diff options
Diffstat (limited to 'contrib/llvm/tools/clang/include/clang/AST/Redeclarable.h')
| -rw-r--r-- | contrib/llvm/tools/clang/include/clang/AST/Redeclarable.h | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/include/clang/AST/Redeclarable.h b/contrib/llvm/tools/clang/include/clang/AST/Redeclarable.h index cd5f186..89a9d3c 100644 --- a/contrib/llvm/tools/clang/include/clang/AST/Redeclarable.h +++ b/contrib/llvm/tools/clang/include/clang/AST/Redeclarable.h @@ -21,6 +21,60 @@ namespace clang { class ASTContext; +// Some notes on redeclarables: +// +// - Every redeclarable is on a circular linked list. +// +// - Every decl has a pointer to the first element of the chain _and_ a +// DeclLink that may point to one of 3 possible states: +// - the "previous" (temporal) element in the chain +// - the "latest" (temporal) element in the chain +// - the an "uninitialized-latest" value (when newly-constructed) +// +// - The first element is also often called the canonical element. Every +// element has a pointer to it so that "getCanonical" can be fast. +// +// - Most links in the chain point to previous, except the link out of +// the first; it points to latest. +// +// - Elements are called "first", "previous", "latest" or +// "most-recent" when referring to temporal order: order of addition +// to the chain. +// +// - To make matters confusing, the DeclLink type uses the term "next" +// for its pointer-storage internally (thus functions like +// NextIsPrevious). It's easiest to just ignore the implementation of +// DeclLink when making sense of the redeclaration chain. +// +// - There's also a "definition" link for several types of +// redeclarable, where only one definition should exist at any given +// time (and the defn pointer is stored in the decl's "data" which +// is copied to every element on the chain when it's changed). +// +// Here is some ASCII art: +// +// "first" "latest" +// "canonical" "most recent" +// +------------+ first +--------------+ +// | | <--------------------------- | | +// | | | | +// | | | | +// | | +--------------+ | | +// | | first | | | | +// | | <---- | | | | +// | | | | | | +// | @class A | link | @interface A | link | @class A | +// | seen first | <---- | seen second | <---- | seen third | +// | | | | | | +// +------------+ +--------------+ +--------------+ +// | data | defn | data | defn | data | +// | | ----> | | <---- | | +// +------------+ +--------------+ +--------------+ +// | | ^ ^ +// | |defn | | +// | link +-----+ | +// +-->-------------------------------------------+ + /// \brief Provides common interface for the Decls that can be redeclared. template<typename decl_type> class Redeclarable { |
