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#include "line_accumulator.h"
#include <cassert>
#include <iostream>
#include <algorithm>
namespace {
static std::mt19937 generator;
std::uint8_t getRandomIndex(
const int seed,
const std::uint8_t n
) {
generator.seed(seed);
return std::uniform_int_distribution<std::uint8_t>{0, n}(generator);
}
std::vector<std::uint8_t> getRandomIndizes(
const int seed,
const std::uint8_t n
) {
generator.seed(seed);
std::vector<std::uint8_t> indizes(n);
std::iota(indizes.begin(), indizes.end(), 0);
std::shuffle(
indizes.begin(),
indizes.end(),
generator
);
return indizes;
}
std::size_t getCharacterLength(const std::string& token) {
std::size_t codeUnitIndex = 0;
std::size_t codePointIndex = 0;
while ( token.data()[codeUnitIndex] ) {
// advance `codePointIndex` if current unit is not a continuation byte
// see RFC3629 for further information
if ( (token.data()[codeUnitIndex] & 0b11000000 ) != 0b10000000 ) {
++codePointIndex;
}
++codeUnitIndex;
}
return codePointIndex;
}
}
namespace justify {
LineAccumulator::LineAccumulator(const std::uint8_t max_length):
max_length_{max_length},
length_{0},
tokens_{} { }
LineAccumulator::~LineAccumulator() {
this->discharge(false);
}
std::uint8_t LineAccumulator::getMissing() const {
return this->max_length_ - this->length_;
}
void LineAccumulator::operator()(const std::string& token) {
const std::size_t tokenLength = getCharacterLength(token);
if ( ( this->length_ + tokenLength ) > this->max_length_ ) {
this->discharge(true);
}
this->tokens_.emplace_back(token, 0);
this->length_ += tokenLength;
if ( this->length_ < this->max_length_ ) {
this->tokens_.back().second += 1;
this->length_ += 1;
}
}
void LineAccumulator::justify() {
const int seed = this->tokens_.size()
+ this->getMissing();
switch ( this->tokens_.size() ) {
// There is no sensible block justification of null or any single token
case 0:
case 1: {
this->length_ = this->max_length_;
break;
}
// i.e. left align the first token and right align the second token
case 2: {
this->tokens_[0].second += this->getMissing();
this->length_ = this->max_length_;
break;
}
// most common branch for normal texts, add the maximum equal amount of
// spaces to all but the last token
default: {
const std::uint8_t base = this->getMissing()
/ (this->tokens_.size() - 2);
std::for_each(
this->tokens_.begin(),
this->tokens_.end() - 2,
[&, base](auto& token) {
token.second += base;
this->length_ += base;
}
);
break;
}
}
assert(this->getMissing() < this->tokens_.size());
switch ( this->getMissing() ) {
case 0: {
break;
}
// randomly distribute missing spaces
case 1: {
this->tokens_[
getRandomIndex(seed, this->tokens_.size() - 2)
].second += 1;
break;
}
default: {
const auto indizes = getRandomIndizes(seed, this->tokens_.size() - 2);
std::for_each(
indizes.begin(),
indizes.begin() + this->getMissing(),
[&](std::uint8_t x) {
this->tokens_[x].second += 1;
this->length_ += 1;
}
);
break;
}
}
}
void LineAccumulator::discharge(const bool full) {
this->length_ -= this->tokens_.back().second;
this->tokens_.back().second = 0;
if ( full ) {
this->justify();
}
for ( const auto& token : this->tokens_ ) {
std::cout << token.first
<< std::string(token.second, ' ');
}
std::cout << '\n';
this->length_ = 0;
this->tokens_.clear();
}
}
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