Re: [jdt-core-dev] Q about relationships between various java language e

[John Arthorne <John_Arthorne@xxxxxxxxxx>]

I'm not a JDT core expert, but I'll
take a stab at answering:

There are essentially two interesting
JDT "models".  The main java model is represented by the
jdt.core.* types such as IField.  This a source-based model that is
the main interface for searching and traversing the java model. It allows
basic manipulation of type structure (such as add or delete members), but
no real support for viewing or modifying the bodies of methods.  It
also supports adding element change listeners to be notified when the model
changes.

The other interesting "model"
is the abstract syntax tree, which can be built for individual complication
units in order to query or manipulate within method bodies.  You typically
build one of these when you need it, and then it gets thrown away.  This
is represented by methods in the "dom" package, for example FieldDeclaration
in your list.  The compiler implementation uses a more powerful version
of the AST (internal.compiler.ast.*), that supports things like code generation,
but this is for internal use only.

I believe the JDOM model has been largely
replaced by AST, but it remains for backwards compatibility.  It was
used as a model for more complex source manipulation (for example refactoring
used to use this). Again, you should probably just use AST instead of this.

For another language writer, I would
suggest something similar.  A "fast" source based model
that is always up to date and is mainly used for browsing and making major
source changes (such adding/deleting files), and a "slow", lazily
built parsed and resolved representation for richer manipulations such
as refactoring.
--

Christopher J Daly <cjdaly@xxxxxxxxxx>
Sent by: jdt-core-dev-admin@xxxxxxxxxxx

10/24/2003 06:46 PM

Please respond to
jdt-core-dev

To	jdt-core-dev@xxxxxxxxxxx
cc
Subject	[jdt-core-dev] Q about relationships between various java language element models in jdt.core

I'm looking into the possibility of an eclipse plugin to support C#, so
I'm
trying to understand how JDT does all the stuff it does.  One thing
that's
confusing me is the number of different (but similar) object models for
representing Java language elements.  For instance if you take Java
fields,
there is:

  org.eclipse.jdt.core.IField

which is implemented by
  org.eclipse.jdt.internal.core.BinaryField   and
  org.eclipse.jdt.internal.core.SourceField

then you have

  org.eclipse.jdt.internal.compiler.ast.FieldDeclaration

as well as

  org.eclipse.jdt.core.dom.FieldDeclaration

finally there is

  org.eclipse.jdt.core.jdom.IDOMField

which is implemented by
 org.eclipse.jdt.internal.core.jdom.DOMField


Can anyone help me answer these questions:

1) are all 4 of these object models considered necessary and good?  
If you
were starting from scratch on support for a new language would you have
all
4?

2) What are the key relationships between the object models?  Are
there
places where you walk a tree of one type to build a tree of another?  I
see
that when the parser runs it creates nodes of the classes in
org.eclipse.jdt.internal.compiler.ast, so when do trees of the other types
get created?

3) Are the org.eclipse.jdt.internal.compiler.ast classes meant to be more
a
model of the syntactic structure of the file, while the other models are
meant to represent the semantic information?  In other words was it
deemed
useful (or necessary) to have a more syntactic / file-oriented model as
well as a more semantic model to do refactoring type stuff, or could they
be combined into one?  Or are the key distinctions between these object
models something else besides syntax vs. semantics?

4) Are there any newsgroups, mailing-lists, or documents that are
specifically for people trying to produce org.eclipse.Xdt - for languages
X
that haven't been hosted on eclipse yet?


thanks in advance,

Chris

_______________________________________________
jdt-core-dev mailing list
jdt-core-dev@xxxxxxxxxxx
http://dev.eclipse.org/mailman/listinfo/jdt-core-dev