struct Foo{
Bar get(){
}
}
auto f = Foo();
f.get();
For example you decide that get was a very poor choice for a name but you have already used it in many different files and manually changing ever occurrence is very annoying.
You also can't really make a global substitution because other types may also have a method called get.
Is there anything for D to help refactor names for types, functions, variables etc?
Here's how I do it:
Change the name in the definition
Recompile
Go to the first error line reported and replace old with new
Goto 2
That's semi-manual, but I find it to be pretty easy and it goes quickly because the compiler error message will bring you right to where you need to be, and most editors can read those error messages well enough to dump you on the correct line, then it is a simple matter of telling it to repeat the last replacement again. (In my vim setup with my hotkeys, I hit F4 for next error message, then dot for repeat last change until it is done. Even a function with a hundred uses can be changed reliably* in a couple minutes.)
You could probably write a script that handles 90% of cases automatically too by just looking for ": Error: " in the compiler's output, extracting the file/line number, and running a plain text replace there. If the word shows up only once and outside a string literal, you can automatically replace it, and if not, ask the user to handle the remaining 10% of cases manually.
But I think it is easy enough to do with my editor hotkeys that I've never bothered trying to script it.
The one case this doesn't catch is if there's another function with the same name that might still compile. That should never happen if you do this change in isolation, because an ambiguous name wouldn't compile without it.
In that case, you could probably do a three-step compiler-assisted change:
Make sure your code compiles before. Then add #disable to the thing you want to rename.
Compile. Every place it complains about it being unusable for being disabled, do the find/replace.
Remove #disable and rename the definition. Recompile again to make sure there's nothing you missed like child classes (the compiler will then complain "method foo does not override any function" so they stand right out too.
So yeah, it isn't fully automated, but just changing it and having the compiler errors help find what's left is good enough for me.
Some limited refactoring support can be found in major IDE plugins like Mono-D or VisualD. I remember that Brian Schott had plans to add similar functionality to his dfix tool by adding dependency on dsymbol but it doesn't seem implemented yet.
Not, however, that all such options are indeed of a very limited robustness right now. This is because figuring out the fully qualified name of any given symbol is very complex task in D, one that requires full semantics analysis to be done 100% correctly. Think about local imports, templates, function overloading, mixins and how it all affects identifying the symbol.
In the long run it is quite certain that we need to wait before reference D compiler frontend becomes available as a library to implement such refactoring tool in clean and truly reliable way.
A good find all feature can be better than a bad refactoring which, as mentioned previously, requires semantic.
Personally I have a find all feature in Coedit which displays the context of a match and works on all the project sources.
It's fast to process the results.
I am currently writing a program that sits on top of a C++ interpreter. The user inputs C++ commands at runtime, which are then passed into the interpreter. For certain patterns, I want to replace the command given with a modified form, so that I can provide additional functionality.
I want to replace anything of the form
A->Draw(B1, B2)
with
MyFunc(A, B1, B2).
My first thought was regular expressions, but that would be rather error-prone, as any of A, B1, or B2 could be arbitrary C++ expressions. As these expressions could themselves contain quoted strings or parentheses, it would be quite difficult to match all cases with a regular expression. In addition, there may be multiple, nested forms of this expression
My next thought was to call clang as a subprocess, use "-dump-ast" to get the abstract syntax tree, modify that, then rebuild it into a command to be passed to the C++ interpreter. However, this would require keeping track of any environment changes, such as include files and forward declarations, in order to give clang enough information to parse the expression. As the interpreter does not expose this information, this seems infeasible as well.
The third thought was to use the C++ interpreter's own internal parsing to convert to an abstract syntax tree, then build from there. However, this interpreter does not expose the ast in any way that I was able to find.
Are there any suggestions as to how to proceed, either along one of the stated routes, or along a different route entirely?
What you want is a Program Transformation System.
These are tools that generally let you express changes to source code, written in source level patterns that essentially say:
if you see *this*, replace it by *that*
but operating on Abstract Syntax Trees so the matching and replacement process is
far more trustworthy than what you get with string hacking.
Such tools have to have parsers for the source language of interest.
The source language being C++ makes this fairly difficult.
Clang sort of qualifies; after all it can parse C++. OP objects
it cannot do so without all the environment context. To the extent
that OP is typing (well-formed) program fragments (statements, etc,.)
into the interpreter, Clang may [I don't have much experience with it
myself] have trouble getting focused on what the fragment is (statement? expression? declaration? ...). Finally, Clang isn't really a PTS; its tree modification procedures are not source-to-source transforms. That matters for convenience but might not stop OP from using it; surface syntax rewrite rule are convenient but you can always substitute procedural tree hacking with more effort. When there are more than a few rules, this starts to matter a lot.
GCC with Melt sort of qualifies in the same way that Clang does.
I'm under the impression that Melt makes GCC at best a bit less
intolerable for this kind of work. YMMV.
Our DMS Software Reengineering Toolkit with its full C++14 [EDIT July 2018: C++17] front end absolutely qualifies. DMS has been used to carry out massive transformations
on large scale C++ code bases.
DMS can parse arbitrary (well-formed) fragments of C++ without being told in advance what the syntax category is, and return an AST of the proper grammar nonterminal type, using its pattern-parsing machinery. [You may end up with multiple parses, e.g. ambiguities, that you'll have decide how to resolve, see Why can't C++ be parsed with a LR(1) parser? for more discussion] It can do this without resorting to "the environment" if you are willing to live without macro expansion while parsing, and insist the preprocessor directives (they get parsed too) are nicely structured with respect to the code fragment (#if foo{#endif not allowed) but that's unlikely a real problem for interactively entered code fragments.
DMS then offers a complete procedural AST library for manipulating the parsed trees (search, inspect, modify, build, replace) and can then regenerate surface source code from the modified tree, giving OP text
to feed to the interpreter.
Where it shines in this case is OP can likely write most of his modifications directly as source-to-source syntax rules. For his
example, he can provide DMS with a rewrite rule (untested but pretty close to right):
rule replace_Draw(A:primary,B1:expression,B2:expression):
primary->primary
"\A->Draw(\B1, \B2)" -- pattern
rewrites to
"MyFunc(\A, \B1, \B2)"; -- replacement
and DMS will take any parsed AST containing the left hand side "...Draw..." pattern and replace that subtree with the right hand side, after substituting the matches for A, B1 and B2. The quote marks are metaquotes and are used to distinguish C++ text from rule-syntax text; the backslash is a metaescape used inside metaquotes to name metavariables. For more details of what you can say in the rule syntax, see DMS Rewrite Rules.
If OP provides a set of such rules, DMS can be asked to apply the entire set.
So I think this would work just fine for OP. It is a rather heavyweight mechanism to "add" to the package he wants to provide to a 3rd party; DMS and its C++ front end are hardly "small" programs. But then modern machines have lots of resources so I think its a question of how badly does OP need to do this.
Try modify the headers to supress the method, then compiling you'll find the errors and will be able to replace all core.
As far as you have a C++ interpreter (as CERN's Root) I guess you must use the compiler to intercept all the Draw, an easy and clean way to do that is declare in the headers the Draw method as private, using some defines
class ItemWithDrawMehtod
{
....
public:
#ifdef CATCHTHEMETHOD
private:
#endif
void Draw(A,B);
#ifdef CATCHTHEMETHOD
public:
#endif
....
};
Then compile as:
gcc -DCATCHTHEMETHOD=1 yourfilein.cpp
In case, user want to input complex algorithms to the application, what I suggest is to integrate a scripting language to the app. So that the user can write code [function/algorithm in defined way] so the app can execute it in the interpreter and get the final results. Ex: Python, Perl, JS, etc.
Since you need C++ in the interpreter http://chaiscript.com/ would be a suggestion.
What happens when someone gets ahold of the Draw member function (auto draw = &A::Draw;) and then starts using draw? Presumably you'd want the same improved Draw-functionality to be called in this case too. Thus I think we can conclude that what you really want is to replace the Draw member function with a function of your own.
Since it seems you are not in a position to modify the class containing Draw directly, a solution could be to derive your own class from A and override Draw in there. Then your problem reduces to having your users use your new improved class.
You may again consider the problem of automatically translating uses of class A to your new derived class, but this still seems pretty difficult without the help of a full C++ implementation. Perhaps there is a way to hide the old definition of A and present your replacement under that name instead, via clever use of header files, but I cannot determine whether that's the case from what you've told us.
Another possibility might be to use some dynamic linker hackery using LD_PRELOAD to replace the function Draw that gets called at runtime.
There may be a way to accomplish this mostly with regular expressions.
Since anything that appears after Draw( is already formatted correctly as parameters, you don't need to fully parse them for the purpose you have outlined.
Fundamentally, the part that matters is the "SYMBOL->Draw("
SYMBOL could be any expression that resolves to an object that overloads -> or to a pointer of a type that implements Draw(...). If you reduce this to two cases, you can short-cut the parsing.
For the first case, a simple regular expression that searches for any valid C++ symbol, something similar to "[A-Za-z_][A-Za-z0-9_\.]", along with the literal expression "->Draw(". This will give you the portion that must be rewritten, since the code following this part is already formatted as valid C++ parameters.
The second case is for complex expressions that return an overloaded object or pointer. This requires a bit more effort, but a short parsing routine to walk backward through just a complex expression can be written surprisingly easily, since you don't have to support blocks (blocks in C++ cannot return objects, since lambda definitions do not call the lambda themselves, and actual nested code blocks {...} can't return anything directly inline that would apply here). Note that if the expression doesn't end in ) then it has to be a valid symbol in this context, so if you find a ) just match nested ) with ( and extract the symbol preceding the nested SYMBOL(...(...)...)->Draw() pattern. This may be possible with regular expressions, but should be fairly easy in normal code as well.
As soon as you have the symbol or expression, the replacement is trivial, going from
SYMBOL->Draw(...
to
YourFunction(SYMBOL, ...
without having to deal with the additional parameters to Draw().
As an added benefit, chained function calls are parsed for free with this model, since you can recursively iterate over the code such as
A->Draw(B...)->Draw(C...)
The first iteration identifies the first A->Draw( and rewrites the whole statement as
YourFunction(A, B...)->Draw(C...)
which then identifies the second ->Draw with an expression "YourFunction(A, ...)->" preceding it, and rewrites it as
YourFunction(YourFunction(A, B...), C...)
where B... and C... are well-formed C++ parameters, including nested calls.
Without knowing the C++ version that your interpreter supports, or the kind of code you will be rewriting, I really can't provide any sample code that is likely to be worthwhile.
One way is to load user code as a DLL, (something like plugins,)
this way, you don't need to compile your actual application, just the user code will be compiled, and you application will load it dynamically.
I tried to look through the syntax tree, but the information is not sufficient enough, so I created a compilation and got the semantic model of the syntax tree. Now I can get properties and fields declarations using OfType<T> extension method where T is PropertyDeclarationSyntax or FieldDeclarationSyntax.
Inside a method.Body.Statements I thought I could look for symbols representing the ones I got from OfType<T>. But I am having a hard time figuring that part out. The syntax tree just identifies the symbol as "IdentifierName", which is not much helpful..
If this is not the correct way of looking at it, please let me know.
Use SemanticModel.GetDeclaredSymbol() on the PropertyDeclartionSyntax or the one of the VariableDeclaratorSyntax inside the FieldDefinitionSyntax. Then use SemanticModel.GetSymbolInfo() on the identifiers and see if they match. (Note that you should use ISymbol.Equals as you might not get reference equal results.
I know how to make YACC generate an AST, but how do you actaully get it? I mean, how do you actaully get the value of the root node from YACC?
Yacc only gives you back one node at a time, and it's always something that you just gave yacc at some earlier time, i.e., whatever you wanted to return from a reduced production or whatever you wanted to return from a terminal symbol. (Sorry, you said you knew that, but some people reading this might not.)
So, take whatever you woud have returned from the root or top rule, and save it (in your attached C reduction code) any way you like.
What Yacc gives you is a parse tree, which is different than an AST. You'd need to construct your AST by yourselves while going through each node of the parse tree (through yacc).
This is how I did it:
in the yacc file (your_grammar.y):
%parse-param {AstNode **pproot}
%parse-param {char **errmsg}
in the calling program (your_program.c):
res = yyparse(&pAst, &errmsg);
AST nodes are allocated and linked as a tree inside yyparse() (you make the logic) and the address of root node is passed back in the pAst pointer.
It's not as elegant as having the parser return an AST directly, but the best way that I've come up with to do this is to have a global data structure (e.g. a vector or linked list), with threadsafe insertion methods if thread safety is needed, and have the top-level yacc rule add its result (a.k.a. $$) to that data structure. Then you can access this result in other functions. Of course, if you're only going to output a single AST, it's probably only necessary to have a single global pointer to that AST, rather than a data structure full of them.
I have the need to parse partial XML fragments (which are presented as std::string), such as this one:
<FOO:node>val</FOO:node>
as xmlDoc objects in libxml2, and because these are fragments, I keep getting the namespace error : Namespace prefix FOO on node is not defined errors spit out into STDERR.
What I am looking for is for either a way to filter just these namespace warnings out or parse the XML fragment straight into a xmlNode object.
I think some sort of hacking around with initGenericErrorDefaultFunc() may be in order to go the first way, but the documentation for libxml2 is absolutely atrocious.
I would frankly prefer to go with the 2nd approach because it would require no error hacking and the node would be already aware of the namespace, but I don't think it's possible because the node has to have a root and XML fragments are not guaranteed to have only one root.
I just need some guidance here of how to rid myself of the namespace error warning.
Thank you very much.
Building on what #Potatoswatter said... can you create a context for the fragments? E.g. concatenate
<dummyRoot xmlns:FOO="dummy-URI">
in front of your fragment, and
</dummyRoot>
afterward, then pass the concatenated string to xmlParseMemory().
Alternatively, why don't you use xmlParseInNodeContext(), which lets you pass in a node to use as context (including namespaces), and the content can be any Well Balanced Chunk (e.g. multiple elements with no single root element).
Either method requires that you know, or can scan to find out, the set of all possible namespace prefixes that the fragment may use.
Is it not an option to pass the xmlParserOptions XML_PARSE_NOERROR and/or XML_PARSE_NOWARNING to the parser?