rosvgtree 0.2.0

/*!
Represents an [SVG](https://www.w3.org/TR/SVG11/Overview.html) document as a read-only tree.

`rosvgtree` is similar to [`roxmltree`](https://github.com/RazrFalcon/roxmltree),
and even uses it for parsing, but instead of producing an XML tree,
it produces an SVG tree by
[post-processing](https://github.com/RazrFalcon/resvg/blob/master/rosvgtree/docs/post-processing.md)
XML, to make SVG parsing easier.
*/

#![forbid(unsafe_code)]
#![warn(missing_docs)]
#![warn(missing_debug_implementations)]
#![warn(missing_copy_implementations)]
#![allow(clippy::collapsible_else_if)]
#![allow(clippy::collapsible_if)]
#![allow(clippy::uninlined_format_args)]

use std::collections::HashMap;
use std::num::NonZeroU32;

#[rustfmt::skip] mod names;
mod parse;
mod text;

pub use names::{AttributeId, ElementId};

pub use roxmltree::{self, Error};

/// An SVG tree container.
///
/// Contains only element and text nodes.
/// Text nodes are present only inside the `text` element.
pub struct Document<'input> {
    nodes: Vec<NodeData>,
    attrs: Vec<Attribute<'input>>,
    links: HashMap<String, NodeId>,
}

impl<'input> Document<'input> {
    /// Returns the root node.
    #[inline]
    pub fn root<'a>(&'a self) -> Node<'a, 'input> {
        Node {
            id: NodeId::new(0),
            d: &self.nodes[0],
            doc: self,
        }
    }

    /// Returns the root element.
    #[inline]
    pub fn root_element<'a>(&'a self) -> Node<'a, 'input> {
        // `unwrap` is safe, because `Document` is guarantee to have at least one element.
        self.root().first_element_child().unwrap()
    }

    /// Returns an iterator over document's descendant nodes.
    ///
    /// Shorthand for `doc.root().descendants()`.
    #[inline]
    pub fn descendants<'a>(&'a self) -> Descendants<'a, 'input> {
        self.root().descendants()
    }

    /// Returns an element by ID.
    ///
    /// Unlike the [`Descendants`] iterator, this is just a HashMap lookup.
    /// Meaning it's way faster.
    #[inline]
    pub fn element_by_id<'a>(&'a self, id: &str) -> Option<Node<'a, 'input>> {
        let node_id = self.links.get(id)?;
        Some(self.get(*node_id))
    }

    #[inline]
    fn get<'a>(&'a self, id: NodeId) -> Node<'a, 'input> {
        Node {
            id,
            d: &self.nodes[id.get_usize()],
            doc: self,
        }
    }
}

impl std::fmt::Debug for Document<'_> {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
        if !self.root().has_children() {
            return write!(f, "Document []");
        }

        macro_rules! writeln_indented {
            ($depth:expr, $f:expr, $fmt:expr) => {
                for _ in 0..$depth { write!($f, "    ")?; }
                writeln!($f, $fmt)?;
            };
            ($depth:expr, $f:expr, $fmt:expr, $($arg:tt)*) => {
                for _ in 0..$depth { write!($f, "    ")?; }
                writeln!($f, $fmt, $($arg)*)?;
            };
        }

        fn print_children(
            parent: Node,
            depth: usize,
            f: &mut std::fmt::Formatter,
        ) -> Result<(), std::fmt::Error> {
            for child in parent.children() {
                if child.is_element() {
                    writeln_indented!(depth, f, "Element {{");
                    writeln_indented!(depth, f, "    tag_name: {:?}", child.tag_name());

                    if !child.attributes().is_empty() {
                        writeln_indented!(depth + 1, f, "attributes: [");
                        for attr in child.attributes() {
                            writeln_indented!(depth + 2, f, "{:?}", attr);
                        }
                        writeln_indented!(depth + 1, f, "]");
                    }

                    if child.has_children() {
                        writeln_indented!(depth, f, "    children: [");
                        print_children(child, depth + 2, f)?;
                        writeln_indented!(depth, f, "    ]");
                    }

                    writeln_indented!(depth, f, "}}");
                } else {
                    writeln_indented!(depth, f, "{:?}", child);
                }
            }

            Ok(())
        }

        writeln!(f, "Document [")?;
        print_children(self.root(), 1, f)?;
        writeln!(f, "]")?;

        Ok(())
    }
}

#[derive(Clone, Copy, Debug)]
struct ShortRange {
    start: u32,
    end: u32,
}

impl ShortRange {
    #[inline]
    fn new(start: u32, end: u32) -> Self {
        ShortRange { start, end }
    }

    #[inline]
    fn to_urange(self) -> std::ops::Range<usize> {
        self.start as usize..self.end as usize
    }
}

#[derive(Clone, Copy, PartialEq, Debug)]
struct NodeId(NonZeroU32);

impl NodeId {
    #[inline]
    fn new(id: u32) -> Self {
        debug_assert!(id < core::u32::MAX);

        // We are using `NonZeroU32` to reduce overhead of `Option<NodeId>`.
        NodeId(NonZeroU32::new(id + 1).unwrap())
    }

    #[inline]
    fn get(self) -> u32 {
        self.0.get() - 1
    }

    #[inline]
    fn get_usize(self) -> usize {
        self.get() as usize
    }
}

impl From<usize> for NodeId {
    #[inline]
    fn from(id: usize) -> Self {
        // We already checked that `id` is limited by u32::MAX.
        debug_assert!(id <= core::u32::MAX as usize);
        NodeId::new(id as u32)
    }
}

enum NodeKind {
    Root,
    Element {
        tag_name: ElementId,
        attributes: ShortRange,
    },
    Text(String),
}

struct NodeData {
    parent: Option<NodeId>,
    next_sibling: Option<NodeId>,
    children: Option<(NodeId, NodeId)>,
    kind: NodeKind,
}

/// An attribute.
#[derive(Clone)]
pub struct Attribute<'input> {
    /// Attribute's name.
    pub name: AttributeId,
    /// Attribute's value.
    pub value: roxmltree::StringStorage<'input>,
}

impl std::fmt::Debug for Attribute<'_> {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
        write!(
            f,
            "Attribute {{ name: {:?}, value: {} }}",
            self.name, self.value
        )
    }
}

/// An SVG node.
#[derive(Clone, Copy)]
pub struct Node<'a, 'input: 'a> {
    id: NodeId,
    doc: &'a Document<'input>,
    d: &'a NodeData,
}

impl Eq for Node<'_, '_> {}

impl PartialEq for Node<'_, '_> {
    #[inline]
    fn eq(&self, other: &Self) -> bool {
        self.id == other.id && std::ptr::eq(self.doc, other.doc) && std::ptr::eq(self.d, other.d)
    }
}

impl<'a, 'input: 'a> Node<'a, 'input> {
    #[inline]
    fn id(&self) -> NodeId {
        self.id
    }

    /// Checks if the current node is an element.
    #[inline]
    pub fn is_element(&self) -> bool {
        matches!(self.d.kind, NodeKind::Element { .. })
    }

    /// Checks if the current node is a text.
    #[inline]
    pub fn is_text(&self) -> bool {
        matches!(self.d.kind, NodeKind::Text(_))
    }

    /// Returns node's document.
    #[inline]
    pub fn document(&self) -> &'a Document<'input> {
        self.doc
    }

    /// Returns element's tag name, unless the current node is text.
    #[inline]
    pub fn tag_name(&self) -> Option<ElementId> {
        match self.d.kind {
            NodeKind::Element { tag_name, .. } => Some(tag_name),
            _ => None,
        }
    }
    /// Returns element's `id` attribute value.
    ///
    /// Returns an empty string otherwise.
    #[inline]
    pub fn element_id(&self) -> &'a str {
        self.attribute(AttributeId::Id).unwrap_or("")
    }

    /// Returns an attribute value.
    #[inline]
    pub fn attribute(&self, aid: AttributeId) -> Option<&'a str> {
        self.attributes()
            .iter()
            .find(|a| a.name == aid)
            .map(|a| a.value.as_str())
    }

    #[inline]
    fn node_attribute(&self, aid: AttributeId) -> Option<Node<'a, 'input>> {
        let value = self.attribute(aid)?;
        let id = if aid == AttributeId::Href {
            svgtypes::IRI::from_str(value).ok().map(|v| v.0)
        } else {
            svgtypes::FuncIRI::from_str(value).ok().map(|v| v.0)
        }?;

        self.document().element_by_id(id)
    }

    /// Checks if an attribute is present.
    #[inline]
    pub fn has_attribute(&self, aid: AttributeId) -> bool {
        self.attributes().iter().any(|a| a.name == aid)
    }

    /// Returns a list of all element's attributes.
    #[inline]
    pub fn attributes(&self) -> &'a [Attribute<'input>] {
        match self.d.kind {
            NodeKind::Element { ref attributes, .. } => &self.doc.attrs[attributes.to_urange()],
            _ => &[],
        }
    }

    #[inline]
    fn attribute_id(&self, aid: AttributeId) -> Option<usize> {
        match self.d.kind {
            NodeKind::Element { ref attributes, .. } => {
                let idx = self.attributes().iter().position(|attr| attr.name == aid)?;
                Some(attributes.start as usize + idx)
            }
            _ => None,
        }
    }

    /// Finds a [`Node`] that contains the required attribute.
    ///
    /// For inheritable attributes walks over ancestors until a node with
    /// the specified attribute is found.
    ///
    /// For non-inheritable attributes checks only the current node and the parent one.
    /// As per SVG spec.
    #[inline]
    pub fn find_attribute(&self, aid: AttributeId) -> Option<Node<'a, 'input>> {
        if aid.is_inheritable() {
            for n in self.ancestors() {
                if n.has_attribute(aid) {
                    return Some(n);
                }
            }

            None
        } else {
            if self.has_attribute(aid) {
                Some(*self)
            } else {
                // Non-inheritable attributes can inherit a value only from a direct parent.
                let n = self.parent_element()?;
                if n.has_attribute(aid) {
                    Some(n)
                } else {
                    None
                }
            }
        }
    }

    /// Returns node's text data.
    ///
    /// For text nodes returns its content. For elements returns the first child node text.
    #[inline]
    pub fn text(&self) -> &'a str {
        match self.d.kind {
            NodeKind::Element { .. } => match self.first_child() {
                Some(child) if child.is_text() => match self.doc.nodes[child.id.get_usize()].kind {
                    NodeKind::Text(ref text) => text,
                    _ => "",
                },
                _ => "",
            },
            NodeKind::Text(ref text) => text,
            _ => "",
        }
    }

    /// Returns a parent node.
    #[inline]
    pub fn parent(&self) -> Option<Self> {
        self.d.parent.map(|id| self.doc.get(id))
    }

    /// Returns the parent element.
    #[inline]
    pub fn parent_element(&self) -> Option<Self> {
        self.ancestors().skip(1).find(|n| n.is_element())
    }

    /// Returns the next sibling.
    #[inline]
    pub fn next_sibling(&self) -> Option<Self> {
        self.d.next_sibling.map(|id| self.doc.get(id))
    }

    /// Returns the first child.
    #[inline]
    pub fn first_child(&self) -> Option<Self> {
        self.d.children.map(|(id, _)| self.doc.get(id))
    }

    /// Returns the first child element.
    #[inline]
    pub fn first_element_child(&self) -> Option<Self> {
        self.children().find(|n| n.is_element())
    }

    /// Returns the last child.
    #[inline]
    pub fn last_child(&self) -> Option<Self> {
        self.d.children.map(|(_, id)| self.doc.get(id))
    }

    /// Checks if the node has child nodes.
    #[inline]
    pub fn has_children(&self) -> bool {
        self.d.children.is_some()
    }

    /// Returns an iterator over ancestor nodes starting at this node.
    #[inline]
    pub fn ancestors(&self) -> Ancestors<'a, 'input> {
        Ancestors(Some(*self))
    }

    /// Returns an iterator over children nodes.
    #[inline]
    pub fn children(&self) -> Children<'a, 'input> {
        Children {
            front: self.first_child(),
            back: self.last_child(),
        }
    }

    /// Returns an iterator which traverses the subtree starting at this node.
    #[inline]
    fn traverse(&self) -> Traverse<'a, 'input> {
        Traverse {
            root: *self,
            edge: None,
        }
    }

    /// Returns an iterator over this node and its descendants.
    #[inline]
    pub fn descendants(&self) -> Descendants<'a, 'input> {
        Descendants(self.traverse())
    }

    /// Returns an iterator over elements linked via `xlink:href`.
    #[inline]
    pub fn href_iter(&self) -> HrefIter<'a, 'input> {
        HrefIter {
            doc: self.document(),
            origin: self.id(),
            curr: self.id(),
            is_first: true,
            is_finished: false,
        }
    }
}

impl std::fmt::Debug for Node<'_, '_> {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
        match self.d.kind {
            NodeKind::Root => write!(f, "Root"),
            NodeKind::Element { .. } => {
                write!(
                    f,
                    "Element {{ tag_name: {:?}, attributes: {:?} }}",
                    self.tag_name(),
                    self.attributes()
                )
            }
            NodeKind::Text(ref text) => write!(f, "Text({:?})", text),
        }
    }
}

/// An iterator over ancestor nodes.
#[derive(Clone, Debug)]
pub struct Ancestors<'a, 'input: 'a>(Option<Node<'a, 'input>>);

impl<'a, 'input: 'a> Iterator for Ancestors<'a, 'input> {
    type Item = Node<'a, 'input>;

    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        let node = self.0.take();
        self.0 = node.as_ref().and_then(Node::parent);
        node
    }
}

/// An iterator over children nodes.
#[derive(Clone, Debug)]
pub struct Children<'a, 'input: 'a> {
    front: Option<Node<'a, 'input>>,
    back: Option<Node<'a, 'input>>,
}

impl<'a, 'input: 'a> Iterator for Children<'a, 'input> {
    type Item = Node<'a, 'input>;

    fn next(&mut self) -> Option<Self::Item> {
        let node = self.front.take();
        if self.front == self.back {
            self.back = None;
        } else {
            self.front = node.as_ref().and_then(Node::next_sibling);
        }
        node
    }
}

#[derive(Clone, Copy, PartialEq, Debug)]
enum Edge<'a, 'input: 'a> {
    Open(Node<'a, 'input>),
    Close(Node<'a, 'input>),
}

#[derive(Clone, Debug)]
struct Traverse<'a, 'input: 'a> {
    root: Node<'a, 'input>,
    edge: Option<Edge<'a, 'input>>,
}

impl<'a, 'input: 'a> Iterator for Traverse<'a, 'input> {
    type Item = Edge<'a, 'input>;

    fn next(&mut self) -> Option<Self::Item> {
        match self.edge {
            Some(Edge::Open(node)) => {
                self.edge = Some(match node.first_child() {
                    Some(first_child) => Edge::Open(first_child),
                    None => Edge::Close(node),
                });
            }
            Some(Edge::Close(node)) => {
                if node == self.root {
                    self.edge = None;
                } else if let Some(next_sibling) = node.next_sibling() {
                    self.edge = Some(Edge::Open(next_sibling));
                } else {
                    self.edge = node.parent().map(Edge::Close);
                }
            }
            None => {
                self.edge = Some(Edge::Open(self.root));
            }
        }

        self.edge
    }
}

/// A descendants iterator.
#[derive(Clone, Debug)]
pub struct Descendants<'a, 'input: 'a>(Traverse<'a, 'input>);

impl<'a, 'input: 'a> Iterator for Descendants<'a, 'input> {
    type Item = Node<'a, 'input>;

    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        for edge in &mut self.0 {
            if let Edge::Open(node) = edge {
                return Some(node);
            }
        }

        None
    }
}

/// An iterator over `xlink:href` references.
#[derive(Clone, Debug)]
pub struct HrefIter<'a, 'input: 'a> {
    doc: &'a Document<'input>,
    origin: NodeId,
    curr: NodeId,
    is_first: bool,
    is_finished: bool,
}

impl<'a, 'input: 'a> Iterator for HrefIter<'a, 'input> {
    type Item = Node<'a, 'input>;

    fn next(&mut self) -> Option<Self::Item> {
        if self.is_finished {
            return None;
        }

        if self.is_first {
            self.is_first = false;
            return Some(self.doc.get(self.curr));
        }

        if let Some(link) = self.doc.get(self.curr).node_attribute(AttributeId::Href) {
            if link.id() == self.curr || link.id() == self.origin {
                log::warn!(
                    "Element '#{}' cannot reference itself via 'xlink:href'.",
                    self.doc.get(self.origin).element_id()
                );
                self.is_finished = true;
                return None;
            }

            self.curr = link.id();
            Some(self.doc.get(self.curr))
        } else {
            None
        }
    }
}

impl ElementId {
    /// Checks if this is a
    /// [graphics element](https://www.w3.org/TR/SVG11/intro.html#TermGraphicsElement).
    pub fn is_graphic(&self) -> bool {
        matches!(
            self,
            ElementId::Circle
                | ElementId::Ellipse
                | ElementId::Image
                | ElementId::Line
                | ElementId::Path
                | ElementId::Polygon
                | ElementId::Polyline
                | ElementId::Rect
                | ElementId::Text
                | ElementId::Use
        )
    }

    /// Checks if this is a
    /// [gradient element](https://www.w3.org/TR/SVG11/intro.html#TermGradientElement).
    pub fn is_gradient(&self) -> bool {
        matches!(self, ElementId::LinearGradient | ElementId::RadialGradient)
    }

    /// Checks if this is a
    /// [paint server element](https://www.w3.org/TR/SVG11/intro.html#TermPaint).
    pub fn is_paint_server(&self) -> bool {
        matches!(
            self,
            ElementId::LinearGradient | ElementId::RadialGradient | ElementId::Pattern
        )
    }
}

impl AttributeId {
    fn is_presentation(&self) -> bool {
        matches!(
            self,
            AttributeId::AlignmentBaseline
                | AttributeId::BaselineShift
                | AttributeId::ClipPath
                | AttributeId::ClipRule
                | AttributeId::Color
                | AttributeId::ColorInterpolation
                | AttributeId::ColorInterpolationFilters
                | AttributeId::ColorRendering
                | AttributeId::Direction
                | AttributeId::Display
                | AttributeId::DominantBaseline
                | AttributeId::Fill
                | AttributeId::FillOpacity
                | AttributeId::FillRule
                | AttributeId::Filter
                | AttributeId::FloodColor
                | AttributeId::FloodOpacity
                | AttributeId::FontFamily
                | AttributeId::FontKerning // technically not presentation
                | AttributeId::FontSize
                | AttributeId::FontSizeAdjust
                | AttributeId::FontStretch
                | AttributeId::FontStyle
                | AttributeId::FontVariant
                | AttributeId::FontWeight
                | AttributeId::GlyphOrientationHorizontal
                | AttributeId::GlyphOrientationVertical
                | AttributeId::ImageRendering
                | AttributeId::Isolation // technically not presentation
                | AttributeId::LetterSpacing
                | AttributeId::LightingColor
                | AttributeId::MarkerEnd
                | AttributeId::MarkerMid
                | AttributeId::MarkerStart
                | AttributeId::Mask
                | AttributeId::MixBlendMode // technically not presentation
                | AttributeId::Opacity
                | AttributeId::Overflow
                | AttributeId::PaintOrder
                | AttributeId::ShapeRendering
                | AttributeId::StopColor
                | AttributeId::StopOpacity
                | AttributeId::Stroke
                | AttributeId::StrokeDasharray
                | AttributeId::StrokeDashoffset
                | AttributeId::StrokeLinecap
                | AttributeId::StrokeLinejoin
                | AttributeId::StrokeMiterlimit
                | AttributeId::StrokeOpacity
                | AttributeId::StrokeWidth
                | AttributeId::TextAnchor
                | AttributeId::TextDecoration
                | AttributeId::TextOverflow
                | AttributeId::TextRendering
                | AttributeId::Transform
                | AttributeId::UnicodeBidi
                | AttributeId::VectorEffect
                | AttributeId::Visibility
                | AttributeId::WhiteSpace
                | AttributeId::WordSpacing
                | AttributeId::WritingMode
        )
    }

    /// Checks if the current attribute is inheritable.
    fn is_inheritable(&self) -> bool {
        if self.is_presentation() {
            !is_non_inheritable(*self)
        } else {
            false
        }
    }

    fn allows_inherit_value(&self) -> bool {
        matches!(
            self,
            AttributeId::AlignmentBaseline
                | AttributeId::BaselineShift
                | AttributeId::ClipPath
                | AttributeId::ClipRule
                | AttributeId::Color
                | AttributeId::ColorInterpolationFilters
                | AttributeId::Direction
                | AttributeId::Display
                | AttributeId::DominantBaseline
                | AttributeId::Fill
                | AttributeId::FillOpacity
                | AttributeId::FillRule
                | AttributeId::Filter
                | AttributeId::FloodColor
                | AttributeId::FloodOpacity
                | AttributeId::FontFamily
                | AttributeId::FontKerning
                | AttributeId::FontSize
                | AttributeId::FontStretch
                | AttributeId::FontStyle
                | AttributeId::FontVariant
                | AttributeId::FontWeight
                | AttributeId::ImageRendering
                | AttributeId::Kerning
                | AttributeId::LetterSpacing
                | AttributeId::MarkerEnd
                | AttributeId::MarkerMid
                | AttributeId::MarkerStart
                | AttributeId::Mask
                | AttributeId::Opacity
                | AttributeId::Overflow
                | AttributeId::ShapeRendering
                | AttributeId::StopColor
                | AttributeId::StopOpacity
                | AttributeId::Stroke
                | AttributeId::StrokeDasharray
                | AttributeId::StrokeDashoffset
                | AttributeId::StrokeLinecap
                | AttributeId::StrokeLinejoin
                | AttributeId::StrokeMiterlimit
                | AttributeId::StrokeOpacity
                | AttributeId::StrokeWidth
                | AttributeId::TextAnchor
                | AttributeId::TextDecoration
                | AttributeId::TextRendering
                | AttributeId::Visibility
                | AttributeId::WordSpacing
                | AttributeId::WritingMode
        )
    }
}

fn is_non_inheritable(id: AttributeId) -> bool {
    matches!(
        id,
        AttributeId::AlignmentBaseline
            | AttributeId::BaselineShift
            | AttributeId::ClipPath
            | AttributeId::Display
            | AttributeId::DominantBaseline
            | AttributeId::Filter
            | AttributeId::FloodColor
            | AttributeId::FloodOpacity
            | AttributeId::Mask
            | AttributeId::Opacity
            | AttributeId::Overflow
            | AttributeId::LightingColor
            | AttributeId::StopColor
            | AttributeId::StopOpacity
            | AttributeId::TextDecoration
            | AttributeId::Transform
    )
}