html_extractor!() { /* proc-macro */ }Expand description
Generates structures that implement HtmlExtractor.
§Syntax
§Defining structures
In this macro, zero or more structures can be defined.
Attributes can be attached to the structures, but currently attributes that may remove the structures (like #[cfg]) will not work.
html_extractor! {
//private structure
Foo {
//fields...
}
//any visibilities and some attributes can be used
#[derive(Debug, Clone)]
pub(crate) Bar {
//fields...
}
}§Defining fields in structures
There are two types of fields, “single field” and “tuple field”. Tuple fields are used to capture data with regex.
Each field definition has a declaration part and an extractor part.
Attributes can be attached to the fields, but currently attributes that may remove the fields (like #[cfg]) will not work.
html_extractor! {
Foo {
//single field
pub foo: usize = (text of "#foo"),
//^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^
// declaration extractor
//tuple field
(pub bar: usize, pub baz: usize) = (text of "#bar-baz", capture with "bar=(.*),baz=(.*)"),
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// declaration extractor
}
}§Extractor part of field definitions
The extractor part of field definitions specifies how to extract data from HTML. Extractor consists of Target, Capture, Collector and Parser specifier.
The order of specifiers does not matter. If the same specifier is written multiple times, the one given later applies.
§Target specifier
Target specifier specifies a selector to select an element (or elements) and what of the selected element is extracted.
If the specified selector is invalid, it will be a compile error.
If text of .. or attr[..] of .. is used, the type of field must implement FromStr.
If elem of .. is used, the type of field must implement HtmlExtractor.
If text of .. is used, leading and trailing whitespace removed from the extracted string.
If presence of .. is used, the type must be bool and any other specifier cannot be used,
use html_extractor::{html_extractor, HtmlExtractor};
html_extractor! {
#[derive(Debug, PartialEq)]
Foo {
// extracts the first text node in the element that first matched the selector "#foo"
foo: usize = (text of "#foo"),
// extracts the third text node in the element that first matched the selector "#bar"
bar: usize = (text[2] of "#bar"),
// extracts attribute "data-baz" in the element that first matched the selector "#baz"
baz: usize = (attr["data-baz"] of "#baz"),
// extracts an element that first matched the selector "#qux" and parse it with `HtmlExtractor::extract()`
qux: Qux = (elem of "#qux"),
// extracts inner HTML of the element that first matched the selector "#grault",
grault: String = (inner_html of "#grault"),
// stores if the elements that matches the selector "#garply" exist.
garply: bool = (presence of "#garply"),
}
#[derive(Debug, PartialEq)]
Qux {
corge: usize = (text of "#corge"),
}
}
fn main() {
let input = r#"
<div id="foo">1</div>
<div id="bar">ignore first<br>ignore second<br>2</div>
<div id="baz" data-baz="3"></div>
<div id="qux">
<div id="corge">4</div>
</div>
<div id="grault">
inner<br>html
</div>
"#;
let foo = Foo::extract_from_str(input).unwrap();
assert_eq!(foo, Foo {
foo: 1,
bar: 2,
baz: 3,
qux: Qux { corge: 4 },
grault: "inner<br>html".to_owned(),
garply: false,
});
}§Capture specifier
Capture specifier specifies an regex that is used to capture desired data from the string that is extracted with target specifier.
The number of captures and the number of tuple elements must be the same.
If the specified regex is invalid, it will be a compile error.
It cannot be used with target specifier elem of ...
If it is used without collect specifier, the field must be a tuple field.
If it is used with collect specifier, the type of the field must be FromIterator of tuple.
use html_extractor::{html_extractor, HtmlExtractor};
html_extractor! {
#[derive(Debug, PartialEq)]
Foo {
// extracts a string from the first text node in the element that matches the selector "#foo-bar",
// and captures two data from the string with the regex "foo=(.*), bar=(.*)"
(foo: usize, bar: usize) = (text of "#foo-bar", capture with "foo=(.*), bar=(.*)"),
// extracts strings from the first text node in all elements that matches the selector ".baz-qux-corge",
// captures three data from each string with the regex "baz=(.*), qux=(.*), corge=(.*)" ,
// and collects into `Vec<(usize, usize, usize)>`
baz_qux_corge: Vec<(usize, usize, usize)> = (text of ".baz-qux-corge", capture with "baz=(.*), qux=(.*), corge=(.*)", collect),
}
}
fn main() {
let input = r#"
<div id="foo-bar">foo=1, bar=2</div>
<div class="baz-qux-corge">baz=1, qux=2, corge=3</div>
<div class="baz-qux-corge">baz=4, qux=5, corge=6</div>
<div class="baz-qux-corge">baz=7, qux=8, corge=9</div>
<div class="baz-qux-corge">baz=10, qux=11, corge=12</div>
"#;
let foo = Foo::extract_from_str(input).unwrap();
assert_eq!(foo, Foo {
foo: 1,
bar: 2,
baz_qux_corge: vec![(1, 2, 3), (4, 5, 6), (7, 8, 9), (10, 11, 12)],
});
}§Collector specifier
Collector specifier specifies how to collect HTML elements.
The default collector is “first”, which collects only the first matched element.
The “collect” collector collects all the element into the type that implements FromIterator.
The “optional” collector collects the first element if it exists. If not, it emits None.
use html_extractor::{html_extractor, HtmlExtractor};
html_extractor! {
#[derive(Debug, PartialEq)]
Foo {
// extracts the first text node from each element that matches the selector ".foo", and collect them into `Vec<usize>`.
foo: Vec<usize> = (text of ".foo", collect),
// extracts all the elements that match that selector "#bar",
// parses them with `HtmlExtractor::extract()`,
// and collects into `Vec<Bar>`.
bar: Vec<Bar> = (elem of "#bar", collect),
// extracts strings from the first text node in all elements that matches the selector ".baz-qux-corge",
// captures three data from each string with the regex "baz=(.*), qux=(.*), corge=(.*)" ,
// and collects into `Vec<(usize, usize, usize)>`
baz_qux_corge: Vec<(usize, usize, usize)> = (text of ".baz-qux-corge", capture with "baz=(.*), qux=(.*), corge=(.*)", collect),
// optionally extracts the first text node in the first element that matches the selector ".grault".
grault: Option<usize> = (text of ".grault", optional),
}
#[derive(Debug, PartialEq)]
Bar {
bar: usize = (text of ".bar-data"),
}
}
fn main() {
let input = r#"
<div class="foo">1</div>
<div class="foo">2</div>
<div class="foo">3</div>
<div class="foo">4</div>
<div id="bar"><div class="bar-data">1</div></div>
<div id="bar"><div class="bar-data">2</div></div>
<div id="bar"><div class="bar-data">3</div></div>
<div id="bar"><div class="bar-data">4</div></div>
<div class="baz-qux-corge">baz=1, qux=2, corge=3</div>
<div class="baz-qux-corge">baz=4, qux=5, corge=6</div>
<div class="baz-qux-corge">baz=7, qux=8, corge=9</div>
<div class="baz-qux-corge">baz=10, qux=11, corge=12</div>
"#;
let foo = Foo::extract_from_str(input).unwrap();
assert_eq!(foo, Foo {
foo: vec![1, 2, 3, 4],
bar: vec![
Bar { bar: 1 },
Bar { bar: 2 },
Bar { bar: 3 },
Bar { bar: 4 },
],
baz_qux_corge: vec![(1, 2, 3), (4, 5, 6), (7, 8, 9), (10, 11, 12)],
grault: None,
});
}§Parser specifier
Parser specifier specifies the parser used to parse the extracted string.
The default parser is ::std::str::FromStr::from_str.
The parser must be Fn(&str) -> Result<_, T> where T: std::fmt::Debug
use html_extractor::{html_extractor, HtmlExtractor};
html_extractor! {
#[derive(Debug, PartialEq)]
Foo {
// extracts using a custom parser.
foo: usize = (text of "#foo", parse with custom_parser),
}
}
fn custom_parser(input: &str) -> Result<usize, std::num::ParseIntError> {
input.replace(",", "").parse()
}
fn main() {
let input = r#"
<div id="foo">1,000,000,000</div>
"#;
let foo = Foo::extract_from_str(input).unwrap();
assert_eq!(foo, Foo {
foo: 1000000000,
});
}§Usage of the generated structures
The generated structures implement trait HtmlExtractor.
See the document of the trait.