91 lines
2.4 KiB
Go
91 lines
2.4 KiB
Go
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package codegen
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import (
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"fmt"
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"strings"
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"text/template"
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)
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// wcTemplate is the Web Component class template.
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// Uses closed Shadow DOM for isolation. Content is set via the shadow root's
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// DOM API using trusted go-html codegen output (never user input).
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var wcTemplate = template.Must(template.New("wc").Parse(`class {{.ClassName}} extends HTMLElement {
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#shadow;
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constructor() {
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super();
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this.#shadow = this.attachShadow({ mode: "closed" });
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}
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connectedCallback() {
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this.#shadow.textContent = "";
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const slot = this.getAttribute("data-slot") || "{{.Slot}}";
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this.dispatchEvent(new CustomEvent("wc-ready", { detail: { tag: "{{.Tag}}", slot } }));
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}
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render(html) {
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const tpl = document.createElement("template");
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tpl.insertAdjacentHTML("afterbegin", html);
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this.#shadow.textContent = "";
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this.#shadow.appendChild(tpl.content.cloneNode(true));
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}
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}`))
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// GenerateClass produces a JS class definition for a custom element.
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func GenerateClass(tag, slot string) (string, error) {
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if !strings.Contains(tag, "-") {
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return "", fmt.Errorf("codegen: custom element tag %q must contain a hyphen", tag)
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}
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var b strings.Builder
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err := wcTemplate.Execute(&b, struct {
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ClassName, Tag, Slot string
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}{
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ClassName: TagToClassName(tag),
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Tag: tag,
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Slot: slot,
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})
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if err != nil {
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return "", fmt.Errorf("codegen: template exec: %w", err)
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}
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return b.String(), nil
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}
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// GenerateRegistration produces the customElements.define() call.
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func GenerateRegistration(tag, className string) string {
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return fmt.Sprintf(`customElements.define("%s", %s);`, tag, className)
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}
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// TagToClassName converts a kebab-case tag to PascalCase class name.
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func TagToClassName(tag string) string {
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parts := strings.Split(tag, "-")
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var b strings.Builder
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for _, p := range parts {
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if len(p) > 0 {
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b.WriteString(strings.ToUpper(p[:1]))
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b.WriteString(p[1:])
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}
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}
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return b.String()
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}
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// GenerateBundle produces all WC class definitions and registrations
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// for a set of HLCRF slot assignments.
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func GenerateBundle(slots map[string]string) (string, error) {
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seen := make(map[string]bool)
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var b strings.Builder
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for slot, tag := range slots {
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if seen[tag] {
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continue
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}
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seen[tag] = true
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cls, err := GenerateClass(tag, slot)
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if err != nil {
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return "", err
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}
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b.WriteString(cls)
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b.WriteByte('\n')
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b.WriteString(GenerateRegistration(tag, TagToClassName(tag)))
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b.WriteByte('\n')
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}
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return b.String(), nil
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}
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