liquid/filters/filters.go

// The filters package defines the standard Liquid filters.
package filters

import (
	"encoding/json"
	"fmt"
	"strings"

	"github.com/osteele/liquid/expressions"
	"github.com/osteele/liquid/generics"
)

// DefineStandardFilters defines the standard Liquid filters.
func DefineStandardFilters() {
	// lists
	expressions.DefineFilter("join", joinFilter)
	expressions.DefineFilter("sort", sortFilter)

	// strings
	expressions.DefineFilter("split", splitFilter)

	// Jekyll
	expressions.DefineFilter("inspect", json.Marshal)
}

func joinFilter(in []interface{}, sep interface{}) interface{} {
	a := make([]string, len(in))
	s := ", "
	if sep != nil {
		s = fmt.Sprint(sep)
	}
	for i, x := range in {
		a[i] = fmt.Sprint(x)
	}
	return strings.Join(a, s)
}

func sortFilter(in []interface{}, key interface{}) []interface{} {
	out := make([]interface{}, len(in))
	for i, v := range in {
		out[i] = v
	}
	if key == nil {
		generics.Sort(out)
	} else {
		generics.SortByProperty(out, key.(string))
	}
	return out
}

func splitFilter(in, sep string) interface{} {
	return strings.Split(in, sep)
}