ref: c6b661de826f3ed8768a97a5178b4e020cb2ace1
dir: /tpl/tplimpl/template_ast_transformers.go/
// Copyright 2016 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 tplimpl
import (
"regexp"
"strings"
htmltemplate "github.com/gohugoio/hugo/tpl/internal/go_templates/htmltemplate"
texttemplate "github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate"
"github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate/parse"
"github.com/gohugoio/hugo/common/maps"
"github.com/gohugoio/hugo/tpl"
"github.com/mitchellh/mapstructure"
"github.com/pkg/errors"
)
type templateType int
const (
templateUndefined templateType = iota
templateShortcode
templatePartial
)
type templateContext struct {
visited map[string]bool
templateNotFound map[string]bool
identityNotFound map[string]bool
lookupFn func(name string) *templateState
// The last error encountered.
err error
// Set when we're done checking for config header.
configChecked bool
t *templateState
// Store away the return node in partials.
returnNode *parse.CommandNode
}
func (c templateContext) getIfNotVisited(name string) *templateState {
if c.visited[name] {
return nil
}
c.visited[name] = true
templ := c.lookupFn(name)
if templ == nil {
// This may be a inline template defined outside of this file
// and not yet parsed. Unusual, but it happens.
// Store the name to try again later.
c.templateNotFound[name] = true
}
return templ
}
func newTemplateContext(
t *templateState,
lookupFn func(name string) *templateState) *templateContext {
return &templateContext{
t: t,
lookupFn: lookupFn,
visited: make(map[string]bool),
templateNotFound: make(map[string]bool),
identityNotFound: make(map[string]bool),
}
}
func applyTemplateTransformers(
t *templateState,
lookupFn func(name string) *templateState) (*templateContext, error) {
if t == nil {
return nil, errors.New("expected template, but none provided")
}
c := newTemplateContext(t, lookupFn)
tree := getParseTree(t.Template)
_, err := c.applyTransformations(tree.Root)
if err == nil && c.returnNode != nil {
// This is a partial with a return statement.
c.t.parseInfo.HasReturn = true
tree.Root = c.wrapInPartialReturnWrapper(tree.Root)
}
return c, err
}
func getParseTree(templ tpl.Template) *parse.Tree {
templ = unwrap(templ)
if text, ok := templ.(*texttemplate.Template); ok {
return text.Tree
}
return templ.(*htmltemplate.Template).Tree
}
const (
partialReturnWrapperTempl = `{{ $_hugo_dot := $ }}{{ $ := .Arg }}{{ with .Arg }}{{ $_hugo_dot.Set ("PLACEHOLDER") }}{{ end }}`
)
var (
partialReturnWrapper *parse.ListNode
)
func init() {
templ, err := texttemplate.New("").Parse(partialReturnWrapperTempl)
if err != nil {
panic(err)
}
partialReturnWrapper = templ.Tree.Root
}
func (c *templateContext) wrapInPartialReturnWrapper(n *parse.ListNode) *parse.ListNode {
wrapper := partialReturnWrapper.CopyList()
withNode := wrapper.Nodes[2].(*parse.WithNode)
retn := withNode.List.Nodes[0]
setCmd := retn.(*parse.ActionNode).Pipe.Cmds[0]
setPipe := setCmd.Args[1].(*parse.PipeNode)
// Replace PLACEHOLDER with the real return value.
// Note that this is a PipeNode, so it will be wrapped in parens.
setPipe.Cmds = []*parse.CommandNode{c.returnNode}
withNode.List.Nodes = append(n.Nodes, retn)
return wrapper
}
// applyTransformations do 2 things:
// 1) Parses partial return statement.
// 2) Tracks template (partial) dependencies and some other info.
func (c *templateContext) applyTransformations(n parse.Node) (bool, error) {
switch x := n.(type) {
case *parse.ListNode:
if x != nil {
c.applyTransformationsToNodes(x.Nodes...)
}
case *parse.ActionNode:
c.applyTransformationsToNodes(x.Pipe)
case *parse.IfNode:
c.applyTransformationsToNodes(x.Pipe, x.List, x.ElseList)
case *parse.WithNode:
c.applyTransformationsToNodes(x.Pipe, x.List, x.ElseList)
case *parse.RangeNode:
c.applyTransformationsToNodes(x.Pipe, x.List, x.ElseList)
case *parse.TemplateNode:
subTempl := c.getIfNotVisited(x.Name)
if subTempl != nil {
c.applyTransformationsToNodes(getParseTree(subTempl.Template).Root)
}
case *parse.PipeNode:
c.collectConfig(x)
for i, cmd := range x.Cmds {
keep, _ := c.applyTransformations(cmd)
if !keep {
x.Cmds = append(x.Cmds[:i], x.Cmds[i+1:]...)
}
}
case *parse.CommandNode:
c.collectPartialInfo(x)
c.collectInner(x)
keep := c.collectReturnNode(x)
for _, elem := range x.Args {
switch an := elem.(type) {
case *parse.PipeNode:
c.applyTransformations(an)
}
}
return keep, c.err
}
return true, c.err
}
func (c *templateContext) applyTransformationsToNodes(nodes ...parse.Node) {
for _, node := range nodes {
c.applyTransformations(node)
}
}
func (c *templateContext) hasIdent(idents []string, ident string) bool {
for _, id := range idents {
if id == ident {
return true
}
}
return false
}
// collectConfig collects and parses any leading template config variable declaration.
// This will be the first PipeNode in the template, and will be a variable declaration
// on the form:
// {{ $_hugo_config:= `{ "version": 1 }` }}
func (c *templateContext) collectConfig(n *parse.PipeNode) {
if c.t.typ != templateShortcode {
return
}
if c.configChecked {
return
}
c.configChecked = true
if len(n.Decl) != 1 || len(n.Cmds) != 1 {
// This cannot be a config declaration
return
}
v := n.Decl[0]
if len(v.Ident) == 0 || v.Ident[0] != "$_hugo_config" {
return
}
cmd := n.Cmds[0]
if len(cmd.Args) == 0 {
return
}
if s, ok := cmd.Args[0].(*parse.StringNode); ok {
errMsg := "failed to decode $_hugo_config in template"
m, err := maps.ToStringMapE(s.Text)
if err != nil {
c.err = errors.Wrap(err, errMsg)
return
}
if err := mapstructure.WeakDecode(m, &c.t.parseInfo.Config); err != nil {
c.err = errors.Wrap(err, errMsg)
}
}
}
// collectInner determines if the given CommandNode represents a
// shortcode call to its .Inner.
func (c *templateContext) collectInner(n *parse.CommandNode) {
if c.t.typ != templateShortcode {
return
}
if c.t.parseInfo.IsInner || len(n.Args) == 0 {
return
}
for _, arg := range n.Args {
var idents []string
switch nt := arg.(type) {
case *parse.FieldNode:
idents = nt.Ident
case *parse.VariableNode:
idents = nt.Ident
}
if c.hasIdent(idents, "Inner") {
c.t.parseInfo.IsInner = true
break
}
}
}
var partialRe = regexp.MustCompile(`^partial(Cached)?$|^partials\.Include(Cached)?$`)
func (c *templateContext) collectPartialInfo(x *parse.CommandNode) {
if len(x.Args) < 2 {
return
}
first := x.Args[0]
var id string
switch v := first.(type) {
case *parse.IdentifierNode:
id = v.Ident
case *parse.ChainNode:
id = v.String()
}
if partialRe.MatchString(id) {
partialName := strings.Trim(x.Args[1].String(), "\"")
if !strings.Contains(partialName, ".") {
partialName += ".html"
}
partialName = "partials/" + partialName
info := c.lookupFn(partialName)
if info != nil {
c.t.Add(info)
} else {
// Delay for later
c.identityNotFound[partialName] = true
}
}
}
func (c *templateContext) collectReturnNode(n *parse.CommandNode) bool {
if c.t.typ != templatePartial || c.returnNode != nil {
return true
}
if len(n.Args) < 2 {
return true
}
ident, ok := n.Args[0].(*parse.IdentifierNode)
if !ok || ident.Ident != "return" {
return true
}
c.returnNode = n
// Remove the "return" identifiers
c.returnNode.Args = c.returnNode.Args[1:]
return false
}
func findTemplateIn(name string, in tpl.Template) (tpl.Template, bool) {
in = unwrap(in)
if text, ok := in.(*texttemplate.Template); ok {
if templ := text.Lookup(name); templ != nil {
return templ, true
}
return nil, false
}
if templ := in.(*htmltemplate.Template).Lookup(name); templ != nil {
return templ, true
}
return nil, false
}