xml plugin initial import

plugins/dbgate-plugin-xml/src/backend/reader.js

@@ -0,0 +1,42 @@
+const fs = require('fs');
+const stream = require('stream');
+const NodeXmlStream = require('node-xml-stream');
+
+class ParseStream extends stream.Transform {
+  constructor({ elementName }) {
+    super({ objectMode: true });
+    this.rowsWritten = 0;
+    this.parser = new NodeXmlStream();
+    this.stack = [];
+    this.parser.on('opentag', (name, attrs) => {
+      this.stack.push({ name, attrs, nodes: {} });
+    });
+    this.parser.on('text', (text) => {
+      if (this.stack.length >= 2) {
+        this.stack[this.stack.length - 2].nodes[this.stack[this.stack.length - 1].name] = text;
+      }
+    });
+    this.parser.on('closetag', (name, attrs) => {
+      if (name == elementName) {
+        this.rowsWritten += 1;
+        this.push({ ...this.stack[this.stack.length - 1].attrs, ...this.stack[this.stack.length - 1].nodes });
+      }
+      this.stack.splice(-1);
+    });
+  }
+  _transform(chunk, encoding, done) {
+    this.parser.write(chunk);
+    done();
+  }
+}
+
+async function reader({ fileName, encoding = 'utf-8', elementName }) {
+  console.log(`Reading file ${fileName}`);
+
+  const fileStream = fs.createReadStream(fileName, encoding);
+  const parser = new ParseStream({ elementName });
+  fileStream.pipe(parser);
+  return parser;
+}
+
+module.exports = reader;