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rss

RSS syndication format library (port of the Rust rss crate)

moon add marianoguerra/rss@0.1.1
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Version
0.1.1
License
Apache-2.0
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12 hours ago
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README

#marianoguerra/rss

An idiomatic MoonBit library for reading and writing the RSS web content syndication format — a port of the Rust rss crate, with full Atom 1.0 support via marianoguerra/atom and a built-in streaming XML engine (marianoguerra/xml).

#Supported versions

  • Reading: RSS 0.90, 0.91, 0.92, 1.0 and 2.0 (plus Atom via from_atom)
  • Writing: RSS 2.0

#Reading

///|
test {
  let channel = try! Channel::read_from(
    "<?xml version=\"1.0\"?><rss version=\"2.0\"><channel><title>News</title><link>https://example.com/</link><description>An example feed.</description><item><title>Hello</title></item></channel></rss>",
  )
  inspect(channel.title, content="News")
  inspect(channel.items[0].title.unwrap_or(""), content="Hello")
}

As a best effort for invalid feeds, elements declared required by RSS 2.0 default to an empty string.

#Writing

///|
test {
  let channel = try! Channel::read_from(
    "<rss version=\"2.0\"><channel><title>T</title><link>https://e.com/</link><description>D</description></channel></rss>",
  )
  let xml = channel.to_xml()
  // Writing then parsing reproduces the same model.
  let again = try! Channel::read_from(xml)
  assert_true(again == channel)
}

#Validation

///|
test {
  let channel = try! Channel::read_from(
    "<rss version=\"2.0\"><channel><title>T</title><link>notaurl</link><description>D</description></channel></rss>",
  )
  let verdict = try {
    ignore(channel.validate())
    "ok"
  } catch {
    _ => "failed"
  }
  inspect(verdict, content="failed")
}

#Extensions

Elements in non-default namespaces are collected generically into Channel.extensions / Item.extensions, and the well-known namespaces are additionally extracted into typed structs:

  • iTunes podcast metadata (itunes_ext)
  • Dublin Core (dublin_core_ext)
  • Syndication (syndication_ext)
  • Atom links (atom_links)

#Atom interop

///|
test {
  let channel = try! Channel::read_from(
    "<rss version=\"2.0\"><channel><title>T</title><link>https://e.com/</link><description>D</description></channel></rss>",
  )
  let feed = channel.to_atom()
  inspect(feed.title.value, content="T")
  let back = try! Channel::from_atom(feed)
  assert_true(back.title == channel.title)
}

#Testing methodology

This port is validated against the Rust crate itself:

  • Golden parity tests — every fixture from the crate's own test suite is parsed by both implementations; the resulting models must be identical, and our writer's output must be byte-identical to Channel::to_string.
  • Live differential testing — scripts/oracle-roundtrip.sh runs four round-trip directions between this library and a vendored Rust oracle CLI (oracle/, pinned to rss = "=2.1.0"). Regenerate goldens after changing fixtures with scripts/gen-goldens.sh (needs cargo).
  • Property-based tests — moonbitlang/quickcheck verifies parse(write(c)) == c and writer idempotence over generated channels whose text exercises escaping edge cases.
  • Fuzzing — deterministic mutation fuzzing over the fixture corpus asserts the parser always returns cleanly and never panics.

The golden files are committed, so moon test runs the full parity suite without a Rust toolchain.

#License

Apache-2.0

#
ExtensionMap

source
type ExtensionMap = Map[String, Map[String, Array[Extension]]]

A map of extension namespace prefixes to local names to elements.

Mirrors rss::extension::ExtensionMap.

#
RssError

source
pub(all) suberror RssError {
  Xml(err~ : 
XmlError)
  InvalidStartTag
  Eof
} derive(Eq, 
Debug)

Errors that occur while reading or writing an RSS channel.
impl Show for RssError

#
ValidationError

source
pub(all) suberror ValidationError {
  Invalid(String)
  Validation(String)
} derive(Eq, 
Debug)

Errors produced when a value fails RSS-spec validation, mirroring rss::validation::ValidationError.

#
Category

source
pub(all) struct Category {
  domain : String?
  name : String
} derive(Eq, 
Debug)

Represents a category in an RSS feed.

#
Category::validate

source
fn Category::validate(self : Category) -> Unit raise ValidationError

Validate this category against the RSS spec.

#
Channel

source
pub(all) struct Channel {
  title : String
  link : String
  description : String
  language : String?
  copyright : String?
  managing_editor : String?
  webmaster : String?
  pub_date : String?
  last_build_date : String?
  categories : Array[Category]
  generator : String?
  docs : String?
  cloud : Cloud?
  rating : String?
  ttl : String?
  image : Image?
  text_input : TextInput?
  skip_hours : Array[String]
  skip_days : Array[String]
  items : Array[Item]
  extensions : Map[String, Map[String, Array[Extension]]]
  atom_links : Array[
Link]
  itunes_ext : ITunesChannelExtension?
  dublin_core_ext : DublinCoreExtension?
  syndication_ext : SyndicationExtension?
  namespaces : Map[String, String]
} derive(Eq, 
Debug)

Represents the channel of an RSS feed.
impl Show for Channel

#
Channel::from_atom

source
fn Channel::from_atom(feed : 
Feed) -> Channel raise RssError

Convert an Atom feed into an RSS channel (the inverse of [to_atom]), so Atom feeds can be consumed with the same API.

#
Channel::from_canon

source
fn Channel::from_canon(json : Json) -> Channel raise RssError

Reconstruct a channel from canonical JSON.

#
Channel::read_from

source
fn Channel::read_from(input : String) -> Channel raise RssError

Parse an RSS feed from any of the supported versions (RSS 0.90, 0.91, 0.92, 1.0 and 2.0).

Mirrors Channel::read_from. As a best effort for invalid feeds, elements the RSS 2.0 spec declares required default to an empty string.

#
Channel::to_atom

source

Convert an RSS channel to an Atom 1.0 feed.

Mapping (documented, lossy by nature — Atom has no cloud/textInput/etc.):
  • title → <title> (plain text)
  • link → <link rel="alternate">
  • description → <subtitle>
  • item guid → entry <id>, falling back to the item link
  • item title/link/description/categories map 1:1

#
Channel::to_canon

source
fn Channel::to_canon(self : Channel) -> Json

Convert a parsed channel to the canonical JSON form.

#
Channel::to_xml

source
fn Channel::to_xml(self : Channel) -> String

Serialise the channel as RSS 2.0 XML.

#
Channel::validate

source
fn Channel::validate(self : Channel) -> Unit raise ValidationError

Validate this channel against the RSS specification.

#
Cloud

source
pub(all) struct Cloud {
  domain : String
  port : String
  path : String
  register_procedure : String
  protocol : String
} derive(Eq, 
Debug)

Represents a cloud in an RSS feed: a registry for update notifications.

#
Cloud::validate

source
fn Cloud::validate(self : Cloud) -> Unit raise ValidationError

Validate this cloud against the RSS spec.

#
DublinCoreExtension

source
pub(all) struct DublinCoreExtension {
  contributors : Array[String]
  coverages : Array[String]
  creators : Array[String]
  dates : Array[String]
  descriptions : Array[String]
  formats : Array[String]
  identifiers : Array[String]
  languages : Array[String]
  publishers : Array[String]
  relations : Array[String]
  rights : Array[String]
  sources : Array[String]
  subjects : Array[String]
  titles : Array[String]
  types : Array[String]
} derive(Eq, 
Debug)

Dublin Core metadata extracted from a channel or item.

Every field is a list because Dublin Core elements are repeatable.

#
DublinCoreExtension::from_map

source
fn DublinCoreExtension::from_map(map : Map[String, Array[Extension]]) -> DublinCoreExtension

Build a Dublin Core extension from parsed generic extensions, mirroring DublinCoreExtension::from_map.

#
Enclosure

source
pub(all) struct Enclosure {
  url : String
  length : String
  mime_type : String
} derive(Eq, 
Debug)

Represents an enclosure (media attachment) in an RSS item.

#
Enclosure::validate

source
fn Enclosure::validate(self : Enclosure) -> Unit raise ValidationError

Validate this enclosure against the RSS spec.

#
Extension

source
pub(all) struct Extension {
  name : String
  value : String?
  attrs : Map[String, String]
  children : Map[String, Array[Extension]]
} derive(Eq, 
Debug)

An element from a non-default namespace, kept generically.

#
Guid

source
pub(all) struct Guid {
  is_permalink : Bool
  value : String
} derive(Eq, 
Debug)

Represents the GUID of an RSS item.

#
ITunesCategory

source
pub(all) struct ITunesCategory {
  text : String
  subcategory : ITunesCategory?
} derive(Eq, 
Debug)

An iTunes category with an optional nested subcategory.

#
ITunesChannelExtension

source
pub(all) struct ITunesChannelExtension {
  author : String?
  block : String?
  categories : Array[ITunesCategory]
  image : String?
  explicit : String?
  complete : String?
  new_feed_url : String?
  owner : ITunesOwner?
  subtitle : String?
  summary : String?
  keywords : String?
  itunes_type : String?
} derive(Eq, 
Debug)

iTunes metadata extracted from a channel.

#
ITunesChannelExtension::from_map

source

Build a channel extension from parsed generic extensions, mirroring ITunesChannelExtension::from_map.

#
ITunesItemExtension

source
pub(all) struct ITunesItemExtension {
  author : String?
  block : String?
  image : String?
  duration : String?
  explicit : String?
  closed_captioned : String?
  order : String?
  subtitle : String?
  summary : String?
  keywords : String?
  episode : String?
  season : String?
  episode_type : String?
} derive(Eq, 
Debug)

iTunes metadata extracted from an item.

#
ITunesItemExtension::from_map

source
fn ITunesItemExtension::from_map(map : Map[String, Array[Extension]]) -> ITunesItemExtension

Build an item extension from parsed generic extensions, mirroring ITunesItemExtension::from_map.

#
ITunesOwner

source
pub(all) struct ITunesOwner {
  name : String?
  email : String?
} derive(Eq, 
Debug)

Contact information for the owner of a podcast.

#
Image

source
pub(all) struct Image {
  url : String
  title : String
  link : String
  width : String?
  height : String?
  description : String?
} derive(Eq, 
Debug)

Represents an image that can be displayed with a channel.

#
Image::validate

source
fn Image::validate(self : Image) -> Unit raise ValidationError

Validate this image against the RSS spec.

#
Item

source
pub(all) struct Item {
  title : String?
  link : String?
  description : String?
  author : String?
  categories : Array[Category]
  comments : String?
  enclosure : Enclosure?
  guid : Guid?
  pub_date : String?
  source : Source?
  content : String?
  extensions : Map[String, Map[String, Array[Extension]]]
  atom_links : Array[
Link]
  itunes_ext : ITunesItemExtension?
  dublin_core_ext : DublinCoreExtension?
} derive(Eq, 
Debug)

Represents an item in an RSS feed.

#
Item::validate

source
fn Item::validate(self : Item) -> Unit raise ValidationError

Validate this item against the RSS spec.

#
Source

source
pub(all) struct Source {
  url : String
  title : String?
} derive(Eq, 
Debug)

Represents the source of an RSS item.

#
Source::validate

source
fn Source::validate(self : Source) -> Unit raise ValidationError

Validate this source against the RSS spec.

#
SyndicationExtension

source
pub(all) struct SyndicationExtension {
  period : UpdatePeriod
  frequency : Int
  base : String
} derive(Eq, 
Debug)

Syndication metadata extracted from a channel (when to refresh, how often, and relative to which base time).

#
SyndicationExtension::from_map

source

Build a syndication extension from parsed generic extensions, mirroring SyndicationExtension::from_map.

#
TextInput

source
pub(all) struct TextInput {
  title : String
  description : String
  name : String
  link : String
} derive(Eq, 
Debug)

Represents a text input that can be displayed with a channel.

#
TextInput::validate

source
fn TextInput::validate(self : TextInput) -> Unit raise ValidationError

Validate this text input against the RSS spec.

#
UpdatePeriod

source
pub(all) enum UpdatePeriod {
  Hourly
  Daily
  Weekly
  Monthly
  Yearly
} derive(Eq, 
Debug)

The update period of a syndicated feed.

#
DUBLIN_CORE_NAMESPACE

source
let DUBLIN_CORE_NAMESPACE : String

The Dublin Core namespace.

#
ITUNES_NAMESPACE

source
let ITUNES_NAMESPACE : String

The iTunes podcast namespace.

#
SYNDICATION_NAMESPACE

source
let SYNDICATION_NAMESPACE : String

The Syndication namespace.

#
canonical_stringify

source
fn canonical_stringify(j : Json) -> String

Compact, deterministic serialisation: object keys are emitted in sorted order (matching serde_json over BTreeMaps).

#
extension_entry

source
fn extension_entry(extensions : Map[String, Map[String, Array[Extension]]], ns : String, name : String) -> Array[Extension]

Record an extension element under ns / name.

#
parse_rfc2822

source
fn parse_rfc2822(s : String) -> Bool

Parse an RFC 822 / RFC 2822 date-time, returning its components. Accepts the common forms used by feeds: [Weekday,] DD Mon YYYY HH:MM[:SS] Zone.

#
sort_json_keys

source
fn sort_json_keys(j : Json) -> Json

Recursively sort JSON object keys so that output is byte-identical to serde_json's BTreeMap-based serialisation used by the oracle.

#
str_lexicographic

source
fn str_lexicographic(a : String, b : String) -> Int

Lexicographic (code-unit wise) string comparison, matching the byte-wise Ord of Rust strings used by the oracle's BTreeMap ordering.

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