llvm/unittests/Support/buffer_ostream_test.cpp

   1 //===- buffer_ostream_test.cpp - buffer_ostream tests ---------------------===//
   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/ADT/SmallString.h"
  10 #include "llvm/Support/raw_ostream.h"
  11 #include "gtest/gtest.h"
  12
  13 using namespace llvm;
  14
  15 namespace {
  16
  17 /// Naive version of raw_svector_ostream that is buffered (by default) and
  18 /// doesn't support pwrite.
  19 class NaiveSmallVectorStream : public raw_ostream {
  20 public:
  21   uint64_t current_pos() const override { return Vector.size(); }
  22   void write_impl(const char *Ptr, size_t Size) override {
  23     Vector.append(Ptr, Ptr + Size);
  24   }
  25
  26   explicit NaiveSmallVectorStream(SmallVectorImpl<char> &Vector)
  27       : Vector(Vector) {}
  28   ~NaiveSmallVectorStream() override { flush(); }
  29
  30   SmallVectorImpl<char> &Vector;
  31 };
  32
  33 TEST(buffer_ostreamTest, Reference) {
  34   SmallString<128> Dest;
  35   {
  36     NaiveSmallVectorStream DestOS(Dest);
  37     buffer_ostream BufferOS(DestOS);
  38
  39     // Writing and flushing should have no effect on Dest.
  40     BufferOS << "abcd";
  41     static_cast<raw_ostream &>(BufferOS).flush();
  42     EXPECT_EQ("", Dest);
  43     DestOS.flush();
  44     EXPECT_EQ("", Dest);
  45   }
  46
  47   // Write should land when constructor is called.
  48   EXPECT_EQ("abcd", Dest);
  49 }
  50
  51 TEST(buffer_ostreamTest, Owned) {
  52   SmallString<128> Dest;
  53   {
  54     auto DestOS = std::make_unique<NaiveSmallVectorStream>(Dest);
  55
  56     // Confirm that NaiveSmallVectorStream is buffered by default.
  57     EXPECT_NE(0u, DestOS->GetBufferSize());
  58
  59     // Confirm that passing ownership to buffer_unique_ostream sets it to
  60     // unbuffered. Also steal a reference to DestOS.
  61     NaiveSmallVectorStream &DestOSRef = *DestOS;
  62     buffer_unique_ostream BufferOS(std::move(DestOS));
  63     EXPECT_EQ(0u, DestOSRef.GetBufferSize());
  64
  65     // Writing and flushing should have no effect on Dest.
  66     BufferOS << "abcd";
  67     static_cast<raw_ostream &>(BufferOS).flush();
  68     EXPECT_EQ("", Dest);
  69     DestOSRef.flush();
  70     EXPECT_EQ("", Dest);
  71   }
  72
  73   // Write should land when constructor is called.
  74   EXPECT_EQ("abcd", Dest);
  75 }
  76
  77 } // end namespace