feat(xml): added indents to xml

Author: dk949

src/XML/common.ts

@@ -1,25 +1,30 @@
 export class baseXMLBUilder {
     protected _data: string[] = [];
+    private tab: string = "    ";
+    private indent: number = 0;
 
     protected putTag(name: string, attr: {[key: string]: string},
         contents?: (() => void) | string) {
-        const attrStr =
-            Object.entries(attr)
+        const attrStr = (() => {
+            const a = Object.entries(attr)
                 .map(([key, value]) => {return `${key}="${value}"`;})
                 .join(' ');
+            return a ? " " + a : "";
+        })();
 
         if (!contents) {
-            this._data.push(`<${name} ${attrStr}/>`);
+            this._data.push(`${this.tab.repeat(this.indent)}<${name}${attrStr} />`);
             return;
         }
 
-        this._data.push(`<${name} ${attrStr}>`);
+        this._data.push(`${this.tab.repeat(this.indent)}<${name}${attrStr}>`);
         if (typeof contents === "function") {
+            this.indent++;
             contents();
-            this._data.push(`</${name}>`);
+            this.indent--
+            this._data.push(`${this.tab.repeat(this.indent)}</${name}>`);
         } else {
-            const tmp: string[] = [contents, `</${name}>`];
-            this._data[this._data.length - 1] += tmp.join("");
+            this._data[this._data.length - 1] += `${contents}</${name}>`;
         }
     }