ClickHouse/base/common/LineReader.cpp

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#include <common/LineReader.h>
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#include <iostream>
#include <string_view>
#include <string.h>
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#include <unistd.h>
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#ifdef OS_LINUX
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/// We can detect if code is linked with one or another readline variants or open the library dynamically.
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# include <dlfcn.h>
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extern "C"
{
char * readline(const char *) __attribute__((__weak__));
char * (*readline_ptr)(const char *) = readline;
}
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#endif
namespace
{
/// Trim ending whitespace inplace
void trim(String & s)
{
s.erase(std::find_if(s.rbegin(), s.rend(), [](int ch) { return !std::isspace(ch); }).base(), s.end());
}
/// Check if multi-line query is inserted from the paste buffer.
/// Allows delaying the start of query execution until the entirety of query is inserted.
bool hasInputData()
{
timeval timeout = {0, 0};
fd_set fds;
FD_ZERO(&fds);
FD_SET(STDIN_FILENO, &fds);
return select(1, &fds, nullptr, nullptr, &timeout) == 1;
}
}
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LineReader::Suggest::WordsRange LineReader::Suggest::getCompletions(const String & prefix, size_t prefix_length) const
{
if (!ready)
return std::make_pair(words.end(), words.end());
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std::string_view last_word;
auto last_word_pos = prefix.find_last_of(word_break_characters);
if (std::string::npos == last_word_pos)
last_word = prefix;
else
last_word = std::string_view(prefix).substr(last_word_pos + 1, std::string::npos);
/// last_word can be empty.
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return std::equal_range(
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words.begin(), words.end(), last_word, [prefix_length](std::string_view s, std::string_view prefix_searched)
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{
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return strncmp(s.data(), prefix_searched.data(), prefix_length) < 0;
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});
}
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LineReader::LineReader(const String & history_file_path_, char extender_, char delimiter_)
: history_file_path(history_file_path_), extender(extender_), delimiter(delimiter_)
{
/// FIXME: check extender != delimiter
}
String LineReader::readLine(const String & first_prompt, const String & second_prompt)
{
String line;
bool is_multiline = false;
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while (auto status = readOneLine(is_multiline ? second_prompt : first_prompt))
{
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if (status == RESET_LINE)
{
line.clear();
is_multiline = false;
continue;
}
if (input.empty())
{
if (!line.empty() && !delimiter && !hasInputData())
break;
else
continue;
}
is_multiline = (input.back() == extender) || (delimiter && input.back() != delimiter) || hasInputData();
if (input.back() == extender)
{
input = input.substr(0, input.size() - 1);
trim(input);
if (input.empty())
continue;
}
line += (line.empty() ? "" : " ") + input;
if (!is_multiline)
break;
}
if (!line.empty() && line != prev_line)
{
addToHistory(line);
prev_line = line;
}
return line;
}
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LineReader::InputStatus LineReader::readOneLine(const String & prompt)
{
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input.clear();
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#ifdef OS_LINUX
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if (!readline_ptr)
{
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for (auto name : {"libreadline.so", "libreadline.so.0", "libeditline.so", "libeditline.so.0"})
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{
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void * dl_handle = dlopen(name, RTLD_LAZY);
if (dl_handle)
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{
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readline_ptr = reinterpret_cast<char * (*)(const char *)>(dlsym(dl_handle, "readline"));
if (readline_ptr)
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{
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break;
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}
}
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}
}
/// Minimal support for readline
if (readline_ptr)
{
char * line_read = (*readline_ptr)(prompt.c_str());
if (!line_read)
return ABORT;
input = line_read;
}
else
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#endif
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{
std::cout << prompt;
std::getline(std::cin, input);
if (!std::cin.good())
return ABORT;
}
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trim(input);
return INPUT_LINE;
}