Trait ion_rs::StreamReader

source · [−]
pub trait StreamReader {
    type Item;
    type Symbol;


Show 28 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_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<String>;
    fn map_string<F, U>(&mut self, f: F) -> IonResult<U>
    where
        F: FnOnce(&str) -> U;
    fn map_string_bytes<F, U>(&mut self, f: F) -> IonResult<U>
    where
        F: FnOnce(&[u8]) -> U;
    fn read_symbol(&mut self) -> IonResult<Self::Symbol>;
    fn read_blob(&mut self) -> IonResult<Vec<u8>>;
    fn map_blob<F, U>(&mut self, f: F) -> IonResult<U>
    where
        F: FnOnce(&[u8]) -> U;
    fn read_clob(&mut self) -> IonResult<Vec<u8>>;
    fn map_clob<F, U>(&mut self, f: F) -> IonResult<U>
    where
        F: FnOnce(&[u8]) -> U;
    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;

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

}
Expand description

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

The type returned by calls to [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.

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

Required Methods

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.

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.

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.

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

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.

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

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

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 [IonError].

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 [IonError].

Attempts to read the current item as an Ion integer and return it as an i64. If the current item is not an integer or an IO error is encountered while reading, returns [IonError].

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 [IonError].

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 [IonError].

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

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 [IonError].

Takes a function that expects a string and, once the string’s bytes are loaded, calls that function passing the string as a parameter. This allows users to avoid materializing the string if they only intend to inspect it for length, pattern matches, etc.

Takes a function that expects a string and, once the string’s bytes are loaded, calls that function passing the string’s raw bytes as a parameter. Some implementations may be able to optimize this by calling the function without first validating that the bytes are utf8. As such, callers MUST NOT depend on the string contents being valid utf8.

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 [IonError].

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

Takes a function that expects a byte slice and, once the blob’s bytes are loaded, calls that function passing the blob’s bytes as a parameter. This allows users to avoid materializing the clob if they only intend to inspect it for length, pattern matches, etc.

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

Takes a function that expects a byte slice and, once the clob’s bytes are loaded, calls that function passing the clob’s bytes as a parameter. This allows users to avoid materializing the clob if they only intend to inspect it for length, pattern matches, etc.

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

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 [next()] to advance to the first child value. If the current value is not a container, returns [IonError].

Positions the cursor at the end of the container currently being traversed. Calling [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 [IonError].

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

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

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

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

Implementors