valeri/src/writer.cpp

#include "writer.hpp"

Result<String> Writer::write_one(Value& obj) {
  switch (obj.tag()) {
    case Tag::Nil:
      return write_nil(*obj.to<Nil>());
    case Tag::Int64:
      return write_int64(*obj.to<Int64>());
    case Tag::Float:
      return write_float(*obj.to<Float>());
    case Tag::Bool:
      return write_bool(*obj.to<Bool>());
    case Tag::ByteArray:
      return write_bytearray(*obj.to<ByteArray>());
    case Tag::String:
      return write_string(*obj.to<String>());
    case Tag::Symbol:
      return write_symbol(*obj.to<Symbol>());
    case Tag::Syntax:
      return write_syntax(*obj.to<Syntax>());
    case Tag::Pair:
      return write_pair(*obj.to<Pair>());
  };
  return String();
}

Result<String> Writer::write_int64(Int64& val) {
  char tmp[32];
  sprintf(tmp, "%lu", val.value());
  size_t len = strlen(tmp);

  return String::create(_arena, tmp);
}

bool needs_dot(char* str) {
  bool has_e = 0;
  bool has_dot = 0;
  for (char* c = str; *c != 0; c++) {
    if (*c == 'e' || *c == 'E') has_e = true;
    if (*c == '.') has_dot = true;
  }
  return !has_e && !has_dot;
}

Result<String> Writer::write_float(Float& val) {
  char tmp[32];
  sprintf(tmp, "%g", val.value());
  size_t len = strlen(tmp);

  if (needs_dot(tmp)) {
    tmp[len] = '.';
    tmp[len + 1] = '0';
    tmp[len + 2] = 0;
    len += 2;
  }

  return String::create(_arena, tmp);
}

Result<String> Writer::write_nil(Nil& val) {
  return String::create(_arena, "nil");
}

Result<String> Writer::write_bool(Bool& val) {
  if (val.value()) return String::create(_arena, "true");

  return String::create(_arena, "false");
}

Result<String> Writer::write_bytearray(ByteArray& val) {
  return ErrorCode::NotImplemented;
}

Result<String> Writer::write_string(String& val) {
  String res = TRY(String::create(_arena, "\""));

  // TODO: optimize this
  for (uint64_t i = 0; i < val.size(); i++) {
    char32_t c = TRY(val[i]);
    const char* replace = 0;
    switch (c) {
      case '\r':
        replace = "\\r";
        break;
      case '\n':
        replace = "\\n";
        break;
      case '\t':
        replace = "\\t";
        break;
      case '\\':
        replace = "\\\\";
        break;
      case '"':
        replace = "\\\"";
        break;
      default:
        break;
    };

    if (replace != 0) {
      res = TRY(res.concat(_arena, replace));
    } else {
      res = TRY(res.concat(_arena, &c, 1));
    }
  }

  res = TRY(res.concat(_arena, "\""));

  return res;
}

int is_valid_symbol_char(char32_t codepoint) {
  return ('a' <= codepoint && codepoint <= 'z') ||
         ('A' <= codepoint && codepoint <= 'Z') ||
         ('0' <= codepoint && codepoint <= '9') || codepoint == '!' ||
         codepoint == '$' || codepoint == '%' || codepoint == '&' ||
         codepoint == '*' || codepoint == '+' || codepoint == '-' ||
         codepoint == '.' || codepoint == '/' || codepoint == ':' ||
         codepoint == '<' || codepoint == '=' || codepoint == '>' ||
         codepoint == '?' || codepoint == '@' || codepoint == '^' ||
         codepoint == '_' || codepoint == '~';
}

Result<String> Writer::write_symbol(Symbol& val) {
  String res = TRY(String::create(_arena, ""));

  // TODO: optimize this
  for (uint64_t i = 0; i < val.size(); i++) {
    char32_t c = TRY(val[i]);

    if (!is_valid_symbol_char(c)) return ErrorCode::InvalidSymbol;

    res = TRY(res.concat(_arena, &c, 1));
  }

  return res;
}

Result<String> Writer::write_syntax(Syntax& val) {
  return ErrorCode::NotImplemented;
}

Result<String> Writer::write_pair(Pair& val) {
  String res = TRY(String::create(_arena, "("));

  Value cur = TRY(val.copy(_arena));

  bool is_first = true;
  while (!cur.is<Nil>()) {
    if (!cur.is<Pair>()) return ErrorCode::MalformedList;

    Pair& pair = *cur.to<Pair>();

    Value first = TRY(pair.first(_arena));
    if (!is_first) res = TRY(res.concat(_arena, " "));

    String first_str = TRY(write_one(first));
    res = TRY(res.concat(_arena, first_str));

    cur = TRY(pair.rest(_arena));
    is_first = false;
  }

  res = TRY(res.concat(_arena, ")"));
  return res;
}