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use std::convert::TryFrom;
use std::fmt::{self, Debug, Formatter};
use std::hash::Hash;
use std::mem;
use std::ops::{Add, AddAssign};
use crate::diag::StrResult;
use crate::geom::SpecAxis;
use crate::layout::{Layout, PackedNode};
use crate::library::{
Decoration, DocumentNode, FlowChild, FlowNode, PageNode, ParChild, ParNode, Spacing,
TextNode,
};
use crate::util::EcoString;
/// A partial representation of a layout node.
///
/// A node is a composable intermediate representation that can be converted
/// into a proper layout node by lifting it to the block or page level.
#[derive(Clone)]
pub enum Node {
/// A word space.
Space,
/// A line break.
Linebreak,
/// A paragraph break.
Parbreak,
/// A page break.
Pagebreak,
/// Plain text.
Text(EcoString),
/// Spacing.
Spacing(SpecAxis, Spacing),
/// An inline node.
Inline(PackedNode),
/// A block node.
Block(PackedNode),
/// A sequence of nodes (which may themselves contain sequences).
Seq(Vec<Self>),
}
impl Node {
/// Create an empty node.
pub fn new() -> Self {
Self::Seq(vec![])
}
/// Create an inline-level node.
pub fn inline<T>(node: T) -> Self
where
T: Layout + Debug + Hash + 'static,
{
Self::Inline(node.pack())
}
/// Create a block-level node.
pub fn block<T>(node: T) -> Self
where
T: Layout + Debug + Hash + 'static,
{
Self::Block(node.pack())
}
/// Decoration this node.
pub fn decorate(self, _: Decoration) -> Self {
// TODO(set): Actually decorate.
self
}
/// Lift to a type-erased block-level node.
pub fn into_block(self) -> PackedNode {
if let Node::Block(packed) = self {
packed
} else {
let mut packer = NodePacker::new();
packer.walk(self);
packer.into_block()
}
}
/// Lift to a document node, the root of the layout tree.
pub fn into_document(self) -> DocumentNode {
let mut packer = NodePacker::new();
packer.walk(self);
packer.into_document()
}
/// Repeat this template `n` times.
pub fn repeat(&self, n: i64) -> StrResult<Self> {
let count = usize::try_from(n)
.map_err(|_| format!("cannot repeat this template {} times", n))?;
// TODO(set): Make more efficient.
Ok(Self::Seq(vec![self.clone(); count]))
}
}
impl Debug for Node {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.pad("<node>")
}
}
impl Default for Node {
fn default() -> Self {
Self::new()
}
}
impl PartialEq for Node {
fn eq(&self, _: &Self) -> bool {
// TODO(set): Figure out what to do here.
false
}
}
impl Add for Node {
type Output = Self;
fn add(self, rhs: Self) -> Self::Output {
// TODO(set): Make more efficient.
Self::Seq(vec![self, rhs])
}
}
impl AddAssign for Node {
fn add_assign(&mut self, rhs: Self) {
*self = mem::take(self) + rhs;
}
}
/// Packs a `Node` into a flow or whole document.
struct NodePacker {
document: Vec<PageNode>,
flow: Vec<FlowChild>,
par: Vec<ParChild>,
}
impl NodePacker {
fn new() -> Self {
Self {
document: vec![],
flow: vec![],
par: vec![],
}
}
fn into_block(mut self) -> PackedNode {
self.parbreak();
FlowNode(self.flow).pack()
}
fn into_document(mut self) -> DocumentNode {
self.parbreak();
self.pagebreak();
DocumentNode(self.document)
}
fn walk(&mut self, node: Node) {
match node {
Node::Space => {
self.push_inline(ParChild::Text(TextNode(' '.into())));
}
Node::Linebreak => {
self.push_inline(ParChild::Text(TextNode('\n'.into())));
}
Node::Parbreak => {
self.parbreak();
}
Node::Pagebreak => {
self.pagebreak();
}
Node::Text(text) => {
self.push_inline(ParChild::Text(TextNode(text)));
}
Node::Spacing(axis, amount) => match axis {
SpecAxis::Horizontal => self.push_inline(ParChild::Spacing(amount)),
SpecAxis::Vertical => self.push_block(FlowChild::Spacing(amount)),
},
Node::Inline(inline) => {
self.push_inline(ParChild::Node(inline));
}
Node::Block(block) => {
self.push_block(FlowChild::Node(block));
}
Node::Seq(list) => {
for node in list {
self.walk(node);
}
}
}
}
fn parbreak(&mut self) {
let children = mem::take(&mut self.par);
if !children.is_empty() {
self.flow.push(FlowChild::Node(ParNode(children).pack()));
}
}
fn pagebreak(&mut self) {
let children = mem::take(&mut self.flow);
self.document.push(PageNode(FlowNode(children).pack()));
}
fn push_inline(&mut self, child: ParChild) {
self.par.push(child);
}
fn push_block(&mut self, child: FlowChild) {
self.parbreak();
self.flow.push(child);
}
}
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