1 //===- LineIterator.h - Iterator to read a text buffer's lines --*- C++ -*-===//
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 #ifndef LLVM_SUPPORT_LINEITERATOR_H
11 #define LLVM_SUPPORT_LINEITERATOR_H
12 
13 #include "llvm/ADT/StringRef.h"
14 #include "llvm/Support/DataTypes.h"
15 #include <iterator>
16 
17 namespace llvm {
18 
19 class MemoryBuffer;
20 
21 /// \brief A forward iterator which reads text lines from a buffer.
22 ///
23 /// This class provides a forward iterator interface for reading one line at
24 /// a time from a buffer. When default constructed the iterator will be the
25 /// "end" iterator.
26 ///
27 /// The iterator is aware of what line number it is currently processing. It
28 /// strips blank lines by default, and comment lines given a comment-starting
29 /// character.
30 ///
31 /// Note that this iterator requires the buffer to be nul terminated.
32 class line_iterator
33     : public std::iterator<std::forward_iterator_tag, StringRef> {
34   const MemoryBuffer *Buffer;
35   char CommentMarker;
36   bool SkipBlanks;
37 
38   unsigned LineNumber;
39   StringRef CurrentLine;
40 
41 public:
42   /// \brief Default construct an "end" iterator.
line_iterator()43   line_iterator() : Buffer(nullptr) {}
44 
45   /// \brief Construct a new iterator around some memory buffer.
46   explicit line_iterator(const MemoryBuffer &Buffer, bool SkipBlanks = true,
47                          char CommentMarker = '\0');
48 
49   /// \brief Return true if we've reached EOF or are an "end" iterator.
is_at_eof()50   bool is_at_eof() const { return !Buffer; }
51 
52   /// \brief Return true if we're an "end" iterator or have reached EOF.
is_at_end()53   bool is_at_end() const { return is_at_eof(); }
54 
55   /// \brief Return the current line number. May return any number at EOF.
line_number()56   int64_t line_number() const { return LineNumber; }
57 
58   /// \brief Advance to the next (non-empty, non-comment) line.
59   line_iterator &operator++() {
60     advance();
61     return *this;
62   }
63   line_iterator operator++(int) {
64     line_iterator tmp(*this);
65     advance();
66     return tmp;
67   }
68 
69   /// \brief Get the current line as a \c StringRef.
70   StringRef operator*() const { return CurrentLine; }
71   const StringRef *operator->() const { return &CurrentLine; }
72 
73   friend bool operator==(const line_iterator &LHS, const line_iterator &RHS) {
74     return LHS.Buffer == RHS.Buffer &&
75            LHS.CurrentLine.begin() == RHS.CurrentLine.begin();
76   }
77 
78   friend bool operator!=(const line_iterator &LHS, const line_iterator &RHS) {
79     return !(LHS == RHS);
80   }
81 
82 private:
83   /// \brief Advance the iterator to the next line.
84   void advance();
85 };
86 }
87 
88 #endif
89