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
78