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lnav/src/formats/logfmt/logfmt.parser.cc

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/**
* Copyright (c) 2021, Timothy Stack
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* * Neither the name of Timothy Stack nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @file logfmt.parser.cc
*/
#include "logfmt.parser.hh"
#include "base/string_util.hh"
#include "config.h"
logfmt::parser::parser(string_fragment sf) : p_next_input(sf) {}
static bool
is_not_eq(char ch)
{
return ch != '=';
}
struct bare_value_predicate {
enum class int_state_t {
INIT,
NEED_DIGIT,
DIGITS,
INVALID,
};
enum class float_state_t {
INIT,
NEED_DIGIT,
DIGITS,
FRACTION_DIGIT,
EXPONENT_INIT,
EXPONENT_NEED_DIGIT,
EXPONENT_DIGIT,
INVALID,
};
int_state_t bvp_int_state{int_state_t::INIT};
float_state_t bvp_float_state{float_state_t::INIT};
size_t bvp_index{0};
bool is_integer() const
{
return this->bvp_int_state == int_state_t::DIGITS;
}
bool is_float() const
{
switch (this->bvp_float_state) {
case float_state_t::DIGITS:
case float_state_t::FRACTION_DIGIT:
case float_state_t::EXPONENT_DIGIT:
return true;
default:
return false;
}
}
bool operator()(char ch)
{
if (ch == ' ') {
return false;
}
bool got_digit = isdigit(ch);
switch (this->bvp_int_state) {
case int_state_t::INIT:
if (got_digit) {
this->bvp_int_state = int_state_t::DIGITS;
} else if (ch == '-') {
this->bvp_int_state = int_state_t::NEED_DIGIT;
} else {
this->bvp_int_state = int_state_t::INVALID;
}
break;
case int_state_t::DIGITS:
case int_state_t::NEED_DIGIT:
if (got_digit) {
this->bvp_int_state = int_state_t::DIGITS;
} else {
this->bvp_int_state = int_state_t::INVALID;
}
break;
case int_state_t::INVALID:
break;
}
switch (this->bvp_float_state) {
case float_state_t::INIT:
if (got_digit) {
this->bvp_float_state = float_state_t::DIGITS;
} else if (ch == '-') {
this->bvp_float_state = float_state_t::NEED_DIGIT;
} else {
this->bvp_float_state = float_state_t::INVALID;
}
break;
case float_state_t::DIGITS:
case float_state_t::NEED_DIGIT:
if (got_digit) {
this->bvp_float_state = float_state_t::DIGITS;
} else if (ch == '.') {
this->bvp_float_state = float_state_t::FRACTION_DIGIT;
} else if (ch == 'e' || ch == 'E') {
this->bvp_float_state = float_state_t::EXPONENT_INIT;
} else {
this->bvp_float_state = float_state_t::INVALID;
}
break;
case float_state_t::FRACTION_DIGIT:
if (got_digit) {
this->bvp_float_state = float_state_t::FRACTION_DIGIT;
} else if (ch == 'e' || ch == 'E') {
this->bvp_float_state = float_state_t::EXPONENT_INIT;
} else {
this->bvp_float_state = float_state_t::INVALID;
}
break;
case float_state_t::EXPONENT_INIT:
if (got_digit) {
this->bvp_float_state = float_state_t::EXPONENT_DIGIT;
} else if (ch == '-' || ch == '+') {
this->bvp_float_state = float_state_t::EXPONENT_NEED_DIGIT;
} else {
this->bvp_float_state = float_state_t::INVALID;
}
break;
case float_state_t::EXPONENT_NEED_DIGIT:
case float_state_t::EXPONENT_DIGIT:
if (got_digit) {
this->bvp_float_state = float_state_t::EXPONENT_DIGIT;
} else {
this->bvp_float_state = float_state_t::INVALID;
}
break;
case float_state_t::INVALID:
break;
}
this->bvp_index += 1;
return true;
}
};
logfmt::parser::step_result
logfmt::parser::step()
{
const static auto IS_DQ = string_fragment::tag1{'"'};
auto remaining = this->p_next_input.skip(isspace);
if (remaining.empty()) {
return end_of_input{};
}
auto pair_opt = remaining.split_while(is_not_eq);
if (!pair_opt) {
return error{remaining.sf_begin, "expecting key followed by '='"};
}
auto key_frag = pair_opt->first;
auto after_eq = pair_opt->second.consume(string_fragment::tag1{'='});
if (!after_eq) {
return error{pair_opt->second.sf_begin, "expecting '='"};
}
auto value_start = after_eq.value();
if (value_start.startswith("\"")) {
string_fragment::quoted_string_body qsb;
auto quoted_pair = value_start.consume_n(1)->split_while(qsb);
if (!quoted_pair) {
return error{value_start.sf_begin + 1, "string body missing"};
}
auto after_quote = quoted_pair->second.consume(IS_DQ);
if (!after_quote) {
return error{quoted_pair->second.sf_begin, "non-terminated string"};
}
this->p_next_input = after_quote.value();
return std::make_pair(
key_frag,
quoted_value{string_fragment{quoted_pair->first.sf_string,
quoted_pair->first.sf_begin - 1,
quoted_pair->first.sf_end + 1}});
}
bare_value_predicate bvp;
auto value_pair = value_start.split_while(bvp);
if (value_pair) {
static const auto TRUE_FRAG = string_fragment::from_const("true");
static const auto FALSE_FRAG = string_fragment::from_const("false");
this->p_next_input = value_pair->second;
if (bvp.is_integer()) {
int_value retval;
strtonum(retval.iv_value,
value_pair->first.data(),
value_pair->first.length());
retval.iv_str_value = value_pair->first;
return std::make_pair(key_frag, retval);
} else if (bvp.is_float()) {
char float_copy[value_pair->first.length() + 1];
float_value retval;
strncpy(float_copy,
value_pair->first.data(),
value_pair->first.length());
float_copy[value_pair->first.length()] = '\0';
retval.fv_value = strtod(float_copy, nullptr);
retval.fv_str_value = value_pair->first;
return std::make_pair(key_frag, retval);
} else if (value_pair->first.iequal(TRUE_FRAG)) {
return std::make_pair(key_frag,
bool_value{true, value_pair->first});
} else if (value_pair->first.iequal(FALSE_FRAG)) {
return std::make_pair(key_frag,
bool_value{false, value_pair->first});
}
return std::make_pair(key_frag, unquoted_value{value_pair->first});
} else {
this->p_next_input = value_start;
return std::make_pair(key_frag, unquoted_value{string_fragment{}});
}
}
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