HTML Selector

An HTML content extraction tool similar to CSS selectors that can precisely extract and process the required content from HTML documents through a simple and intuitive query language.

Example

use query::Query;

fn main() {
    let html = r#"
    <div class="a">
        <p>text 1</p>
        <p>text 2</p>
        <p>text 3</p>
    </div>
    <div class="b">
        <p>text 4</p>
        <p>text 5</p>
        <p>text 6</p>
    </div>
    "#;
    let q = Query::new(html);
    let result = q.query(r#"(class a > tag p:1:2 | class b > tag p:0) > text @replace," ","""#).texts();
    println!("{:?}", result); // ["text2", "text3", "text4"]
}

Basic Selectors

Selector	Syntax	Description
Class Selector	`class className`	Select elements with the specified class name
ID Selector	`id IDValue`	Select elements with the specified ID
Tag Selector	`tag tagName`	Select elements with the specified HTML tag
Attribute Selector	`attr "attributeName"`	Select elements with the specified attribute
Attribute Value Selector	`attr "attributeName" "value"`	Select elements with the attribute matching the specified value

Text Extraction

Operation	Syntax	Description
Text Content	`text`	Extract the text content of elements
Link Address	`href`	Extract the href attribute value of elements
Image Address	`src`	Extract the src attribute value of elements

Pipeline Operations

The pipeline operator > is used to connect multiple selectors for layer-by-layer querying:

class main > tag p > text

This query first selects elements with the class "main", then finds p tags within them, and finally extracts the text content of these p tags.

Regular Expression Matching

Using the tilde ~ allows for regular expression matching:

class ~".*ain" > tag p > text

This query selects elements with class names matching the regular expression .*ain, for example, it can match "main", "again", etc.

Index Selection

You can add an index after the selector to select elements at specific positions:

Index Syntax	Example	Description
Single Index	`class a:1`	Select the 2nd element (index starts from 0)
Range Index	`class a:1:3`	Select elements with indices from 1 to 3
Range with Step	`class a:1:10:2`	Select elements with indices from 1 to 10 with a step of 2
Multiple Indices	`class a:1,3,5`	Select elements with indices 1, 3, and 5

Text Processing Functions

Using the @ symbol can invoke built-in text processing functions:

Function	Syntax	Description
trim	`text @trim`	Remove whitespace from both ends of the text
replace	`text @replace,A,B`	Replace A with B in the text
format	`text @format,"{}value"`	Format the text with the specified template
join	`text @join,","`	Join multiple texts with the specified separator
lowercase	`text @lowercase`	Convert text to lowercase
uppercase	`text @uppercase`	Convert text to uppercase
contains	`text @contains,A`	Get the string containing a certain substring
starts_with	`text @starts_with,A`	Get the string whose beginning contains a certain substring
starts_with	`text @ends_with,A`	Get the string whose ending contains a certain substring

Multiple functions can be chained:

class main > text @trim @replace,A,a @lowercase

Set Operations

Operator	Example	Description
\|	`expr1 \| expr2`	Union, merge two selection results
&	`expr1 & expr2`	Intersection, get common elements from two results
^	`expr1 ^ expr2`	Difference, exclude elements of expr2 from expr1

Complex set operations can be grouped with parentheses:

(((class a ^ class c) | class b) > tag a | class main > tag a) > text @trim

htmls 0.1.4