//===--- SourceManager.h - Track and cache source files ---------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief Defines the SourceManager interface.
///
/// There are three different types of locations in a file: a spelling
/// location, an expansion location, and a presumed location.
///
/// Given an example of:
/// \code
/// #define min(x, y) x < y ? x : y
/// \endcode
///
/// and then later on a use of min:
/// \code
/// #line 17
/// return min(a, b);
/// \endcode
///
/// The expansion location is the line in the source code where the macro
/// was expanded (the return statement), the spelling location is the
/// location in the source where the macro was originally defined,
/// and the presumed location is where the line directive states that
/// the line is 17, or any other line.
///
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