Is there a way to record specific line/character positions from generated FreeMarker templates? The purpose would be to highlight specific sections of the generated output file without having to parse the generated output file.
For example, let's say I have this template:
function foo()
{
ordinary_crap();
ordinary_crap();
do_something_special();<#mark foospecial>
ordinary_crap();
}
function bar()
{
ordinary_crap();
do_something_really_special();<#mark barspecial>
ordinary_crap();
ordinary_crap();
}
function baz()
{
foo();<#mark foo_call_1>
ordinary_crap();
bar();<#mark bar_call_1>
}
I want the <#mark> directive not to yield any generated output, but to associate mark names foospecial, barspecial, foo_call_1 and bar_call_1 with the line and position-within-a-line of where the <#mark> directives are located in the generated output. The example above I showed independent single points but it would be also useful to have begin/end pairs to mark specific ranges.
The alternatives I can see are
parsing the output independently -- not always possible, for example what if there are several identical instances of something in the output, and I want to highlight a specific one of those?
adding "mark hints" and removing them via my own postprocessing step. For example
<mark name="years">Fourscore and seven</mark> years ago
something really brilliant happened to a really nice guy named
<mark name="niceguyname">Fred</mark>.
Then I could postprocess this and remove the <mark > tags (assuming they don't conflict with the rest of the content), recording positions as I go.
But both of these seem kind of hacky.
From your TemplateDirectiveModel implementation (I assume that's how you implement mark, not with #macro), call env.getCurrentDirectiveCallPlace(). The returned DirectiveCallPlace has getBeginColumn() and getBeginLine() methods.
So, given that Java has little to no support to unsigned types, I'm right now writing a small API to handle these (for now, I have UnsignedByte and UnsignedInt). The algorithm is simple: store each of them as their higher representation (byte->short, int->long), extends the Number class and implement some calculation and representation utility methods.
The problem is: it is actually very verbose - and boring - to have to, every time, code things like:
UnsignedByte value = new UnsignedByte(15);
UnsignedByte convert = new UnsignedByte(someIntValue);
I was wondering: is there any way to implement, on Eclipse, something like a "file pre-processor", in a way that it will automatically replace some pre-defined strings with other pre-defined strings before compiling the files?
For example: replace U(x) with new UnsignedByte(x), so it would be possible to use:
UnsignedByte value = U(15);
UnsignedByte convert = U(someIntValue);
Yes, I could create a method called U(...) and use import static, but even then, it would be so much trouble doing it for every class that I would use my unsigned types.
I could write a simple Java program that would replace these expressions in a file, but the problem is: How could I integrate that on Eclipse, in a way that it would call/use it every time a Java file is compiled?
I would recommend using Eclipse Templates for doing this instead. I know its not exactly what you ask for but its very simple and can be achieved out of the box.
When you write sysout in Eclipse and press Ctrl+Space it gives you an option to replace that with System.out.println();
You can find more information in the following link
How to add shortcut keys for java code in eclipse
I can point you at how one project I know of does this, they have a set of Python scripts that generate a whole set of classes (java files) from a template base file. They run the script manually, as opposed to part of the build.
Have a look here for the specific example. In this code they have a class for operating on double, but from this class they want to generate code to operate on float, int, etc all in the same way.
There is, of course, a big debate about whether generated code should be checked in or not to source repository. I leave that issue aside and hope that the above example is good to get you going.
I'm working on some unit tests for localization in our Android app. Right now my unit test checks all of our different format strings for all of our different locales to make sure the translators didn't mess them up (which they tend to do). Basically I'm making sure that calling String.format() won't throw a format exception.
The only downside is I need to manually add every string to the test. I'm working on a replacement test that uses reflection to find every string in R.string. Getting the strings isn't a problem, but is there any easy way to determine the number and types of arguments a format string expects?
String.format() doesn't complain if you pass it too many arguments so I could probably just pass a big array of Integers (which could get unboxed to %d or toString()'ed to %s) and look for format exceptions. Still, it would be a little nicer if I could pass the correct types of arguments in the correct amounts :)
Honestly, I think the method of checking for an Exception is the best one you'll come across without using your own fully-fledged parser.
If you are seriously interested in writing a code to find all the elements (that will be come arguments) from the format(...) method of Formatter.java (I can't find an anchor, so you just have to control+f format(Lo and you'll find it). This code is also available in the SDK under sources\android-16\java\util, in the private method doFormat.
It's actually a relatively simple code once you learn the methods it uses to find each section and parse it. I think with a bit of work, and perhaps a bit of copy-paste from Formatter, you could set up your very own code that would simply find the elements of the String, instead of substituting them.
I'm making a command-line based tool in Java, and I was thinking I might be able to make it all a bit easier on my self if I could take user input and automatically find the needed functions based on the users input.
What I want to do, is, that if a user types:
User create newUser
The java code looks for a class called user, then looks for a function called create, and inputs newUser as the first argument of the function. Meaning typing the command "User create newUser" would make the java code trigger this line of code:
User.create("newUser");
And of cause, return errors if the class or function was not found, or so.
So far I've been playing with
Class.forName(cmdArg[0])
Where cmdArg[0] is the first word given by the Scanner, found by splitting where there's spaces.
Anyway, is it possible to achieve this in Java? Any help would be much appreciated.
My solution:
Okay, i got it working, my final solution was a combination of duffymo's and user978548's answer, my solution looks like this:
Class comArgs[] = new Class[1];
comArgs[0] = String.class;
String[] args = new String[1];
args[0] = commandArray[2];
Class.forName("code."+commandArray[0])
.getDeclaredMethod(commandArray[1], comArgs)
.invoke(null, args);
This is surrounded by a try/catch with allot of exceptions, but it works.
I also have a HashMap for which commands i want to receive.
The args variable can should be as long as the number of arguments needed for the called method.
You can use the features built into the java.lang.Class class:
Class.forName(args[0]).newInstance();
Have your users input the fully-resolved class name and you don't have to worry about all those shenanigans. You'll need them anyway, because the short name might not be unique.
Another approach is to put the Class instances that you want users to be able to create in a Map and have them input the key.
as duffymo said, Class.forName(args[0]).newInstance(); for the class, and as Chin Boon said, you have all that you want in reflections method. Like, to run your method:
Object.class.getMethods()[find your method here].invoke(obj, args)
What you are looking for is Java reflection.
duffymo is correct - reflection is what you are prob talking about.
However, I would maybe suggest looking at a combination of Builder/Factory design patterns to make this a little nicer rather than using reflection to attempt to find the class/methods you want (although obviously this depends on the context of the problem and I am making some assumptions here!).
I need to change the signature of a method used all over the codebase.
Specifically, the method void log(String) will take two additional arguments (Class c, String methodName), which need to be provided by the caller, depending on the method where it is called. I can't simply pass null or similar.
To give an idea of the scope, Eclipse found 7000 references to that method, so if I change it the whole project will go down. It will take weeks for me to fix it manually.
As far as I can tell Eclipse's refactoring plugin of Eclipse is not up to the task, but I really want to automate it.
So, how can I get the job done?
Great, I can copy a previous answer of mine and I just need to edit a tiny little bit:
I think what you need to do is use a source code parser like javaparser to do this.
For every java source file, parse it to a CompilationUnit, create a Visitor, probably using ModifierVisitor as base class, and override (at least) visit(MethodCallExpr, arg). Then write the changed CompilationUnit to a new File and do a diff afterwards.
I would advise against changing the original source file, but creating a shadow file tree may me a good idea (e.g. old file: src/main/java/com/mycompany/MyClass.java, new file src/main/refactored/com/mycompany/MyClass.java, that way you can diff the entire directories).
Eclipse is able to do that using Refactor -> Change Method signature and provide default values for the new parameters.
For the class parameter the defaultValue should be this.getClass() but you are right in your comment I don't know how to do for the method name parameter.
IntelliJ IDEA shouldn't have any trouble with this.
I'm not a Java expert, but something like this could work. It's not a perfect solution (it may even be a very bad solution), but it could get you started:
Change the method signature with IntelliJ's refactoring tools, and specify default values for the 2 new parameters:
c: self.getClass()
methodName: Thread.currentThread().getStackTrace()[1].getMethodName()
or better yet, simply specify null as the default values.
I think that there are several steps to dealing with this, as it is not just a technical issue but a 'situation':
Decline to do it in short order due to the risk.
Point out the issues caused by not using standard frameworks but reinventing the wheel (as Paul says).
Insist on using Log4j or equivalent if making the change.
Use Eclipse refactoring in sensible chunks to make the changes and deal with the varying defaults.
I have used Eclipse refactoring on quite large changes for fixing old smelly code - nowadays it is fairly robust.
Maybe I'm being naive, but why can't you just overload the method name?
void thing(paramA) {
thing(paramA, THE_DEFAULT_B, THE_DEFAULT_C)
}
void thing(paramA, paramB, paramC) {
// new method
}
Do you really need to change the calling code and the method signature? What I'm getting at is it looks like the added parameters are meant to give you the calling class and method to add to your log data. If the only requirement is just adding the calling class/method to the log data then Thread.currentThread().getStackTrace() should work. Once you have the StackTraceElement[] you can get the class name and method name for the caller.
If the lines you need replaced fall into a small number of categories, then what you need is Perl:
find -name '*.java' | xargs perl -pi -e 's/log\(([^,)]*?)\)/log(\1, "foo", "bar")/g'
I'm guessing that it wouldn't be too hard to hack together a script which would put the classname (derived from the filename) in as the second argument. Getting the method name in as the third argument is left as an exercise to the reader.
Try refactor using intellij. It has a feature called SSR (Structural Search and Replace). You can refer classes, method names, etc for a context. (seanizer's answer is more promising, I upvoted it)
I agree with Seanizer's answer that you want a tool that can parse Java. That's necessary but not sufficient; what you really want is a tool that can carry out a reliable mass-change.
To do this, you want a tool that can parse Java, can pattern match against the parsed code, install the replacement call, and spit out the answer without destroying the rest of the source code.
Our DMS Software Reengineering Toolkit can do all of this for a variety of languages, including Java. It parses complete java systems of source, builds abstract syntax trees (for the entire set of code).
DMS can apply pattern-directed, source-to-source transformations to achieve the desired change.
To achieve the OP's effect, he would apply the following program transformation:
rule replace_legacy_log(s:STRING): expression -> expression
" log(\s) " -> " log( \s, \class\(\), \method\(\) ) "
What this rule says is, find a call to log which has a single string argument, and replace it with a call to log with two more arguments determined by auxiliary functions class and method.
These functions determine the containing method name and containing class name for the AST node root where the rule finds a match.
The rule is written in "source form", but actually matches against the AST and replaces found ASTs with the modified AST.
To get back the modified source, you ask DMS to simply prettyprint (to make a nice layout) or fidelity print (if you want the layout of the old code preserved). DMS preserves comments, number radixes, etc.\
If the exisitng application has more than one defintion of the "log" function, you'll need to add a qualifier:
... if IsDesiredLog().
where IsDesiredLog uses DMS's symbol table and inheritance information to determine if the specific log refers to the definition of interest.
Il fact your problem is not to use a click'n'play engine that will allow you to replace all occurences of
log("some weird message");
by
log(this.getClass(), new Exception().getStackTrace()[1].getMethodName());
As it has few chances to work on various cases (like static methods, as an example).
I would tend to suggest you to take a look at spoon. This tool allows source code parsing and transformation, allowing you to achieve your operation in a -obviously code based- slow, but controlled operation.
However, you could alos consider transforming your actual method with one exploring stack trace to get information or, even better, internally use log4j and a log formatter that displays the correct information.
I would search and replace log( with log(#class, #methodname,
Then write a little script in any language (even java) to find the class name and the method names and to replace the #class and #method tokens...
Good luck
If the class and method name are required for "where did this log come from?" type data, then another option is to print out a stack trace in your log method. E.g.
public void log(String text)
{
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw, true);
new Throwable.printStackTrace(pw);
pw.flush();
sw.flush();
String stackTraceAsLog = sw.toString();
//do something with text and stackTraceAsLog
}