I have this method in a class that's throwing a Cannot bind attributes in a Nil type object. Did you forget a '.new'?
method parse() {
grammar FindHeaders {
token TOP { [<not-header> | <header>]+ $ }
token not-header { ^^ <![#]> \N* \n }
token header { ^^ '#'{ 1 .. 6 } <content> \n }
token content { \N+ }
}
class HeaderActions {
method content($match) {
return if $match ~~ m/^^\#\s+<[A..Z]>+e*s/ || $match !~~ m/<[a..z]>/;
return if $match ~~ m/\|/ && ( $match ~~ m:i/project/ || $match ~~ m:i/\+\w/ );
my $tc = Lingua::EN::Titlecase.new($match);
my $new_title = $tc.title;
make($new_title);
}
}
my $t = $!content;
FindHeaders.parse($t, actions => HeaderActions.new);
}
As far as I can tell, this code matches what's in the official documentation. So not sure why I'm getting this error. I have no idea what attribute or Nil object the compiler is referring to. If I comment out the line with the make method, everything works fine.
method content($match) {
There's a reason that action methods typically use $/ as the argument name: because the make function looks for $/ in order to associate the provided object to it. You can use $match, but then need to call the make method on that instead:
$match.make($new_title);
The mention of Nil is because the failed match earlier in the action method resulted in $/ being set to Nil.
I guess you avoided the more idiomatic $/ as the parameter of the action method because it gets in the way of doing further matching in the action method. Doing further matching in action methods means that the text is being parsed twice (once in the grammar and again the action), which is not so efficient, and usually best avoided (by moving the parsing work into the grammar).
As a final style point, declaring grammars and action classes in a method is neat encapsulation if they are only used there, but it would be wise to my scope them (my grammar FindHeaders { ... }), otherwise they shall end up installed in the nearest enclosing package anyway.
Err - bit of a guess here but looks like this error is generated during creation of a new object. That points to the line my $tc = Lingua::EN::Titlecase.new($match). I wonder if you want to pass a Str into this function call e.g. with "$match" or ~$match...
Related
I am currently facing a problem within my Radius configuration and wanted to ask you for help.
I'am using the FreeRadius-Version 3.0.23
Within the authorize section in radiusd.conf I am trying to create the following unlang expression.
I have users in the following format:
super1
super2
...
user1
user2
NAS-Identifier:
SUP-A
SUP-B
SUP-C
SUP-D
I want to extract something from the NAS identifier using a regex and append to the user.
=> super1-A
=> super2-D
However, it doesn't work with the following expression because the extracted value is no longer available in the second IF statement.
if ( NAS-Identifier =~ /^SUP\\-([ABCD])/ ) {
=> The extracted value is only available at this point
=> Or is it possible to define a local variable with the value?
if ( "%{User-Name}" !~ /^super\\d+/ )
update request {
User-Name := "%{User-Name}-%{1}" (However, I need the value here)
}
}
}
This is my workaround:
if ( "%{User-Name}" !~ /^super\\d+/ && NAS-Identifier =~ /^SUP\\-([ABCD])/ ) {
update request {
User-Name := "%{User-Name}-%{1}"
}
}
I would really appreciate your help as I couldn't find anything in the FreeRadius documentation.
Thanks in advance.
According to the FreeRadius documentation:
Every time a regular expression is evaluated, whether it matches or not, the capture group values will be cleared.
So, in your case, you can reverse the order of conditions:
if ( "%{User-Name}" !~ /^super\\d+/ ) {
if ( NAS-Identifier =~ /^SUP-([ABCD])/ ) {
update request {
User-Name := "%{User-Name}-%{1}"
}
}
}
Note that the - char is not any special regex metacharacter when used outside character classes, no need to escape it here.
I've got a Node module file containing about 100 exported methods, which looks something like this:
exports.methodOne = async user_id => {
// other method contents
};
exports.methodTwo = async user_id => {
// other method contents
fooMethod();
};
exports.methodThree = async user_id => {
// other method contents
fooMethod();
};
Goal: What I'd like to do is figure out how to grab the name of any method which contains a call to fooMethod, and return the correct method names: methodTwo and methodThree. I wrote a regex which gets kinda close:
exports\.(\w+).*(\n.*?){1,}fooMethod
Problem: using my example code from above, though, it would effectively match methodOne and methodThree because it finds the first instance of export and then the first instance of fooMethod and goes on from there. Here's a regex101 example.
I suspect I could make use of lookaheads or lookbehinds, but I have little experience with those parts of regex, so any guidance would be much appreciated!
Edit: Turns out regex is poorly-suited for this type of task. #ctcherry advised using a parser, and using that as a springboard, I was able to learn about Abstract Syntax Trees (ASTs) and the recast tool which lets you traverse the tree after using various tools (acorn and others) to parse your code into tree form.
With these tools in hand, I successfully built a script to parse and traverse my node app's files, and was able to find all methods containing fooMethod as intended.
Regex isn't the best tool to tackle all the parts of this problem, ideally we could rely on something higher level, a parser.
One way to do this is to let the javascript parse itself during load and execution. If your node module doesn't include anything that would execute on its own (or at least anything that would conflict with the below), you can put this at the bottom of your module, and then run the module with node mod.js.
console.log(Object.keys(exports).filter(fn => exports[fn].toString().includes("fooMethod(")));
(In the comments below it is revealed that the above isn't possible.)
Another option would be to use a library like https://github.com/acornjs/acorn (there are other options) to write some other javascript that parses your original target javascript, then you would have a tree structure you could use to perform your matching and eventually return the function names you are after. I'm not an expert in that library so unfortunately I don't have sample code for you.
This regex matches (only) the method names that contain a call to fooMethod();
(?<=exports\.)\w+(?=[^{]+\{[^}]+fooMethod\(\)[^}]+};)
See live demo.
Assuming that all methods have their body enclosed within { and }, I would make an approach to get to the final regex like this:
First, find a regex to get the individual methods. This can be done using this regex:
exports\.(\w+)(\s|.)*?\{(\s|.)*?\}
Next, we are interested in those methods that have fooMethod in them before they close. So, look for } or fooMethod.*}, in that order. So, let us name the group searching for fooMethod as FOO and the name of the method calling it as METH. When we iterate the matches, if group FOO is present in a match, we will use the corresponding METH group, else we will reject it.
exports\.(?<METH>\w+)(\s|.)*?\{(\s|.)*?(\}|(?<FOO>fooMethod)(\s|.)*?\})
Explanation:
exports\.(?<METH>\w+): Till the method name (you have already covered this)
(\s|.)*?\{(\s|.)*?: Some code before { and after, non-greedy so that the subsequent group is given preference
(\}|(?<FOO>fooMethod)(\s|.)*?\}): This has 2 parts:
\}: Match the method close delimiter, OR
(?<FOO>fooMethod)(\s|.)*?\}): The call to fooMethod followed by optional code and method close delimiter.
Here's a JavaScript code that demostrates this:
let p = /exports\.(?<METH>\w+)(\s|.)*?\{(\s|.)*?(\}|(?<FOO>fooMethod)(\s|.)*?\})/g
let input = `exports.methodOne = async user_id => {
// other method contents
};
exports.methodTwo = async user_id => {
// other method contents
fooMethod();
};
exports.methodThree = async user_id => {
// other method contents
fooMethod();
};';`
let match = p.exec( input );
while( match !== null) {
if( match.groups.FOO !== undefined ) console.log( match.groups.METH );
match = p.exec( input )
}
I need a custom validator to ban a specific list of banned words from a textarea field.
I need exactly this type of implementation, I know that it's not logically correct to let the user type part of a query but it's exactly what I need.
I tried with a regExp but it has a strange behaviour.
My RegExp
/(drop|update|truncate|delete|;|alter|insert)+./gi
my Validator
export function forbiddenWordsValidator(sqlRe: RegExp): ValidatorFn {
return (control: AbstractControl): { [key: string]: any } | null => {
const forbidden = sqlRe.test(control.value);
return forbidden ? { forbiddenSql: { value: control.value } } : null;
};
}
my formControl:
whereCondition: new FormControl("", [
Validators.required,
forbiddenWordsValidator(this.BAN_SQL_KEYWORDS)...
It works only in certain cases and I don't understand why does the same string works one time and doesn't work if i delete a char and rewrite it or sometimes if i type a whitespace the validator returns ok.
There are several issues here:
The global g modifier leads to unexpected alternated results when used in RegExp#test and similar methods that move the regex index after a valid match, it must be removed
. at the end requires any 1 char other than line break char, hence it must be removed.
Use
/drop|update|truncate|delete|;|alter|insert/i
Or, to match the words as whole words use
/\b(?:drop|update|truncate|delete|alter|insert)\b|;/i
This way, insert in insertion and drop in dropout won't get "caught" (=matched).
See the regex demo.
it's not a great idea to give such power to the user
I am writing new Perl 5 module Class::Tiny::ConstrainedAccessor to check type constraints when you touch object attributes, either by setting or by getting a default value. I am writing the unit tests and want to run the accessors for the latter case. However, I am concerned that Perl may optimize away my accessor-function call since the return value is discarded. Will it? If so, can I tell it not to? Is the corresponding behaviour documented? If the answer is as simple as "don't worry about it," that's good enough, but a reference to the docs would be appreciated :) .
The following MCVE succeeds when I run it on my Perl 5.26.2 x64 Cygwin. However, I don't know if that is guaranteed, or if it just happens to work now and may change someday.
use 5.006; use strict; use warnings; use Test::More; use Test::Exception;
dies_ok { # One I know works
my $obj = Klass->new; # Default value of "attribute" is invalid
diag $obj->accessor; # Dies, because the default is invalid
} 'Bad default dies';
dies_ok {
my $obj = Klass->new;
$obj->accessor; # <<< THE QUESTION --- Will this always run?
} 'Dies even without diag';
done_testing();
{ package Klass;
sub new { my $class = shift; bless {#_}, $class }
sub check { shift; die 'oops' if #_ and $_[0] eq 'bad' }
sub default { 'bad' }
sub accessor {
my $self = shift;
if(#_) { $self->check($_[0]); return $self->{attribute} = $_[0] } # W
elsif(exists $self->{attribute}) { return $self->{attribute} } # R
else {
# Request to read the attribute, but no value is assigned yet.
# Use the default.
$self->check($self->default); # <<<---- What I want to exercise
return $self->{attribute} = $self->default;
}
} #accessor()
} #Klass
This question deals with variables, but not functions. perlperf says that Perl will optimize away various things, but other than ()-prototyped functions, it's not clear to me what.
In JavaScript, I would say void obj.accessor();, and then I would know for sure it would run but the result would be discarded. However, I can't use undef $obj->accessor; for a similar effect; compilation legitimately fails with Can't modify non-lvalue subroutine call of &Klass::accessor.
Perl doesn't ever optimize away sub calls, and sub calls with side effects shouldn't be optimised away in any language.
undef $obj->accessor means something similar to $obj->accessor = undef
The following code is taken from the Perl 6 documentation, and I am trying to learn more about it before more experimentation:
proto token command {*}
token command:sym<create> { <sym> }
token command:sym<retrieve> { <sym> }
token command:sym<update> { <sym> }
token command:sym<delete> { <sym> }
Is the * in the first line a whatever-star? Can it be something else, such as
proto token command { /give me an apple/ }
Can "sym" be something else, such as
command:eat<apple> { <eat> } ?
{*} tells the runtime to call the correct candidate.
Rather than force you to write {{*}} for the common case of just call the correct one, the compiler allows you to shorten it to just {*}
That is the case for all proto routines like sub, method, regex, token, and rule.
In the case of the regex proto routines, only a bare {*} is allowed.
The main reason is probably because no-one has really come up with a good way to make it work sensibly in the regex sub-language.
So here is an example of a proto sub that does some things that are common to all of the candidates.
#! /usr/bin/env perl6
use v6.c;
for #*ARGS { $_ = '--stdin' when '-' }
# find out the number of bytes
proto sub MAIN (|) {
try {
# {*} calls the correct multi
# then we get the number of elems from its result
# and try to say it
say {*}.elems # <-------------
}
# if {*} returns a Failure note the error message to $*ERR
or note $!.message;
}
#| the number of bytes on the clipboard
multi sub MAIN () {
xclip
}
#| the number of bytes in a file
multi sub MAIN ( Str $filename ){
$filename.IO.slurp(:!chomp,:bin)
}
#| the number of bytes from stdin
multi sub MAIN ( Bool :stdin($)! ){
$*IN.slurp-rest(:bin)
}
sub xclip () {
run( «xclip -o», :out )
.out.slurp-rest( :bin, :close );
}
This answers your second question. Yes, it's late.
You have to distinguish two different syms (or eats). The one that's on the definition of the token as an "adverb" (or extended syntax identifier, whatever you want to call it), and the one that's on the token itself.
If you use <eat> in the token body, Perl 6 will simply not find it. You will get an error like
No such method 'eat' for invocant of type 'Foo'
Where Foo would be the name of the grammar. <sym> is a predefined token, which matches the value of the adverb (or pair value) in the token.
You could, in principle, use the extended syntax to define a multi token (or rule, or regex). However, if you try to define it in this way, you will get a different error:
Can only use <sym> token in a proto regex
So, the answer to your second question is no, and no.