encodeDoubleField function

List<int> encodeDoubleField(
  1. List<int> buffer,
  2. int fieldNumber,
  3. double value
)

Encodes a double field (wire type 1) into buffer.

Proto3 rule: if value is +0.0, nothing is written. Note -0.0 IS written — it is a distinct wire value from +0.0 and must round-trip. The IEEE 754 double-precision value is serialized as a field tag followed by 8 little-endian bytes.

Returns the same buffer list, possibly with bytes appended.

Implementation

List<int> encodeDoubleField(List<int> buffer, int fieldNumber, double value) {
  // Use `identical` (not `==`) so -0.0 is preserved: identical(-0.0, 0.0) is
  // false, so negative zero falls through and is serialized.
  if (identical(value, 0.0)) return buffer;
  encodeTag(buffer, fieldNumber, 1);
  buffer.addAll(_encodeDoubleBytes(value));
  return buffer;
}