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 
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 
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 
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 
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