1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 //
15 // Output extension hooks for the Format library.
16 // `internal::InvokeFlush` calls the appropriate flush function for the
17 // specified output argument.
18 // `BufferRawSink` is a simple output sink for a char buffer. Used by SnprintF.
19 // `FILERawSink` is a std::FILE* based sink. Used by PrintF and FprintF.
20
21 #ifndef ABSL_STRINGS_INTERNAL_STR_FORMAT_OUTPUT_H_
22 #define ABSL_STRINGS_INTERNAL_STR_FORMAT_OUTPUT_H_
23
24 #include <cstdio>
25 #include <ostream>
26 #include <string>
27
28 #include "absl/base/port.h"
29 #include "absl/strings/string_view.h"
30
31 namespace absl {
32 ABSL_NAMESPACE_BEGIN
33 namespace str_format_internal {
34
35 // RawSink implementation that writes into a char* buffer.
36 // It will not overflow the buffer, but will keep the total count of chars
37 // that would have been written.
38 class BufferRawSink {
39 public:
BufferRawSink(char * buffer,size_t size)40 BufferRawSink(char* buffer, size_t size) : buffer_(buffer), size_(size) {}
41
total_written()42 size_t total_written() const { return total_written_; }
43 void Write(string_view v);
44
45 private:
46 char* buffer_;
47 size_t size_;
48 size_t total_written_ = 0;
49 };
50
51 // RawSink implementation that writes into a FILE*.
52 // It keeps track of the total number of bytes written and any error encountered
53 // during the writes.
54 class FILERawSink {
55 public:
FILERawSink(std::FILE * output)56 explicit FILERawSink(std::FILE* output) : output_(output) {}
57
58 void Write(string_view v);
59
count()60 size_t count() const { return count_; }
error()61 int error() const { return error_; }
62
63 private:
64 std::FILE* output_;
65 int error_ = 0;
66 size_t count_ = 0;
67 };
68
69 // Provide RawSink integration with common types from the STL.
AbslFormatFlush(std::string * out,string_view s)70 inline void AbslFormatFlush(std::string* out, string_view s) {
71 out->append(s.data(), s.size());
72 }
AbslFormatFlush(std::ostream * out,string_view s)73 inline void AbslFormatFlush(std::ostream* out, string_view s) {
74 out->write(s.data(), s.size());
75 }
76
AbslFormatFlush(FILERawSink * sink,string_view v)77 inline void AbslFormatFlush(FILERawSink* sink, string_view v) {
78 sink->Write(v);
79 }
80
AbslFormatFlush(BufferRawSink * sink,string_view v)81 inline void AbslFormatFlush(BufferRawSink* sink, string_view v) {
82 sink->Write(v);
83 }
84
85 // This is a SFINAE to get a better compiler error message when the type
86 // is not supported.
87 template <typename T>
88 auto InvokeFlush(T* out, string_view s) -> decltype(AbslFormatFlush(out, s)) {
89 AbslFormatFlush(out, s);
90 }
91
92 } // namespace str_format_internal
93 ABSL_NAMESPACE_END
94 } // namespace absl
95
96 #endif // ABSL_STRINGS_INTERNAL_STR_FORMAT_OUTPUT_H_
97