I have a simple rule in ANTLR:
title returns [ElementVector<Element> v]
#init{
$v = new ElementVector<Element>() ;
}
: '[]'
| '[' title_args {$v.add($title_args.ele);} (',' title_args {$v = $title_args.ele ;})* ']'
;
with title_args being:
title_args returns [Element ele]
: author {$ele = new Element("author", $author.text); }
| location {$ele = new Element("location", $location.text); }
;
Trying to compile that I get confronted with a 127 error in the title rule: title_args is a non-unique reference.
I've followed the solution given to another similar question in this website (How to deal with list return values in ANTLR) however it only seems to work with lexical rules.
Is there a specific way to go around it ?
Thank you,
Christos
You have 2 title_args in your expression, you need to alias them. Try this:
| '[' t1=title_args {$v.add($t1.ele);} (',' t2=title_args {$v = $t2.ele ;})* ']'
t1 and t2 are arbitrary aliases you can choose anything you want as long as they match up.
I think the problem is your reusing the title_args var. Try changing one of those variable names.
Yeah, I had the same problem.
You need to change one of the variable names; for example, do like the following:
title_args
title_args1
in your code instead of using title_args twice.
If title_args is a parser rule, then just create the same rule with the name title_args1.
So, basically there would be two rules with the same functionality.
Related
How to properly format a math expression before passing it to the math_expressions package in flutter?
Context
I'm using math_expressions package but there are two cases I found when it throws an error:
A. Missing an asterisk before a parenthesis.
B. Missing parenthesis within the expression.
E.g.
// Throws error
final expression = "8(3+1)"; // A
final expression = "8(3+1"; // B
// Executes correctly
final expression = "8*(3+1)";
final Parser parser = Parser();
Expression exp = parser.parse(expression);
ContextModel cm = ContextModel();
final double result = exp.evaluate(EvaluationType.REAL, cm);
I'm aware of the syntactic requirement of the package so I'd like to properly format the expression before passing it to the parser since I cannot guarantee user input will comply to the requirement mentioned before.
What I've got so far
A. Missing an asterisk before a parenthesis:
I read about the replaceAllMapped method but I don't really know how to start from here in order to add the missing asterisks when needed.
B. Missing parenthesis within the expression. (solved)
Hypothesis
A. Missing an asterisk before a parenthesis:
I think the way is to create an array of digits, search for coincidences of a digit + parenthesis and then replace it with the addition of an asterisk like this: digit + "*" + parenthesis
Any ideas on how to solve this appropriately?
I have written following grammar
Model:
package = PackageDec?
greetings+=Greeting*
usage+=Usage* ;
PackageDec:
'package' name=QualifiedName ;
Greeting:
'greet' name=ID '{' ops += Operation* '}' ;
Operation:
'op' name=ID ('(' ')' '{' '}')? ;
QualifiedName:
ID ('.' ID)*;
Usage:
'use';
With above i can write following script.
package p1.p2
greet G1 {op f1 op f2 }
Now i need to write something like this:
package p1.p2
greet G1 {op f1 op f2 op f3}
use p1.p2.G1.f1
use p1.p2.G1
use p1.p2.G1.f3
To support that i changed Usage RULE like this
Usage:
'use' head=[Greet|QualifiedName] =>('.' tail=[Operation])?
However when i generate xtext artifacts it is complaining about multiple alternatives.
Please let me know how to write correct grammar rule for this.
This is because QualifiedName consumes dots (.). Adding ('.' ...)? makes two alternatives. Consider input
a.b.c
This could be parsed as
head="a" tail = "b.c"
head="a.b" tail = "c"
If I understand your intention of using predicate => right, than you just have to replace
head=[Greet|QualifiedName]
with
head=[Greet]
In this case however you will not be able to parse references with dots.
As a solution I would recommend to substitute your dot with some other character. For example with colon:
Usage:
'use' head=[Greet|QualifiedName] (':' tail=[Operation])?
When writing a macro, I have a variable, {$#2}, that either starts with a 1 or 2 digit number followed by a ".", or it doesn't. When it starts in that way, I want to put the number into a rexxvar, which I have called C.
I have tried
#if [ DATATYPE(LEFT({$#2},1), "W") ] \
#evaluate ^^ ^parse '{$#2} C '.' .^ \
#endif \
This, and every variation I can think of, gives errors saying the #IF line contains invalid characters.
How should I do this?
I am using PPWizard, and Regina - but I can't create either tag.
Thanks
Ian
I do not use PPWizard so this could all be wrong, but
Looking at PPWizard #if, the if should be either
#if DATATYPE(LEFT({$#2},1), "W")
or
#if [ DATATYPE(LEFT({$#2},1), "W") <> 0 ]
But I do not know wether you can imbed the {$#2} or not (I do not know PPWizard)
For the parse statement one of these may be what you want
#evaluate ^^ ^parse value '{$#2}' with C '.' .^
or
#evaluate ^^ ^parse var {$#2} C '.' .^
See rexx parse syntax
An alternative way might try the Define Rexx tag and do it in rexx. More people could help you with pure rexx. i.e the rexx would be
if DATATYPE(LEFT(value_to_process,1), "W") then do
parse var value_to_process C '.'
end
where value_to_process is the value to be checked (i.e. {$#2})
For others.
The final answer to the problem is to write
#RexxVar value_to_process = {$#2}
#evaluate+ ^^ ^if DATATYPE(LEFT(value_to_process,1), "W") then do; parse var value_to_process C '.'; end^ \
in the macro I was creating.
Thanks Bruce. Your reply was most helpful on my route to a solution.
Here is my naive approach:
# puppet/init.pp
$x = 'hello ' +
'goodbye'
This does not work. How does one concatenate strings in Puppet?
Keyword variable interpolation:
$value = "${one}${two}"
Source: http://docs.puppetlabs.com/puppet/4.3/reference/lang_variables.html#interpolation
Note that although it might work without the curly braces, you should always use them.
I use the construct where I put the values into an array an then 'join' them.
In this example my input is an array and after those have been joined with the ':2181,' the resulting value is again put into an array that is joined with an empty string as separator.
$zookeeperservers = [ 'node1.example.com', 'node2.example.com', 'node3.example.com' ]
$mesosZK = join([ "zk://" , join($zookeeperservers,':2181,') ,":2181/mesos" ],'')
resulting value of $mesosZK
zk://node1.example.com:2181,node2.example.com:2181,node3.example.com:2181/mesos
Another option not mentioned in other answers is using Puppet's sprintf() function, which functions identically to the Ruby function behind it. An example:
$x = sprintf('hello user %s', 'CoolUser')
Verified to work perfectly with puppet. As mentioned by chutz, this approach can also help you concatenate the output of functions.
The following worked for me.
puppet apply -e ' $y = "Hello" $z = "world" $x = "$y $z" notify { "$x": } '
notice: Hello world
notice: /Stage[main]//Notify[Hello world]/message: defined 'message' as 'Hello world'
notice: Finished catalog run in 0.04 seconds
The following works as well:
$abc = "def"
file { "/tmp/$abc":
You could use the join() function from puppetlabs-stdlib. I was thinking there should be a string concat function there, but I don't see it. It'd be easy to write one.
As stated in docs, you can just use ${varname} interpolation. And that works with function calls as well:
$mesosZK = "zk://${join($zookeeperservers,':2181,')}:2181/mesos"
$x = "${dirname($file)}/anotherfile"
Could not use {} with function arguments though: got Syntax error at '}'.
In PERL, NET::LDAP, I'm trying to use-
my $psearch-$ldap->search(
base => $my_base,
attr => ["mail","employeeNumber","physicalDeliveryOfficeName"],
filter => "(&(mail=*)(!(employeeNumber=9*)) (&(physicalDeliveryOfficeName=100)) (|(physicalDeliveryOfficeName=274)))");
Saying "give me everyone with a mail entry, where employee number does not begin with 9 and the physicalDeliveryOfficeName is either 100 or 274".
I can get it to work using just 100 or using just 274 but I can't seem to figure out how to specify 100 OR 274.
I can't seem to find the correct filter string, ready pull my hair out... please help!!
I can't test this, but LDAP queries use prefix notation while we're use to using infix notation. Imagine if you want something that's either a dog or a cat. In infix notation, it would look something like this:
((ANIMAL = "cat") OR (ANIMAL = "dog"))
With prefix notation, the boolean operator goes at the beginning of the query:
(OR (ANIMAL = "cat") (ANIMAL = "dog"))
The advantage to prefixed notation comes when you do more than two checks per boolean. Here I'm looking for something that's either a cat, a dog or a wombat:
(OR (ANIMAL = "cat") (ANIMAL = "dog") (ANIMAL = "wombat"))
Notice that I only needed a single boolean operator in the front of my statement. This will OR together all three statements. With our standard infix notation, I would have to have a second OR operator:
((ANIMAL = "cat") OR (ANIMAL = "dog") OR (ANIMAL = "wombat"))
Prefix notation was created by a Polish Mathematician named Jan Lukasiewicz back in 1924 in Warsaw Univeristy and thus became known as Polish Notation. Later on, it was discovered that computers could work an equation from front to back if the equation was written in postfix notation which is the reverse of Polish Notation. Thus, Reverse Polish Notation (or RPN) was born.
Early HP calculators used RPN notation which became the Geek Sheik thing back in the early 1970s. Imagine the sense of brain superiority you get when you hand your calculator to someone and they have no early idea how to use it. The only way to be cooler back then was to have a Curta.
Okay, enough walking down nostalgia lane. Let's get back to the problem...
The easiest way to construct an infix operation is to build a tree diagram of what you want. Thus, you should sketch out your LDAP query as a tree:
AND
/ | \
/ | \
/ | \
/ | \
/ | \
/ | \
/ | \
OR employee!=9* mail=*
/ \
/ \
/ \
/ \
/ \
phyDelOfficeName=100 phyDelOfficeName=274
To build a query based upon this tree, start with the bottom of the tree, and work your way up each layer. The bottom part of our tree is the OR part of our query:
(OR (physicalDeliveryOfficeName = 100) (physicalDeliveryOfficeName = 274))
Using LDAP's OR operator, the pipe (|) and removing the extra spaces, we get:
(|(physicalDeliveryOfficeName = 100)(physicalDeliveryOfficeName = 274))
When I build an LDAP query, I like to save each section as a Perl scalar variable. It makes it a bit easier to use:
$or_part = "|(physicalDeliveryOfficeName=100)(physicalDeliveryOfficeName=274)";
Notice I've left off the outer pair or parentheses. The outer set of parentheses return when you string all the queries back together. However, some people put them anyway. An extra set of parentheses doesn't hurt an LDAP query.
Now for the other two parts of the query:
$mailAddrExists = "mail=*";
$not_emp_starts_9 = "!(employee=9*)";
And, now we AND all three sections together:
"(&($mailAddrExists)($not_emp_starts_9)($or_part))"
Note that a single ampersand weaves it all together. I can substitute back each section to see the full query:
(&(mail=*)(!(employee=9*))(|(physicalDeliveryOfficeName=100)(physicalDeliveryOfficeName=274)))
Or like this:
my $psearch-$ldap->search(
base => $my_base,
attr => ["mail","employeeNumber","physicalDeliveryOfficeName"],
filter => "(&(mail=*)(!(employee=9*))(|(physicalDeliveryOfficeName=100)(physicalDeliveryOfficeName=274)))",
);
Or piecemeal:
my $mail = "mail=*";
my $employee = "!(employee=9*)";
my $physicalAddress = "|(physicalDeliveryOfficeName=100)"
. "(physicalDeliveryOfficeName=274)";
my $psearch-$ldap->search(
base => $my_base,
attr => ["mail","employeeNumber","physicalDeliveryOfficeName"],
filter => "(&($mail)($employee)($physicalAddress))",
);
As I said before, I can't test this. I hope it works. If nothing else, I hope you understand how to create an LDAP query and can figure out how to do it yourself.