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70 lines
2.1 KiB
70 lines
2.1 KiB
package post
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import (
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"fmt"
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"io"
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"text/template"
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)
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// PreprocessFunctions are functions which can be used by posts themselves to
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// interleave dynamic content into their bodies. Usually this is used for
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// properly constructing URLs, but also for things like displaying images.
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type PreprocessFunctions struct {
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// BlogURL returns the given string, rooted to the blog's base url (which
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// may or may not include path components itself).
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//
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// The given path should not have a leading slash.
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BlogURL func(path string) string
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// AssetURL returns the URL of the asset with the given ID.
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AssetURL func(id string) string
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// PostURL returns the URL of the post with the given ID.
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PostURL func(id string) string
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// StaticURL returns the URL of a file being served from the static
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// directory. The given path should _not_ include the prefixed 'static/'
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// path element.
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StaticURL func(path string) string
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// Image returns a string which should be inlined into the post body in
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// order to display an.
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//
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// The first argument to Image _must_ be the ID of an image asset. The
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// second argument _may_ be a description of the image which will be used as
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// alt text, or possibly displayed to the user with the image.
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Image func(args ...string) (string, error)
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}
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func (funcs PreprocessFunctions) ToFuncsMap() template.FuncMap {
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return template.FuncMap{
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"BlogURL": funcs.BlogURL,
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"AssetURL": funcs.AssetURL,
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"PostURL": funcs.PostURL,
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"StaticURL": funcs.StaticURL,
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"Image": funcs.Image,
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}
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}
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// PreprocessBody interprets the Post's Body as a text template which may use
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// any of the functions found in PreprocessFunctions (all must be set). It
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// executes the template and writes the result to the given writer.
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func (p Post) PreprocessBody(into io.Writer, funcs PreprocessFunctions) error {
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tpl := template.New("")
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tpl.Funcs(funcs.ToFuncsMap())
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tpl, err := tpl.Parse(p.Body)
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if err != nil {
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return fmt.Errorf("parsing post body as template: %w", err)
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}
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if err := tpl.Execute(into, nil); err != nil {
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return fmt.Errorf("executing post body as template: %w", err)
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}
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return nil
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}
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