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
9#include "llvm/Support/LineIterator.h"
10#include "llvm/Support/MemoryBuffer.h"
11
12using namespace llvm;
13
14static 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
22static 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
34line_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
50void 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}
94