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      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/Optional.h"
     13 #include "llvm/ADT/StringRef.h"
     14 #include "llvm/Support/DataTypes.h"
     15 #include "llvm/Support/MemoryBufferRef.h"
     16 #include <iterator>
     17 
     18 namespace llvm {
     19 
     20 class MemoryBuffer;
     21 
     22 /// A forward iterator which reads text lines from a buffer.
     23 ///
     24 /// This class provides a forward iterator interface for reading one line at
     25 /// a time from a buffer. When default constructed the iterator will be the
     26 /// "end" iterator.
     27 ///
     28 /// The iterator is aware of what line number it is currently processing. It
     29 /// strips blank lines by default, and comment lines given a comment-starting
     30 /// character.
     31 ///
     32 /// Note that this iterator requires the buffer to be nul terminated.
     33 class line_iterator {
     34   Optional<MemoryBufferRef> Buffer;
     35   char CommentMarker = '\0';
     36   bool SkipBlanks = true;
     37 
     38   unsigned LineNumber = 1;
     39   StringRef CurrentLine;
     40 
     41 public:
     42   using iterator_category = std::forward_iterator_tag;
     43   using value_type = StringRef;
     44   using difference_type = std::ptrdiff_t;
     45   using pointer = value_type *;
     46   using reference = value_type &;
     47 
     48   /// Default construct an "end" iterator.
     49   line_iterator() = default;
     50 
     51   /// Construct a new iterator around an unowned memory buffer.
     52   explicit line_iterator(const MemoryBufferRef &Buffer, bool SkipBlanks = true,
     53                          char CommentMarker = '\0');
     54 
     55   /// Construct a new iterator around some memory buffer.
     56   explicit line_iterator(const MemoryBuffer &Buffer, bool SkipBlanks = true,
     57                          char CommentMarker = '\0');
     58 
     59   /// Return true if we've reached EOF or are an "end" iterator.
     60   bool is_at_eof() const { return !Buffer; }
     61 
     62   /// Return true if we're an "end" iterator or have reached EOF.
     63   bool is_at_end() const { return is_at_eof(); }
     64 
     65   /// Return the current line number. May return any number at EOF.
     66   int64_t line_number() const { return LineNumber; }
     67 
     68   /// Advance to the next (non-empty, non-comment) line.
     69   line_iterator &operator++() {
     70     advance();
     71     return *this;
     72   }
     73   line_iterator operator++(int) {
     74     line_iterator tmp(*this);
     75     advance();
     76     return tmp;
     77   }
     78 
     79   /// Get the current line as a \c StringRef.
     80   StringRef operator*() const { return CurrentLine; }
     81   const StringRef *operator->() const { return &CurrentLine; }
     82 
     83   friend bool operator==(const line_iterator &LHS, const line_iterator &RHS) {
     84     return LHS.Buffer == RHS.Buffer &&
     85            LHS.CurrentLine.begin() == RHS.CurrentLine.begin();
     86   }
     87 
     88   friend bool operator!=(const line_iterator &LHS, const line_iterator &RHS) {
     89     return !(LHS == RHS);
     90   }
     91 
     92 private:
     93   /// Advance the iterator to the next line.
     94   void advance();
     95 };
     96 }
     97 
     98 #endif
     99