Code Analysis and Refactoring with CDT

Code Analysis and Refactoring with the CDT Doug Schaefer Wind River CDT Project Lead.

What is the CDT?
A C/C++ Development Environment on Eclipse
Intellig ent Code Editor
Source Navigation features using an index and internal parser
Build with integration with different tool chains
Debug with integration with different debug engines
Out of the box support for GNU tools
To facilitate testing and to ease adoption
Extended by many vendors to support their own platforms
Wind River, QNX, Nokia/Symbian, IBM, Intel, and many more

What is the CDT Used For?
Embedded Development
Leading IDE solution for the mobile and device market
Adopted as IDE by most RTOS and silicon vendors
Linux development
Included in most enterprise Linux distributions
Red Hat working to create “Visual Studio” for Linux
High Performance Computing
Basis for Parallel Tools Platform and Fortran IDEs
Cross Platform Development
Windows, Linux, MacOS X, most RTOSes, ...

Why does the CDT have a parser?
Original intention was to support UML modeling and code gen
Started by the CDT team at Rational
Started with Outline view support
CmodelBuilder to populate the Cmodel
Moved on to populate index
Full AST to capture symbol defs and references
And now we have refactoring
And they said it couldn't be done!

The C Model
Adaptation of resources to C/C++ type things
mainly intended to populate Project Navigator and Outline View
Adds to Resource level
ICProject, source and output folders, source and binary files
And inside the file level
ITranslationUnit and IBinary
Entry point is the CoreModel class
No nice OSGi service yet, not even an adapter
e.g., ICProject cproj = CoreModel.getDefault.create(project);
Root element is ICElement, open type hierarchy to see it all

CModel is good, but...
Focused mainly on UI type things
Simple, easy to understand
But not necessarily the most accurate representation
Traditional compilers have Abstract Syntax Trees
Starts at the token level
Arranged in syntax tree
Semantic analysis support for “understanding” what's in the tree
Enough information to translate into executable object code
The CDT has an AST!

Getting a CDT AST
Entry point is ITranslationUnit from the Cmodel
IASTTranslationUnit ast = tu.getAST();
Uses parser to create a Full AST
Determines language from content type
Invokes associated parser for the language
Produces a language dependent AST
ICASTTranslationUnit, ICPPASTTranslationUnit
ASTVisitor provided to facilitate walking the AST
Trasitional visitor pattern, accept/visit/leave

Semantic Analysis
“Bindings” connect Declarations and References
Represent semantic concepts and their properties
IBinding is root of type hierarchy
IASTName represents point of declaration and reference
getBinding() returns IBinding for given name
Find Declarations and References from IASTTranslationUnit
IASTName[] getDeclarationsInAST(IBinding binding)
IASTName[] getReferencesInAST(IBinding binding)

AST is great, but...
Creating Full AST is expensive
both size (lots of objects) and time (parsing is compute intensive)
Finding all References in a large project prohibitive
Parsing every source file very time consuming (hours).
We need a caching strategy...

Introducing the Index and Indexer
Index captures all Names and Bindings in a project
Stored in a hand coded database
Used for C/C++ Search, Open Declaration
Indexer runs in the background on file saves
Parses files and walks AST adding names and bindings to DB
Mode added to AST to reuse contents of Index instead of parsing Header files
Huge performance improvement similar to pre-compiled headers
Some cost in accuracy due to conditional compile directives

Parsing using the Index
Parsers operate in different modes/styles
e.g. ITranslationUnit.AST_SKIP_INDEXED_HEADERS
Pass in Index and flags to parser
ITranslationUnit.getAST(IIndex index, int style)
Get Index from Index Manager
CCorePlugin.getIndexManager().getIndex(ICProject[] projects)
Acquire and release read index lock to avoid collision with indexer

Using the Index
Use index in AST searches
IName[] IASTTranslationUnit.getReferences(IBinding[] binding)
IName super class for AST Names and Index Names
IBindings are handled automagically
If parsed using skip headers
IASTName.getBinding() will return the binding from the index
Information can be retrieved from the index directly
e.g., IIndex.findBindings() which takes a Pattern and an IndexFilter

A Simple Static Analysis Tool
Find all functions that call 'printf'
Find ICProject, get IIndex for it
IIndex.findBinding() for IFunction bindings called printf
IIndex.findReference() for the binding
For each reference name, create AST for containing file
Find IASTNode at the offset in the reference name
Search node parents looking for IASTFunctionDefinition
Get declarator for function and print out the IASTName for it

Introducing CDT Refactoring
Very similar to JDT Refactoring
Reuses the LTK plug-in contributed by JDT team
Uses semantic analysis capabilities to create TextEdits
CRefactoring is root of type hierarchy
Three steps
checkInitialConditions to set up for refactoring for user options
checkFinalConditions to ensure user entered options are valid
collectModifications to set up refactoring changes

AST Rewriting and the LTK
ModificationCollector manages ASTRewrites
ASTRewrite creates TextEdits to affect AST changes
Insert, remove, replace nodes
LTK uses TextEdits to show preview and to execute the change
Which makes refactoring easy to create
LTK also provides UI framework for co-ordinating refactoring
Add your own input page for user selectable options

Simple Refactoring
Change calls to printf with calls to log collector
Left as an exercise for the reader...
Look at the current set of CDT refactorings
Extract Constant
Extract Function
Generate Getters and Setters
Hide Method
Implement Method

Next Steps
Framework needs documentation
Spread the word on what can be done and how
Framework a bit young and needs exercise
Architecture needs a little clean up, but not much
Feel free to submit bugs, patches, and new functionality
Discuss on cdt-dev mailing list
Let your imagination go wild and see what the CDT can do for you!

http://cdtdoug.blogspot.com	828
http://www.eclipsecon.org	61
http://www.slideshare.net	33
http://cdtdoug.blogspot.ro	10
http://cdtdoug.blogspot.de	9
http://cdtdoug.blogspot.fr	6
http://cdtdoug.blogspot.co.il	4
http://cdtdoug.blogspot.ru	3
http://cdtdoug.blogspot.jp	3
http://cdtdoug.blogspot.in	3
http://cdtdoug.blogspot.se	3
http://cdtdoug.blogspot.it	3
http://cdtdoug.blogspot.ch	3
http://static.slideshare.net	3
http://webcache.googleusercontent.com	3
http://cdtdoug.blogspot.ca	2
http://209.85.129.132	2
http://cdtdoug.blogspot.co.uk	2
http://cdtdoug.blogspot.sk	2
http://cdtdoug.blogspot.com.es	2
http://cdtdoug.blogspot.com.br	2
http://cdtdoug.blogspot.fi	2
http://203.208.37.132	1
http://cdtdoug.blogspot.co.at	1
http://cdtdoug.blogspot.kr	1
http://cdtdoug.blogspot.com.ar	1
http://cdtdoug.blogspot.hu	1
http://cdtdoug.blogspot.dk	1
http://cdtdoug.blogspot.pt	1
https://webcache.googleusercontent.com	1
http://cdtdoug.blogspot.be	1
http://cdtdoug.blogspot.nl	1
http://74.125.93.132	1

Code Analysis and Refactoring with CDT

by dschaefer on Nov 17, 2008

Accessibility

Categories

Upload Details

Usage Rights

33 Embeds 1,000

Statistics

Code Analysis and Refactoring with CDT Presentation Transcript