Method encode

nodedb-strict/src/encode.rs:77–159

Encode a row of values into a Binary Tuple. `values` must have exactly `schema.len()` entries. A `Value::Null` is allowed only if the corresponding column is nullable.

(&self, values: &[Value])

    /// `values` must have exactly `schema.len()` entries. A `Value::Null` is
    /// allowed only if the corresponding column is nullable.
    pub fn encode(&self, values: &[Value]) -> Result<Vec<u8>, StrictError> {
        let n_cols = self.schema.columns.len();
        if values.len() != n_cols {
            return Err(StrictError::ValueCountMismatch {
                expected: n_cols,
                got: values.len(),
            });
        }

        // Pre-size: header + fixed + offset_table. Variable data appended later.
        let offset_table_size = (self.var_indices.len() + 1) * 4;
        let base_size = self.header_size + self.fixed_section_size + offset_table_size;
        let mut buf = vec![0u8; base_size];

        // 1. Magic, format version, schema version.
        buf[0..4].copy_from_slice(&MAGIC.to_le_bytes());
        buf[4] = FORMAT_VERSION;
        buf[5..9].copy_from_slice(&self.schema.version.to_le_bytes());

        // 2. Null bitmap + fixed fields + type validation.
        let bitmap_start = 9;
        let fixed_start = self.header_size;

        for (i, (col, val)) in self.schema.columns.iter().zip(values.iter()).enumerate() {
            let is_null = matches!(val, Value::Null);

            if is_null {
                if !col.nullable {
                    return Err(StrictError::NullViolation(col.name.clone()));
                }
                // Set null bit: byte = i / 8, bit = i % 8.
                buf[bitmap_start + i / 8] |= 1 << (i % 8);
                // Fixed fields remain zeroed; no variable data emitted.
                continue;
            }

            // Type check (with coercion).
            if !col.column_type.accepts(val) {
                return Err(StrictError::TypeMismatch {
                    column: col.name.clone(),
                    expected: col.column_type,
                });
            }

            // Write fixed-size value.
            if let Some(offset) = self.fixed_offsets[i] {
                let dst = fixed_start + offset;
                encode_fixed(&mut buf[dst..], &col.column_type, val);
            }
            // Variable-length values are handled in the offset table pass below.
        }

        // 3. Variable-length fields: build offset table + variable data.
        let offset_table_start = self.header_size + self.fixed_section_size;
        let mut var_data: Vec<u8> = Vec::new();

        for (var_idx, &col_idx) in self.var_indices.iter().enumerate() {
            // Write current offset.