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
12 using namespace llvm;
13
isAtLineEnd(const char * P)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
skipIfAtLineEnd(const char * & P)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
line_iterator(const MemoryBuffer & Buffer,bool SkipBlanks,char CommentMarker)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
advance()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 }
94