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      1 //===- RewriteBuffer.h - Buffer rewriting interface -------------*- C++ -*-===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 
      9 #ifndef LLVM_CLANG_REWRITE_CORE_REWRITEBUFFER_H
     10 #define LLVM_CLANG_REWRITE_CORE_REWRITEBUFFER_H
     11 
     12 #include "clang/Basic/LLVM.h"
     13 #include "clang/Rewrite/Core/DeltaTree.h"
     14 #include "clang/Rewrite/Core/RewriteRope.h"
     15 #include "llvm/ADT/StringRef.h"
     16 
     17 namespace clang {
     18 
     19 /// RewriteBuffer - As code is rewritten, SourceBuffer's from the original
     20 /// input with modifications get a new RewriteBuffer associated with them.  The
     21 /// RewriteBuffer captures the modified text itself as well as information used
     22 /// to map between SourceLocation's in the original input and offsets in the
     23 /// RewriteBuffer.  For example, if text is inserted into the buffer, any
     24 /// locations after the insertion point have to be mapped.
     25 class RewriteBuffer {
     26   friend class Rewriter;
     27 
     28   /// Deltas - Keep track of all the deltas in the source code due to insertions
     29   /// and deletions.
     30   DeltaTree Deltas;
     31 
     32   RewriteRope Buffer;
     33 
     34 public:
     35   using iterator = RewriteRope::const_iterator;
     36 
     37   iterator begin() const { return Buffer.begin(); }
     38   iterator end() const { return Buffer.end(); }
     39   unsigned size() const { return Buffer.size(); }
     40 
     41   /// Initialize - Start this rewrite buffer out with a copy of the unmodified
     42   /// input buffer.
     43   void Initialize(const char *BufStart, const char *BufEnd) {
     44     Buffer.assign(BufStart, BufEnd);
     45   }
     46   void Initialize(StringRef Input) {
     47     Initialize(Input.begin(), Input.end());
     48   }
     49 
     50   /// Write to \p Stream the result of applying all changes to the
     51   /// original buffer.
     52   /// Note that it isn't safe to use this function to overwrite memory mapped
     53   /// files in-place (PR17960). Consider using a higher-level utility such as
     54   /// Rewriter::overwriteChangedFiles() instead.
     55   ///
     56   /// The original buffer is not actually changed.
     57   raw_ostream &write(raw_ostream &Stream) const;
     58 
     59   /// RemoveText - Remove the specified text.
     60   void RemoveText(unsigned OrigOffset, unsigned Size,
     61                   bool removeLineIfEmpty = false);
     62 
     63   /// InsertText - Insert some text at the specified point, where the offset in
     64   /// the buffer is specified relative to the original SourceBuffer.  The
     65   /// text is inserted after the specified location.
     66   void InsertText(unsigned OrigOffset, StringRef Str,
     67                   bool InsertAfter = true);
     68 
     69 
     70   /// InsertTextBefore - Insert some text before the specified point, where the
     71   /// offset in the buffer is specified relative to the original
     72   /// SourceBuffer. The text is inserted before the specified location.  This is
     73   /// method is the same as InsertText with "InsertAfter == false".
     74   void InsertTextBefore(unsigned OrigOffset, StringRef Str) {
     75     InsertText(OrigOffset, Str, false);
     76   }
     77 
     78   /// InsertTextAfter - Insert some text at the specified point, where the
     79   /// offset in the buffer is specified relative to the original SourceBuffer.
     80   /// The text is inserted after the specified location.
     81   void InsertTextAfter(unsigned OrigOffset, StringRef Str) {
     82     InsertText(OrigOffset, Str);
     83   }
     84 
     85   /// ReplaceText - This method replaces a range of characters in the input
     86   /// buffer with a new string.  This is effectively a combined "remove/insert"
     87   /// operation.
     88   void ReplaceText(unsigned OrigOffset, unsigned OrigLength,
     89                    StringRef NewStr);
     90 
     91 private:
     92   /// getMappedOffset - Given an offset into the original SourceBuffer that this
     93   /// RewriteBuffer is based on, map it into the offset space of the
     94   /// RewriteBuffer.  If AfterInserts is true and if the OrigOffset indicates a
     95   /// position where text is inserted, the location returned will be after any
     96   /// inserted text at the position.
     97   unsigned getMappedOffset(unsigned OrigOffset,
     98                            bool AfterInserts = false) const{
     99     return Deltas.getDeltaAt(2*OrigOffset+AfterInserts)+OrigOffset;
    100   }
    101 
    102   /// AddInsertDelta - When an insertion is made at a position, this
    103   /// method is used to record that information.
    104   void AddInsertDelta(unsigned OrigOffset, int Change) {
    105     return Deltas.AddDelta(2*OrigOffset, Change);
    106   }
    107 
    108   /// AddReplaceDelta - When a replacement/deletion is made at a position, this
    109   /// method is used to record that information.
    110   void AddReplaceDelta(unsigned OrigOffset, int Change) {
    111     return Deltas.AddDelta(2*OrigOffset+1, Change);
    112   }
    113 };
    114 
    115 } // namespace clang
    116 
    117 #endif // LLVM_CLANG_REWRITE_CORE_REWRITEBUFFER_H
    118