# LuaRock "htmlparser"
Parse HTML text into a tree of elements with selectors
[1]: https://api.jquery.com/category/selectors/
## Install
Htmlparser is a listed [LuaRock](http://luarocks.org/repositories/rocks/). Install using [LuaRocks](http://www.luarocks.org/): `luarocks install htmlparser`
### Dependencies
Htmlparser depends on [Lua 5.1-5.3](https://www.lua.org/download.html) or [LuaJIT](https://luajit.org/download.html), which provides 5.1-compatible ABI.
To be able to run the tests, [lunitx](https://github.com/dcurrie/lunit) also comes along as a LuaRock
## Usage
Start off with
```lua
local htmlparser = require("htmlparser")
```
Then, parse some html:
```lua
local root = htmlparser.parse(htmlstring)
```
Optionally, you can pass loop-limit value (integer). This value means the deepness of the tree, after which parser will give up. Default value is 1000.
Also, global variable `htmlparser_looplimit` is supported (while this optional argument takes priority over global value)
The input to parse may be the contents of a complete html document, or any valid html snippet, as long as all tags are correctly opened and closed.
Now, find specific contained elements by selecting:
```lua
local elements = root:select(selectorstring)
```
Or in shorthand:
```lua
local elements = root(selectorstring)
```
This wil return a list of elements, all of which are of the same type as the root element, and thus support selecting as well, if ever needed:
```lua
for _,e in ipairs(elements) do
print(e.name)
local subs = e(subselectorstring)
for _,sub in ipairs(subs) do
print("", sub.name)
end
end
```
The root element is a container for the top level elements in the parsed text, i.e. the `` element in a parsed html document would be a child of the returned root element.
## Selectors
Supported selectors are a subset of [jQuery's selectors][1]:
- `"*"` all contained elements
- `"element"` elements with the given tagname
- `"#id"` elements with the given id attribute value
- `".class"` elements with the given classname in the class attribute
- `"[attribute]"` elements with an attribute of the given name
- `"[attribute='value']"` equals: elements with the given value for the given attribute
- `"[attribute!='value']"` not equals: elements without the given attribute, or having the attribute, but with a different value
- `"[attribute|='value']"` prefix: attribute's value is given value, or starts with given value, followed by a hyphen (`-`)
- `"[attribute*='value']"` contains: attribute's value contains given value
- `"[attribute~='value']"` word: attribute's value is a space-separated token, where one of the tokens is the given value
- `"[attribute^='value']"` starts with: attribute's value starts with given value
- `"[attribute$='value']"` ends with: attribute's value ends with given value
- `":not(selectorstring)"` elements not selected by given selector string
- `"ancestor descendant"` elements selected by the `descendant` selector string, that are a descendant of any element selected by the `ancestor` selector string
- `"parent > child"` elements selected by the `child` selector string, that are a child element of any element selected by the `parent` selector string
Selectors can be combined; e.g. `".class:not([attribute]) element.class"`
## Element type
All tree elements provide, apart from `:select` and `()`, the following accessors:
### Basic
- `.name` the element's tagname
- `.attributes` a table with keys and values for the element's attributes; `{}` if none
- `.id` the value of the element's id attribute; `nil` if not present
- `.classes` an array with the classes listed in element's class attribute; `{}` if none
- `:getcontent()` the raw text between the opening and closing tags of the element; `""` if none
- `.nodes` an array with the element's child elements, `{}` if none
- `.parent` the element that contains this element; `root.parent` is `nil`
### Other
- `.index` sequence number of elements in order of appearance; root index is `0`
- `:gettext()` the complete element text, starting with `""` or `""`
- `.level` how deep the element is in the tree; root level is `0`
- `.root` the root element of the tree; `root.root` is `root`
- `.deepernodes` a [Set][1] containing all elements in the tree beneath this element, including this element's `.nodes`; `{}` if none
- `.deeperelements` a table with a key for each distinct tagname in `.deepernodes`, containing a [Set][1] of all deeper element nodes with that name; `{}` if none
- `.deeperattributes` as `.deeperelements`, but keyed on attribute name
- `.deeperids` as `.deeperelements`, but keyed on id value
- `.deeperclasses` as `.deeperelements`, but keyed on class name
## Limitations
- Attribute values in selector strings cannot contain any spaces
- The spaces before and after the `>` in a `parent > child` relation are mandatory
- `line1
line2")`, `root.nodes[1]:getcontent()` is `"line1
line2"`, while `root.nodes[1].nodes[1].name` is `"br"`
- No start or end tags are implied when [omitted](http://www.w3.org/TR/html5/syntax.html#optional-tags). Only the [void elements](http://www.w3.org/TR/html5/syntax.html#void-elements) should not have an end tag
- No validation is done for tag or attribute names or nesting of element types. The list of void elements is in fact the only part specific to HTML
## Examples
See `./doc/sample.lua`
## Tests
See `./tst/init.lua`
## License
LGPL+; see `./doc/LICENSE`