1//===- LineIterator.cpp - Implementation of line iteration ----------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "llvm/Support/LineIterator.h"
11#include "llvm/Support/MemoryBuffer.h"
12
13using namespace llvm;
14
15static bool isAtLineEnd(const char *P) {
16  if (*P == '\n')
17    return true;
18  if (*P == '\r' && *(P + 1) == '\n')
19    return true;
20  return false;
21}
22
23static bool skipIfAtLineEnd(const char *&P) {
24  if (*P == '\n') {
25    ++P;
26    return true;
27  }
28  if (*P == '\r' && *(P + 1) == '\n') {
29    P += 2;
30    return true;
31  }
32  return false;
33}
34
35line_iterator::line_iterator(const MemoryBuffer &Buffer, bool SkipBlanks,
36                             char CommentMarker)
37    : Buffer(Buffer.getBufferSize() ? &Buffer : nullptr),
38      CommentMarker(CommentMarker), SkipBlanks(SkipBlanks), LineNumber(1),
39      CurrentLine(Buffer.getBufferSize() ? Buffer.getBufferStart() : nullptr,
40                  0) {
41  // Ensure that if we are constructed on a non-empty memory buffer that it is
42  // a null terminated buffer.
43  if (Buffer.getBufferSize()) {
44    assert(Buffer.getBufferEnd()[0] == '\0');
45    // Make sure we don't skip a leading newline if we're keeping blanks
46    if (SkipBlanks || !isAtLineEnd(Buffer.getBufferStart()))
47      advance();
48  }
49}
50
51void line_iterator::advance() {
52  assert(Buffer && "Cannot advance past the end!");
53
54  const char *Pos = CurrentLine.end();
55  assert(Pos == Buffer->getBufferStart() || isAtLineEnd(Pos) || *Pos == '\0');
56
57  if (skipIfAtLineEnd(Pos))
58    ++LineNumber;
59  if (!SkipBlanks && isAtLineEnd(Pos)) {
60    // Nothing to do for a blank line.
61  } else if (CommentMarker == '\0') {
62    // If we're not stripping comments, this is simpler.
63    while (skipIfAtLineEnd(Pos))
64      ++LineNumber;
65  } else {
66    // Skip comments and count line numbers, which is a bit more complex.
67    for (;;) {
68      if (isAtLineEnd(Pos) && !SkipBlanks)
69        break;
70      if (*Pos == CommentMarker)
71        do {
72          ++Pos;
73        } while (*Pos != '\0' && !isAtLineEnd(Pos));
74      if (!skipIfAtLineEnd(Pos))
75        break;
76      ++LineNumber;
77    }
78  }
79
80  if (*Pos == '\0') {
81    // We've hit the end of the buffer, reset ourselves to the end state.
82    Buffer = nullptr;
83    CurrentLine = StringRef();
84    return;
85  }
86
87  // Measure the line.
88  size_t Length = 0;
89  while (Pos[Length] != '\0' && !isAtLineEnd(&Pos[Length])) {
90    ++Length;
91  }
92
93  CurrentLine = StringRef(Pos, Length);
94}
95