ref: d6ed17c60fd13c933347110c720afa09e04df1c8
dir: /resources/page/permalinks.go/
// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package page
import (
"fmt"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"time"
"github.com/pkg/errors"
"github.com/gohugoio/hugo/helpers"
)
// PermalinkExpander holds permalin mappings per section.
type PermalinkExpander struct {
// knownPermalinkAttributes maps :tags in a permalink specification to a
// function which, given a page and the tag, returns the resulting string
// to be used to replace that tag.
knownPermalinkAttributes map[string]pageToPermaAttribute
expanders map[string]func(Page) (string, error)
ps *helpers.PathSpec
}
// Time for checking date formats. Every field is different than the
// Go reference time for date formatting. This ensures that formatting this date
// with a Go time format always has a different output than the format itself.
var referenceTime = time.Date(2019, time.November, 9, 23, 1, 42, 1, time.UTC)
// Return the callback for the given permalink attribute and a boolean indicating if the attribute is valid or not.
func (p PermalinkExpander) callback(attr string) (pageToPermaAttribute, bool) {
if callback, ok := p.knownPermalinkAttributes[attr]; ok {
return callback, true
}
if referenceTime.Format(attr) != attr {
return p.pageToPermalinkDate, true
}
return nil, false
}
// NewPermalinkExpander creates a new PermalinkExpander configured by the given
// PathSpec.
func NewPermalinkExpander(ps *helpers.PathSpec) (PermalinkExpander, error) {
p := PermalinkExpander{ps: ps}
p.knownPermalinkAttributes = map[string]pageToPermaAttribute{
"year": p.pageToPermalinkDate,
"month": p.pageToPermalinkDate,
"monthname": p.pageToPermalinkDate,
"day": p.pageToPermalinkDate,
"weekday": p.pageToPermalinkDate,
"weekdayname": p.pageToPermalinkDate,
"yearday": p.pageToPermalinkDate,
"section": p.pageToPermalinkSection,
"sections": p.pageToPermalinkSections,
"title": p.pageToPermalinkTitle,
"slug": p.pageToPermalinkSlugElseTitle,
"filename": p.pageToPermalinkFilename,
}
patterns := ps.Cfg.GetStringMapString("permalinks")
if patterns == nil {
return p, nil
}
e, err := p.parse(patterns)
if err != nil {
return p, err
}
p.expanders = e
return p, nil
}
// Expand expands the path in p according to the rules defined for the given key.
// If no rules are found for the given key, an empty string is returned.
func (l PermalinkExpander) Expand(key string, p Page) (string, error) {
expand, found := l.expanders[key]
if !found {
return "", nil
}
return expand(p)
}
func (l PermalinkExpander) parse(patterns map[string]string) (map[string]func(Page) (string, error), error) {
expanders := make(map[string]func(Page) (string, error))
// Allow " " and / to represent the root section.
const sectionCutSet = " /" + string(os.PathSeparator)
for k, pattern := range patterns {
k = strings.Trim(k, sectionCutSet)
if !l.validate(pattern) {
return nil, &permalinkExpandError{pattern: pattern, err: errPermalinkIllFormed}
}
pattern := pattern
matches := attributeRegexp.FindAllStringSubmatch(pattern, -1)
callbacks := make([]pageToPermaAttribute, len(matches))
replacements := make([]string, len(matches))
for i, m := range matches {
replacement := m[0]
attr := replacement[1:]
replacements[i] = replacement
callback, ok := l.callback(attr)
if !ok {
return nil, &permalinkExpandError{pattern: pattern, err: errPermalinkAttributeUnknown}
}
callbacks[i] = callback
}
expanders[k] = func(p Page) (string, error) {
if matches == nil {
return pattern, nil
}
newField := pattern
for i, replacement := range replacements {
attr := replacement[1:]
callback := callbacks[i]
newAttr, err := callback(p, attr)
if err != nil {
return "", &permalinkExpandError{pattern: pattern, err: err}
}
newField = strings.Replace(newField, replacement, newAttr, 1)
}
return newField, nil
}
}
return expanders, nil
}
// pageToPermaAttribute is the type of a function which, given a page and a tag
// can return a string to go in that position in the page (or an error)
type pageToPermaAttribute func(Page, string) (string, error)
var attributeRegexp = regexp.MustCompile(`:\w+`)
// validate determines if a PathPattern is well-formed
func (l PermalinkExpander) validate(pp string) bool {
fragments := strings.Split(pp[1:], "/")
var bail = false
for i := range fragments {
if bail {
return false
}
if len(fragments[i]) == 0 {
bail = true
continue
}
matches := attributeRegexp.FindAllStringSubmatch(fragments[i], -1)
if matches == nil {
continue
}
for _, match := range matches {
k := match[0][1:]
if _, ok := l.callback(k); !ok {
return false
}
}
}
return true
}
type permalinkExpandError struct {
pattern string
err error
}
func (pee *permalinkExpandError) Error() string {
return fmt.Sprintf("error expanding %q: %s", pee.pattern, pee.err)
}
var (
errPermalinkIllFormed = errors.New("permalink ill-formed")
errPermalinkAttributeUnknown = errors.New("permalink attribute not recognised")
)
func (l PermalinkExpander) pageToPermalinkDate(p Page, dateField string) (string, error) {
// a Page contains a Node which provides a field Date, time.Time
switch dateField {
case "year":
return strconv.Itoa(p.Date().Year()), nil
case "month":
return fmt.Sprintf("%02d", int(p.Date().Month())), nil
case "monthname":
return p.Date().Month().String(), nil
case "day":
return fmt.Sprintf("%02d", p.Date().Day()), nil
case "weekday":
return strconv.Itoa(int(p.Date().Weekday())), nil
case "weekdayname":
return p.Date().Weekday().String(), nil
case "yearday":
return strconv.Itoa(p.Date().YearDay()), nil
}
return p.Date().Format(dateField), nil
}
// pageToPermalinkTitle returns the URL-safe form of the title
func (l PermalinkExpander) pageToPermalinkTitle(p Page, _ string) (string, error) {
return l.ps.URLize(p.Title()), nil
}
// pageToPermalinkFilename returns the URL-safe form of the filename
func (l PermalinkExpander) pageToPermalinkFilename(p Page, _ string) (string, error) {
name := p.File().TranslationBaseName()
if name == "index" {
// Page bundles; the directory name will hopefully have a better name.
dir := strings.TrimSuffix(p.File().Dir(), helpers.FilePathSeparator)
_, name = filepath.Split(dir)
}
return l.ps.URLize(name), nil
}
// if the page has a slug, return the slug, else return the title
func (l PermalinkExpander) pageToPermalinkSlugElseTitle(p Page, a string) (string, error) {
if p.Slug() != "" {
return l.ps.URLize(p.Slug()), nil
}
return l.pageToPermalinkTitle(p, a)
}
func (l PermalinkExpander) pageToPermalinkSection(p Page, _ string) (string, error) {
return p.Section(), nil
}
func (l PermalinkExpander) pageToPermalinkSections(p Page, _ string) (string, error) {
return p.CurrentSection().SectionsPath(), nil
}