1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
use std::fmt::Write;
use typst_library::diag::{bail, At, SourceResult, StrResult};
use typst_library::foundations::Repr;
use typst_library::html::{charsets, tag, HtmlDocument, HtmlElement, HtmlNode, HtmlTag};
use typst_library::layout::Frame;
use typst_syntax::Span;
/// Encodes an HTML document into a string.
pub fn html(document: &HtmlDocument) -> SourceResult<String> {
let mut w = Writer { pretty: true, ..Writer::default() };
w.buf.push_str("<!DOCTYPE html>");
write_indent(&mut w);
write_element(&mut w, &document.root)?;
if w.pretty {
w.buf.push('\n');
}
Ok(w.buf)
}
#[derive(Default)]
struct Writer {
/// The output buffer.
buf: String,
/// The current indentation level
level: usize,
/// Whether pretty printing is enabled.
pretty: bool,
}
/// Write a newline and indent, if pretty printing is enabled.
fn write_indent(w: &mut Writer) {
if w.pretty {
w.buf.push('\n');
for _ in 0..w.level {
w.buf.push_str(" ");
}
}
}
/// Encode an HTML node into the writer.
fn write_node(w: &mut Writer, node: &HtmlNode) -> SourceResult<()> {
match node {
HtmlNode::Tag(_) => {}
HtmlNode::Text(text, span) => write_text(w, text, *span)?,
HtmlNode::Element(element) => write_element(w, element)?,
HtmlNode::Frame(frame) => write_frame(w, frame),
}
Ok(())
}
/// Encode plain text into the writer.
fn write_text(w: &mut Writer, text: &str, span: Span) -> SourceResult<()> {
for c in text.chars() {
if charsets::is_valid_in_normal_element_text(c) {
w.buf.push(c);
} else {
write_escape(w, c).at(span)?;
}
}
Ok(())
}
/// Encode one element into the write.
fn write_element(w: &mut Writer, element: &HtmlElement) -> SourceResult<()> {
w.buf.push('<');
w.buf.push_str(&element.tag.resolve());
for (attr, value) in &element.attrs.0 {
w.buf.push(' ');
w.buf.push_str(&attr.resolve());
w.buf.push('=');
w.buf.push('"');
for c in value.chars() {
if charsets::is_valid_in_attribute_value(c) {
w.buf.push(c);
} else {
write_escape(w, c).at(element.span)?;
}
}
w.buf.push('"');
}
w.buf.push('>');
if tag::is_void(element.tag) {
return Ok(());
}
let pretty = w.pretty;
if !element.children.is_empty() {
let pretty_inside = allows_pretty_inside(element.tag)
&& element.children.iter().any(|node| match node {
HtmlNode::Element(child) => wants_pretty_around(child.tag),
_ => false,
});
w.pretty &= pretty_inside;
let mut indent = w.pretty;
w.level += 1;
for c in &element.children {
let pretty_around = match c {
HtmlNode::Tag(_) => continue,
HtmlNode::Element(child) => w.pretty && wants_pretty_around(child.tag),
HtmlNode::Text(..) | HtmlNode::Frame(_) => false,
};
if core::mem::take(&mut indent) || pretty_around {
write_indent(w);
}
write_node(w, c)?;
indent = pretty_around;
}
w.level -= 1;
write_indent(w);
}
w.pretty = pretty;
w.buf.push_str("</");
w.buf.push_str(&element.tag.resolve());
w.buf.push('>');
Ok(())
}
/// Whether we are allowed to add an extra newline at the start and end of the
/// element's contents.
///
/// Technically, users can change CSS `display` properties such that the
/// insertion of whitespace may actually impact the visual output. For example,
/// <https://www.w3.org/TR/css-text-3/#example-af2745cd> shows how adding CSS
/// rules to `<p>` can make it sensitive to whitespace. For this reason, we
/// should also respect the `style` tag in the future.
fn allows_pretty_inside(tag: HtmlTag) -> bool {
(tag::is_block_by_default(tag) && tag != tag::pre)
|| tag::is_tabular_by_default(tag)
|| tag == tag::li
}
/// Whether newlines should be added before and after the element if the parent
/// allows it.
///
/// In contrast to `allows_pretty_inside`, which is purely spec-driven, this is
/// more subjective and depends on preference.
fn wants_pretty_around(tag: HtmlTag) -> bool {
allows_pretty_inside(tag) || tag::is_metadata(tag) || tag == tag::pre
}
/// Escape a character.
fn write_escape(w: &mut Writer, c: char) -> StrResult<()> {
// See <https://html.spec.whatwg.org/multipage/syntax.html#syntax-charref>
match c {
'&' => w.buf.push_str("&"),
'<' => w.buf.push_str("<"),
'>' => w.buf.push_str(">"),
'"' => w.buf.push_str("""),
'\'' => w.buf.push_str("'"),
c if charsets::is_w3c_text_char(c) && c != '\r' => {
write!(w.buf, "&#x{:x};", c as u32).unwrap()
}
_ => bail!("the character {} cannot be encoded in HTML", c.repr()),
}
Ok(())
}
/// Encode a laid out frame into the writer.
fn write_frame(w: &mut Writer, frame: &Frame) {
// FIXME: This string replacement is obviously a hack.
let svg = typst_svg::svg_frame(frame)
.replace("<svg class", "<svg style=\"overflow: visible;\" class");
w.buf.push_str(&svg);
}
|
