[LibTooling] Add retrieval of extended AST-node source to FixIt library
Summary:
Introduces variants of `getText` and `getSourceRange` that extract the source text of an AST node potentially with a trailing token.
Some of the new functions manipulate `CharSourceRange`s, rather than `SourceRange`s, because they document and dynamically enforce their type. So, this revision also updates the corresponding existing FixIt functions to manipulate `CharSourceRange`s. This change is not strictly necessary, but seems like the correct choice, to keep the API self-consistent.
This revision is the first in a series intended to improve the abstractions available to users for writing source-to-source transformations. A full discussion of the end goal can be found on the cfe-dev list with subject "[RFC] Easier source-to-source transformations with clang tooling".
Reviewers: ilya-biryukov
Reviewed By: ilya-biryukov
Subscribers: kimgr, riccibruno, JonasToth, jdoerfert, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D58556
llvm-svn: 356095