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oxigraph/lib/src/model/blank_node.rs

237 lines
7.3 KiB

use rand::random;
use rio_api::model as rio;
use std::error::Error;
use std::fmt;
use std::io::Write;
use std::str;
/// An RDF [blank node](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node).
///
/// The common way to create a new blank node is to use the `BlankNode::default` trait method.
///
/// It is also possible to create a blank node from a blank node identifier using the `BlankNode::new` method.
/// The blank node identifier must be valid according to N-Triples, Turtle and SPARQL grammars.
///
/// The default string formatter is returning a N-Triples, Turtle and SPARQL compatible representation:
/// ```
/// use oxigraph::model::BlankNode;
///
/// assert_eq!(
/// "_:a122",
/// BlankNode::new("a122")?.to_string()
/// );
/// # Result::<_,oxigraph::model::BlankNodeIdParseError>::Ok(())
/// ```
#[derive(Eq, PartialEq, Debug, Clone, Hash)]
pub struct BlankNode(BlankNodeContent);
#[derive(PartialEq, Eq, Debug, Clone, Hash)]
enum BlankNodeContent {
Named(String),
Anonymous { id: u128, str: [u8; 32] },
}
impl BlankNode {
/// Creates a blank node from a unique identifier.
///
/// The blank node identifier must be valid according to N-Triples, Turtle and SPARQL grammars.
///
/// In most cases, it is much more convenient to create a blank node using `BlankNode::default()`.
/// `BlankNode::default()` creates a random ID that could be easily inlined by Oxigraph stores.
pub fn new(id: impl Into<String>) -> Result<Self, BlankNodeIdParseError> {
let id = id.into();
validate_blank_node_identifier(&id)?;
Ok(Self::new_unchecked(id))
}
/// Creates a blank node from a unique identifier without validation.
///
/// It is the caller's responsibility to ensure that `id` is a valid blank node identifier
/// according to N-Triples, Turtle and SPARQL grammars.
///
/// Except if you really know what you do, you should use [`new`](#method.new).
pub fn new_unchecked(id: impl Into<String>) -> Self {
let id = id.into();
if let Ok(numerical_id) = u128::from_str_radix(&id, 16) {
let result = Self::new_from_unique_id(numerical_id);
if result.as_str() == id {
result
} else {
Self(BlankNodeContent::Named(id))
}
} else {
Self(BlankNodeContent::Named(id))
}
}
/// Creates a blank node from a unique numerical id
///
/// In most cases, it is much more convenient to create a blank node using `BlankNode::default()`.
pub fn new_from_unique_id(id: impl Into<u128>) -> Self {
let id = id.into();
let mut str = [0; 32];
write!(&mut str[..], "{:x}", id).unwrap();
Self(BlankNodeContent::Anonymous { id, str })
}
/// Returns the underlying ID of this blank node
pub fn as_str(&self) -> &str {
match &self.0 {
BlankNodeContent::Named(id) => id,
BlankNodeContent::Anonymous { str, .. } => {
let len = str.iter().position(|x| x == &0).unwrap_or(32);
str::from_utf8(&str[..len]).unwrap()
}
}
}
/// Returns the underlying ID of this blank node
pub fn into_string(self) -> String {
match self.0 {
BlankNodeContent::Named(id) => id,
BlankNodeContent::Anonymous { str, .. } => {
let len = str.iter().position(|x| x == &0).unwrap_or(32);
str::from_utf8(&str[..len]).unwrap().to_owned()
}
}
}
/// Returns the internal numerical ID of this blank node, if it exists
pub(crate) fn id(&self) -> Option<u128> {
match self.0 {
BlankNodeContent::Named(_) => None,
BlankNodeContent::Anonymous { id, .. } => Some(id),
}
}
}
impl fmt::Display for BlankNode {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
rio::BlankNode::from(self).fmt(f)
}
}
impl Default for BlankNode {
/// Builds a new RDF [blank node](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node) with a unique id
fn default() -> Self {
Self::new_from_unique_id(random::<u128>())
}
}
impl<'a> From<&'a BlankNode> for rio::BlankNode<'a> {
fn from(node: &'a BlankNode) -> Self {
rio::BlankNode { id: node.as_str() }
}
}
fn validate_blank_node_identifier(id: &str) -> Result<(), BlankNodeIdParseError> {
let mut chars = id.chars();
let front = chars.next().ok_or(BlankNodeIdParseError {})?;
match front {
'0'..='9'
| '_'
| ':'
| 'A'..='Z'
| 'a'..='z'
| '\u{00C0}'..='\u{00D6}'
| '\u{00D8}'..='\u{00F6}'
| '\u{00F8}'..='\u{02FF}'
| '\u{0370}'..='\u{037D}'
| '\u{037F}'..='\u{1FFF}'
| '\u{200C}'..='\u{200D}'
| '\u{2070}'..='\u{218F}'
| '\u{2C00}'..='\u{2FEF}'
| '\u{3001}'..='\u{D7FF}'
| '\u{F900}'..='\u{FDCF}'
| '\u{FDF0}'..='\u{FFFD}'
| '\u{10000}'..='\u{EFFFF}' => (),
_ => return Err(BlankNodeIdParseError {}),
}
for c in chars {
match c {
'.' // validated later
| '-'
| '0'..='9'
| '\u{00B7}'
| '\u{0300}'..='\u{036F}'
| '\u{203F}'..='\u{2040}'
| '_'
| ':'
| 'A'..='Z'
| 'a'..='z'
| '\u{00C0}'..='\u{00D6}'
| '\u{00D8}'..='\u{00F6}'
| '\u{00F8}'..='\u{02FF}'
| '\u{0370}'..='\u{037D}'
| '\u{037F}'..='\u{1FFF}'
| '\u{200C}'..='\u{200D}'
| '\u{2070}'..='\u{218F}'
| '\u{2C00}'..='\u{2FEF}'
| '\u{3001}'..='\u{D7FF}'
| '\u{F900}'..='\u{FDCF}'
| '\u{FDF0}'..='\u{FFFD}'
| '\u{10000}'..='\u{EFFFF}' => (),
_ => return Err(BlankNodeIdParseError {}),
}
}
// Could not end with a dot
if id.ends_with('.') {
Err(BlankNodeIdParseError {})
} else {
Ok(())
}
}
/// An error raised during `BlankNode` validation.
#[allow(missing_copy_implementations)]
#[derive(Debug)]
pub struct BlankNodeIdParseError {}
impl fmt::Display for BlankNodeIdParseError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "The blank node identifier is invalid")
}
}
impl Error for BlankNodeIdParseError {}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn as_str_partial() {
let b = BlankNode::new_from_unique_id(0x42_u128);
assert_eq!(b.as_str(), "42");
}
#[test]
fn as_str_full() {
let b = BlankNode::new_from_unique_id(0x7777_6666_5555_4444_3333_2222_1111_0000_u128);
assert_eq!(b.as_str(), "77776666555544443333222211110000");
}
#[test]
fn new_validation() {
assert!(BlankNode::new("").is_err());
assert!(BlankNode::new("a").is_ok());
assert!(BlankNode::new("-").is_err());
assert!(BlankNode::new("a-").is_ok());
assert!(BlankNode::new(".").is_err());
assert!(BlankNode::new("a.").is_err());
assert!(BlankNode::new("a.a").is_ok());
}
#[test]
fn new_numerical() {
assert_eq!(
BlankNode::new("100a").unwrap(),
BlankNode::new_from_unique_id(0x100a_u128),
);
assert_ne!(
BlankNode::new("100A").unwrap(),
BlankNode::new_from_unique_id(0x100a_u128)
);
}
}