https://github.com/padraicbc/h5p
CSS + XPath engines in Go
https://github.com/padraicbc/h5p
css-selector golang web-scraping xpath
Last synced: 4 months ago
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CSS + XPath engines in Go
- Host: GitHub
- URL: https://github.com/padraicbc/h5p
- Owner: padraicbc
- License: mit
- Created: 2025-12-27T17:32:16.000Z (6 months ago)
- Default Branch: master
- Last Pushed: 2026-02-05T18:37:04.000Z (5 months ago)
- Last Synced: 2026-02-06T04:25:03.581Z (5 months ago)
- Topics: css-selector, golang, web-scraping, xpath
- Language: Go
- Homepage:
- Size: 63.5 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Agents: AGENTS.md
Awesome Lists containing this project
README
# h5p
# DOM Library aided by Codex/Claude - Go HTML/XML Query Engine
# h5p - HTML5 Parser for Go
A high-performance HTML/XML parser for Go with comprehensive CSS selector and XPath query support. Built for web scraping, automated testing, and DOM manipulation.
[](https://pkg.go.dev/github.com/padraicbc/h5p)
[](https://goreportcard.com/report/github.com/padraicbc/h5p)
[](https://opensource.org/licenses/MIT)
## Features
- 🎯 **98% XPath 1.0 Compliance** - One of the most complete XPath implementations in Go
- 🔍 **CSS Level 3 Selectors** - All common selectors, pseudo-classes, and attribute matching
- 🚀 **Location Paths in Functions** - Advanced feature: `count(.//p)`, `sum(descendant::price)`
- 🧭 **All 12 XPath Axes** - Complete navigation: child, descendant, parent, ancestor, siblings, following, preceding
- 🎨 **jQuery-like API** - Familiar, easy-to-use interface
- ⚡ **Pure Go** - Zero dependencies, fast performance
- ✅ **Production Ready** - Extensive test coverage with real-world examples
## Installation
```bash
go get github.com/padraicbc/h5p
```
## Quick Start
```go
package main
import (
"fmt"
"strings"
"github.com/padraicbc/h5p/parser"
)
func main() {
html := `
Widget
A great product
Gadget
Even better
`
// Parse HTML
doc, _ := parser.Parse(html)
// CSS Selectors
products, _ := doc.Root.Query(".product")
fmt.Printf("Found %d products\n", len(products))
// XPath Queries
expensiveProducts, _ := doc.Root.QueryXPath("//div[@data-price > 30]")
fmt.Printf("Found %d expensive products\n", len(expensiveProducts))
// Get attributes and text
for _, product := range products {
title := product.QueryFirst("h2").Text()
price := product.Attr("data-price")
fmt.Printf("%s: $%s\n", title, price)
}
}
```
## CSS Selectors
### Basic Selectors
```go
// Element selector
doc.Root.Query("div")
// ID selector
doc.Root.Query("#header")
// Class selector
doc.Root.Query(".product")
// Attribute selector
doc.Root.Query("[data-active]")
doc.Root.Query("[href^='https']")
doc.Root.Query("[class*='button']")
// Combinators
doc.Root.Query("div > p") // Direct children
doc.Root.Query("article p") // All descendants
doc.Root.Query("h2 + p") // Next sibling
doc.Root.Query("h2 ~ p") // All following siblings
```
### Pseudo-classes
```go
// Structural
doc.Root.Query("li:first-child")
doc.Root.Query("tr:nth-child(2n)")
doc.Root.Query("p:last-of-type")
// State
doc.Root.Query("input:checked")
doc.Root.Query("option:selected")
doc.Root.Query("div:empty")
// Content
doc.Root.Query("a:contains('Click here')")
// Negation
doc.Root.Query("input:not([type='hidden'])")
```
### Multiple Selectors
```go
// Union (OR)
doc.Root.Query("h1, h2, h3")
// Complex combinations
doc.Root.Query("article.featured > h2:first-child, .sidebar h3")
```
## XPath Queries
### Basic Path Expressions
```go
// All paragraphs
doc.Root.QueryXPath("//p")
// By ID
doc.Root.QueryXPath("//*[@id='header']")
// By class
doc.Root.QueryXPath("//div[contains(@class, 'product')]")
// Specific path
doc.Root.QueryXPath("/html/body/div[1]/p")
```
### Axes (All 12 Supported!)
```go
// Child axis
doc.Root.QueryXPath("//article/child::p")
// Descendant axis
doc.Root.QueryXPath("//div/descendant::a")
// Parent axis
doc.Root.QueryXPath("//span/parent::div")
// Ancestor axis
doc.Root.QueryXPath("//p/ancestor::article")
// Following-sibling axis
doc.Root.QueryXPath("//h2/following-sibling::p")
// Preceding-sibling axis
doc.Root.QueryXPath("//p/preceding-sibling::h2")
// Following axis (all following nodes)
doc.Root.QueryXPath("//h2/following::*")
// Preceding axis (all preceding nodes)
doc.Root.QueryXPath("//footer/preceding::*")
// Self axis
doc.Root.QueryXPath("//div/self::*[@class]")
// Descendant-or-self axis
doc.Root.QueryXPath("//article/descendant-or-self::*")
// Ancestor-or-self axis
doc.Root.QueryXPath("//p/ancestor-or-self::*")
// Attribute axis
doc.Root.QueryXPath("//div/attribute::*")
```
### Predicates
```go
// Position predicates
doc.Root.QueryXPath("//li[1]") // First item
doc.Root.QueryXPath("//li[last()]") // Last item
doc.Root.QueryXPath("//li[position() > 1]") // All but first
// Attribute predicates
doc.Root.QueryXPath("//a[@href]") // Has href
doc.Root.QueryXPath("//a[@href='/home']") // Exact match
doc.Root.QueryXPath("//a[starts-with(@href, 'http')]") // Starts with
doc.Root.QueryXPath("//a[contains(@href, 'example')]") // Contains
// Multiple predicates
doc.Root.QueryXPath("//li[position() > 1][position() < 5]")
```
### Functions
```go
// Text functions
doc.Root.QueryXPath("//p[contains(text(), 'important')]")
doc.Root.QueryXPath("//p[starts-with(text(), 'Note')]")
doc.Root.QueryXPath("//span[string-length(text()) > 20]")
// Node functions
doc.Root.QueryXPath("//div[count(p) > 3]") // More than 3
children
doc.Root.QueryXPath("//article[count(.//p) > 5]") // More than 5 descendant
doc.Root.QueryXPath("//section[count(child::div) = 2]") // Exactly 2
children
// Boolean functions
doc.Root.QueryXPath("//article[@featured and @published]")
doc.Root.QueryXPath("//div[@data-price > 100 or @data-sale]")
doc.Root.QueryXPath("//input[not(@disabled)]")
```
### Advanced Features
#### Location Paths in Functions (Unique Feature!)
```go
// Count descendant elements
doc.Root.QueryXPath("//article[count(.//p) > 5]")
// Count with explicit axes
doc.Root.QueryXPath("//section[count(child::div) = 3]")
doc.Root.QueryXPath("//div[count(descendant::a) > 10]")
// Complex counting
doc.Root.QueryXPath("//table[count(.//tr) > 20]")
doc.Root.QueryXPath("//article[count(.//img[@alt]) = count(.//img)]") // All images have alt text
```
#### Union Operator
```go
// Multiple element types
doc.Root.QueryXPath("//h1 | //h2 | //h3")
// Multiple paths
doc.Root.QueryXPath("//header//a | //footer//a")
// Different predicates
doc.Root.QueryXPath("//div[@featured] | //article[@published]")
```
## API Reference
### Query Methods
```go
// CSS Selectors
Query(selector string) ([]*Node, error) // Find all matching nodes
QueryFirst(selector string) *Node // Find first matching node
// XPath
QueryXPath(xpath string) ([]*Node, error) // Find all matching nodes
QueryXPathFirst(xpath string) (*Node, error) // Find first matching node
```
### Node Methods
```go
// Content extraction
Text() string // Get text content (including descendants)
Attr(name string) string // Get attribute value
HasAttr(name string) bool // Check if attribute exists
// Tree navigation
Parent *Node // Parent node
Children []*Node // Child nodes
NextSibling() *Node // Next sibling
PrevSibling() *Node // Previous sibling
// Conversion
ToMarkdown() string // Convert to Markdown (for semantic HTML)
```
### Document Methods
```go
// Parsing
parser.Parse(html string) (*Document, error)
parser.ParseReader(r io.Reader) (*Document, error)
// Access
doc.Root // Root node of the document
```
## Real-World Examples
### Web Scraping
```go
// Scrape product information
doc, _ := parser.Parse(html)
products, _ := doc.Root.QueryXPath("//div[@class='product']")
for _, product := range products {
name := product.QueryFirst("h2").Text()
price := product.Attr("data-price")
rating, _ := product.QueryXPath(".//span[@class='rating']/@data-value")
fmt.Printf("%s - $%s (Rating: %s)\n", name, price, rating[0].Text())
}
```
### Data Extraction
```go
// Extract all external links
externalLinks, _ := doc.Root.QueryXPath("//a[starts-with(@href, 'http')]")
// Find all images without alt text
imagesNoAlt, _ := doc.Root.QueryXPath("//img[not(@alt)]")
// Get all table data
rows, _ := doc.Root.QueryXPath("//table[@id='data']//tr[position() > 1]")
for _, row := range rows {
cells, _ := row.QueryXPath("./td")
for _, cell := range cells {
fmt.Print(cell.Text(), "\t")
}
fmt.Println()
}
```
### Form Analysis
```go
// Find all required fields
requiredFields, _ := doc.Root.Query("input[required], select[required], textarea[required]")
// Find unchecked checkboxes
unchecked, _ := doc.Root.Query("input[type='checkbox']:not([checked])")
// Count form elements
inputCount, _ := doc.Root.QueryXPath("count(//form[@id='signup']//input)")
```
### Content Analysis
```go
// Find long paragraphs
longParas, _ := doc.Root.QueryXPath("//p[string-length(text()) > 500]")
// Articles with multiple images
richArticles, _ := doc.Root.QueryXPath("//article[count(.//img) >= 3]")
// Sections with specific heading structure
sections, _ := doc.Root.QueryXPath("//section[h2 and count(h3) > 2]")
```
## XPath Feature Coverage
### ✅ Fully Supported (98%)
**Axes (12/13):**
- child, descendant, parent, ancestor
- following-sibling, preceding-sibling
- following, preceding
- self, descendant-or-self, ancestor-or-self
- attribute
**Node Tests:**
- Element names, wildcards (`*`)
- `text()`, `node()`, `comment()`, `processing-instruction()`
**Operators:**
- Comparison: `=`, `!=`, `<`, `>`, `<=`, `>=`
- Boolean: `and`, `or`, `not()`
- Arithmetic: `+`, `-`, `*`, `div`, `mod`
- Union: `|`
**Functions:**
- Node set: `count()`, `id()`, `last()`, `position()`
- String: `concat()`, `contains()`, `starts-with()`, `substring()`, `string-length()`, `normalize-space()`
- Boolean: `boolean()`, `not()`, `true()`, `false()`
- Number: `number()`, `sum()`, `ceiling()`, `floor()`, `round()`
**Advanced Features:**
- ✅ Location paths in functions: `count(.//p)`
- ✅ Multiple predicates
- ✅ Nested predicates
- ✅ Union operator
- ✅ All comparison operators
### ❌ Not Supported (2%)
- `namespace::` axis (rarely used)
- Variables (`$var`)
- Namespace prefix registration
- Some edge cases in namespace handling
## Documentation
- [Full API Documentation](https://pkg.go.dev/github.com/padraicbc/h5p)
- [CSS Selector Examples](docs/CSS_EXAMPLES.md)
- [XPath Examples](docs/XPATH_EXAMPLES.md)
- [XPath Feature Support](docs/XPATH_FEATURE_SUPPORT.md)
## Contributing
Contributions are welcome! Please feel free to submit a Pull Request.
1. Fork the repository
2. Create your feature branch (`git checkout -b feature/amazing-feature`)
3. Commit your changes (`git commit -m 'Add some amazing feature'`)
4. Push to the branch (`git push origin feature/amazing-feature`)
5. Open a Pull Request
## Testing
```bash
# Run all tests
go test ./...
# Run with coverage
go test -cover ./...
# Run benchmarks
go test -bench=. ./...
```
## License
This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
## Acknowledgments
- HTML5 parsing spec
- W3C XPath 1.0 specification
- CSS Selectors Level 3 specification
---
**Why h5p?** I needed a Go library that combined the best of both worlds: the familiarity of CSS selectors AND the power of XPath. Most libraries offer one or the other, but not both with full feature support. h5p delivers comprehensive CSS Level 3 and 98% XPath 1.0 compliance in a single, zero-dependency package.
Perfect for web scraping, automated testing, content extraction, and any task requiring robust HTML/DOM querying. 🚀