I would like to understand how can I analyze methods / functions body to find types that are explicitly referenced from it. I have success analyzing method declaration (return type, parameter types, etc..), however I have no idea how to do that for body.
Assuming following function:
String someFunction(int param) {
final list = <String>['a', 'b', 'c']; // -> DartTypes: String, List<String>
final myClass = MyClass<Arg>(); // -> DartTypes: Arg, MyClass<Arg>
final functionCall = anotherFunction<FunctionArg<Arg>>(); // -> DartTypes: Arg, FunctionArg<Arg>
return 'result';
}
// At is point I would like to know that my function depends on
// String, List<String>, Arg, MyClass<Arg>, FunctionArg<Arg>
// in term of DartType instances with proper typeArguments.
I tried getting AstNode for method element described here: https://stackoverflow.com/a/57043177/2033394
However I could not get elements from nodes to figure out their types. Their declaredElement values are always null. So I can not get back to Element API from AST API.
If you've used the exact snippet from the answer you've referenced, the problem is likely in getParsedLibraryByElement(). This method only parses the referenced library - meaning that you'll get an AST that doesn't necessarily have semantic references (like the declaredElement of AST nodes) set.
Instead, you'll want to use getResolvedLibraryByElement. The AST returned by that method will have its types and references fully resolved.
With the resolved AST, you could visit the body of the method with a custom visitor to find type references. Your definition of "referenced types" isn't really exact - but perhaps you can collect types in visitNamedType for type references and visitVariableDeclaration to collect the types of variables.
we are trying to add parameters to a transformation at the runtime. The only possible way to do so, is to set every single parameter and not a node. We don't know yet how to create a node for the setParameter.
Current setParameter:
QName TEST XdmAtomicValue 24
Expected setParameter:
<TempNode> <local>Value1</local> </TempNode>
We searched and tried to create a XdmNode and XdmItem.
If you want to create an XdmNode by parsing XML, the best way to do it is:
DocumentBuilder db = processor.newDocumentBuilder();
XdmNode node = db.build(new StreamSource(
new StringReader("<doc><elem/></doc>")));
You could also pass a string containing lexical XML as the parameter value, and then convert it to a tree by calling the XPath parse-xml() function.
If you want to construct the XdmNode programmatically, there are a number of options:
DocumentBuilder.newBuildingStreamWriter() gives you an instance of BuildingStreamWriter which extends XmlStreamWriter, and you can create the document by writing events to it using methods such as writeStartElement, writeCharacters, writeEndElement; at the end call getDocumentNode() on the BuildingStreamWriter, which gives you an XdmNode. This has the advantage that XmlStreamWriter is a standard API, though it's not actually a very nice one, because the documentation isn't very good and as a result implementations vary in their behaviour.
Another event-based API is Saxon's Push class; this differs from most push-based event APIs in that rather than having a flat sequence of methods like:
builder.startElement('x');
builder.characters('abc');
builder.endElement();
you have a nested sequence:
Element x = Document.elem('x');
x.text('abc');
x.close();
As mentioned by Martin, there is the "sapling" API: Saplings.doc().withChild(elem(...).withChild(elem(...)) etc. This API is rather radically different from anything you might be familiar with (though it's influenced by the LINQ API for tree construction on .NET) but once you've got used to it, it reads very well. The Sapling API constructs a very light-weight tree in memory (hance the name), and converts it to a fully-fledged XDM tree with a final call of SaplingDocument.toXdmNode().
If you're familiar with DOM, JDOM2, or XOM, you can construct a tree using any of those libraries and then convert it for use by Saxon. That's a bit convoluted and only really intended for applications that are already using a third-party tree model heavily (or for users who love these APIs and prefer them to anything else).
In the Saxon Java s9api, you can construct temporary trees as SaplingNode/SaplingElement/SaplingDocument, see https://www.saxonica.com/html/documentation12/javadoc/net/sf/saxon/sapling/SaplingDocument.html and https://www.saxonica.com/html/documentation12/javadoc/net/sf/saxon/sapling/SaplingElement.html.
To give you a simple example constructing from a Map, as you seem to want to do:
Processor processor = new Processor();
Map<String, String> xsltParameters = new HashMap<>();
xsltParameters.put("foo", "value 1");
xsltParameters.put("bar", "value 2");
SaplingElement saplingElement = new SaplingElement("Test");
for (Map.Entry<String, String> param : xsltParameters.entrySet())
{
saplingElement = saplingElement.withChild(new SaplingElement(param.getKey()).withText(param.getValue()));
}
XdmNode paramNode = saplingElement.toXdmNode(processor);
System.out.println(paramNode);
outputs e.g. <Test><bar>value 2</bar><foo>value 1</foo></Test>.
So the key is to understand that withChild() returns a new SaplingElement.
The code can be compacted using streams e.g.
XdmNode paramNode2 = Saplings.elem("root").withChild(
xsltParameters
.entrySet()
.stream()
.map(p -> Saplings.elem(p.getKey()).withText(p.getValue()))
.collect(Collectors.toList())
.toArray(SaplingElement[]::new))
.toXdmNode(processor);
System.out.println(paramNode2);
There seems to be no examples online, according to the documentation Path, ParentMap's constructor accepts "Stmt *ASTRoot", which may means that later the ParentMap instance will find parents under the AST subtree under "ASTRoot". But how to get the root node of a translation unit? I tried
virtual bool VisitTranslationUnitDecl(TranslationUnitDecl *decl) {
//decl->dump();
Stmt *stmt = decl->getBody();
mParentMap = new ParentMap(stmt);
return true;
}
The goal is to create a ParentMap around the root nood then use it in other Visit*** callbacks during the scan process. But decl->getBody() is null. decl->dump() will print everything, and even scan the AST for the second time decl->getBody() is still null.
How to get the root Stmt of an AST? What is the right/better way to use ParentMap?
ParentMap is not really intended to be used on its own. You can use ASTContext::getParents, which constructs and maintains ParentMap.
I am trying to disable a CAN node from sending messages. I have a function defined in CANoe:
long ILNodeControlStop(char aNodeName[])
When I try to use this in my CAPL script it shows type of parameters do not match. The error might be a very simple one, but I am not able to find it.
Suppose my node name is BECM. So I will use it as,
on start
{
//some variables;
}
on key 'a'
{
ILNodeControlStop(BECM);
}
This throws an error 'Type of parameters do not match'. Do I have to declare something in variables section ? (Using Node layer IL functions)
Pay attention to the parameter type. It is not dbNode, it is char array.
So you have to pass it as a char array (string in common language).
ILNodeControlStop("BECM");
Also, consider using the ILStartSim(), ILStopSim() variants, check out their help and their availability.
I'm trying to write a function that does type casting, which seems to be a frequently occurring activity in Rascal code. But I can't seem to get it right. The following and several variations on it fail.
public &T cast(type[&T] tp, value v) throws str {
if (tp tv := v)
return tv;
else
throw "cast failed";
}
Can someone help me out?
Some more info: I frequently use pattern matching against a pattern of the form "Type Var" (i.e. against a variable declaration) in order to tell Rascal that an expression has a certain type, e.g.
map[str,value] m := myexp
This is usually in cases where I know that myexp has type map[str,value], but omitting the matching would make Rascal's type checking mechanism complain.
In order to be a bit more defensive against mistakes, I usually wrap the matching construct in an if-then-else where an exception is raised if the match fails:
if (map[str,value] m := myexp) {
// use m
} else {
throw "cast failed";
}
I would like to shorten all such similar pieces of code using a single function that does the job generically, so that I can write instead
cast(#map[str,value], myexp)
PS. Also see How to cast a value type to Map in Rascal?
It seems that the best way to write this, if you truly need to do this, is the following:
public map[str,value] cast(map[str,value] v) = v;
public default map[str,value] cast(value v) { throw "cast failed!"; }
Then you could just say
m = cast(myexp);
and it would do what you want to do -- the actual pattern matching is moved into the function signature for cast, with a case specific to the type you are wanting to use and a case that handles everything that doesn't otherwise match.
However, I'm still not sure why you are using type value, either here (inside the map) or in the linked question. The "standard" Rascal way of handling cases where you could have one of multiple choices is to define these with a user-defined data type and constructors. You could then use pattern matching to match the constructors, or use the is and has keywords to interrogate a value to check to see if it was created using a specific constructor or if it has a specific field, respectively. The rule for fields is that all occurrences of a field in the constructor definitions for a given ADT have the same type. So, it may help to know more about your usage scenario to see if this definition of cast is the best option or if there is a better solution to your problem.
EDITED
If you are reading JSON, an alternate way to do it is to use the JSON grammar and AST that also live in that part of the library (I think the one you are using is more of a stream reader, like our current text readers and writers, but I would need to look at the code more to be sure). You can then do something like this (long output included to give an idea of the results):
rascal>import lang::json::\syntax::JSON;
ok
rascal>import lang::json::ast::JSON;
ok
rascal>import lang::json::ast::Implode;
ok
ascal>js = buildAST(parse(#JSONText, |project://rascal/src/org/rascalmpl/library/lang/json/examples/twitter01.json|));
Value: object((
"since_id":integer(0),
"refresh_url":string("?since_id=202744362520678400&q=amsterdam&lang=en"),
"page":integer(1),
"since_id_str":string("0"),
"completed_in":float(0.058),
"results_per_page":integer(25),
"next_page":string("?page=2&max_id=202744362520678400&q=amsterdam&lang=en&rpp=25"),
"max_id_str":string("202744362520678400"),
"query":string("amsterdam"),
"max_id":integer(202744362520678400),
"results":array([
object((
"from_user":string("adekamel"),
"profile_image_url_https":string("https:\\/\\/si0.twimg.com\\/profile_images\\/2206104506\\/339515338_normal.jpg"),
"in_reply_to_status_id_str":string("202730522013728768"),
"to_user_id":integer(215350297),
"from_user_id_str":string("366868475"),
"geo":null(),
"in_reply_to_status_id":integer(202730522013728768),
"profile_image_url":string("http:\\/\\/a0.twimg.com\\/profile_images\\/2206104506\\/339515338_normal.jpg"),
"to_user_id_str":string("215350297"),
"from_user_name":string("nurul amalya \\u1d54\\u1d25\\u1d54"),
"created_at":string("Wed, 16 May 2012 12:56:37 +0000"),
"id_str":string("202744362520678400"),
"text":string("#Donnalita122 #NaishahS #fatihahmS #oishiihotchoc #yummy_DDG #zaimar93 #syedames I\'m here at Amsterdam :O"),
"to_user":string("Donnalita122"),
"metadata":object(("result_type":string("recent"))),
"iso_language_code":string("en"),
"from_user_id":integer(366868475),
"source":string("<a href="http:\\/\\/blackberry.com\\/twitter" rel="nofollow">Twitter for BlackBerry\\u00ae<\\/a>"),
"id":integer(202744362520678400),
"to_user_name":string("Rahmadini Hairuddin")
)),
object((
"from_user":string("kelashby"),
"profile_image_url_https":string("https:\\/\\/si0.twimg.com\\/profile_images\\/1861086809\\/me_beach_normal.JPG"),
"to_user_id":integer(0),
"from_user_id_str":string("291446599"),
"geo":null(),
"profile_image_url":string("http:\\/\\/a0.twimg.com\\/profile_images\\/1861086809\\/me_beach_normal.JPG"),
"to_user_id_str":string("0"),
"from_user_name":string("Kelly Ashby"),
"created_at":string("Wed, 16 May 2012 12:56:25 +0000"),
"id_str":string("202744310872018945"),
"text":string("45 days til freedom! Cannot wait! After Paris: London, maybe Amsterdam, then southern France, then CANADA!!!!"),
"to_user":null(),
"metadata":object(("result_type":string("recent"))),
"iso_language_code":string("en"),
"from_user_id":integer(291446599),
"source":string("<a href="http:\\/\\/mobile.twitter.com" rel="nofollow">Mobile Web<\\/a>"),
"id":integer(202744310872018945),
"to_user_name":null()
)),
object((
"from_user":string("johantolsma"),
"profile_image_url_https":string("https:\\/\\/si0.twimg.com\\/profile_images\\/1961917557\\/image_normal.jpg"),
"to_user_id":integer(0),
"from_user_id_str":string("23632499"),
"geo":null(),
"profile_image_url":string("http:\\/\\/a0.twimg.com\\/profile_images\\/1961917557\\/image_normal.jpg"),
"to_user_id_str":string("0"),
"from_user_name":string("Johan Tolsma"),
"created_at":string("Wed, 16 May 2012 12:56:16 +0000"),
"id_str":string("202744274050236416"),
"text":string("RT #agerolemou: Office space for freelancers in Amsterdam http:\\/\\/t.co\\/6VfHuLeK"),
"to_user":null(),
"metadata":object(("result_type":string("recent"))),
"iso_language_code":string("en"),
"from_user_id":integer(23632499),
"source":string("<a href="http:\\/\\/itunes.apple.com\\/us\\/app\\/twitter\\/id409789998?mt=12" rel="nofollow">Twitter for Mac<\\/a>"),
"id":integer(202744274050236416),
"to_user_name":null()
)),
object((
"from_user":string("hellosophieg"),
"profile_image_url_https":string("https:\\/\\/si0.twimg.com\\/profile_images\\/2213055219\\/image_normal.jpg"),
"to_user_id":integer(0),
"from_user_id_str":string("41153106"),
"geo":null(),
"profile_image_url":string("http:\\/\\/a0.twimg.com\\/profile_images\\/2213055219\\/image_normal.jp...
rascal>js is object;
bool: true
rascal>js.members<0>;
set[str]: {"since_id","refresh_url","page","since_id_str","completed_in","results_per_page","next_page","max_id_str","query","max_id","results"}
rascal>js.members["results_per_page"];
Value: integer(25)
You can then use pattern matching, over the types defined in lang::json::ast::json, to extract the information you need.
The code has a bug. This is the fixed code:
public &T cast(type[&T] tp, value v) throws str {
if (&T tv := v)
return tv;
else
throw "cast failed";
}
Note that we do not wish to include this in the standard library. Rather lets collect cases where we need it and find out how to fix it in another way.
If you find you need this casting often, then you might be avoiding the better parts of Rascal, such as pattern based dispatch. See also the answer by Mark Hills.