Add Get Current XPath

This commit also moves some shared code to a common class.

Issue: #85

src/xpath/commands/getCurrentXPath.ts

@@ -0,0 +1,21 @@
+import { window } from "vscode";
+import { TextEditor, TextEditorEdit } from "vscode";
+import { DOMParser } from "xmldom";
+
+import { XPathBuilder } from "../xpath-builder";
+
+export function getCurrentXPath(editor: TextEditor, edit: TextEditorEdit): void {
+    if (!editor.selection) {
+        window.showInformationMessage("Please put your cursor in an element or attribute name.");
+
+        return;
+    }
+
+    const document = new DOMParser().parseFromString(editor.document.getText());
+    const xpath = new XPathBuilder(document).build(editor.selection.start);
+
+    window.showInputBox({
+        value: xpath,
+        valueSelection: undefined
+    });
+}

src/xpath/commands/index.ts

@@ -1 +1,2 @@
 export * from "./evaluateXPath";
+export * from "./getCurrentXPath";

src/xpath/index.ts

@@ -1 +1,2 @@
+export * from "./xpath-builder";
 export * from "./xpath-evaluator";

src/xpath/xpath-builder.ts

@@ -0,0 +1,41 @@
+import { Position } from "vscode";
+import { DOMParser } from "xmldom";
+
+import { XmlTraverser } from "../common";
+
+export class XPathBuilder {
+
+    private _xmlTraverser: XmlTraverser;
+
+    constructor(private _xmlDocument: Document) {
+        this._xmlTraverser = new XmlTraverser(this._xmlDocument);
+    }
+
+    build(position: Position): string {
+        const selectedNode = this._xmlTraverser.getNodeAtPosition(position);
+
+        return this._buildCore(selectedNode);
+    }
+
+    private _buildCore(selectedNode: Node): string {
+        if (selectedNode === this._xmlDocument.documentElement) {
+            return `/${selectedNode.nodeName}`;
+        }
+
+        if (!this._xmlTraverser.isElement(selectedNode)) {
+            return `${this._buildCore((selectedNode as any).ownerElement)}/@${selectedNode.nodeName}`;
+        }
+
+        else if (this._xmlTraverser.hasSimilarSiblings(selectedNode)) {
+            const siblings = this._xmlTraverser.getSiblings(selectedNode);
+            const xPathIndex = (siblings.indexOf(selectedNode) + 1);
+
+            return `${this._buildCore(selectedNode.parentNode)}/${selectedNode.nodeName}[${xPathIndex}]`;
+        }
+
+        else {
+            return `${this._buildCore(selectedNode.parentNode)}/${selectedNode.nodeName}`;
+        }
+    }
+
+}