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 : line_iterator(Buffer.getMemBufferRef(), SkipBlanks, CommentMarker) {}
37
38line_iterator::line_iterator(const MemoryBufferRef &Buffer, bool SkipBlanks,
39 char CommentMarker)
40 : Buffer(Buffer.getBufferSize() ? std::optional<MemoryBufferRef>(Buffer)
41 : std::nullopt),
42 CommentMarker(CommentMarker), SkipBlanks(SkipBlanks),
43 CurrentLine(Buffer.getBufferSize() ? Buffer.getBufferStart() : nullptr,
44 0) {
45 // Ensure that if we are constructed on a non-empty memory buffer that it is
46 // a null terminated buffer.
47 if (Buffer.getBufferSize()) {
48 assert(Buffer.getBufferEnd()[0] == '\0');
49 // Make sure we don't skip a leading newline if we're keeping blanks
50 if (SkipBlanks || !isAtLineEnd(P: Buffer.getBufferStart()))
51 advance();
52 }
53}
54
55void line_iterator::advance() {
56 assert(Buffer && "Cannot advance past the end!");
57
58 const char *Pos = CurrentLine.end();
59 assert(Pos == Buffer->getBufferStart() || isAtLineEnd(Pos) || *Pos == '\0');
60
61 if (skipIfAtLineEnd(P&: Pos))
62 ++LineNumber;
63 if (!SkipBlanks && isAtLineEnd(P: Pos)) {
64 // Nothing to do for a blank line.
65 } else if (CommentMarker == '\0') {
66 // If we're not stripping comments, this is simpler.
67 while (skipIfAtLineEnd(P&: Pos))
68 ++LineNumber;
69 } else {
70 // Skip comments and count line numbers, which is a bit more complex.
71 for (;;) {
72 if (isAtLineEnd(P: Pos) && !SkipBlanks)
73 break;
74 if (*Pos == CommentMarker)
75 do {
76 ++Pos;
77 } while (*Pos != '\0' && !isAtLineEnd(P: Pos));
78 if (!skipIfAtLineEnd(P&: Pos))
79 break;
80 ++LineNumber;
81 }
82 }
83
84 if (*Pos == '\0') {
85 // We've hit the end of the buffer, reset ourselves to the end state.
86 Buffer = std::nullopt;
87 CurrentLine = StringRef();
88 return;
89 }
90
91 // Measure the line.
92 size_t Length = 0;
93 while (Pos[Length] != '\0' && !isAtLineEnd(P: &Pos[Length])) {
94 ++Length;
95 }
96
97 CurrentLine = StringRef(Pos, Length);
98}
99