1 //===- LineIterator.h - Iterator to read a text buffer's lines --*- C++ -*-===//
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 #ifndef LLVM_SUPPORT_LINEITERATOR_H
10 #define LLVM_SUPPORT_LINEITERATOR_H
11 
12 #include "llvm/ADT/StringRef.h"
13 #include "llvm/Support/DataTypes.h"
14 #include <iterator>
15 
16 namespace llvm {
17 
18 class MemoryBuffer;
19 
20 /// A forward iterator which reads text lines from a buffer.
21 ///
22 /// This class provides a forward iterator interface for reading one line at
23 /// a time from a buffer. When default constructed the iterator will be the
24 /// "end" iterator.
25 ///
26 /// The iterator is aware of what line number it is currently processing. It
27 /// strips blank lines by default, and comment lines given a comment-starting
28 /// character.
29 ///
30 /// Note that this iterator requires the buffer to be nul terminated.
31 class line_iterator
32     : public std::iterator<std::forward_iterator_tag, StringRef> {
33   const MemoryBuffer *Buffer = nullptr;
34   char CommentMarker = '\0';
35   bool SkipBlanks = true;
36 
37   unsigned LineNumber = 1;
38   StringRef CurrentLine;
39 
40 public:
41   /// Default construct an "end" iterator.
42   line_iterator() = default;
43 
44   /// Construct a new iterator around some memory buffer.
45   explicit line_iterator(const MemoryBuffer &Buffer, bool SkipBlanks = true,
46                          char CommentMarker = '\0');
47 
48   /// Return true if we've reached EOF or are an "end" iterator.
49   bool is_at_eof() const { return !Buffer; }
50 
51   /// Return true if we're an "end" iterator or have reached EOF.
52   bool is_at_end() const { return is_at_eof(); }
53 
54   /// Return the current line number. May return any number at EOF.
55   int64_t line_number() const { return LineNumber; }
56 
57   /// Advance to the next (non-empty, non-comment) line.
58   line_iterator &operator++() {
59     advance();
60     return *this;
61   }
62   line_iterator operator++(int) {
63     line_iterator tmp(*this);
64     advance();
65     return tmp;
66   }
67 
68   /// Get the current line as a \c StringRef.
69   StringRef operator*() const { return CurrentLine; }
70   const StringRef *operator->() const { return &CurrentLine; }
71 
72   friend bool operator==(const line_iterator &LHS, const line_iterator &RHS) {
73     return LHS.Buffer == RHS.Buffer &&
74            LHS.CurrentLine.begin() == RHS.CurrentLine.begin();
75   }
76 
77   friend bool operator!=(const line_iterator &LHS, const line_iterator &RHS) {
78     return !(LHS == RHS);
79   }
80 
81 private:
82   /// Advance the iterator to the next line.
83   void advance();
84 };
85 }
86 
87 #endif
88