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macros.go
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macros.go
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package main
import (
"errors"
"github.com/flyx/askew/attributes"
"github.com/flyx/askew/data"
"github.com/flyx/askew/walker"
"github.com/flyx/net/html"
)
type macroDiscovery struct {
syms *data.Symbols
}
func (md *macroDiscovery) Process(n *html.Node) (descend bool, replacement *html.Node, err error) {
name := attributes.Val(n.Attr, "name")
if name == "" {
return false, nil, errors.New(": attribute `name` missing")
}
pkg, _ := md.syms.Packages[md.syms.CurPkg]
for _, file := range pkg.Files {
_, ok := file.Macros[name]
if ok {
return false, nil, errors.New(": duplicate name `" + name + "`")
}
}
sd := slotDiscovery{slots: make([]data.Slot, 0, 16), syms: md.syms}
w := walker.Walker{TextNode: walker.Allow{}, StdElements: walker.Allow{},
Text: walker.Allow{}, Embed: walker.Allow{}, Construct: walker.Allow{},
Include: &includeProcessor{md.syms}, Slot: &sd}
first, last, err := w.WalkChildren(n, &walker.Siblings{Cur: n.FirstChild})
if err != nil {
return false, nil, err
}
curFile := md.syms.CurAskewFile()
if curFile.Macros == nil {
curFile.Macros = make(map[string]data.Macro)
}
curFile.Macros[name] = data.Macro{Slots: sd.slots, First: first, Last: last}
// removes the macro and stops parent walker from descending
return false, &html.Node{Type: html.TextNode, Data: ""}, nil
}
type slotDiscovery struct {
syms *data.Symbols
slots []data.Slot
}
func (sd *slotDiscovery) Process(n *html.Node) (descend bool, replacement *html.Node, err error) {
name := attributes.Val(n.Attr, "name")
if name == "" {
return false, nil, errors.New("missing attribute `name`")
}
sd.slots = append(sd.slots, data.Slot{Name: name, Node: n})
w := walker.Walker{TextNode: walker.Allow{}, StdElements: walker.Allow{},
Text: walker.Allow{}, Embed: walker.Allow{}, Construct: walker.Allow{},
Include: &includeProcessor{sd.syms}}
n.FirstChild, n.LastChild, err = w.WalkChildren(n, &walker.Siblings{Cur: n.FirstChild})
return false, nil, err
}
type includeProcessor struct {
syms *data.Symbols
}
func (ip *includeProcessor) Process(n *html.Node) (descend bool, replacement *html.Node, err error) {
name := attributes.Val(n.Attr, "name")
if name == "" {
return false, nil, errors.New(": `name` attribute missing")
}
m, err := ip.syms.ResolveMacro(name)
if err != nil {
return false, nil, errors.New(": failed to process: " + err.Error())
}
vm := valueMapper{slots: m.Slots, values: make([]*html.Node, len(m.Slots)),
syms: ip.syms}
w := walker.Walker{TextNode: walker.WhitespaceOnly{}, StdElements: &vm}
n.FirstChild, n.LastChild, err = w.WalkChildren(n, &walker.Siblings{Cur: n.FirstChild})
if err != nil {
return
}
instantiator := macroInstantiator{
slots: m.Slots, values: vm.values}
ec := elmCopier{&instantiator}
instantiator.w =
walker.Walker{TextNode: textCopier{}, StdElements: &ec, Text: &ec,
Slot: &slotReplacer{&instantiator}, Embed: &ec, Construct: &ec}
replacement, _, err = instantiator.w.WalkChildren(nil, &walker.Siblings{Cur: m.First})
return
}
type valueMapper struct {
syms *data.Symbols
slots []data.Slot
values []*html.Node
}
func (vm *valueMapper) Process(n *html.Node) (descend bool, replacement *html.Node, err error) {
var iAttrs attributes.IncludeChild
if err = attributes.ExtractAskewAttribs(n, &iAttrs); err != nil {
return
}
// re-add other askew attributes to node as they will be processed later.
for name, val := range iAttrs.Others {
n.Attr = append(n.Attr, html.Attribute{Key: "a:" + name, Val: val})
}
if iAttrs.Slot == "" {
return false, nil, errors.New(": child of a:include has no attribute `a:slot`")
}
found := false
for i := range vm.slots {
if vm.slots[i].Name == iAttrs.Slot {
if vm.values[i] != nil {
return false, nil, errors.New(": dupicate value for slot `" + iAttrs.Slot + "`")
}
vm.values[i] = n
n.PrevSibling = nil
n.NextSibling = nil
n.Parent = nil
found = true
break
}
}
if !found {
return false, nil, errors.New(": unknown slot `" + iAttrs.Slot + "`")
}
w := walker.Walker{TextNode: walker.Allow{}, StdElements: walker.Allow{},
Text: walker.Allow{}, Embed: walker.Allow{}, Construct: walker.Allow{},
Include: &includeProcessor{vm.syms}}
n.FirstChild, n.LastChild, err = w.WalkChildren(n, &walker.Siblings{Cur: n.FirstChild})
return false, &html.Node{Type: html.CommentNode}, nil
}
type macroInstantiator struct {
slots []data.Slot
values []*html.Node
w walker.Walker
}
type textCopier struct{}
func (textCopier) Process(n *html.Node) (descend bool, replacement *html.Node, err error) {
replacement = &html.Node{Type: n.Type, Data: n.Data}
return
}
type elmCopier struct {
mi *macroInstantiator
}
func (ec *elmCopier) Process(n *html.Node) (descend bool, replacement *html.Node, err error) {
replacement = &html.Node{
Type: n.Type, DataAtom: n.DataAtom, Data: n.Data, Namespace: n.Namespace,
Attr: append([]html.Attribute(nil), n.Attr...)}
replacement.FirstChild, replacement.LastChild, err = ec.mi.w.WalkChildren(
replacement, &walker.Siblings{Cur: n.FirstChild})
return
}
type slotReplacer struct {
mi *macroInstantiator
}
func (sl *slotReplacer) Process(n *html.Node) (descend bool, replacement *html.Node, err error) {
for i := range sl.mi.slots {
if sl.mi.slots[i].Node != n {
continue
}
if sl.mi.values[i] == nil {
replacement, _, err = sl.mi.w.WalkChildren(nil, &walker.Siblings{Cur: n.FirstChild})
if replacement == nil {
replacement = &html.Node{Type: html.TextNode}
}
} else {
replacement = sl.mi.values[i]
}
return
}
return false, nil, errors.New("did not find matching slot (should never happen)")
}
type unitDescender struct {
syms *data.Symbols
}
func (cd *unitDescender) Process(n *html.Node) (descend bool, replacement *html.Node, err error) {
w := walker.Walker{TextNode: walker.Allow{}, StdElements: walker.Allow{}, Include: &includeProcessor{cd.syms},
Handlers: walker.Allow{}, Controller: walker.Allow{}, Data: walker.Allow{},
Embed: walker.Allow{}, Construct: walker.Allow{}, Text: walker.Allow{}}
n.FirstChild, n.LastChild, err = w.WalkChildren(n, &walker.Siblings{Cur: n.FirstChild})
return false, nil, err
}
type importRemover struct{}
func (importRemover) Process(n *html.Node) (descend bool, replacement *html.Node, err error) {
return false, &html.Node{Type: html.TextNode}, nil
}
func processMacros(nodes []*html.Node, syms *data.Symbols) (dummyParent *html.Node, err error) {
dummyParent = &html.Node{Type: html.ElementNode}
if len(nodes) > 0 {
dummyParent.FirstChild = nodes[0]
dummyParent.LastChild = nodes[len(nodes)-1]
w := walker.Walker{TextNode: walker.WhitespaceOnly{},
Component: &unitDescender{syms: syms},
Site: &unitDescender{syms: syms},
Macro: ¯oDiscovery{syms: syms},
Import: importRemover{}}
_, _, err = w.WalkChildren(dummyParent, &walker.NodeSlice{Items: nodes})
}
return
}