1//===- RewriteBuffer.h - Buffer rewriting interface -----------------------===//
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#include "llvm/ADT/RewriteBuffer.h"
10#include "llvm/Support/raw_ostream.h"
11
12using namespace llvm;
13
14raw_ostream &RewriteBuffer::write(raw_ostream &Stream) const {
15 // Walk RewriteRope chunks efficiently using MoveToNextPiece() instead of the
16 // character iterator.
17 for (RopePieceBTreeIterator I = begin(), E = end(); I != E;
18 I.MoveToNextPiece())
19 Stream << I.piece();
20 return Stream;
21}
22
23/// Return true if this character is non-new-line whitespace:
24/// ' ', '\\t', '\\f', '\\v', '\\r'.
25static inline bool isWhitespaceExceptNL(unsigned char c) {
26 return c == ' ' || c == '\t' || c == '\f' || c == '\v' || c == '\r';
27}
28
29void RewriteBuffer::RemoveText(unsigned OrigOffset, unsigned Size,
30 bool removeLineIfEmpty) {
31 // Nothing to remove, exit early.
32 if (Size == 0)
33 return;
34
35 unsigned RealOffset = getMappedOffset(OrigOffset, AfterInserts: true);
36 assert(RealOffset + Size <= Buffer.size() && "Invalid location");
37
38 // Remove the dead characters.
39 Buffer.erase(Offset: RealOffset, NumBytes: Size);
40
41 // Add a delta so that future changes are offset correctly.
42 AddReplaceDelta(OrigOffset, Change: -Size);
43
44 if (removeLineIfEmpty) {
45 // Find the line that the remove occurred and if it is completely empty
46 // remove the line as well.
47
48 iterator curLineStart = begin();
49 unsigned curLineStartOffs = 0;
50 iterator posI = begin();
51 for (unsigned i = 0; i != RealOffset; ++i) {
52 if (*posI == '\n') {
53 curLineStart = posI;
54 ++curLineStart;
55 curLineStartOffs = i + 1;
56 }
57 ++posI;
58 }
59
60 unsigned lineSize = 0;
61 posI = curLineStart;
62 while (posI != end() && isWhitespaceExceptNL(c: *posI)) {
63 ++posI;
64 ++lineSize;
65 }
66 if (posI != end() && *posI == '\n') {
67 Buffer.erase(Offset: curLineStartOffs, NumBytes: lineSize + 1 /* + '\n'*/);
68 // FIXME: Here, the offset of the start of the line is supposed to be
69 // expressed in terms of the original input not the "real" rewrite
70 // buffer. How do we compute that reliably? It might be tempting to use
71 // curLineStartOffs + OrigOffset - RealOffset, but that assumes the
72 // difference between the original and real offset is the same at the
73 // removed text and at the start of the line, but that's not true if
74 // edits were previously made earlier on the line. This bug is also
75 // documented by a FIXME on the definition of
76 // clang::Rewriter::RewriteOptions::RemoveLineIfEmpty. A reproducer for
77 // the implementation below is the test RemoveLineIfEmpty in
78 // clang/unittests/Rewrite/RewriteBufferTest.cpp.
79 AddReplaceDelta(OrigOffset: curLineStartOffs, Change: -(lineSize + 1 /* + '\n'*/));
80 }
81 }
82}
83
84void RewriteBuffer::InsertText(unsigned OrigOffset, StringRef Str,
85 bool InsertAfter) {
86 // Nothing to insert, exit early.
87 if (Str.empty())
88 return;
89
90 unsigned RealOffset = getMappedOffset(OrigOffset, AfterInserts: InsertAfter);
91 Buffer.insert(Offset: RealOffset, Start: Str.begin(), End: Str.end());
92
93 // Add a delta so that future changes are offset correctly.
94 AddInsertDelta(OrigOffset, Change: Str.size());
95}
96
97/// ReplaceText - This method replaces a range of characters in the input
98/// buffer with a new string. This is effectively a combined "remove+insert"
99/// operation.
100void RewriteBuffer::ReplaceText(unsigned OrigOffset, unsigned OrigLength,
101 StringRef NewStr) {
102 unsigned RealOffset = getMappedOffset(OrigOffset, AfterInserts: true);
103 Buffer.erase(Offset: RealOffset, NumBytes: OrigLength);
104 Buffer.insert(Offset: RealOffset, Start: NewStr.begin(), End: NewStr.end());
105 if (OrigLength != NewStr.size())
106 AddReplaceDelta(OrigOffset, Change: NewStr.size() - OrigLength);
107}
108