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|
use core::fmt;
use std::str::FromStr;
#[derive(Clone, Debug, PartialEq)]
pub enum QueryComponent {
/// Every child element of the tag
Element(QueryElement),
DirectElement(QueryElement),
}
#[derive(Clone, Debug, Default, PartialEq)]
pub struct QueryElement {
pub tag: Option<String>,
pub class: Option<String>,
pub id: Option<String>,
}
#[rustfmt::skip] // leave me alone
impl FromStr for QueryElement {
type Err = QueryParseError;
fn from_str(raw: &str) -> Result<Self, Self::Err> {
let mut element = QueryElement::default();
if let Some(idx) = raw.find(' ') {
return Err(QueryParseError::MalformedComponent {
raw: raw.into(),
idx,
error: "spaces not allowed in element queries".into()
});
}
let mut wrk = raw;
loop {
// Guards the match from a panic
if wrk.is_empty() { break; }
let part = match wrk[1..].find(['#', '.']) {
None => {
// Last part
let part = wrk;
wrk = &wrk[wrk.len()..];
part
},
Some(idx) => {
let part = &wrk[..idx+1];
wrk = &wrk[idx+1..];
part
}
};
if let Some(id) = part.strip_prefix('#') {
println!("id {id}");
element.id = Some(id.into());
} else if let Some(class) = part.strip_prefix('.') {
println!("class {class}");
element.class = Some(class.into());
} else {
element.tag = Some(part.into());
}
}
Ok(element)
}
}
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 components.is_empty() {
return Err(QueryParseError::StartsDirect);
}
if next_direct {
return Err(QueryParseError::DoubleDirect);
} else {
next_direct = true;
}
}
raw = &raw[idx + 1..];
part
}
};
if part.is_empty() {
continue;
}
let element: QueryElement = part.parse()?;
if next_direct {
components.push(QueryComponent::DirectElement(element));
next_direct = false;
} else {
components.push(QueryComponent::Element(element));
}
}
}
#[derive(Debug)]
pub enum QueryParseError {
StartsDirect,
EndsInDirect,
DoubleDirect,
MalformedComponent {
raw: String,
idx: usize,
error: String,
},
}
impl fmt::Display for QueryParseError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::StartsDirect => {
write!(f, "cannot start query with a direct relation")
}
Self::EndsInDirect => {
write!(
f,
"Query ends with '>' which does not make sense. Are you missing a selector?"
)
}
Self::DoubleDirect => {
write!(f, "Two direct descendent selectors (>) appeard together")
}
Self::MalformedComponent { raw, idx, error } => {
write!(f, "{error}\n{raw}\n{:>width$}^", width = idx - 1)
}
}
}
}
#[cfg(test)]
mod test {
use crate::query::{QueryComponent, QueryElement};
use super::parse_query;
macro_rules! txt {
() => {
None
};
($txt:expr) => {
Some(String::from($txt))
};
}
#[test]
fn parses_query_element() {
let raw = "main#wide.post";
let parse = parse_query(raw).unwrap();
assert_eq!(
parse,
vec![QueryComponent::Element(QueryElement {
tag: txt!("main"),
id: txt!("wide"),
class: txt!("post")
})]
)
}
#[test]
fn parses_direct_query_element() {
let raw = "> main#wide.post";
let parse = parse_query(raw).unwrap();
assert_eq!(
parse,
vec![QueryComponent::DirectElement(QueryElement {
tag: txt!("main"),
id: txt!("wide"),
class: txt!("post")
})]
)
}
}
|
