1 | #pragma once |
2 | |
3 | #include <IO/ReadBuffer.h> |
4 | #include <IO/WriteBuffer.h> |
5 | #include <IO/ReadHelpers.h> |
6 | #include <IO/WriteHelpers.h> |
7 | |
8 | #include <functional> |
9 | |
10 | |
11 | namespace DB |
12 | { |
13 | |
14 | /** Implements the ability to write and read data in/from WriteBuffer/ReadBuffer |
15 | * with the help of << and >> operators and also manipulators, |
16 | * providing a way of using, similar to iostreams. |
17 | * |
18 | * It is neither a subset nor an extension of iostreams. |
19 | * |
20 | * Example usage: |
21 | * |
22 | * DB::WriteBufferFromFileDescriptor buf(STDOUT_FILENO); |
23 | * buf << DB::double_quote << "Hello, world!" << '\n' << DB::flush; |
24 | * |
25 | * Outputs `char` type (usually it's Int8) as a symbol, not as a number. |
26 | */ |
27 | |
28 | /// Manipulators. |
29 | enum EscapeManip { escape }; /// For strings - escape special characters. In the rest, as usual. |
30 | enum QuoteManip { quote }; /// For strings, dates, datetimes - enclose in single quotes with escaping. In the rest, as usual. |
31 | enum DoubleQuoteManip { double_quote }; /// For strings, dates, datetimes - enclose in double quotes with escaping. In the rest, as usual. |
32 | enum BinaryManip { binary }; /// Output in binary format. |
33 | |
34 | struct EscapeManipWriteBuffer : std::reference_wrapper<WriteBuffer> { using std::reference_wrapper<WriteBuffer>::reference_wrapper; }; |
35 | struct QuoteManipWriteBuffer : std::reference_wrapper<WriteBuffer> { using std::reference_wrapper<WriteBuffer>::reference_wrapper; }; |
36 | struct DoubleQuoteManipWriteBuffer : std::reference_wrapper<WriteBuffer> { using std::reference_wrapper<WriteBuffer>::reference_wrapper; }; |
37 | struct BinaryManipWriteBuffer : std::reference_wrapper<WriteBuffer> { using std::reference_wrapper<WriteBuffer>::reference_wrapper; }; |
38 | |
39 | struct EscapeManipReadBuffer : std::reference_wrapper<ReadBuffer> { using std::reference_wrapper<ReadBuffer>::reference_wrapper; }; |
40 | struct QuoteManipReadBuffer : std::reference_wrapper<ReadBuffer> { using std::reference_wrapper<ReadBuffer>::reference_wrapper; }; |
41 | struct DoubleQuoteManipReadBuffer : std::reference_wrapper<ReadBuffer> { using std::reference_wrapper<ReadBuffer>::reference_wrapper; }; |
42 | struct BinaryManipReadBuffer : std::reference_wrapper<ReadBuffer> { using std::reference_wrapper<ReadBuffer>::reference_wrapper; }; |
43 | |
44 | |
45 | template <typename T> WriteBuffer & operator<< (WriteBuffer & buf, const T & x) { writeText(x, buf); return buf; } |
46 | /// If you do not use the manipulators, the string is displayed without an escape, as is. |
47 | template <> inline WriteBuffer & operator<< (WriteBuffer & buf, const String & x) { writeString(x, buf); return buf; } |
48 | template <> inline WriteBuffer & operator<< (WriteBuffer & buf, const char & x) { writeChar(x, buf); return buf; } |
49 | |
50 | inline WriteBuffer & operator<< (WriteBuffer & buf, const char * x) { writeCString(x, buf); return buf; } |
51 | |
52 | inline EscapeManipWriteBuffer operator<< (WriteBuffer & buf, EscapeManip) { return buf; } |
53 | inline QuoteManipWriteBuffer operator<< (WriteBuffer & buf, QuoteManip) { return buf; } |
54 | inline DoubleQuoteManipWriteBuffer operator<< (WriteBuffer & buf, DoubleQuoteManip) { return buf; } |
55 | inline BinaryManipWriteBuffer operator<< (WriteBuffer & buf, BinaryManip) { return buf; } |
56 | |
57 | template <typename T> WriteBuffer & operator<< (EscapeManipWriteBuffer buf, const T & x) { writeText(x, buf.get()); return buf; } |
58 | template <typename T> WriteBuffer & operator<< (QuoteManipWriteBuffer buf, const T & x) { writeQuoted(x, buf.get()); return buf; } |
59 | template <typename T> WriteBuffer & operator<< (DoubleQuoteManipWriteBuffer buf, const T & x) { writeDoubleQuoted(x, buf.get()); return buf; } |
60 | template <typename T> WriteBuffer & operator<< (BinaryManipWriteBuffer buf, const T & x) { writeBinary(x, buf.get()); return buf; } |
61 | |
62 | inline WriteBuffer & operator<< (EscapeManipWriteBuffer buf, const char * x) { writeAnyEscapedString<'\''>(x, x + strlen(x), buf.get()); return buf; } |
63 | inline WriteBuffer & operator<< (QuoteManipWriteBuffer buf, const char * x) { writeAnyQuotedString<'\''>(x, x + strlen(x), buf.get()); return buf; } |
64 | inline WriteBuffer & operator<< (DoubleQuoteManipWriteBuffer buf, const char * x) { writeAnyQuotedString<'"'>(x, x + strlen(x), buf.get()); return buf; } |
65 | inline WriteBuffer & operator<< (BinaryManipWriteBuffer buf, const char * x) { writeStringBinary(x, buf.get()); return buf; } |
66 | |
67 | /// The manipulator calls the WriteBuffer method `next` - this makes the buffer reset. For nested buffers, the reset is not recursive. |
68 | enum FlushManip { flush }; |
69 | |
70 | inline WriteBuffer & operator<< (WriteBuffer & buf, FlushManip) { buf.next(); return buf; } |
71 | |
72 | |
73 | template <typename T> ReadBuffer & operator>> (ReadBuffer & buf, T & x) { readText(x, buf); return buf; } |
74 | template <> inline ReadBuffer & operator>> (ReadBuffer & buf, String & x) { readString(x, buf); return buf; } |
75 | template <> inline ReadBuffer & operator>> (ReadBuffer & buf, char & x) { readChar(x, buf); return buf; } |
76 | |
77 | /// If you specify a string literal for reading, this will mean - make sure there is a sequence of bytes and skip it. |
78 | inline ReadBuffer & operator>> (ReadBuffer & buf, const char * x) { assertString(x, buf); return buf; } |
79 | |
80 | inline EscapeManipReadBuffer operator>> (ReadBuffer & buf, EscapeManip) { return buf; } |
81 | inline QuoteManipReadBuffer operator>> (ReadBuffer & buf, QuoteManip) { return buf; } |
82 | inline DoubleQuoteManipReadBuffer operator>> (ReadBuffer & buf, DoubleQuoteManip) { return buf; } |
83 | inline BinaryManipReadBuffer operator>> (ReadBuffer & buf, BinaryManip) { return buf; } |
84 | |
85 | template <typename T> ReadBuffer & operator>> (EscapeManipReadBuffer buf, T & x) { readText(x, buf.get()); return buf; } |
86 | template <typename T> ReadBuffer & operator>> (QuoteManipReadBuffer buf, T & x) { readQuoted(x, buf.get()); return buf; } |
87 | template <typename T> ReadBuffer & operator>> (DoubleQuoteManipReadBuffer buf, T & x) { readDoubleQuoted(x, buf.get()); return buf; } |
88 | template <typename T> ReadBuffer & operator>> (BinaryManipReadBuffer buf, T & x) { readBinary(x, buf.get()); return buf; } |
89 | |
90 | } |
91 | |