llvm/lib/Support/LineIterator.cpp

   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     : line_iterator(Buffer.getMemBufferRef(), SkipBlanks, CommentMarker) {}
  37
  38 line_iterator::line_iterator(const MemoryBufferRef &Buffer, bool SkipBlanks,
  39                              char CommentMarker)
  40     : Buffer(Buffer.getBufferSize() ? std::optional<MemoryBufferRef>(Buffer)
  41                                     : std::nullopt),
  42       CommentMarker(CommentMarker), SkipBlanks(SkipBlanks),
  43       CurrentLine(Buffer.getBufferSize() ? Buffer.getBufferStart() : nullptr,
  44                   0) {
  45   // Ensure that if we are constructed on a non-empty memory buffer that it is
  46   // a null terminated buffer.
  47   if (Buffer.getBufferSize()) {
  48     assert(Buffer.getBufferEnd()[0] == '\0');
  49     // Make sure we don't skip a leading newline if we're keeping blanks
  50     if (SkipBlanks || !isAtLineEnd(Buffer.getBufferStart()))
  51       advance();
  52   }
  53 }
  54
  55 void line_iterator::advance() {
  56   assert(Buffer && "Cannot advance past the end!");
  57
  58   const char *Pos = CurrentLine.end();
  59   assert(Pos == Buffer->getBufferStart() || isAtLineEnd(Pos) || *Pos == '\0');
  60
  61   if (skipIfAtLineEnd(Pos))
  62     ++LineNumber;
  63   if (!SkipBlanks && isAtLineEnd(Pos)) {
  64     // Nothing to do for a blank line.
  65   } else if (CommentMarker == '\0') {
  66     // If we're not stripping comments, this is simpler.
  67     while (skipIfAtLineEnd(Pos))
  68       ++LineNumber;
  69   } else {
  70     // Skip comments and count line numbers, which is a bit more complex.
  71     for (;;) {
  72       if (isAtLineEnd(Pos) && !SkipBlanks)
  73         break;
  74       if (*Pos == CommentMarker)
  75         do {
  76           ++Pos;
  77         } while (*Pos != '\0' && !isAtLineEnd(Pos));
  78       if (!skipIfAtLineEnd(Pos))
  79         break;
  80       ++LineNumber;
  81     }
  82   }
  83
  84   if (*Pos == '\0') {
  85     // We've hit the end of the buffer, reset ourselves to the end state.
  86     Buffer = std::nullopt;
  87     CurrentLine = StringRef();
  88     return;
  89   }
  90
  91   // Measure the line.
  92   size_t Length = 0;
  93   while (Pos[Length] != '\0' && !isAtLineEnd(&Pos[Length])) {
  94     ++Length;
  95   }
  96
  97   CurrentLine = StringRef(Pos, Length);
  98 }