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Diffstat (limited to 'docs/IntroductionToTheClangAST.rst')
| -rw-r--r-- | docs/IntroductionToTheClangAST.rst | 63 |
1 files changed, 27 insertions, 36 deletions
diff --git a/docs/IntroductionToTheClangAST.rst b/docs/IntroductionToTheClangAST.rst index 81eb7ed..600a6c8 100644 --- a/docs/IntroductionToTheClangAST.rst +++ b/docs/IntroductionToTheClangAST.rst @@ -7,6 +7,12 @@ AST. It is targeted at developers who either want to contribute to Clang, or use tools that work based on Clang's AST, like the AST matchers. +.. raw:: html + + <center><iframe width="560" height="315" src="http://www.youtube.com/embed/VqCkCDFLSsc?vq=hd720" frameborder="0" allowfullscreen></iframe></center> + +`Slides <http://llvm.org/devmtg/2013-04/klimek-slides.pdf>`_ + Introduction ============ @@ -27,9 +33,8 @@ Examining the AST ================= A good way to familarize yourself with the Clang AST is to actually look -at it on some simple example code. Clang has a builtin AST-dump modes, -which can be enabled with the flags ``-ast-dump`` and ``-ast-dump-xml``. Note -that ``-ast-dump-xml`` currently only works with debug builds of clang. +at it on some simple example code. Clang has a builtin AST-dump mode, +which can be enabled with the flag ``-ast-dump``. Let's look at a simple example AST: @@ -41,40 +46,26 @@ Let's look at a simple example AST: return result; } - # Clang by default is a frontend for many tools; -cc1 tells it to directly - # use the C++ compiler mode. -undef leaves out some internal declarations. - $ clang -cc1 -undef -ast-dump-xml test.cc + # Clang by default is a frontend for many tools; -Xclang is used to pass + # options directly to the C++ frontend. + $ clang -Xclang -ast-dump -fsyntax-only test.cc + TranslationUnitDecl 0x5aea0d0 <<invalid sloc>> ... cutting out internal declarations of clang ... - <TranslationUnit ptr="0x4871160"> - <Function ptr="0x48a5800" name="f" prototype="true"> - <FunctionProtoType ptr="0x4871de0" canonical="0x4871de0"> - <BuiltinType ptr="0x4871250" canonical="0x4871250"/> - <parameters> - <BuiltinType ptr="0x4871250" canonical="0x4871250"/> - </parameters> - </FunctionProtoType> - <ParmVar ptr="0x4871d80" name="x" initstyle="c"> - <BuiltinType ptr="0x4871250" canonical="0x4871250"/> - </ParmVar> - <Stmt> - (CompoundStmt 0x48a5a38 <t2.cc:1:14, line:4:1> - (DeclStmt 0x48a59c0 <line:2:3, col:24> - 0x48a58c0 "int result = - (ParenExpr 0x48a59a0 <col:16, col:23> 'int' - (BinaryOperator 0x48a5978 <col:17, col:21> 'int' '/' - (ImplicitCastExpr 0x48a5960 <col:17> 'int' <LValueToRValue> - (DeclRefExpr 0x48a5918 <col:17> 'int' lvalue ParmVar 0x4871d80 'x' 'int')) - (IntegerLiteral 0x48a5940 <col:21> 'int' 42)))") - (ReturnStmt 0x48a5a18 <line:3:3, col:10> - (ImplicitCastExpr 0x48a5a00 <col:10> 'int' <LValueToRValue> - (DeclRefExpr 0x48a59d8 <col:10> 'int' lvalue Var 0x48a58c0 'result' 'int')))) - - </Stmt> - </Function> - </TranslationUnit> - -In general, ``-ast-dump-xml`` dumps declarations in an XML-style format and -statements in an S-expression-style format. The toplevel declaration in + `-FunctionDecl 0x5aeab50 <test.cc:1:1, line:4:1> f 'int (int)' + |-ParmVarDecl 0x5aeaa90 <line:1:7, col:11> x 'int' + `-CompoundStmt 0x5aead88 <col:14, line:4:1> + |-DeclStmt 0x5aead10 <line:2:3, col:24> + | `-VarDecl 0x5aeac10 <col:3, col:23> result 'int' + | `-ParenExpr 0x5aeacf0 <col:16, col:23> 'int' + | `-BinaryOperator 0x5aeacc8 <col:17, col:21> 'int' '/' + | |-ImplicitCastExpr 0x5aeacb0 <col:17> 'int' <LValueToRValue> + | | `-DeclRefExpr 0x5aeac68 <col:17> 'int' lvalue ParmVar 0x5aeaa90 'x' 'int' + | `-IntegerLiteral 0x5aeac90 <col:21> 'int' 42 + `-ReturnStmt 0x5aead68 <line:3:3, col:10> + `-ImplicitCastExpr 0x5aead50 <col:10> 'int' <LValueToRValue> + `-DeclRefExpr 0x5aead28 <col:10> 'int' lvalue Var 0x5aeac10 'result' 'int' + +The toplevel declaration in a translation unit is always the `translation unit declaration <http://clang.llvm.org/doxygen/classclang_1_1TranslationUnitDecl.html>`_. In this example, our first user written declaration is the `function |
