Add some auxiliary methods and doc string to XmlXPath

Author: jameslan

src/nodes.mts

@@ -192,8 +192,8 @@ export abstract class XmlNode {
 
     private compiledXPathEval(xpath: XmlXPath) {
         const context = xmlXPathNewContext(this._doc._docPtr);
-        if (xpath._namespaces) {
-            Object.entries(xpath._namespaces)
+        if (xpath.namespaces) {
+            Object.entries(xpath.namespaces)
                 .forEach(([prefix, uri]) => {
                     xmlXPathRegisterNs(context, prefix, uri);
                 });

src/xpath.mts

@@ -11,17 +11,47 @@ export interface NamespaceMap {
     [prefix: string]: string;
 }
 
+/**
+ * XPath object.
+ *
+ * This object compiles the xpath at creation,
+ * which could be reused many times, even for different documents.
+ *
+ * Note: This object requires to be {@link dispose}d explicitly.
+ */
 export class XmlXPath {
     _xpath: XmlXPathCompExprPtr;
 
-    _namespaces: NamespaceMap | undefined;
+    private readonly _xpathSource;
+
+    private readonly _namespaces: NamespaceMap | undefined;
 
     constructor(xpath: string, namespaces?: NamespaceMap) {
+        this._xpathSource = xpath;
         this._xpath = xmlXPathCtxtCompile(0, xpath);
         this._namespaces = namespaces;
     }
 
+    /**
+     * Dispose the XmlXPath.
+     *
+     * This needs to be called explicitly to avoid resource leak.
+     */
     dispose() {
         xmlXPathFreeCompExpr(this._xpath);
     }
+
+    /**
+     * Namespaces and prefixes used.
+     */
+    get namespaces(): NamespaceMap | undefined {
+        return this._namespaces;
+    }
+
+    /**
+     * XPath string.
+     */
+    toString(): string {
+        return this._xpathSource;
+    }
 }

test/xpath.spec.mts

@@ -32,5 +32,24 @@ describe('XPath', () => {
         const xpath = new XmlXPath('/book/m:title', { m: 'http://foo' });
         expect(doc.get(xpath)?.content).to.equal('Harry Potter');
         expect(doc.find(xpath).map((node) => node.content)).to.deep.equal(['Harry Potter']);
+        xpath.dispose();
+    });
+
+    it('should return undefined if namespace is not provided', () => {
+        const xpath = new XmlXPath(('/book'));
+        expect(xpath.namespaces).to.be.undefined;
+        xpath.dispose();
+    });
+
+    it('should return namespaces passed in', () => {
+        const xpath = new XmlXPath('/book/m:title', { m: 'http://foo' });
+        expect(xpath.namespaces).to.deep.equal({ m: 'http://foo' });
+        xpath.dispose();
+    });
+
+    it('should return xpath string by toString', () => {
+        const xpath = new XmlXPath(('/book'));
+        expect(xpath.toString()).to.equal('/book');
+        xpath.dispose();
     });
 });