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|
#[derive(Clone, Debug, PartialEq)]
pub enum QueryComponent {
/// Every child element of the tag
TagName(String),
/// Only direct children with the tag
DirectTagName(String),
/// The child element with the ID
Id(String),
/// Only direct children with the tag
DirectId(String),
/// Every child that has the class
Class(String),
/// Only direct children with the class
DirectClass(String),
}
pub fn parse_query(mut raw: &str) -> Result<Vec<QueryComponent>, QueryParseError> {
let mut components = vec![];
let mut next_direct = false;
loop {
if raw.is_empty() {
break Ok(components);
}
let part = match raw.find(['>', ' ']) {
None => {
let part = raw;
raw = &raw[raw.len()..raw.len()];
part
}
Some(idx) => {
let part = &raw[..idx];
if &raw[idx..idx + 1] == ">" {
if next_direct {
return Err(QueryParseError::DoubleDirect);
} else {
next_direct = true;
}
}
raw = &raw[idx + 1..];
part
}
};
if part.is_empty() {
continue;
}
if let Some(id) = part.strip_prefix('#') {
if id.contains(['#', '.']) {
return Err(QueryParseError::UnknownComponent {
malformed: id.into(),
});
}
if next_direct {
components.push(QueryComponent::DirectId(id.into()));
next_direct = false;
} else {
components.push(QueryComponent::Id(id.into()));
}
} else if let Some(class) = part.strip_prefix('.') {
if class.contains(['#', '.']) {
return Err(QueryParseError::UnknownComponent {
malformed: class.into(),
});
}
if next_direct {
components.push(QueryComponent::DirectClass(class.into()));
next_direct = false;
} else {
components.push(QueryComponent::Class(class.into()));
}
} else {
if part.contains(['#', '.']) {
return Err(QueryParseError::UnknownComponent {
malformed: part.into(),
});
}
if next_direct {
components.push(QueryComponent::DirectTagName(part.into()));
next_direct = false;
} else {
components.push(QueryComponent::TagName(part.into()));
}
}
}
}
#[derive(Debug, thiserror::Error)]
pub enum QueryParseError {
#[error("Query ends with '>' which does not make sense. Are you missing a selector?")]
EndsInDirect,
#[error("Two direct descendent selectors (>) appeard together")]
DoubleDirect,
#[error(
"The component {malformed} does not make sense. Valid selectors are #id, .class, and tag"
)]
UnknownComponent { malformed: String },
}
#[cfg(test)]
mod test {
use super::parse_query;
macro_rules! qc {
($tag:expr) => {
$crate::query::QueryComponent::TagName(String::from($tag))
};
(>$tag:expr) => {
$crate::query::QueryComponent::DirectTagName(String::from($tag))
};
(ID $tag:expr) => {
$crate::query::QueryComponent::Id(String::from($tag))
};
(>ID $tag:expr) => {
$crate::query::QueryComponent::DirectId(String::from($tag))
};
(. $tag:expr) => {
$crate::query::QueryComponent::Class(String::from($tag))
};
(>. $tag:expr) => {
$crate::query::QueryComponent::DirectClass(String::from($tag))
};
}
#[test]
fn parses_tags() {
let raw = "main section p";
let parse = parse_query(raw).unwrap();
assert_eq!(parse, vec![qc!("main"), qc!("section"), qc!("p")])
}
#[test]
fn parses_direct_tags() {
let raw = "main > section > p";
let parse = parse_query(raw).unwrap();
assert_eq!(parse, vec![qc!("main"), qc!(> "section"), qc!(> "p")])
}
#[test]
fn parses_id() {
let raw = "main #job";
let parse = parse_query(raw).unwrap();
assert_eq!(parse, vec![qc!("main"), qc!(ID "job")])
}
#[test]
fn parses_direct_id() {
let raw = "main > #job";
let parse = parse_query(raw).unwrap();
assert_eq!(parse, vec![qc!("main"), qc!(>ID "job")])
}
#[test]
fn parses_class() {
let raw = "main .post";
let parse = parse_query(raw).unwrap();
assert_eq!(parse, vec![qc!("main"), qc!(."post")])
}
#[test]
fn parses_direct_class() {
let raw = "main > .post";
let parse = parse_query(raw).unwrap();
assert_eq!(parse, vec![qc!("main"), qc!(>."post")])
}
#[test]
fn parses_complex() {
let raw = "main > article";
let parse = parse_query(raw).unwrap();
assert_eq!(parse, vec![qc!("main"), qc!(>."post")])
}
}
|
