include/llvm/Support/LineIterator.h

   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;
  34   char CommentMarker;
  35   bool SkipBlanks;
  36
  37   unsigned LineNumber;
  38   StringRef CurrentLine;
  39
  40 public:
  41   /// Default construct an "end" iterator.
  42   line_iterator() : Buffer(nullptr) {}
  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