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105 lines
5.6 KiB
Markdown
105 lines
5.6 KiB
Markdown
#LuaRock "htmlparser"
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Parse HTML text into a tree of elements with selectors
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[1]: http://wscherphof.github.com/lua-set/
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[2]: http://api.jquery.com/category/selectors/
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##License
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MIT; see `./doc/LICENSE`
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##Install
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Htmlparser is a listed [LuaRock](http://luarocks.org/repositories/rocks/). Install using [LuaRocks](http://www.luarocks.org/): `luarocks install htmlparser`
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###Dependencies
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Htmlparser depends on [Lua 5.2](http://www.lua.org/download.html), and on the ["set"][1] LuaRock, which is installed along automatically. To be able to run the tests, [lunitx](https://github.com/dcurrie/lunit) also comes along as a LuaRock
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##Usage
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Start off with
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```lua
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require("luarocks.loader")
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local htmlparser = require("htmlparser")
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```
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Then, parse some html:
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```lua
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local root = htmlparser.parse(htmlstring)
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```
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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.
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Now, find sepcific contained elements by selecting:
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```lua
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local elements = root:select(selectorstring)
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```
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Or in shorthand:
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```lua
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local elements = root(selectorstring)
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```
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This wil return a [Set][1] of elements, all of which are of the same type as the root element, and thus support selecting as well, if ever needed:
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```lua
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for e in pairs(elements) do
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print(e.name)
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local subs = e(subselectorstring)
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for sub in pairs(subs) do
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print("", sub.name)
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end
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end
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```
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The root element is a container for the top level elements in the parsed text, i.e. the `<html>` element in a parsed html document would be a child of the returned root element.
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##Selectors
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Supported selectors are a subset of [jQuery's selectors][2]:
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- `"*"` all contained elements
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- `"element"` elements with the given tagname
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- `"#id"` elements with the given id attribute value
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- `".class"` elements with the given classname in the class attribute
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- `"[attribute]"` elements with an attribute of the given name
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- `"[attribute='value']"` equals: elements with the given value for the attribute with the given name
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- `"[attribute!='value']"` not equals: elements without an attribute of the given name, or with that attribute, but with a value that is different from the given value
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- `"[attribute|='value']"` prefix: attribute's value is given value, or starts with given value, followed by a hyphen (`-`)
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- `"[attribute*='value']"` contains: attribute's value contains given value
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- `"[attribute~='value']"` word: attribute's value is a space-separated token, where one of the tokens is the given value
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- `"[attribute^='value']"` starts with: attribute's value starts with given value
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- `"[attribute$='value']"` ends with: attribute's value ends with given value
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- `":not(selectorstring)"` elements not selected by given selector string
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- `"ancestor descendant"` elements selected by the `descendant` selector string, that are a descendant of any element selected by the `ancestor` selector string
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- `"parent > child"` elements selected by the `child` selector string, that are a child element of any element selected by the `parent` selector string
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Selectors can be combined; e.g. `".class:not([attribute]) element.class"`
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###Limitations
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- Attribute values in selectors currently cannot contain any spaces, since space is interpreted as a delimiter between the `ancestor` and `descendant`, `parent` and `>`, or `>` and `child` parts of the selector
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- Consequently, for the `parent > child` relation, the spaces before and after the `>` are mandatory
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- Attribute values in selectors currently also cannot contain any of `#`, `.`, `[`, `]`, `:`, `(`, or `)`
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- `<!` elements are not parsed, including doctype, comments, and CDATA
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- Textnodes are not seperate entries in the tree, so the content of `<p>line1<br />line2</p>` is plainly `"line1<br />line2"`
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- All start and end tags should be explicitly specified in the text to be parsed; omitted tags (as [permitted](http://www.w3.org/TR/html5/syntax.html#optional-tags) by the the HTML spec) are NOT implied. Only the [void](http://www.w3.org/TR/html5/syntax.html#void-elements) elements naturally don't need (and mustn't have) an end tag
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- The HTML text is not validated in any way; tag and attribute names and the nesting of different tags is completely arbitrary. The only HTML-specific part of the parser is that it knows which tags are void elements
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##Examples
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See `./doc/sample.lua`
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##Tests
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See `./tst/init.lua`
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##Element type
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All tree elements provide, apart from `:select` and `()`, the following accessors:
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###Basic
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- `.name` the element's tagname
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- `.attributes` a table with keys and values for the element's attributes; `{}` if none
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- `.id` the value of the element's id attribute; `nil` if not present
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- `.classes` an array with the classes listed in element's class attribute; `{}` if none
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- `:getcontent()` the raw text between the opening and closing tags of the element; `""` if none
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- `.nodes` an array with the element's child elements, `{}` if none
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- `.parent` the elements that contains this element; `root.parent` is `nil`
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###Other
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- `:gettext()` the raw text of the complete element, starting with `"<tagname"` and ending with `"/>"`
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- `.level` how deep the element is in the tree; root level is `0`
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- `.root` the root element of the tree; `root.root` is `root`
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- `.deepernodes` a [Set][1] containing all elements in the tree beneath this element, including this element's `.nodes`; `{}` if none
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- `.deeperelements` a table with a key for each distinct tagname in `.deepernodes`, containing a [Set][1] of all deeper element nodes with that name; `{}` in none
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- `.deeperattributes` as `.deeperelements`, but keyed on attribute name
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- `.deeperids` as `.deeperelements`, but keyed on id value
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- `.deeperclasses` as `.deeperelements`, but keyed on class name
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