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extern crate nom;
mod ast;
use ast::{Node, NodeKind};
use nom::{
branch::alt,
bytes::complete::{escaped, is_not, tag_no_case, take_until},
character::complete::{alphanumeric0, anychar, char, multispace0, one_of},
combinator::opt,
IResult,
};
use nom_locate::{position, LocatedSpan};
type Span<'a> = LocatedSpan<&'a str>;
pub fn parse(s: &str) -> Node {
let (_, children) = parse_internal(Span::new(s), None).unwrap();
return Node {
kind: NodeKind::Root,
name: "",
value: None,
children: children,
attributes: vec![],
line: 0,
offset: 0,
};
}
fn parse_internal<'a>(
s: Span<'a>,
current_tag: Option<&'a str>,
) -> IResult<Span<'a>, Vec<Node<'a>>> {
let mut _s = s;
let mut children = vec![];
while _s.len() > 0 {
let (_, pos) = position(_s)?;
let (s, text) = match opt(alt((
take_until("<mt"),
take_until("</mt"),
take_until("<$mt"),
)))(_s)?
{
(s, Some(text)) => (s, text),
_ => (Span::new(""), _s),
};
if text.len() > 0 {
children.push(Node {
kind: NodeKind::Text,
name: "",
value: Some(text.fragment()),
children: vec![],
attributes: vec![],
line: pos.location_line(),
offset: pos.location_offset(),
});
}
if s.len() == 0 {
break;
}
let (_, end_tag) = opt(tag_no_case("</"))(s)?;
if end_tag.is_some() && current_tag.is_some() {
let (s, _) = tag_no_case(format!("</mt:{}>", current_tag.unwrap()).as_str())(s)?;
_s = s;
break;
} else {
let (s, node) = parse_tag(s)?;
children.push(node);
_s = s;
};
}
return Ok((_s, children));
}
fn parse_attribute_values(s: Span) -> IResult<Span, Vec<ast::AttributeValue>> {
let (mut _s, _) = opt(char(','))(s)?;
let mut values: Vec<ast::AttributeValue> = vec![];
while _s.len() > 0 {
match _s.chars().nth(0) {
Some('"') | Some('\'') => {}
_ => break,
}
let (s, ch) = alt((char('"'), char('\'')))(_s)?;
let (s, value) = escaped(
is_not(format!("{}\\", ch).as_str()),
'\\',
one_of(format!("{}", ch).as_str()),
)(s)?;
let (s, _) = char(ch)(s)?;
let (_, pos) = position(s)?;
values.push(ast::AttributeValue {
value: value.fragment(),
line: pos.location_line(),
offset: pos.location_offset(),
});
_s = s;
}
return if values.len() > 0 {
Ok((_s, values))
} else {
Ok((s, values))
};
}
fn parse_attribute(s0: Span) -> IResult<Span, Option<ast::Attribute>> {
let (s, _) = multispace0(s0)?;
let (_, name) = alphanumeric0(s)?;
if name.len() == 0 {
return Ok((s, None));
}
let (_, pos) = position(s)?;
let (s, name) = take_until("=")(s)?;
let (s, _) = char('=')(s)?;
let (s, values) = parse_attribute_values(s)?;
return Ok((
s,
Some(ast::Attribute {
name: name.fragment(),
values,
line: pos.location_line(),
offset: pos.location_offset(),
}),
));
}
fn parse_attributes(s: Span) -> IResult<Span, Vec<ast::Attribute>> {
let mut s0 = s;
let mut attributes = vec![];
loop {
let (s, attribute) = parse_attribute(s0)?;
match attribute {
Some(attribute) => {
s0 = s;
attributes.push(attribute)
}
None => break,
}
}
return Ok((s0, attributes));
}
fn parse_tag(s: Span) -> IResult<Span, Node> {
let (s, head) = alt((tag_no_case("<mt"), tag_no_case("<$mt")))(s)?;
let (s, _) = opt(char(':'))(s)?;
let (s, name) = alphanumeric0(s)?;
let (s, attributes) = parse_attributes(s)?;
let (s, pos) = position(s)?;
let (s, tail) = take_until(">")(s)?;
let (s, _) = anychar(s)?;
let kind = if tail.len() >= 1
&& (head.chars().nth(1).unwrap() == '$' || tail.chars().rev().nth(0).unwrap() == '/')
{
NodeKind::FunctionTag
} else {
NodeKind::BlockTag
};
if matches!(kind, NodeKind::BlockTag) {
let (s, children) = parse_internal(s, Some(name.fragment()))?;
return Ok((
s,
Node {
kind,
name: name.fragment(),
value: None,
children,
attributes,
line: pos.location_line(),
offset: pos.location_offset(),
},
));
}
return Ok((
s,
Node {
kind,
name: name.fragment(),
value: None,
children: vec![],
attributes,
line: pos.location_line(),
offset: pos.location_offset(),
},
));
}
pub fn serialize(node: Node) -> String {
let mut s = String::new();
match node.kind {
NodeKind::Text => {
s.push_str(node.value.unwrap());
}
NodeKind::FunctionTag => {
s.push_str(&format!("<$mt:{}", node.name));
for attr in node.attributes {
s.push_str(&format!(r#" {}="{}""#, attr.name, attr.values[0].value));
}
s.push_str("$>");
}
NodeKind::BlockTag => {
s.push_str(&format!("<mt:{}", node.name));
for attr in node.attributes {
s.push_str(&format!(r#" {}="{}""#, attr.name, attr.values[0].value));
}
s.push_str(">");
for child in node.children {
s.push_str(&serialize(child));
}
s.push_str(&format!("</mt:{}>", node.name));
}
NodeKind::Root => {
for child in node.children {
s.push_str(&serialize(child));
}
}
}
return s;
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn parse_serialize() {
let input = r#"
<html>
<body>
<mt:Entries limit="10\"20">
<mtEntryTitle encode_html="1"/>
</mt:Entries>
</body>
</html>"#;
let root = parse(input);
let serialized = serialize(root);
assert_eq!(serialized, r#"
<html>
<body>
<mt:Entries limit="10\"20">
<$mt:EntryTitle encode_html="1"$>
</mt:Entries>
</body>
</html>"#)
}
}