Testing with VSCode 1.52.1 / LSP 3.16
I enabled dot to trigger completion like:
'completionProvider': {
'triggerCharacters': [
'.', '#',
]
},
But seems textDocument/didChange is sent before the completion request, with the dot insertion, it renders the whole source being invalid syntax, so I lost AST to work out desired completion response.
Is this norm? How other implementations are dealing this scenario? They all implement a partial parser to get partial AST with invalid dot standing there? Or other workarounds?
Partial AST is probably the cleanest way of doing it. You could also manually try to iterate backwards in the input until you find the start of the expression being “dotted”, parse that as an expression, and then use a previously known good AST to look up the type and provide completions
Related
I would like to avoid to use programming in the PARSER grammar file and use a semantic check in the listener. Can I do it ? How to do it ? Do I throw an exception ? Call a method of the parser ?
Thank you.
Edit : I said lexer, it's a mistake. I mean PARSER.
Easiest is to use Recognizer#addErrorListener(ANTLRErrorListener) to capture semantic and other errors -- the parser extends Recognizer.
Check for the existence of captured errors after the parser runs to decide whether/how to continue.
To affect how the parser handles errors, use Parser#setErrorHandler(ANTLRErrorStrategy). The runtime includes a BailErrorStrategy that can be used to stop the parser when a syntactic error is encountered.
How does one convert an ASTNode (or at least a CompilationUnit) into a valid piece of source code?
The documentation says that one shouldn't use toString, but doesn't mention any alternatives:
Returns a string representation of this node suitable for debugging purposes only.
CompilationUnits have rewrite, but that one does not work for ASTs created by hand.
Formatting options would be nice to have, but I'd basically be satisfied with anything that turns arbitrary ASTNodes into semantically equivalent source code.
In JDT the normal way for AST manipulation is to start with a basic CompilationUnit and then use a rewriter to add content. Then ASTRewriteAnalyzer / ASTRewriteFormatter should take care of creating formatted source code. Creating a CU just containing a stub type declaration shouldn't be hard, so that's one option.
If that doesn't suite your needs, you may want to experiement with directly calling the internal org.eclipse.jdt.internal.core.dom.rewrite.ASTRewriteFlattener.asString(ASTNode, RewriteEventStore). If not editing existing files, you may probably ignore the events collected in the RewriteEventStore, just use the returned String.
JSON is not a subset of JavaScript. I need my output to be 100% valid JavaScript; it will be evaluated as such -- i.e., JSON.stringify will not (always) work for my needs.
Is there a JavaScript stringifier for Node?
As a bonus, it would be nice if it could stringify objects.
You can use JSON.stringify and afterwards replace the remaining U+2028 and U+2029 characters. As the article linked states, the characters can only occur in the strings, so we can safely replace them by their escaped versions without worrying about replacing characters where we should not be replacing them:
JSON.stringify('ro\u2028cks').replace(/\u2028/g,'\\u2028').replace(/\u2029/g,'\\u2029')
From the last paragraph in the article you linked:
The solution
Luckily, the solution is simple: If we look at the JSON specification we see that the only place where a U+2028 or U+2029 can occur is in a string. Therefore we can simply replace every U+2028 with \u2028 (the escape sequence) and U+2029 with \u2029 whenever we need to send out some JSONP.
It’s already been fixed in Rack::JSONP and I encourage all frameworks or libraries that send out JSONP to do the same. It’s a one-line patch in most languages and the result is still 100% valid JSON.
Within Node.js, I am using querystring.stringify() to encode an object into a query string for usage in a URL. Values that have spaces are encoded as %20.
I'm working with a particularly finicky web service that will only accept spaces encoded as +, as used to be commonly done prior to RFC3986.
Is there a way to set an option for querystring so that it encodes spaces as +?
Currently I am simply doing a .replace() to replace all instances of %20 with +, but this is a bit tedious if there is an option I can set ahead of time.
If anyone still facing this issue, "qs" npm package has feature to encode spaces as +
qs.stringify({ a: 'b c' }, { format : 'RFC1738' })
I can't think of any library doing that by default, and unfortunately, I'd say your implementation may be the more efficient way to do this, since any other option would probably either do what you're already doing, or will use slower non-compiled pure JavaScript code.
What about asking the web service provider to follow the RFC?
https://github.com/kvz/phpjs is a node.js package that provides all the php functions. The http_build_query implementation at the time of writing this only supports urlencode (the query string includes + instead of spaces), but hopefully soon will include the enc_type parameter / rawurlencode (%20's for spaces).
See http://php.net/http_build_query.
RFC1738 (+'s) will be the default enc_type either way, so you can use it immediately for your purposes.
I'm getting a garbled JSON string from a HTTP request, so I'm looking for a temp solution to select the JSON string only.
The request.params() returns this:
[{"insured_initials":"Tt","insured_surname":"Test"}=, _=1329793147757,
callback=jQuery1707229194729661704_1329793018352
I would like everything from the start of the '{' to the end of the '}'.
I found lots of examples of doing similar things with other languages, but the purpose of this is not to only solve the problem, but also to learn Scala. Will someone please show me how to select that {....} part?
Regexps should do the trick:
"\\{.*\\}".r.findFirstIn("your json string here")
As Jens said, a regular expression usually suffices for this. However, the syntax is a bit different:
"""\{.*\}""".r
creates an object of scala.util.matching.Regex, which provides the typical query methods you may want to do on a regular expression.
In your case, you are simply interested in the first occurrence in a sequence, which is done via findFirstIn:
scala> """\{.*\}""".r.findFirstIn("""[{"insured_initials":"Tt","insured_surname":"Test"}=, _=1329793147757,callback=jQuery1707229194729661704_1329793018352""")
res1: Option[String] = Some({"insured_initials":"Tt","insured_surname":"Test"})
Note that it returns on Option type, which you can easily use in a match to find out if the regexp was found successfully or not.
Edit: A final point to watch out for is that the regular expressions normally do not match over linebreaks, so if your JSON is not fully contained in the first line, you may want to think about eliminating the linebreaks first.