Struct eccodes::codes_handle::CodesHandle[−][src]

pub struct CodesHandle { /* fields omitted */ }
Expand description

Main structure used to operate on the GRIB file. It takes a full ownership of the accessed file. It can be constructed either using a file or a memory buffer.

Implementations

The constructor that takes a path to an existing file and a requested ProductKind and returns the CodesHandle object.

Example

let file_path = Path::new("./data/iceland.grib");
let product_kind = ProductKind::GRIB;

let handle = CodesHandle::new_from_file(file_path, product_kind).unwrap();

The function opens the file as File and then utilises fdopen() function to associate io::RawFd from File with a stream represented by libc::FILE pointer.

The constructor takes a path as an argument instead of File to ensure that fdopen() uses the same mode as File. The file descriptor does not take the ownership of a file, therefore the File is safely closed when it is dropped.

Errors

Returns CodesError::CantOpenFile with io::Error when the file cannot be opened.

Returns CodesError::LibcNonZero with errno information when the stream cannot be created from the file descriptor.

Returns CodesError::Internal with error code when internal codes_handle cannot be created.

Returns CodesError::NoMessages when there is no message of requested type in the provided file.

The constructor that takes data of file present in memory in Bytes format and a requested ProductKind and returns the CodesHandle object.

Example

let product_kind = ProductKind::GRIB;
let file_data =
    reqwest::get("https://github.com/ScaleWeather/eccodes/blob/main/data/iceland.grib?raw=true")
        .await
        .unwrap()
        .bytes()
        .await
        .unwrap();

let handle = CodesHandle::new_from_memory(file_data, product_kind).unwrap();

The function associates the data in memory with a stream represented by libc::FILE pointer using fmemopen() function.

The constructor takes a full ownership of the data inside Bytes, which is safely dropped during the CodesHandle drop.

Errors

Returns CodesError::LibcNonZero with errno information when the file stream cannot be created.

Returns CodesError::Internal with error code when internal codes_handle cannot be created.

Returns CodesError::NoMessages when there is no message of requested type in the provided file.

Trait Implementations

Formats the value using the given formatter. Read more

Executes the destructor for this type. This method calls fclose() from libc for graceful cleanup.

Currently it is assumed that under normal circumstances this destructor never fails. However in some edge cases fclose can return non-zero code. In such case all pointers and file descriptors are safely deleted. However memory leaks can still occur.

If any function called in the destructor returns an error warning will appear in log. If bugs occurs during CodesHandle drop please enable log output and post issue on Github.

FallibleIterator implementation for CodesHandle to access GRIB messages inside file.

To access GRIB messages the ecCodes library uses a method similar to a C-style iterator. It digests the FILE * multiple times each time returning the codes_handle raw pointer to a message inside the file. This method would be unsafe to expose directly. Therefore this crate utilizes the Iterator to provide the access to GRIB messages in a safe and convienient way.

FallibleIterator is used instead of classic Iterator because internal ecCodes functions can return error codes when the GRIB file is corrupted and for some other reasons. The usage of FallibleIterator is sligthly different than usage of Iterator, check its documentation for more details.

Using the FallibleIterator is the only way to read KeyedMessages from the file. Its basic usage is simply with while let statement (similar to for loop for classic Iterator):

let file_path = Path::new("./data/iceland-surface.grib");
let product_kind = ProductKind::GRIB;

let mut handle = CodesHandle::new_from_file(file_path, product_kind).unwrap();

while let Some(message) = handle.next().unwrap() {
    let key = message.read_key("name").unwrap();

    if let KeyType::Str(name) = key.value {
        println!("{:?}", name);    
    }
}

The FallibleIterator can be collected to convert the handle into a Vector of KeyedMessages. For example:

let file_path = Path::new("./data/iceland-surface.grib");
let product_kind = ProductKind::GRIB;

let handle = CodesHandle::new_from_file(file_path, product_kind).unwrap();

let handle_collected: Vec<KeyedMessage> = handle.collect().unwrap();

Use of filter(), map() and other methods provided with Iterator allow for more advanced extracting of GRIB messages from the file.

Errors

The next() method will return CodesInternal when internal ecCodes function returns non-zero code.

The type being iterated over.

The error type.

Advances the iterator and returns the next value. Read more

Returns bounds on the remaining length of the iterator. Read more

Consumes the iterator, returning the number of remaining items.

Returns the last element of the iterator.

Returns the nth element of the iterator.

Returns an iterator starting at the same point, but stepping by the given amount at each iteration. Read more

Returns an iterator which yields the elements of this iterator followed by another. Read more

Returns an iterator that yields pairs of this iterator’s and another iterator’s values. Read more

Returns an iterator which applies a fallible transform to the elements of the underlying iterator. Read more

Calls a fallible closure on each element of an iterator.

Returns an iterator which uses a predicate to determine which values should be yielded. The predicate may fail; such failures are passed to the caller. Read more

Returns an iterator which both filters and maps. The closure may fail; such failures are passed along to the consumer. Read more

Returns an iterator which yields the current iteration count as well as the value. Read more

Returns an iterator that can peek at the next element without consuming it. Read more

Returns an iterator that skips elements based on a predicate.

Returns an iterator that yields elements based on a predicate.

Returns an iterator which skips the first n values of this iterator.

Returns an iterator that yields only the first n values of this iterator. Read more

Returns an iterator which applies a stateful map to values of this iterator. Read more

Returns an iterator which maps this iterator’s elements to iterators, yielding those iterators’ values.

Returns an iterator which flattens an iterator of iterators, yielding those iterators’ values.

Returns an iterator which yields this iterator’s elements and ends after the first Ok(None). Read more

Returns an iterator which passes each element to a closure before returning it.

Borrow an iterator rather than consuming it. Read more

Transforms the iterator into a collection. Read more

Transforms the iterator into two collections, partitioning elements by a closure.

Applies a function over the elements of the iterator, producing a single final value. Read more

Applies a function over the elements of the iterator, producing a single final value. Read more

Determines if all elements of this iterator match a predicate.

Determines if any element of this iterator matches a predicate.

Returns the first element of the iterator that matches a predicate.

Applies a function to the elements of the iterator, returning the first non-None result.

Returns the position of the first element of this iterator that matches a predicate. The predicate may fail; such failures are returned to the caller. Read more

Returns the maximal element of the iterator.

Returns the element of the iterator which gives the maximum value from the function. Read more

Returns the element that gives the maximum value with respect to the function.

Returns the minimal element of the iterator.

Returns the element of the iterator which gives the minimum value from the function. Read more

Returns the element that gives the minimum value with respect to the function.

Returns an iterator that yields this iterator’s items in the opposite order. Read more

Converts an iterator of pairs into a pair of containers.

Returns an iterator which clones all of its elements.

Returns an iterator which repeas this iterator endlessly.

Lexicographically compares the elements of this iterator to that of another. Read more

Lexicographically compares the elements of this iterator to that of another. Read more

Determines if the elements of this iterator are equal to those of another. Read more

Determines if the elements of this iterator are not equal to those of another. Read more

Determines if the elements of this iterator are lexicographically less than those of another. Read more

Determines if the elements of this iterator are lexicographically less than or equal to those of another. Read more

Determines if the elements of this iterator are lexicographically greater than those of another. Read more

Determines if the elements of this iterator are lexicographically greater than or equal to those of another. Read more

Returns a normal (non-fallible) iterator over Result<Item, Error>.

Returns an iterator which applies a transform to the errors of the underlying iterator. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Performs the conversion.

Performs the conversion.

The elements of the iterator.

The error value of the iterator.

The iterator.

Creates a fallible iterator from a value.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.