LLVM  9.0.0svn
LineIterator.cpp
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1 //===- LineIterator.cpp - Implementation of line iteration ----------------===//
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 
11 
12 using namespace llvm;
13 
14 static bool isAtLineEnd(const char *P) {
15  if (*P == '\n')
16  return true;
17  if (*P == '\r' && *(P + 1) == '\n')
18  return true;
19  return false;
20 }
21 
22 static bool skipIfAtLineEnd(const char *&P) {
23  if (*P == '\n') {
24  ++P;
25  return true;
26  }
27  if (*P == '\r' && *(P + 1) == '\n') {
28  P += 2;
29  return true;
30  }
31  return false;
32 }
33 
34 line_iterator::line_iterator(const MemoryBuffer &Buffer, bool SkipBlanks,
35  char CommentMarker)
36  : Buffer(Buffer.getBufferSize() ? &Buffer : nullptr),
37  CommentMarker(CommentMarker), SkipBlanks(SkipBlanks), LineNumber(1),
38  CurrentLine(Buffer.getBufferSize() ? Buffer.getBufferStart() : nullptr,
39  0) {
40  // Ensure that if we are constructed on a non-empty memory buffer that it is
41  // a null terminated buffer.
42  if (Buffer.getBufferSize()) {
43  assert(Buffer.getBufferEnd()[0] == '\0');
44  // Make sure we don't skip a leading newline if we're keeping blanks
45  if (SkipBlanks || !isAtLineEnd(Buffer.getBufferStart()))
46  advance();
47  }
48 }
49 
50 void line_iterator::advance() {
51  assert(Buffer && "Cannot advance past the end!");
52 
53  const char *Pos = CurrentLine.end();
54  assert(Pos == Buffer->getBufferStart() || isAtLineEnd(Pos) || *Pos == '\0');
55 
56  if (skipIfAtLineEnd(Pos))
57  ++LineNumber;
58  if (!SkipBlanks && isAtLineEnd(Pos)) {
59  // Nothing to do for a blank line.
60  } else if (CommentMarker == '\0') {
61  // If we're not stripping comments, this is simpler.
62  while (skipIfAtLineEnd(Pos))
63  ++LineNumber;
64  } else {
65  // Skip comments and count line numbers, which is a bit more complex.
66  for (;;) {
67  if (isAtLineEnd(Pos) && !SkipBlanks)
68  break;
69  if (*Pos == CommentMarker)
70  do {
71  ++Pos;
72  } while (*Pos != '\0' && !isAtLineEnd(Pos));
73  if (!skipIfAtLineEnd(Pos))
74  break;
75  ++LineNumber;
76  }
77  }
78 
79  if (*Pos == '\0') {
80  // We've hit the end of the buffer, reset ourselves to the end state.
81  Buffer = nullptr;
82  CurrentLine = StringRef();
83  return;
84  }
85 
86  // Measure the line.
87  size_t Length = 0;
88  while (Pos[Length] != '\0' && !isAtLineEnd(&Pos[Length])) {
89  ++Length;
90  }
91 
92  CurrentLine = StringRef(Pos, Length);
93 }
This class represents lattice values for constants.
Definition: AllocatorList.h:23
size_t getBufferSize() const
Definition: MemoryBuffer.h:61
line_iterator()
Default construct an "end" iterator.
Definition: LineIterator.h:42
#define P(N)
static bool isAtLineEnd(const char *P)
This interface provides simple read-only access to a block of memory, and provides simple methods for...
Definition: MemoryBuffer.h:41
static bool skipIfAtLineEnd(const char *&P)
const char * getBufferEnd() const
Definition: MemoryBuffer.h:60
const char * getBufferStart() const
Definition: MemoryBuffer.h:59
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
iterator end() const
Definition: StringRef.h:103