Enum Reader

pub enum Reader {
    PrimitiveReader(TypePtr, Box<TripletIter>),
    OptionReader(i16, Box<Reader>),
    GroupReader(Option<TypePtr>, i16, Vec<Reader>),
    RepeatedReader(TypePtr, i16, i16, Box<Reader>),
    KeyValueReader(TypePtr, i16, i16, Box<Reader>, Box<Reader>),
}

Reader tree for record assembly

Variants

PrimitiveReader(TypePtr, Box<TripletIter>)

Primitive reader with type information and triplet iterator

OptionReader(i16, Box<Reader>)

Optional reader with definition level of a parent and a reader

GroupReader(Option<TypePtr>, i16, Vec<Reader>)

Group (struct) reader with type information, definition level and list of child readers. When it represents message type, type information is None

RepeatedReader(TypePtr, i16, i16, Box<Reader>)

Reader for repeated values, e.g. lists, contains type information, definition level, repetition level and a child reader

KeyValueReader(TypePtr, i16, i16, Box<Reader>, Box<Reader>)

Reader of key-value pairs, e.g. maps, contains type information, definition level, repetition level, child reader for keys and child reader for values

Implementations

impl Reader

fn option(repetition: Repetition, def_level: i16, reader: Reader) -> Self

Wraps reader in option reader based on repetition.

fn is_element_type(repeated_type: &Type) -> bool

Returns true if repeated type is an element type for the list. Used to determine legacy list types. This method is copied from Spark Parquet reader and is based on the reference: https://github.com/apache/parquet-format/blob/master/LogicalTypes.md #backward-compatibility-rules

fn read(&mut self) -> Result<Row>

Reads current record as Row from the reader tree. Automatically advances all necessary readers. This must be called on the root level reader (i.e., for Message type). Otherwise, it will panic.

fn read_field(&mut self) -> Result<Field>

Reads current record as Field from the reader tree. Automatically advances all necessary readers.

fn field_name(&self) -> &str

Returns field name for the current reader.

fn repetition(&self) -> Repetition

Returns repetition for the current reader.

fn has_next(&self) -> bool

Returns true, if current reader has more values, false otherwise. Method does not advance internal iterator.

fn current_def_level(&self) -> i16

Returns current definition level, Method does not advance internal iterator.

fn current_rep_level(&self) -> i16

Returns current repetition level. Method does not advance internal iterator.

fn advance_columns(&mut self) -> Result<()>

Advances leaf columns for the current reader.

Trait Implementations

impl Display for Reader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.