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
15line_iterator::line_iterator(const MemoryBuffer &Buffer, char CommentMarker)
16    : Buffer(Buffer.getBufferSize() ? &Buffer : nullptr),
17      CommentMarker(CommentMarker), LineNumber(1),
18      CurrentLine(Buffer.getBufferSize() ? Buffer.getBufferStart() : nullptr,
19                  0) {
20  // Ensure that if we are constructed on a non-empty memory buffer that it is
21  // a null terminated buffer.
22  if (Buffer.getBufferSize()) {
23    assert(Buffer.getBufferEnd()[0] == '\0');
24    advance();
25  }
26}
27
28void line_iterator::advance() {
29  assert(Buffer && "Cannot advance past the end!");
30
31  const char *Pos = CurrentLine.end();
32  assert(Pos == Buffer->getBufferStart() || *Pos == '\n' || *Pos == '\0');
33
34  if (CommentMarker == '\0') {
35    // If we're not stripping comments, this is simpler.
36    size_t Blanks = 0;
37    while (Pos[Blanks] == '\n')
38      ++Blanks;
39    Pos += Blanks;
40    LineNumber += Blanks;
41  } else {
42    // Skip comments and count line numbers, which is a bit more complex.
43    for (;;) {
44      if (*Pos == CommentMarker)
45        do {
46          ++Pos;
47        } while (*Pos != '\0' && *Pos != '\n');
48      if (*Pos != '\n')
49        break;
50      ++Pos;
51      ++LineNumber;
52    }
53  }
54
55  if (*Pos == '\0') {
56    // We've hit the end of the buffer, reset ourselves to the end state.
57    Buffer = nullptr;
58    CurrentLine = StringRef();
59    return;
60  }
61
62  // Measure the line.
63  size_t Length = 0;
64  do {
65    ++Length;
66  } while (Pos[Length] != '\0' && Pos[Length] != '\n');
67
68  CurrentLine = StringRef(Pos, Length);
69}
70