On ruby I can do
require "stringio"
def with_captured_stdout
begin
old_stdout = $stdout
$stdout = StringIO.new('','w')
yield
$stdout.string
ensure
$stdout = old_stdout
end
end
and later call it like
str = with_captured_stdout { Solution.main("Greetings from Javatlacati") }
but on crystal-lang I can refer to global variable $stdout without getting the corresponding error
$global_variables are not supported, use ##class_variables instead
is there any workaround? Thank you in advance.
Currently there's no easy way to capture stdout or stderr in the crystal standard library, however here's a shard which looks to do that: https://github.com/mosop/stdio.
Related
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'm currently using a not-very-Scala-like approach to parse large Unix mailbox files. I'm still learning the language and would like to challenge myself to find a better way, however, I do not believe I have a solid grasp on just what can be done with an Iterator and how to effectively use it.
I'm currently using org.apache.james.mime4j, and I use the org.apache.james.mime4j.mboxiterator.MboxIterator to get a java.util.Iterator from a file, as so:
// registers an implementation of a ContentHandler that
// allows me to construct an object representing an email
// using callbacks
val handler: ContentHandler = new MyHandler();
// creates a parser that parses a SINGLE email from a given InputStream
val parser: MimeStreamParser = new MimeStreamParser(configBuilder.build());
// register my handler
parser.setContentHandler(handler);
// Get a java.util.Iterator
val iterator = MboxIterator.fromFile(fileName).build();
// For each email, process it using above Handler
iterator.forEach(p => parser.parse(p.asInputStream(Charsets.UTF_8)))
From my understanding, the Scala Iterator is much more robust, and probably a lot more capable of handling something like this, especially because I won't always be able to fit the full file in memory.
I need to construct my own version of the MboxIterator. I dug through the source for MboxIterator and was able to find a good RegEx pattern to use to determine the beginning of individual email messages with, however, I'm drawing a blank from now on.
I created the RegEx like so:
val MESSAGE_START = Pattern.compile(FromLinePatterns.DEFAULT, Pattern.MULTILINE);
What I want to do (based on what I know so far):
Build a FileInputStream from an MBOX file.
Use Iterator.continually(stream.read()) to read through the stream
Use .takeWhile() to continue to read until the end of the stream
Chunk the Stream using something like MESSAGE_START.matcher(someString).find(), or use it to find the indexes the separate the message
Read the chunks created, or read the bits in between the indexes created
I feel like I should be able to use map(), find(), filter() and collect() to accomplish this, but I'm getting thrown off by the fact that they only give me Ints to work with.
How would I accomplish this?
EDIT:
After doing some more thinking on the subject, I thought of another way to describe what I think I need to do:
I need to keep reading from the stream until I get a string that matches my RegEx
Maybe group the previously read bytes?
Send it off to be processed somewhere
Remove it from the scope somehow so it doesn't get grouped the next time I run into a match
Continue to read the stream until I find the next match.
Profit???
EDIT 2:
I think I'm getting closer. Using a method like this gets me an iterator of iterators. However, there are two issues: 1. Is this a waste of memory? Does this mean everything gets read into memory? 2. I still need to figure out a way to split by the match, but still include it in the iterator returned.
def split[T](iter: Iterator[T])(breakOn: T => Boolean):
Iterator[Iterator[T]] =
new Iterator[Iterator[T]] {
def hasNext = iter.hasNext
def next = {
val cur = iter.takeWhile(!breakOn(_))
iter.dropWhile(breakOn)
cur
}
}.withFilter(l => l.nonEmpty)
If I understand correctly, you want to lazily chunk a large file delimited by a regex recognizable pattern.
You could try to return an Iterator for each request but the correct iterator management would not be trivial.
I'd be inclined to hide all file and iterator management from the client.
class MBox(filePath :String) {
private val file = io.Source.fromFile(filePath)
private val itr = file.getLines().buffered
private val header = "From .+ \\d{4}".r //adjust to taste
def next() :Option[String] =
if (itr.hasNext) {
val sb = new StringBuilder()
sb.append(itr.next() + "\n")
while (itr.hasNext && !header.matches(itr.head))
sb.append(itr.next() + "\n")
Some(sb.mkString)
} else {
file.close()
None
}
}
testing:
val mbox = new MBox("so.txt")
mbox.next()
//res0: Option[String] =
//Some(From MAILER-DAEMON Fri Jul 8 12:08:34 2011
//some text AAA
//some text BBB
//)
mbox.next()
//res1: Option[String] =
//Some(From MAILER-DAEMON Mon Jun 8 12:18:34 2012
//small text
//)
mbox.next()
//res2: Option[String] =
//Some(From MAILER-DAEMON Tue Jan 8 11:18:14 2013
//some text CCC
//some text DDD
//)
mbox.next() //res3: Option[String] = None
There is only one Iterator per open file and only the safe methods are invoked on it. The file text is realized (loaded) only on request and the client gets just what's requested, if available. Instead of all lines in one long String you could return each line as part of a collection, Seq[String], if that's more applicable.
UPDATE: This can be modified for easy iteration.
class MBox(filePath :String) extends Iterator[String] {
private val file = io.Source.fromFile(filePath)
private val itr = file.getLines().buffered
private val header = "From .+ \\d{4}".r //adjust to taste
def next() :String = {
val sb = new StringBuilder()
sb.append(itr.next() + "\n")
while (itr.hasNext && !header.matches(itr.head))
sb.append(itr.next() + "\n")
sb.mkString
}
def hasNext: Boolean =
if (itr.hasNext) true else {file.close(); false}
}
Now you can .foreach(), .map(), .flatMap(), etc. But you can also do dangerous things like .toList which will load the entire file.
Wanting to capture a variable called scanNumber in the http response loking like this:
{"resultCode":"SUCCESS","errorCode":null,"errorMessage":null,"profile":{"fullName":"TestFirstName TestMiddleName TestLastName","memberships":[{"name":"UA Gold Partner","number":"123-456-123-123","scanNumber":"123-456-123-123"}]}}
How can I do this with a regular experssion?
The tool I am using is Gatling stress tool (with the Scala DSL)
I have tried to do it like this:
.check(jsonPath("""${scanNumber}""").saveAs("scanNr")))
But I get the error:
---- Errors --------------------------------------------------------------------
> Check extractor resolution crashed: No attribute named 'scanNu 5 (100,0%)
mber' is defined
You were close first time.
What you actually want is:
.check(jsonPath("""$..scanNumber""").saveAs("scanNr")))
or possibly:
.check(jsonPath("""$.profile.memberships[0].scanNumber""").saveAs("scanNr")))
Note that this uses jsonPath, not regular expressions. JsonPath should more reliable than regex for this.
Check out the JsonPath spec for more advanced usage.
use this regex to match this in anywhere in json:
/"scanNumber":"[^"]+"/
and if you want to match just happens in structure you said use:
/\{[^{[]+\{[^{[]+\[\{[^{[]*("scanNumber":"[^"]+")/
Since json fields may change its order you should make your regex more tolerant for those changes:
val j = """{"resultCode":"SUCCESS","errorCode":null,"errorMessage":null,"profile":{"fullName":"TestFirstName TestMiddleName TestLastName","memberships":[{"name":"UA Gold Partner","number":"123-456-123-123","scanNumber":"123-456-123-123"}]}}"""
val scanNumberRegx = """\{.*"memberships":\[\{.*"scanNumber":"([^"]*)".*""".r
val scanNumberRegx(scanNumber) = j
scanNumber //String = 123-456-123-123
This will work even if the json fields will be in different order (but of course keep the structure)
In my application, I have a dictionary of phrases that are used throughout of the application. This same dictionary is used to create PDFs and Excel Spreadsheets.
The dictionary looks like so:
GLOBAL_MRD_VOCAB = {
'fiscal_year': _('Fiscal Year'),
'region': _('Region / Focal Area'),
'prepared_by': _('Preparer Name'),
'review_cycle':_('Review Period'),
... snip ...
}
In the code to produce the PDF, I have:
fy = dashboard_v.fiscal_year
fy_label = GLOBAL_MRD_VOCAB['fiscal_year']
rg = dashboard_v.dashboard.region
rg_label = GLOBAL_MRD_VOCAB['region']
rc = dashboard_v.review_cycle
rc_label = GLOBAL_MRD_VOCAB['review_cycle']
pb = dashboard_v.prepared_by
pb_label = GLOBAL_MRD_VOCAB['prepared_by']
Now, when the PDF is produced, in the PDF, I don't see these labels but rather, I see:
<django.utils.functional.__proxy__ object at 0x10106fdd0>
Can somebody help me with this? How do I get the properly translated labels?
Thanks
Eric
"Lazy translation"
The result of a ugettext_lazy() call can be used wherever you would use a unicode string (an object with type unicode) in Python. If you try to use it where a bytestring (a str object) is expected, things will not work as expected, since a ugettext_lazy() object doesn't know how to convert itself to a bytestring. You can't use a unicode string inside a bytestring, either, so this is consistent with normal Python behavior.
...
If you ever see output that looks like "hello <django.utils.functional...>", you have tried to insert the result of ugettext_lazy() into a bytestring. That's a bug in your code.
Either pass it to unicode() to get the unicode from it, or don't use lazy translation.
I have been given the 3 functions below. Can anybody please help me to understand these? I am trying to port an application to C++ using Qt, but I don't understand these functions. So please help me!
Thanks in advance.
function 1:
def read_key
puts "read pemkey: \"#{#pkey}\"" if #verbose
File.open(#pkey, 'rb') do |io|
#key = OpenSSL::PKey::RSA.new(io)
end
end
function 2:
def generate_key
puts "generate pemkey to \"#{#pkey_o}\"" if #verbose
#key = OpenSSL::PKey::RSA.generate(KEY_SIZE)
# save key
File.open(#pkey_o, 'wb') do |file|
file << #key.export()
end
end
function 3:
def sign_zip
puts "sign zip" if #verbose
plain = nil
File.open(#zip, 'rb') do |file|
plain = file.read
end
#sig = #key.sign(OpenSSL::Digest::SHA1.new, plain)
end
There are probably two things about the above code that are confusing you, which if clarified, will help understand it.
First, #verbose and #key are instance variables, what a C++ programmer might call "member variables." The "if #verbose" following the puts statement literally means only do the puts if #verbose is true. #verbose never needs to be declared a bool--you just start using it. If it's never initialized, it's "nil" which evaluates to false.
Second, the do/end parts are code blocks. Many Ruby methods take a code block and execute it with a variable declared in those pipe characters. An example would be "array.each do |s| puts s; end" which might look like "for(int i = 0; i < array.size(); ++i) { s = array[i]; puts(s); }" in C++. For File.open, |io| is the file instance opened, and "read" is one of its methods.
These are all methods. #{#pkey_o} is string interpolation, substituting in the contents of an instance variable (called pkey_o; Ruby instance variables begin with # and class variables – unused here – begin with ##).
File.open(#pkey, 'rb') do |io|
#key = OpenSSL::PKey::RSA.new(io)
end
That opens the file whose name is stored in #pkey, stores the file handle in io (a block-local variable) and uses that with OpenSSL::PKey::RSA.new, whose result is stored in #key. Finally, it closes the file handle when the block is finished (at the end) whether or not it is a successful exit or an error case (in which case an exception would be thrown, but it would still be thrown). When translating this to C++, use of the RAII pattern is entirely reasonable (if you were going to Java, I'd say to use try/finally).