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use crate::Result;
use options::FormattingOptions;
use pest::{iterators::Pairs, Parser};
use serde::{Deserialize, Serialize};
use std::borrow::Cow;
use std::{default::Default, fmt::Display};
use crate::error::Error;
use crate::grammar::Grammar;
use crate::Rule;
pub mod element;
pub mod formatting;
pub mod node;
pub mod options;
pub mod span;
use node::Node;
/// Document, DocumentFragment or Empty
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub enum DomVariant {
/// This means that the parsed html had the representation of an html document. The doctype is optional but a document should only have one root node with the name of html.
/// Example:
/// ```text
/// <!doctype html>
/// <html>
/// <head></head>
/// <body>
/// <h1>Hello world</h1>
/// </body>
/// </html>
/// ```
Document,
/// A document fragment means that the parsed html did not have the representation of a document. A fragment can have multiple root children of any name except html, body or head.
/// Example:
/// ```text
/// <h1>Hello world</h1>
/// ```
DocumentFragment,
/// An empty dom means that the input was empty
Empty,
}
/// **The main struct** & the result of the parsed html
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
#[serde(rename_all = "camelCase")]
pub struct Dom<'s> {
/// The type of the tree that was parsed
pub tree_type: DomVariant,
/// All of the root children in the tree
#[serde(borrow, skip_serializing_if = "Vec::is_empty")]
pub children: Vec<Node<'s>>,
/// A collection of all warnings during parsing
#[serde(skip_serializing)]
pub warnings: Vec<String>,
}
impl<'s> Default for Dom<'s> {
fn default() -> Self {
Self {
tree_type: DomVariant::Empty,
children: vec![],
warnings: vec![],
}
}
}
impl<'s> Dom<'s> {
/// Create a new empty dom element
pub fn new() -> Self {
Self::default()
}
/// Parse a dom from a html string
pub fn parse(input: &'s str) -> Result<Self> {
let pairs = match Grammar::parse(Rule::html, input) {
Ok(pairs) => pairs,
Err(error) => return Err(formatting::error_msg(error)),
};
Self::build_dom(pairs)
}
/// Create the dom from a json string
pub fn parse_json(json: &'s str) -> Result<Self> {
Ok(serde_json::from_str(json)?)
}
/// Output the dom as a json formatted string
pub fn to_json(&self) -> Result<String> {
Ok(serde_json::to_string(self)?)
}
/// Output the dom as a pretty json formatted string
pub fn to_json_pretty(&self) -> Result<String> {
Ok(serde_json::to_string_pretty(self)?)
}
/// Write the dom as a html string with the given formatting options
pub fn fmt_opt<W>(&self, f: &mut W, o: &FormattingOptions) -> std::fmt::Result
where
W: std::fmt::Write,
{
for child in self.children.iter() {
child.fmt_opt(f, o, 0)?;
write!(f, "\n")?;
}
Ok(())
}
fn build_dom(pairs: Pairs<'s, Rule>) -> Result<Self> {
let mut dom = Self::default();
// NOTE: The logic is roughly as follows:
// 1) A document containing nothing but comments is DomVariant::Empty even though it will have
// children in this first pass. We fix this in the next section. This allows us to use
// DomVariant::Empty to indicate "we haven't decided the type yet".
// 2) If the type is DomVariant::Empty _so far_, then it can be changed to DomVariant::Document
// or DomVariant::DocumentFragment. DomVariant is only selected in this stage if we see a
// DOCTYPE tag. Comments do not change the type.
// 3) If the type is non-empty, we don't re-set the type. We do look for conflicts between
// the type and the tokens in the next stage.
for pair in pairs {
match pair.as_rule() {
// A <!DOCTYPE> tag means a full-fledged document. Note that because of the way
// the grammar is written, we will only get this token if the <!DOCTYPE> occurs
// before any other tag; otherwise it will be parsed as a custom tag.
Rule::doctype => {
if dom.tree_type == DomVariant::Empty {
dom.tree_type = DomVariant::Document;
}
}
// If we see an element, build the sub-tree and add it as a child. If we don't
// have a document type yet (i.e. "empty"), select DocumentFragment
Rule::node_element => match Node::build_node_element(pair, &mut dom.warnings) {
Ok(el) => {
if let Some(node) = el {
if dom.tree_type == DomVariant::Empty {
dom.tree_type = DomVariant::DocumentFragment;
};
dom.children.push(node);
}
}
Err(error) => {
dom.warnings.push(format!("{}", error));
}
},
// Similar to an element, we add it as a child and select DocumentFragment if we
// don't already have a document type.
Rule::node_text => {
if dom.tree_type == DomVariant::Empty {
dom.tree_type = DomVariant::DocumentFragment;
}
let text = pair.as_str();
if !text.trim().is_empty() {
dom.children.push(Node::Text(Cow::Borrowed(text)));
}
}
// Store comments as a child, but it doesn't affect the document type selection
// until the next phase (validation).
Rule::node_comment => {
dom.children
.push(Node::Comment(Cow::Borrowed(pair.into_inner().as_str())));
}
// Ignore 'end of input', which then allows the catch-all unreachable!() arm to
// function properly.
Rule::EOI => (),
// This should be unreachable, due to the way the grammar is written
_ => unreachable!("[build dom] unknown rule: {:?}", pair.as_rule()),
};
}
// Implement some checks on the generated dom's data and initial type. The type may be
// modified in this section.
match dom.tree_type {
// A DomVariant::Empty can only have comments. Anything else is an error.
DomVariant::Empty => {
for node in &dom.children {
if let Node::Comment(_) = node {
// An "empty" document, but it has comments - this is where we cleanup the
// earlier assumption that a document with only comments is "empty".
// Really, it is a "fragment".
dom.tree_type = DomVariant::DocumentFragment
} else {
// Anything else (i.e. Text() or Element() ) can't happen at the top level;
// if we had seen one, we would have set the document type above
unreachable!("[build dom] empty document with an Element {:?}", node)
}
}
}
// A DomVariant::Document can only have comments and an <HTML> node at the top level.
// Only one <HTML> tag is permitted.
DomVariant::Document => {
if dom
.children
.iter()
.filter(|x| match x {
Node::Element(el) if el.name.to_lowercase() == "html" => true,
_ => false,
})
.count()
> 1
{
return Err(Error::Parsing(format!("Document with multiple HTML tags",)));
}
}
// A DomVariant::DocumentFragment should not have <HEAD>, or <BODY> tags at the
// top-level. If we find an <HTML> tag, then we consider this a Document instead (if
// it comes before any other elements, and if there is only one <HTML> tag).
DomVariant::DocumentFragment => {
let mut seen_html = false;
let mut seen_elements = false;
for node in &dom.children {
match node {
// Nodes other than <HTML> - reject <HEAD> and <BODY>
Node::Element(ref el) if el.name.to_lowercase() != "html" => {
if el.name == "head" || el.name == "body" {
return Err(Error::Parsing(format!(
"A document fragment should not include {}",
el.name
)));
}
seen_elements = true;
}
// <HTML> Nodes - one (before any other elements) is okay
Node::Element(ref el) if el.name.to_lowercase() == "html" => {
if seen_html || seen_elements {
return Err(Error::Parsing(format!(
"A document fragment should not include {}",
el.name
)));
};
// A fragment with just an <HTML> tag is a document
dom.tree_type = DomVariant::Document;
seen_html = true;
}
// Comment() and Text() nodes are permitted at the top-level of a
// DocumentFragment
_ => (),
}
}
}
}
// The result is the validated tree
Ok(dom)
}
}
impl<'s> Display for Dom<'s> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.fmt_opt(f, &FormattingOptions::pretty())
}
}