue = (Boolean.TRUE.equals(subjectValue.getValue())) ? trueEvaluator.evaluate(attributes).getValue() : falseEvaluator.evaluate(attributes).getValue();
return new StringQueryResult(ifElseValue);
}
@Override
public Evaluator<?> getSubjectEvaluator() {
return subject;
}
}

17
nifi-commons/nifi-expression-language/src/test/java/org/apache/nifi/attribute/expression/language/TestQuery.java
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@ -1684,6 +1684,23 @@ public class TestQuery {
verifyEquals("${string:unescapeHtml4()}", attributes, "special ♣");
}
@Test
public void testIfElse() {
final Map<String, String> attributes = new HashMap<>();
verifyEquals("${attr:isNull():ifElse('a', 'b')}", attributes, "a");
verifyEquals("${attr:ifElse('a', 'b')}", attributes, "b");
attributes.put("attr", "hello");
verifyEquals("${attr:isNull():ifElse('a', 'b')}", attributes, "b");
verifyEquals("${attr:ifElse('a', 'b')}", attributes, "b");
attributes.put("attr", "true");
verifyEquals("${attr:ifElse('a', 'b')}", attributes, "a");
verifyEquals("${attr2:isNull():ifElse('a', 'b')}", attributes, "a");
verifyEquals("${literal(true):ifElse('a', 'b')}", attributes, "a");
verifyEquals("${literal(true):ifElse(false, 'b')}", attributes, "false");
}
private void verifyEquals(final String expression, final Map<String, String> attributes, final Object expectedResult) {
verifyEquals(expression,attributes, null, expectedResult);
}

37
nifi-docs/src/main/asciidoc/expression-language-guide.adoc
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@ -228,7 +228,7 @@ interpreted as literals. For example these two expressions are valid (without th
One of the most powerful features of the Expression Language is the ability to compare an attribute value against
some other value. This is used often, for example, to configure how a Processor should route data. The following
functions are used for performing boolean logic, such as comparing two values.
Each of these functions returns a value of type Boolean.
Each of these functions are designed to work on values of type Boolean.
[.function]
@ -480,6 +480,37 @@ ${filename:toLower():equals( ${filename} ):or(
[.function]
=== ifElse
*Description*: [.description]#Evaluates the first argument if the Subject evaluates to true, or the second argument
if the Subject evaluates to false.#
*Subject Type*: [.subject]#Boolean#
*Arguments*:
- [.argName]#_EvaluateIfTrue_# : [.argDesc]#The value to return if the Subject is true#
- [.argName]#_EvaluateIfFalse_# : [.argDesc]#The value to return if the Subject is false#
*Return Type*: [.returnType]#String#
*Examples*: If the "filename" attribute has the value "a brand new filename.txt", the "nullFilename" attribute has
the value null, and the "bool" attribute has the value "true", then the following expressions will provide
the following results:
.ifElse Examples
|===================================================================
| Expression | Value
| `${bool:ifElse('a','b')}` | `a`
| `${literal(true):ifElse('a','b')}` | `a`
| `${nullFilename:isNull():ifElse('file does not exist', 'located file')}` | `file does not exist`
| `${nullFilename:ifElse('found', 'not_found')}` | `not_found`
| `${filename:ifElse('found', 'not_found')}` | `not_found`
| `${filename:isNull():not():ifElse('found', 'not_found')}` | `found`
|===================================================================
@ -963,10 +994,6 @@ Expressions will provide the following results:
will return 0.
[[encode]]
== Encode/Decode Functions