lix/tests/unit/libutil-support/tests/terminal-code-eater.cc

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#include "terminal-code-eater.hh"
#include "escape-char.hh"
#include <assert.h>
#include <cstdint>
#include <iostream>
namespace nix {
static constexpr const bool DEBUG_EATER = false;
void TerminalCodeEater::feed(char c, std::function<void(char)> on_char)
{
auto isParamChar = [](char v) -> bool { return v >= 0x30 && v <= 0x3f; };
auto isIntermediateChar = [](char v) -> bool { return v >= 0x20 && v <= 0x2f; };
auto isFinalChar = [](char v) -> bool { return v >= 0x40 && v <= 0x7e; };
if constexpr (DEBUG_EATER) {
std::cerr << "eater" << MaybeHexEscapedChar{c} << "\n";
}
switch (state) {
case State::ExpectESC:
switch (c) {
case '\e':
transition(State::ExpectESCSeq);
return;
// Just eat \r, since it is part of clearing a line
case '\r':
return;
default: break;
}
if constexpr (DEBUG_EATER) {
std::cerr << "eater uneat" << MaybeHexEscapedChar{c} << "\n";
}
on_char(c);
break;
case State::ExpectESCSeq:
switch (c) {
// CSI
case '[':
transition(State::InCSIParams);
return;
default:
transition(State::ExpectESC);
return;
}
break;
// https://en.wikipedia.org/wiki/ANSI_escape_code#CSI_(Control_Sequence_Introducer)_sequences
// A CSI sequence is: CSI [\x30-\x3f]* [\x20-\x2f]* [\x40-\x7e]
// ^ params ^ intermediates ^ final byte
case State::InCSIParams:
if (isFinalChar(c)) {
transition(State::ExpectESC);
return;
} else if (isIntermediateChar(c)) {
transition(State::InCSIIntermediates);
return;
} else if (isParamChar(c)) {
return;
} else {
// Corrupt escape sequence? Throw an assert, for now.
// transition(State::ExpectESC);
assert(false && "Corrupt terminal escape sequence");
return;
}
break;
case State::InCSIIntermediates:
if (isFinalChar(c)) {
transition(State::ExpectESC);
return;
} else if (isIntermediateChar(c)) {
return;
} else {
// Corrupt escape sequence? Throw an assert, for now.
// transition(State::ExpectESC);
assert(false && "Corrupt terminal escape sequence in intermediates");
return;
}
break;
}
}
void TerminalCodeEater::transition(State new_state)
{
state = new_state;
}
};