lib/Basic/PrimitiveParsing.cpp

//===--- PrimitiveParsing.cpp - Primitive parsing routines ----------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Primitive parsing routines useful in various places in the compiler.
///
//===----------------------------------------------------------------------===//

#include "swift/Basic/PrimitiveParsing.h"
#include "llvm/ADT/SmallVector.h"

using namespace llvm;

unsigned swift::measureNewline(const char *BufferPtr, const char *BufferEnd) {
  if (BufferPtr == BufferEnd)
    return 0;

  if (*BufferPtr == '\n')
    return 1;

  assert(*BufferPtr == '\r');
  unsigned Bytes = 1;
  if (BufferPtr != BufferEnd && *BufferPtr == '\n')
    Bytes++;
  return Bytes;
}

void
swift::trimLeadingWhitespaceFromLines(StringRef RawText,
                                      unsigned WhitespaceToTrim,
                                      SmallVectorImpl<StringRef> &OutLines) {
  SmallVector<StringRef, 8> Lines;

  bool IsFirstLine = true;

  while (!RawText.empty()) {
    size_t Pos = RawText.find_first_of("\n\r");
    if (Pos == StringRef::npos)
      Pos = RawText.size();

    StringRef Line = RawText.substr(0, Pos);
    Lines.push_back(Line);
    if (!IsFirstLine) {
      size_t NonWhitespacePos = RawText.find_first_not_of(' ');
      if (NonWhitespacePos != StringRef::npos)
        WhitespaceToTrim =
            std::min(WhitespaceToTrim,
                     static_cast<unsigned>(NonWhitespacePos));
    }
    IsFirstLine = false;

    RawText = RawText.drop_front(Pos);
    unsigned NewlineBytes = measureNewline(RawText);
    RawText = RawText.drop_front(NewlineBytes);
  }

  IsFirstLine = true;
  for (auto &Line : Lines) {
    if (!IsFirstLine) {
      Line = Line.drop_front(WhitespaceToTrim);
    }
    IsFirstLine = false;
  }

  OutLines.append(Lines.begin(), Lines.end());
}