Following to my previous question, I subclssed CronExpression and changed getSet to be public. this method gets int type, and i have a String containing the cron expression. How do I get the info about this expression (hour\days\etc) ? what do I need to pass to getSet method? or maybe I should use another method? this is very unclear for me.
The problem with CronExpression is that even though it states it:
Provides a parser and evaluator for unix-like cron expressions.
The API is obscure and hidden under protected methods. By far it is not a general-purpose CRON expression parser. However with a few tweaks you can easily take advantage of the parsing logic:
class MyCronExpression extends CronExpression {
public MyCronExpression(String cronExpression) throws ParseException
{
super(cronExpression);
}
public TreeSet<Integer> getSeconds()
{
return super.getSet(CronExpression.SECOND);
}
public TreeSet<Integer> getMinutes()
{
return super.getSet(CronExpression.MINUTE);
}
public TreeSet<Integer> getHours()
{
return super.getSet(CronExpression.HOUR);
}
//...
}
Usage:
final MyCronExpression cronExpression = new MyCronExpression("0 30 9,12,15 * * ?");
System.out.println(cronExpression.getSeconds()); //0
System.out.println(cronExpression.getMinutes()); //30
System.out.println(cronExpression.getHours()); //9, 12, 15
You might be tempted to parse CRON expression manually using regular expressions... Here is a regex from job_scheduling_data_2_0.xsd Quartz schema:
(((([0-9]|[0-5][0-9]),)*([0-9]|[0-5][0-9]))|(([\*]|[0-9]|[0-5][0-9])(/|-)([0-9]|[0-5][0-9]))|([\?])|([\*]))[\s](((([0-9]|[0-5][0-9]),)*([0-9]|[0-5][0-9]))|(([\*]|[0-9]|[0-5][0-9])(/|-)([0-9]|[0-5][0-9]))|([\?])|([\*]))[\s](((([0-9]|[0-1][0-9]|[2][0-3]),)*([0-9]|[0-1][0-9]|[2][0-3]))|(([\*]|[0-9]|[0-1][0-9]|[2][0-3])(/|-)([0-9]|[0-1][0-9]|[2][0-3]))|([\?])|([\*]))[\s](((([1-9]|[0][1-9]|[1-2][0-9]|[3][0-1]),)*([1-9]|[0][1-9]|[1-2][0-9]|[3][0-1])(C)?)|(([1-9]|[0][1-9]|[1-2][0-9]|[3][0-1])(/|-)([1-9]|[0][1-9]|[1-2][0-9]|[3][0-1])(C)?)|(L(-[0-9])?)|(L(-[1-2][0-9])?)|(L(-[3][0-1])?)|(LW)|([1-9]W)|([1-3][0-9]W)|([\?])|([\*]))[\s](((([1-9]|0[1-9]|1[0-2]),)*([1-9]|0[1-9]|1[0-2]))|(([1-9]|0[1-9]|1[0-2])(/|-)([1-9]|0[1-9]|1[0-2]))|(((JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC),)*(JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC))|((JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)(-|/)(JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC))|([\?])|([\*]))[\s]((([1-7],)*([1-7]))|([1-7](/|-)([1-7]))|(((MON|TUE|WED|THU|FRI|SAT|SUN),)*(MON|TUE|WED|THU|FRI|SAT|SUN)(C)?)|((MON|TUE|WED|THU|FRI|SAT|SUN)(-|/)(MON|TUE|WED|THU|FRI|SAT|SUN)(C)?)|(([1-7]|(MON|TUE|WED|THU|FRI|SAT|SUN))?(L|LW)?)|(([1-7]|MON|TUE|WED|THU|FRI|SAT|SUN)#([1-7])?)|([\?])|([\*]))([\s]?(([\*])?|(19[7-9][0-9])|(20[0-9][0-9]))?| (((19[7-9][0-9])|(20[0-9][0-9]))(-|/)((19[7-9][0-9])|(20[0-9][0-9])))?| ((((19[7-9][0-9])|(20[0-9][0-9])),)*((19[7-9][0-9])|(20[0-9][0-9])))?)
Or maybe someone knows a better general-purpose CRON expression parser for Java?
Related
I am working on a project where we migrate massive number (more than 12000) views to Hadoop/Impala from Oracle. I have written a small Java utility to extract view DDL from Oracle and would like to use ANTLR4 to traverse the AST and generate an Impala-compatible view DDL statement.
The most of the work is relatively simple, only involves re-writing some Oracle specific syntax quirks to Impala style. However, I am facing an issue, where I am not sure I have the best answer yet: we have a number of special cases, where values from a date field are extracted in multiple nested function calls. For example, the following extracts the day from a Date field:
TO_NUMBER(TO_CHAR(d.R_DATE , 'DD' ))
I have an ANTLR4 grammar declared for Oracle SQL and hence get the visitor callback when it reaches TO_NUMBER and TO_CHAR as well, but I would like to have special handling for this special case.
Is not there any other way than implementing the handler method for the outer function and then resorting to manual traversal of the nested structure to see
I have something like in the generated Visitor class:
#Override
public String visitNumber_function(PlSqlParser.Number_functionContext ctx) {
// FIXME: seems to be dodgy code, can it be improved?
String functionName = ctx.name.getText();
if (functionName.equalsIgnoreCase("TO_NUMBER")) {
final int childCount = ctx.getChildCount();
if (childCount == 4) {
final int functionNameIndex = 0;
final int openRoundBracketIndex = 1;
final int encapsulatedValueIndex = 2;
final int closeRoundBracketIndex = 3;
ParseTree encapsulated = ctx.getChild(encapsulatedValueIndex);
if (encapsulated instanceof TerminalNode) {
throw new IllegalStateException("TerminalNode is found at: " + encapsulatedValueIndex);
}
String customDateConversionOrNullOnOtherType =
customDateConversionFromToNumberAndNestedToChar(encapsulated);
if (customDateConversionOrNullOnOtherType != null) {
// the child node contained our expected child element, so return the converted value
return customDateConversionOrNullOnOtherType;
}
// otherwise the child was something unexpected, signalled by null
// so simply fall-back to the default handler
}
}
// some other numeric function, default handling
return super.visitNumber_function(ctx);
}
private String customDateConversionFromToNumberAndNestedToChar(ParseTree parseTree) {
// ...
}
For anyone hitting the same issue, the way to go seems to be:
changing the grammar definition and introducing custom sub-types for
the encapsulated expression of the nested function.
Then, I it is possible to hook into the processing at precisely the desired location of the Parse tree.
Using a second custom ParseTreeVisitor that captures the values of function call and delegates back the processing of the rest of the sub-tree to the main, "outer" ParseTreeVisitor.
Once the second custom ParseTreeVisitor has finished visiting all the sub-ParseTrees I had the context information I required and all the sub-tree visited properly.
I'm reasonably proficient with Groovy insofar as my job requires, but not having a background in OOP means that some things still elude me, so apologies if some of the wording is a little off here (feel free to edit if you can make the question clearer).
I'm trying to create an overloaded method where the signature (ideally) differs only in the return type of the single Closure parameter. The Closure contains a method call that returns either an ItemResponse or ListResponse object, both of which could contain an object/objects of any type (which is the type I would like to infer).
The following code is a simplified version of what I'm trying to implement - an error handling method which takes a reference to a service call, safely attempts to resolve it, and returns the item/items from the response as appropriate:
public <T> T testMethod(Closure<ItemResponse<T>> testCall) {
testCall.call().item as T
}
public <T> List<T> testMethod(Closure<ListResponse<T>> testCall) {
testCall.call().items as T
}
Obviously this doesn't work, but is there any alternate approach/workaround that would achieve the desired outcome?
I'm trying to create an overloaded method where the signature
(ideally) differs only in the return type of the single Closure
parameter.
You cannot do that because the return type is not part of the method signature. For example, the following is not valid:
class Demo {
int doit() {}
String doit() {}
}
As mentioned by yourself and #jeffscottbrown, you can't have two methods with the same parameters but different return value. The workaround I can see here is to use a call-back closure. The return value of your testMethod would default to Object and you would provide an "unwrapper" that would the bit after the closure call (extract item or items). Try this out in your GroovyConsole:
class ValueHolder <T> {
T value
}
Closure<List<Integer>> c = {
[1]
}
Closure<ValueHolder<String>> d = {
new ValueHolder(value:'hello world')
}
Closure liu = {List l ->
l.first()
}
Closure vhsu = {ValueHolder vh ->
vh.value
}
// this is the generic method
public <T> Object testMethod(Closure<T> testCall, Closure<T> unwrapper) {
unwrapper(testCall.call()) as T
}
println testMethod(c, liu)
println testMethod(d, vhsu)
It works with both a list or a value holder.
I want to add a custom xpath extension function to the Saxon-HE transformer. This custom function should accept one or more arguments. Let's use the string concatenation analogy for concatenating one or more string arguments. Following the sample on the saxon page, i wrote the following code:
ExtensionFunction myconcat = new ExtensionFunction() {
public QName getName() {
return new QName("http://mycompany.com/", "myconcat");
}
public SequenceType getResultType() {
return SequenceType.makeSequenceType(
ItemType.STRING, OccurrenceIndicator.ONE
);
}
public net.sf.saxon.s9api.SequenceType[] getArgumentTypes() {
return new SequenceType[]{
SequenceType.makeSequenceType(
ItemType.STRING, OccurrenceIndicator.ONE_OR_MORE)};
}
public XdmValue call(XdmValue[] arguments) throws SaxonApiException {
//concatenate the strings here....
String result = "concatenated string";
return new XdmAtomicValue(result);
}
};
i have expected that the following xpath expression would work in an xsl file
<xsl:value-of select="myconcat('a','b','c','...')">
Unfortunately i got the following exception:
XPST0017: Function myconcat must have 1 argument
What is the right way of creating a custom function for this use case?
Thanks.
The standard mechanisms for creating extension functions don't allow a variable number of arguments (it's not really pukka to have such functions in the XPath view of the world - concat() is very much an exception).
You can do it by creating your own implementation of the class FunctionLibrary and adding your FunctionLibrary to the static context of the XSLT engine - but you're deep into Saxon internals if you attempt that, so be prepared for a rough ride.
I am in the process of converting some tests from Hamcrest to AssertJ. In Hamcrest I use the following snippet:
assertThat(list, either(contains(Tags.SWEETS, Tags.HIGH))
.or(contains(Tags.SOUPS, Tags.RED)));
That is, the list may be either that or that. How can I express this in AssertJ? The anyOf function (of course, any is something else than either, but that would be a second question) takes a Condition; I have implemented that myself, but it feels as if this should be a common case.
Edited:
Since 3.12.0 AssertJ provides satisfiesAnyOf which succeeds is one of the given assertion succeeds,
assertThat(list).satisfiesAnyOf(
listParam -> assertThat(listParam).contains(Tags.SWEETS, Tags.HIGH),
listParam -> assertThat(listParam).contains(Tags.SOUPS, Tags.RED)
);
Original answer:
No, this is an area where Hamcrest is better than AssertJ.
To write the following assertion:
Set<String> goodTags = newLinkedHashSet("Fine", "Good");
Set<String> badTags = newLinkedHashSet("Bad!", "Awful");
Set<String> tags = newLinkedHashSet("Fine", "Good", "Ok", "?");
// contains is statically imported from ContainsCondition
// anyOf succeeds if one of the conditions is met (logical 'or')
assertThat(tags).has(anyOf(contains(goodTags), contains(badTags)));
you need to create this Condition:
import static org.assertj.core.util.Lists.newArrayList;
import java.util.Collection;
import org.assertj.core.api.Condition;
public class ContainsCondition extends Condition<Iterable<String>> {
private Collection<String> collection;
public ContainsCondition(Iterable<String> values) {
super("contains " + values);
this.collection = newArrayList(values);
}
static ContainsCondition contains(Collection<String> set) {
return new ContainsCondition(set);
}
#Override
public boolean matches(Iterable<String> actual) {
Collection<String> values = newArrayList(actual);
for (String string : collection) {
if (!values.contains(string)) return false;
}
return true;
};
}
It might not be what you if you expect that the presence of your tags in one collection implies they are not in the other one.
Inspired by this thread, you might want to use this little repo I put together, that adapts the Hamcrest Matcher API into AssertJ's Condition API. Also includes a handy-dandy conversion shell script.
I'm wondering if it's possible to filter logs by properties of passed arguments to a specific function. To be more specific, here's where I'm starting:
_dispatcher.getLogs(callsTo("dispatchEvent", new isInstanceOf<PinEvent>()));
I'd like to further filter this by PinEvent.property = "something"
In pseudo-code, I guess it'd look like this:
_dispatcher.getLogs(callsTo("dispatchEvent", new isInstanceOf<PinEvent>("property":"something")));
Any ideas? I know I can loop through the entire log list, but that seems dirty, and I would think there'd be a better way.
Thanks :-)
You can write your own matcher and use it instead of isInstanceOf
or derive from isInstanceOf and extend this matcher with the missing functionality.
I don't know of a matcher that does this out of the box (but I must admit that I didn't yet work very much with them).
While waiting for responses I whipped this up real quick. It's probably not perfect, but it does allow you to combine an isInstanceOf with this matcher using allOf. ex:
allOf(new isInstanceOf<MyThing>(), new ContainsProperty("property", "propertyValue"));
And here's the Matcher:
class ContainsProperty extends Matcher {
final String _name;
final dynamic _value;
const ContainsProperty(String name, dynamic value):this._name = name, this._value = value;
bool matches(obj, Map matchState) {
try {
InstanceMirror objMirror = reflect(obj);
InstanceMirror propMirror = objMirror.getField(new Symbol(_name));
return propMirror.reflectee == _value;
} catch (e) {
return false;
}
}
Description describe(Description description) {
description.add("contains property \"${_name}\" with value \"${_value}\"");
}
}