425 lines
11 KiB
Markdown
425 lines
11 KiB
Markdown
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# amber
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--
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import "github.com/eknkc/amber"
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Amber is an elegant templating engine for Go Programming Language
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It is inspired from HAML and Jade
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### Tags
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A tag is simply a word:
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html
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is converted to
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<html></html>
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It is possible to add ID and CLASS attributes to tags:
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div#main
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span.time
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are converted to
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<div id="main"></div>
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<span class="time"></span>
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Any arbitrary attribute name / value pair can be added this way:
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a[href="http://www.google.com"]
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You can mix multiple attributes together
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a#someid[href="/"][title="Main Page"].main.link Click Link
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gets converted to
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<a id="someid" class="main link" href="/" title="Main Page">Click Link</a>
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It is also possible to define these attributes within the block of a tag
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a
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#someid
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[href="/"]
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[title="Main Page"]
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.main
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.link
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| Click Link
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### Doctypes
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To add a doctype, use `!!!` or `doctype` keywords:
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!!! transitional
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// <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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or use `doctype`
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doctype 5
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// <!DOCTYPE html>
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Available options: `5`, `default`, `xml`, `transitional`, `strict`, `frameset`, `1.1`, `basic`, `mobile`
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### Tag Content
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For single line tag text, you can just append the text after tag name:
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p Testing!
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would yield
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<p>Testing!</p>
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For multi line tag text, or nested tags, use indentation:
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html
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head
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title Page Title
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body
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div#content
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p
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| This is a long page content
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| These lines are all part of the parent p
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a[href="/"] Go To Main Page
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### Data
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Input template data can be reached by key names directly. For example, assuming the template has been
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executed with following JSON data:
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{
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"Name": "Ekin",
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"LastName": "Koc",
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"Repositories": [
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"amber",
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"dateformat"
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],
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"Avatar": "/images/ekin.jpg",
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"Friends": 17
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}
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It is possible to interpolate fields using `#{}`
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p Welcome #{Name}!
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would print
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<p>Welcome Ekin!</p>
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Attributes can have field names as well
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a[title=Name][href="/ekin.koc"]
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would print
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<a title="Ekin" href="/ekin.koc"></a>
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### Expressions
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Amber can expand basic expressions. For example, it is possible to concatenate strings with + operator:
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p Welcome #{Name + " " + LastName}
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Arithmetic expressions are also supported:
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p You need #{50 - Friends} more friends to reach 50!
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Expressions can be used within attributes
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img[alt=Name + " " + LastName][src=Avatar]
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### Variables
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It is possible to define dynamic variables within templates,
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all variables must start with a $ character and can be assigned as in the following example:
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div
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$fullname = Name + " " + LastName
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p Welcome #{$fullname}
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If you need to access the supplied data itself (i.e. the object containing Name, LastName etc fields.) you can use `$` variable
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p $.Name
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### Conditions
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For conditional blocks, it is possible to use `if <expression>`
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div
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if Friends > 10
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p You have more than 10 friends
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else if Friends > 5
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p You have more than 5 friends
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else
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p You need more friends
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Again, it is possible to use arithmetic and boolean operators
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div
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if Name == "Ekin" && LastName == "Koc"
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p Hey! I know you..
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There is a special syntax for conditional attributes. Only block attributes can have conditions;
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div
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.hasfriends ? Friends > 0
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This would yield a div with `hasfriends` class only if the `Friends > 0` condition holds. It is
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perfectly fine to use the same method for other types of attributes:
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div
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#foo ? Name == "Ekin"
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[bar=baz] ? len(Repositories) > 0
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### Iterations
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It is possible to iterate over arrays and maps using `each`:
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each $repo in Repositories
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p #{$repo}
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would print
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p amber
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p dateformat
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It is also possible to iterate over values and indexes at the same time
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each $i, $repo in Repositories
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p
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.even ? $i % 2 == 0
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.odd ? $i % 2 == 1
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### Mixins
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Mixins (reusable template blocks that accept arguments) can be defined:
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mixin surprise
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span Surprise!
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mixin link($href, $title, $text)
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a[href=$href][title=$title] #{$text}
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and then called multiple times within a template (or even within another mixin definition):
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div
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+surprise
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+surprise
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+link("http://google.com", "Google", "Check out Google")
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Template data, variables, expressions, etc., can all be passed as arguments:
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+link(GoogleUrl, $googleTitle, "Check out " + $googleTitle)
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### Imports
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A template can import other templates using `import`:
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a.amber
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p this is template a
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b.amber
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p this is template b
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c.amber
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div
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import a
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import b
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gets compiled to
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div
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p this is template a
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p this is template b
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### Inheritance
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A template can inherit other templates. In order to inherit another template, an `extends` keyword should be used.
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Parent template can define several named blocks and child template can modify the blocks.
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master.amber
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!!! 5
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html
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head
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block meta
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meta[name="description"][content="This is a great website"]
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title
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block title
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| Default title
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body
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block content
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subpage.amber
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extends master
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block title
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| Some sub page!
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block append meta
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// This will be added after the description meta tag. It is also possible
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// to prepend someting to an existing block
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meta[name="keywords"][content="foo bar"]
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block content
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div#main
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p Some content here
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### License
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(The MIT License)
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Copyright (c) 2012 Ekin Koc <ekin@eknkc.com>
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Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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## Usage
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```go
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var DefaultOptions = Options{true, false}
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var DefaultDirOptions = DirOptions{".amber", true}
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```
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#### func Compile
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```go
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func Compile(input string, options Options) (*template.Template, error)
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```
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Parses and compiles the supplied amber template string. Returns corresponding Go
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Template (html/templates) instance. Necessary runtime functions will be injected
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and the template will be ready to be executed.
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#### func CompileFile
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```go
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func CompileFile(filename string, options Options) (*template.Template, error)
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```
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Parses and compiles the contents of supplied filename. Returns corresponding Go
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Template (html/templates) instance. Necessary runtime functions will be injected
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and the template will be ready to be executed.
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#### func CompileDir
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```go
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func CompileDir(dirname string, dopt DirOptions, opt Options) (map[string]*template.Template, error)
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```
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Parses and compiles the contents of a supplied directory name. Returns a mapping of template name (extension stripped) to corresponding Go Template (html/template) instance. Necessary runtime functions will be injected and the template will be ready to be executed.
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If there are templates in subdirectories, its key in the map will be it's path relative to `dirname`. For example:
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```
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templates/
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|-- index.amber
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|-- layouts/
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|-- base.amber
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```
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```go
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templates, err := amber.CompileDir("templates/", amber.DefaultDirOptions, amber.DefaultOptions)
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templates["index"] // index.amber Go Template
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templates["layouts/base"] // base.amber Go Template
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```
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By default, the search will be recursive and will match only files ending in ".amber". If recursive is turned off, it will only search the top level of the directory. Specified extension must start with a period.
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#### type Compiler
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```go
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type Compiler struct {
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// Compiler options
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Options
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}
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```
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Compiler is the main interface of Amber Template Engine. In order to use an
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Amber template, it is required to create a Compiler and compile an Amber source
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to native Go template.
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compiler := amber.New()
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// Parse the input file
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err := compiler.ParseFile("./input.amber")
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if err == nil {
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// Compile input file to Go template
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tpl, err := compiler.Compile()
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if err == nil {
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// Check built in html/template documentation for further details
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tpl.Execute(os.Stdout, somedata)
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}
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}
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#### func New
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```go
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func New() *Compiler
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```
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Create and initialize a new Compiler
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#### func (*Compiler) Compile
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```go
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func (c *Compiler) Compile() (*template.Template, error)
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```
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Compile amber and create a Go Template (html/templates) instance. Necessary
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runtime functions will be injected and the template will be ready to be
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executed.
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#### func (*Compiler) CompileString
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```go
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func (c *Compiler) CompileString() (string, error)
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```
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Compile template and return the Go Template source You would not be using this
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unless debugging / checking the output. Please use Compile method to obtain a
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template instance directly.
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#### func (*Compiler) CompileWriter
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```go
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func (c *Compiler) CompileWriter(out io.Writer) (err error)
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```
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Compile amber and write the Go Template source into given io.Writer instance You
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would not be using this unless debugging / checking the output. Please use
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Compile method to obtain a template instance directly.
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#### func (*Compiler) Parse
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```go
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func (c *Compiler) Parse(input string) (err error)
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```
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Parse given raw amber template string.
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#### func (*Compiler) ParseFile
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```go
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func (c *Compiler) ParseFile(filename string) (err error)
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```
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Parse the amber template file in given path
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#### type Options
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```go
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type Options struct {
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// Setting if pretty printing is enabled.
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// Pretty printing ensures that the output html is properly indented and in human readable form.
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// If disabled, produced HTML is compact. This might be more suitable in production environments.
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// Defaukt: true
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PrettyPrint bool
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// Setting if line number emiting is enabled
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// In this form, Amber emits line number comments in the output template. It is usable in debugging environments.
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// Default: false
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LineNumbers bool
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}
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```
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#### type DirOptions
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```go
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// Used to provide options to directory compilation
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type DirOptions struct {
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// File extension to match for compilation
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Ext string
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// Whether or not to walk subdirectories
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Recursive bool
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}
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```
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