about summary refs log tree commit diff
path: root/absl/strings/internal/str_format/bind.cc
blob: c4eddd17ddbe56a76c5ec1a5184079bf107166bc (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
#include "absl/strings/internal/str_format/bind.h"

#include <cerrno>
#include <limits>
#include <sstream>
#include <string>

namespace absl {
namespace str_format_internal {

namespace {

inline bool BindFromPosition(int position, int* value,
                             absl::Span<const FormatArgImpl> pack) {
  assert(position > 0);
  if (static_cast<size_t>(position) > pack.size()) {
    return false;
  }
  // -1 because positions are 1-based
  return FormatArgImplFriend::ToInt(pack[position - 1], value);
}

class ArgContext {
 public:
  explicit ArgContext(absl::Span<const FormatArgImpl> pack) : pack_(pack) {}

  // Fill 'bound' with the results of applying the context's argument pack
  // to the specified 'props'. We synthesize a BoundConversion by
  // lining up a UnboundConversion with a user argument. We also
  // resolve any '*' specifiers for width and precision, so after
  // this call, 'bound' has all the information it needs to be formatted.
  // Returns false on failure.
  bool Bind(const UnboundConversion *props, BoundConversion *bound);

 private:
  absl::Span<const FormatArgImpl> pack_;
};

inline bool ArgContext::Bind(const UnboundConversion* unbound,
                             BoundConversion* bound) {
  const FormatArgImpl* arg = nullptr;
  int arg_position = unbound->arg_position;
  if (static_cast<size_t>(arg_position - 1) >= pack_.size()) return false;
  arg = &pack_[arg_position - 1];  // 1-based

  if (!unbound->flags.basic) {
    int width = unbound->width.value();
    bool force_left = false;
    if (unbound->width.is_from_arg()) {
      if (!BindFromPosition(unbound->width.get_from_arg(), &width, pack_))
        return false;
      if (width < 0) {
        // "A negative field width is taken as a '-' flag followed by a
        // positive field width."
        force_left = true;
        width = -width;
      }
    }

    int precision = unbound->precision.value();
    if (unbound->precision.is_from_arg()) {
      if (!BindFromPosition(unbound->precision.get_from_arg(), &precision,
                            pack_))
        return false;
    }

    bound->set_width(width);
    bound->set_precision(precision);
    bound->set_flags(unbound->flags);
    if (force_left)
      bound->set_left(true);
  } else {
    bound->set_flags(unbound->flags);
    bound->set_width(-1);
    bound->set_precision(-1);
  }

  bound->set_length_mod(unbound->length_mod);
  bound->set_conv(unbound->conv);
  bound->set_arg(arg);
  return true;
}

template <typename Converter>
class ConverterConsumer {
 public:
  ConverterConsumer(Converter converter, absl::Span<const FormatArgImpl> pack)
      : converter_(converter), arg_context_(pack) {}

  bool Append(string_view s) {
    converter_.Append(s);
    return true;
  }
  bool ConvertOne(const UnboundConversion& conv, string_view conv_string) {
    BoundConversion bound;
    if (!arg_context_.Bind(&conv, &bound)) return false;
    return converter_.ConvertOne(bound, conv_string);
  }

 private:
  Converter converter_;
  ArgContext arg_context_;
};

template <typename Converter>
bool ConvertAll(const UntypedFormatSpecImpl format,
                absl::Span<const FormatArgImpl> args, Converter converter) {
  if (format.has_parsed_conversion()) {
    return format.parsed_conversion()->ProcessFormat(
        ConverterConsumer<Converter>(converter, args));
  } else {
    return ParseFormatString(format.str(),
                             ConverterConsumer<Converter>(converter, args));
  }
}

class DefaultConverter {
 public:
  explicit DefaultConverter(FormatSinkImpl* sink) : sink_(sink) {}

  void Append(string_view s) const { sink_->Append(s); }

  bool ConvertOne(const BoundConversion& bound, string_view /*conv*/) const {
    return FormatArgImplFriend::Convert(*bound.arg(), bound, sink_);
  }

 private:
  FormatSinkImpl* sink_;
};

class SummarizingConverter {
 public:
  explicit SummarizingConverter(FormatSinkImpl* sink) : sink_(sink) {}

  void Append(string_view s) const { sink_->Append(s); }

  bool ConvertOne(const BoundConversion& bound, string_view /*conv*/) const {
    UntypedFormatSpecImpl spec("%d");

    std::ostringstream ss;
    ss << "{" << Streamable(spec, {*bound.arg()}) << ":" << bound.flags();
    if (bound.width() >= 0) ss << bound.width();
    if (bound.precision() >= 0) ss << "." << bound.precision();
    ss << bound.length_mod() << bound.conv() << "}";
    Append(ss.str());
    return true;
  }

 private:
  FormatSinkImpl* sink_;
};

}  // namespace

bool BindWithPack(const UnboundConversion* props,
                  absl::Span<const FormatArgImpl> pack,
                  BoundConversion* bound) {
  return ArgContext(pack).Bind(props, bound);
}

std::string Summarize(const UntypedFormatSpecImpl format,
                 absl::Span<const FormatArgImpl> args) {
  typedef SummarizingConverter Converter;
  std::string out;
  {
    // inner block to destroy sink before returning out. It ensures a last
    // flush.
    FormatSinkImpl sink(&out);
    if (!ConvertAll(format, args, Converter(&sink))) {
      return "";
    }
  }
  return out;
}

bool FormatUntyped(FormatRawSinkImpl raw_sink,
                   const UntypedFormatSpecImpl format,
                   absl::Span<const FormatArgImpl> args) {
  FormatSinkImpl sink(raw_sink);
  using Converter = DefaultConverter;
  return ConvertAll(format, args, Converter(&sink));
}

std::ostream& Streamable::Print(std::ostream& os) const {
  if (!FormatUntyped(&os, format_, args_)) os.setstate(std::ios::failbit);
  return os;
}

std::string& AppendPack(std::string* out, const UntypedFormatSpecImpl format,
                   absl::Span<const FormatArgImpl> args) {
  size_t orig = out->size();
  if (ABSL_PREDICT_FALSE(!FormatUntyped(out, format, args))) {
    out->erase(orig);
  }
  return *out;
}

int FprintF(std::FILE* output, const UntypedFormatSpecImpl format,
            absl::Span<const FormatArgImpl> args) {
  FILERawSink sink(output);
  if (!FormatUntyped(&sink, format, args)) {
    errno = EINVAL;
    return -1;
  }
  if (sink.error()) {
    errno = sink.error();
    return -1;
  }
  if (sink.count() > std::numeric_limits<int>::max()) {
    errno = EFBIG;
    return -1;
  }
  return static_cast<int>(sink.count());
}

int SnprintF(char* output, size_t size, const UntypedFormatSpecImpl format,
             absl::Span<const FormatArgImpl> args) {
  BufferRawSink sink(output, size ? size - 1 : 0);
  if (!FormatUntyped(&sink, format, args)) {
    errno = EINVAL;
    return -1;
  }
  size_t total = sink.total_written();
  if (size) output[std::min(total, size - 1)] = 0;
  return static_cast<int>(total);
}

}  // namespace str_format_internal
}  // namespace absl