Trait ion_rs::IonReader

pub trait IonReader {
    type Item;
    type Symbol;

    // Required methods
    fn ion_version(&self) -> (u8, u8);
    fn next(&mut self) -> IonResult<Self::Item>;
    fn current(&self) -> Self::Item;
    fn ion_type(&self) -> Option<IonType>;
    fn annotations<'a>(
        &'a self
    ) -> Box<dyn Iterator<Item = IonResult<Self::Symbol>> + 'a>;
    fn field_name(&self) -> IonResult<Self::Symbol>;
    fn is_null(&self) -> bool;
    fn read_null(&mut self) -> IonResult<IonType>;
    fn read_bool(&mut self) -> IonResult<bool>;
    fn read_i64(&mut self) -> IonResult<i64>;
    fn read_int(&mut self) -> IonResult<Int>;
    fn read_f32(&mut self) -> IonResult<f32>;
    fn read_f64(&mut self) -> IonResult<f64>;
    fn read_decimal(&mut self) -> IonResult<Decimal>;
    fn read_string(&mut self) -> IonResult<Str>;
    fn read_str(&mut self) -> IonResult<&str>;
    fn read_symbol(&mut self) -> IonResult<Self::Symbol>;
    fn read_blob(&mut self) -> IonResult<Blob>;
    fn read_clob(&mut self) -> IonResult<Clob>;
    fn read_timestamp(&mut self) -> IonResult<Timestamp>;
    fn step_in(&mut self) -> IonResult<()>;
    fn step_out(&mut self) -> IonResult<()>;
    fn parent_type(&self) -> Option<IonType>;
    fn depth(&self) -> usize;

    // Provided methods
    fn has_annotations(&self) -> bool { ... }
    fn number_of_annotations(&self) -> usize { ... }
}

This trait captures the format-agnostic parser functionality needed to navigate within an Ion stream and read the values encountered into native Rust data types.

Once a value has successfully been read from the stream using one of the read_* functions, calling that function again may return an Err. This is left to the discretion of the implementor.

Required Associated Types

type Item

The type returned by calls to Self::next, indicating the next entity in the stream. Reader implementations representing different levels of abstraction will surface different sets of encoding artifacts. While an application-level Reader would only surface Ion values, a lower level Reader might surface symbol tables, Ion version markers, etc.

type Symbol

The types used to represent field names, annotations, and symbol values at this Reader’s level of abstraction.

Required Methods

fn ion_version(&self) -> (u8, u8)

Returns the (major, minor) version of the Ion stream being read. If ion_version is called before an Ion Version Marker has been read, the version (1, 0) will be returned.

fn next(&mut self) -> IonResult<Self::Item>

Attempts to advance the cursor to the next value in the stream at the current depth. If no value is encountered, returns None; otherwise, returns the Ion type of the next value.

fn current(&self) -> Self::Item

Returns a value describing the stream entity over which the Reader is currently positioned. Depending on the Reader’s level of abstraction, that entity may or may not be an Ion value.

fn ion_type(&self) -> Option<IonType>

If the current item is a value, returns that value’s Ion type. Otherwise, returns None.

fn annotations<'a>( &'a self ) -> Box<dyn Iterator<Item = IonResult<Self::Symbol>> + 'a>

Returns an iterator that will yield each of the annotations for the current value in order. If there is no current value, returns an empty iterator.

fn field_name(&self) -> IonResult<Self::Symbol>

If the current item is a field within a struct, returns Ok(_) with a Self::Symbol representing the field’s name; otherwise, returns an crate::IonError::IllegalOperation.

Implementations may also return an error for other reasons; for example, if Self::Symbol is a text data type but the field name is an undefined symbol ID, the reader may return a decoding error.

fn is_null(&self) -> bool

Returns true if the reader is currently positioned over an Ion null of any type.

fn read_null(&mut self) -> IonResult<IonType>

Attempts to read the current item as an Ion null and return its Ion type. If the current item is not a null or an IO error is encountered while reading, returns crate::IonError.

fn read_bool(&mut self) -> IonResult<bool>

Attempts to read the current item as an Ion boolean and return it as a bool. If the current item is not a boolean or an IO error is encountered while reading, returns crate::IonError.

fn read_i64(&mut self) -> IonResult<i64>

Attempts to read the current item as an Ion integer and return it as an i64. If the current item is not an integer, the integer is too large to be represented as an i64, or an IO error is encountered while reading, returns crate::IonError.

fn read_int(&mut self) -> IonResult<Int>

Attempts to read the current item as an Ion integer and return it as an Int. If the current item is not an integer or an IO error is encountered while reading, returns crate::IonError.

fn read_f32(&mut self) -> IonResult<f32>

Attempts to read the current item as an Ion float and return it as an f32. If the current item is not a float or an IO error is encountered while reading, returns crate::IonError.

fn read_f64(&mut self) -> IonResult<f64>

Attempts to read the current item as an Ion float and return it as an f64. If the current item is not a float or an IO error is encountered while reading, returns crate::IonError.

fn read_decimal(&mut self) -> IonResult<Decimal>

Attempts to read the current item as an Ion decimal and return it as a crate::Decimal. If the current item is not a decimal or an IO error is encountered while reading, returns crate::IonError.

fn read_string(&mut self) -> IonResult<Str>

Attempts to read the current item as an Ion string and return it as a String. If the current item is not a string or an IO error is encountered while reading, returns crate::IonError.

fn read_str(&mut self) -> IonResult<&str>

Attempts to read the current item as an Ion string and return it as a &str. If the current item is not a string or an IO error is encountered while reading, returns crate::IonError.

fn read_symbol(&mut self) -> IonResult<Self::Symbol>

Attempts to read the current item as an Ion symbol and return it as a Self::Symbol. If the current item is not a symbol or an IO error is encountered while reading, returns crate::IonError.

fn read_blob(&mut self) -> IonResult<Blob>

Attempts to read the current item as an Ion blob and return it as a Vec<u8>. If the current item is not a blob or an IO error is encountered while reading, returns crate::IonError.

fn read_clob(&mut self) -> IonResult<Clob>

Attempts to read the current item as an Ion clob and return it as a Vec<u8>. If the current item is not a clob or an IO error is encountered while reading, returns crate::IonError.

fn read_timestamp(&mut self) -> IonResult<Timestamp>

Attempts to read the current item as an Ion timestamp and return crate::Timestamp. If the current item is not a timestamp or an IO error is encountered while reading, returns crate::IonError.

fn step_in(&mut self) -> IonResult<()>

If the current value is a container (i.e. a struct, list, or s-expression), positions the cursor at the beginning of that container’s sequence of child values. The application must call Self::next() to advance to the first child value. If the current value is not a container, returns crate::IonError.

fn step_out(&mut self) -> IonResult<()>

Positions the cursor at the end of the container currently being traversed. Calling Self::next() will position the cursor over the item that follows the container. If the cursor is not in a container (i.e. it is already at the top level), returns crate::IonError.

fn parent_type(&self) -> Option<IonType>

If the reader is positioned at the top level, returns None. Otherwise, returns Some(_) with the parent container’s crate::IonType.

fn depth(&self) -> usize

Returns a usize indicating the Reader’s current level of nesting. That is: the number of times the Reader has stepped into a container without later stepping out. At the top level, this method returns 0.

Provided Methods

fn has_annotations(&self) -> bool

If the reader is positioned over a value with one or more annotations, returns true. Otherwise, returns false.

fn number_of_annotations(&self) -> usize

Returns the number of annotations on the current value. If there is no current value, returns zero.

Implementations on Foreign Types

impl<R: RawReader + ?Sized> IonReader for Box<R>

Allows a Box<dyn RawReader> to be used as a RawReader. Note: this implementation contains some methods that are not object safe and so cannot be invoked. For the moment, calling these methods via dynamic dispatch will result in a panic. Longer-term, they will be replaced by object safe methods. See: https://github.com/amazon-ion/ion-rust/issues/335

type Item = RawStreamItem

type Symbol = RawSymbolToken

fn ion_version(&self) -> (u8, u8)

fn next(&mut self) -> IonResult<Self::Item>

fn current(&self) -> Self::Item

fn ion_type(&self) -> Option<IonType>

fn annotations<'a>( &'a self ) -> Box<dyn Iterator<Item = IonResult<Self::Symbol>> + 'a>

fn field_name(&self) -> IonResult<Self::Symbol>

fn is_null(&self) -> bool

fn read_null(&mut self) -> IonResult<IonType>

fn read_bool(&mut self) -> IonResult<bool>

fn read_i64(&mut self) -> IonResult<i64>

fn read_int(&mut self) -> IonResult<Int>

fn read_f32(&mut self) -> IonResult<f32>

fn read_f64(&mut self) -> IonResult<f64>

fn read_decimal(&mut self) -> IonResult<Decimal>

fn read_string(&mut self) -> IonResult<Str>

fn read_str(&mut self) -> IonResult<&str>

fn read_symbol(&mut self) -> IonResult<Self::Symbol>

fn read_blob(&mut self) -> IonResult<Blob>

fn read_clob(&mut self) -> IonResult<Clob>

fn read_timestamp(&mut self) -> IonResult<Timestamp>

fn step_in(&mut self) -> IonResult<()>

fn step_out(&mut self) -> IonResult<()>

fn parent_type(&self) -> Option<IonType>

fn depth(&self) -> usize

Implementors

impl IonReader for ElementStreamReader

type Item = StreamItem

type Symbol = Symbol

impl<A: AsRef<[u8]> + Expandable> IonReader for RawBinaryReader<A>

type Item = RawStreamItem

type Symbol = RawSymbolToken

impl<A: AsRef<[u8]> + Expandable> IonReader for RawTextReader<A>

type Item = RawStreamItem

type Symbol = RawSymbolToken

impl<R: BufferedRawReader, T: ToIonDataSource> IonReader for BlockingRawReader<R, T>

type Item = <R as IonReader>::Item

type Symbol = <R as IonReader>::Symbol

impl<R: RawReader> IonReader for UserReader<R>

type Item = StreamItem

type Symbol = Symbol

impl<R: RawReader> IonReader for SystemReader<R>

type Item = SystemStreamItem

type Symbol = Symbol