1//===-- llvm/Support/FormattedStream.cpp - Formatted streams ----*- C++ -*-===//
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// This file contains the implementation of formatted_raw_ostream.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Support/FormattedStream.h"
14#include "llvm/Support/ConvertUTF.h"
15#include "llvm/Support/Debug.h"
16#include "llvm/Support/Unicode.h"
17#include "llvm/Support/raw_ostream.h"
18#include <algorithm>
19
20using namespace llvm;
21
22/// UpdatePosition - Examine the given char sequence and figure out which
23/// column we end up in after output, and how many line breaks are contained.
24/// This assumes that the input string is well-formed UTF-8, and takes into
25/// account Unicode characters which render as multiple columns wide.
26void formatted_raw_ostream::UpdatePosition(const char *Ptr, size_t Size) {
27 unsigned &Column = Position.first;
28 unsigned &Line = Position.second;
29
30 auto ProcessUTF8CodePoint = [&Line, &Column](StringRef CP) {
31 int Width = sys::unicode::columnWidthUTF8(Text: CP);
32 if (Width != sys::unicode::ErrorNonPrintableCharacter)
33 Column += Width;
34
35 // The only special whitespace characters we care about are single-byte.
36 if (CP.size() > 1)
37 return;
38
39 switch (CP[0]) {
40 case '\n':
41 Line += 1;
42 [[fallthrough]];
43 case '\r':
44 Column = 0;
45 break;
46 case '\t':
47 // Assumes tab stop = 8 characters.
48 Column += (8 - (Column & 0x7)) & 0x7;
49 break;
50 }
51 };
52
53 // If we have a partial UTF-8 sequence from the previous buffer, check that
54 // first.
55 if (PartialUTF8Char.size()) {
56 size_t BytesFromBuffer =
57 getNumBytesForUTF8(firstByte: PartialUTF8Char[0]) - PartialUTF8Char.size();
58 if (Size < BytesFromBuffer) {
59 // If we still don't have enough bytes for a complete code point, just
60 // append what we have.
61 PartialUTF8Char.append(RHS: StringRef(Ptr, Size));
62 return;
63 } else {
64 // The first few bytes from the buffer will complete the code point.
65 // Concatenate them and process their effect on the line and column
66 // numbers.
67 PartialUTF8Char.append(RHS: StringRef(Ptr, BytesFromBuffer));
68 ProcessUTF8CodePoint(PartialUTF8Char);
69 PartialUTF8Char.clear();
70 Ptr += BytesFromBuffer;
71 Size -= BytesFromBuffer;
72 }
73 }
74
75 // Now scan the rest of the buffer.
76 unsigned NumBytes;
77 for (const char *End = Ptr + Size; Ptr < End; Ptr += NumBytes) {
78 // Fast path for printable ASCII characters without special handling.
79 if (*Ptr >= 0x20 && *Ptr <= 0x7e) {
80 NumBytes = 1;
81 ++Column;
82 continue;
83 }
84
85 NumBytes = getNumBytesForUTF8(firstByte: *Ptr);
86
87 // The buffer might end part way through a UTF-8 code unit sequence for a
88 // Unicode scalar value if it got flushed. If this happens, we can't know
89 // the display width until we see the rest of the code point. Stash the
90 // bytes we do have, so that we can reconstruct the whole code point later,
91 // even if the buffer is being flushed.
92 if ((unsigned)(End - Ptr) < NumBytes) {
93 PartialUTF8Char = StringRef(Ptr, End - Ptr);
94 return;
95 }
96
97 ProcessUTF8CodePoint(StringRef(Ptr, NumBytes));
98 }
99}
100
101/// ComputePosition - Examine the current output and update line and column
102/// counts.
103void formatted_raw_ostream::ComputePosition(const char *Ptr, size_t Size) {
104 if (DisableScan)
105 return;
106
107 // If our previous scan pointer is inside the buffer, assume we already
108 // scanned those bytes. This depends on raw_ostream to not change our buffer
109 // in unexpected ways.
110 if (Ptr <= Scanned && Scanned <= Ptr + Size)
111 // Scan all characters added since our last scan to determine the new
112 // column.
113 UpdatePosition(Ptr: Scanned, Size: Size - (Scanned - Ptr));
114 else
115 UpdatePosition(Ptr, Size);
116
117 // Update the scanning pointer.
118 Scanned = Ptr + Size;
119}
120
121/// PadToColumn - Align the output to some column number.
122///
123/// \param NewCol - The column to move to.
124///
125formatted_raw_ostream &formatted_raw_ostream::PadToColumn(unsigned NewCol) {
126 // Figure out what's in the buffer and add it to the column count.
127 ComputePosition(Ptr: getBufferStart(), Size: GetNumBytesInBuffer());
128
129 // Output spaces until we reach the desired column.
130 indent(NumSpaces: std::max(a: int(NewCol - getColumn()), b: 1));
131 return *this;
132}
133
134void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
135 // Figure out what's in the buffer and add it to the column count.
136 ComputePosition(Ptr, Size);
137
138 // Write the data to the underlying stream (which is unbuffered, so
139 // the data will be immediately written out).
140 TheStream->write(Ptr, Size);
141
142 // Reset the scanning pointer.
143 Scanned = nullptr;
144}
145
146/// fouts() - This returns a reference to a formatted_raw_ostream for
147/// standard output. Use it like: fouts() << "foo" << "bar";
148formatted_raw_ostream &llvm::fouts() {
149 static formatted_raw_ostream S(outs());
150 return S;
151}
152
153/// ferrs() - This returns a reference to a formatted_raw_ostream for
154/// standard error. Use it like: ferrs() << "foo" << "bar";
155formatted_raw_ostream &llvm::ferrs() {
156 static formatted_raw_ostream S(errs());
157 return S;
158}
159
160/// fdbgs() - This returns a reference to a formatted_raw_ostream for
161/// the debug stream. Use it like: fdbgs() << "foo" << "bar";
162formatted_raw_ostream &llvm::fdbgs() {
163 static formatted_raw_ostream S(dbgs());
164 return S;
165}
166