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diff --git a/docs/IntroductionToTheClangAST.html b/docs/IntroductionToTheClangAST.html deleted file mode 100644 index 28175dd..0000000 --- a/docs/IntroductionToTheClangAST.html +++ /dev/null @@ -1,139 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" - "http://www.w3.org/TR/html4/strict.dtd"> -<html> -<head> -<title>Introduction to the Clang AST</title> -<link type="text/css" rel="stylesheet" href="../menu.css" /> -<link type="text/css" rel="stylesheet" href="../content.css" /> -</head> -<body> - -<!--#include virtual="../menu.html.incl"--> - -<div id="content"> - -<h1>Introduction to the Clang AST</h1> -<p>This document gives a gentle introduction to the mysteries of the Clang 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.</p> -<!-- FIXME: Add link once we have an AST matcher document --> - -<!-- ======================================================================= --> -<h2 id="intro">Introduction</h2> -<!-- ======================================================================= --> - -<p>Clang's AST is different from ASTs produced by some other compilers in that it closely -resembles both the written C++ code and the C++ standard. For example, -parenthesis expressions and compile time constants are available in an unreduced -form in the AST. This makes Clang's AST a good fit for refactoring tools.</p> - -<p>Documentation for all Clang AST nodes is available via the generated -<a href="http://clang.llvm.org/doxygen">Doxygen</a>. The doxygen online -documentation is also indexed by your favorite search engine, which will make -a search for clang and the AST node's class name usually turn up the doxygen -of the class you're looking for (for example, search for: clang ParenExpr).</p> - -<!-- ======================================================================= --> -<h2 id="examine">Examining the AST</h2> -<!-- ======================================================================= --> - -<p>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.</p> - -<p>Let's look at a simple example AST:</p> -<pre> -# cat test.cc -int f(int x) { - int result = (x / 42); - 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 -... 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> -</pre> -<p>In general, -ast-dump-xml dumps declarations in an XML-style format and -statements in an S-expression-style format. -The toplevel declaration in a translation unit is always the -<a href="http://clang.llvm.org/doxygen/classclang_1_1TranslationUnitDecl.html">translation unit declaration</a>. -In this example, our first user written declaration is the -<a href="http://clang.llvm.org/doxygen/classclang_1_1FunctionDecl.html">function declaration</a> -of 'f'. The body of 'f' is a <a href="http://clang.llvm.org/doxygen/classclang_1_1CompoundStmt.html">compound statement</a>, -whose child nodes are a <a href="http://clang.llvm.org/doxygen/classclang_1_1DeclStmt.html">declaration statement</a> -that declares our result variable, and the -<a href="http://clang.llvm.org/doxygen/classclang_1_1ReturnStmt.html">return statement</a>.</p> - -<!-- ======================================================================= --> -<h2 id="context">AST Context</h2> -<!-- ======================================================================= --> - -<p>All information about the AST for a translation unit is bundled up in the class -<a href="http://clang.llvm.org/doxygen/classclang_1_1ASTContext.html">ASTContext</a>. -It allows traversal of the whole translation unit starting from -<a href="http://clang.llvm.org/doxygen/classclang_1_1ASTContext.html#abd909fb01ef10cfd0244832a67b1dd64">getTranslationUnitDecl</a>, -or to access Clang's <a href="http://clang.llvm.org/doxygen/classclang_1_1ASTContext.html#a4f95adb9958e22fbe55212ae6482feb4">table of identifiers</a> -for the parsed translation unit.</p> - -<!-- ======================================================================= --> -<h2 id="nodes">AST Nodes</h2> -<!-- ======================================================================= --> - -<p>Clang's AST nodes are modeled on a class hierarchy that does not have a common -ancestor. Instead, there are multiple larger hierarchies for basic node types like -<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a> and -<a href="http://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>. Many -important AST nodes derive from <a href="http://clang.llvm.org/doxygen/classclang_1_1Type.html">Type</a>, -<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>, -<a href="http://clang.llvm.org/doxygen/classclang_1_1DeclContext.html">DeclContext</a> or -<a href="http://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>, -with some classes deriving from both Decl and DeclContext.</p> -<p>There are also a multitude of nodes in the AST that are not part of a -larger hierarchy, and are only reachable from specific other nodes, -like <a href="http://clang.llvm.org/doxygen/classclang_1_1CXXBaseSpecifier.html">CXXBaseSpecifier</a>. -</p> - -<p>Thus, to traverse the full AST, one starts from the <a href="http://clang.llvm.org/doxygen/classclang_1_1TranslationUnitDecl.html">TranslationUnitDecl</a> -and then recursively traverses everything that can be reached from that node -- this information has to be encoded for each specific node type. This algorithm -is encoded in the <a href="http://clang.llvm.org/doxygen/classclang_1_1RecursiveASTVisitor.html">RecursiveASTVisitor</a>. -See the <a href="http://clang.llvm.org/docs/RAVFrontendAction.html">RecursiveASTVisitor tutorial</a>.</p> - -<p>The two most basic nodes in the Clang AST are statements (<a href="http://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>) -and declarations (<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>). -Note that expressions (<a href="http://clang.llvm.org/doxygen/classclang_1_1Expr.html">Expr</a>) -are also statements in Clang's AST.</p> - -</div> -</body> -</html> - |
