From 87e7f2f40bd66ba8c56b81b7982d962e8695dc7d Mon Sep 17 00:00:00 2001
From: Dmitriy Pleshevskiy <dmitriy@ideascup.me>
Date: Fri, 18 Mar 2022 22:14:42 +0300
Subject: [PATCH] refac(str): improve encoding

---
 lib/str.mjs | 21 ++++++++++++---------
 src/str.mts | 38 +++++++++++++++++++++++---------------
 2 files changed, 35 insertions(+), 24 deletions(-)

diff --git a/lib/str.mjs b/lib/str.mjs
index 451da25..6adb48b 100644
--- a/lib/str.mjs
+++ b/lib/str.mjs
@@ -18,27 +18,24 @@ function encodeTextNode(node) {
 function encodeNode(node) {
     const encodedChildren = isNil(node.children)
         ? undefined
-        : node.children.map(encodeAnyNode).filter((c) => Boolean(c));
+        : node.children.map(encodeAnyNode);
     return node instanceof Elem
         ? encodeHtmlElement(node.tagName, node.attrs, encodedChildren)
         : encodeHtmlFragment(encodedChildren);
 }
 function encodeHtmlFragment(children) {
-    return children?.join("") ?? "";
+    return concat(children ?? []);
 }
 function encodeHtmlElement(tagName, attrs, children) {
-    const open = `<${tagName} ${encodeAttrs(attrs)}>`;
+    const open = `<${join(" ", [tagName, encodeAttrs(attrs)])}>`;
     if (isNil(children))
         return open;
-    return `${open}${children.join("")}</${tagName}>`;
+    return `${open}${concat(children)}</${tagName}>`;
 }
 function encodeAttrs(attrs) {
     if (!attrs)
-        return "";
-    return Object.entries(attrs)
-        .map(([key, value]) => encodeAttr(key, value))
-        .filter(Boolean)
-        .join(" ");
+        return null;
+    return join(" ", Object.entries(attrs).map(([key, value]) => encodeAttr(key, value)));
 }
 function encodeAttr(key, value) {
     if (isNil(value))
@@ -47,3 +44,9 @@ function encodeAttr(key, value) {
         return value ? key : null;
     return `${key}="${value}"`;
 }
+function concat(arr) {
+    return join("", arr);
+}
+function join(sep, arr) {
+    return arr.filter(Boolean).join(sep);
+}
diff --git a/src/str.mts b/src/str.mts
index fd69ce8..ea859a9 100644
--- a/src/str.mts
+++ b/src/str.mts
@@ -1,6 +1,6 @@
 import { Renderer } from "./types.mjs";
-import { isBool, isNil, Nullable } from "./lang.mjs";
-import { AnyNode, Elem, Frag, TextNode } from "./nodes.mjs";
+import { isBool, isNil, Nilable, Nullable } from "./lang.mjs";
+import { AnyNode, Elem, ElemAttrs, Frag, TextNode } from "./nodes.mjs";
 
 export class StrRenderer implements Renderer<string> {
   render(node: Elem): string {
@@ -23,33 +23,33 @@ function encodeTextNode(node: TextNode): string {
 function encodeNode(node: Elem | Frag): string {
   const encodedChildren = isNil(node.children)
     ? undefined
-    : node.children.map(encodeAnyNode).filter((c): c is string => Boolean(c));
+    : node.children.map(encodeAnyNode);
   return node instanceof Elem
     ? encodeHtmlElement(node.tagName, node.attrs, encodedChildren)
     : encodeHtmlFragment(encodedChildren);
 }
 
-function encodeHtmlFragment(children?: string[]): string {
-  return children?.join("") ?? "";
+function encodeHtmlFragment(children?: Nilable<string>[]): string {
+  return concat(children ?? []);
 }
 
 function encodeHtmlElement(
   tagName: string,
-  attrs?: Record<string, unknown>,
-  children?: string[]
+  attrs?: ElemAttrs,
+  children?: Nilable<string>[]
 ): string {
-  const open = `<${tagName} ${encodeAttrs(attrs)}>`;
+  const open = `<${join(" ", [tagName, encodeAttrs(attrs)])}>`;
   if (isNil(children)) return open;
-  return `${open}${children.join("")}</${tagName}>`;
+  return `${open}${concat(children)}</${tagName}>`;
 }
 
-function encodeAttrs(attrs?: Record<string, unknown>): Nullable<string> {
-  if (!attrs) return "";
+function encodeAttrs(attrs?: ElemAttrs): Nullable<string> {
+  if (!attrs) return null;
 
-  return Object.entries(attrs)
-    .map(([key, value]) => encodeAttr(key, value))
-    .filter(Boolean)
-    .join(" ");
+  return join(
+    " ",
+    Object.entries(attrs).map(([key, value]) => encodeAttr(key, value))
+  );
 }
 
 function encodeAttr(key: string, value: unknown): Nullable<string> {
@@ -57,3 +57,11 @@ function encodeAttr(key: string, value: unknown): Nullable<string> {
   if (isBool(value)) return value ? key : null;
   return `${key}="${value}"`;
 }
+
+function concat(arr: Nilable<string>[]): string {
+  return join("", arr);
+}
+
+function join(sep: string, arr: Nilable<string>[]): string {
+  return arr.filter(Boolean).join(sep);
+}