Add failsafe for stream parsers

Ensure both open and close tags have been read.

src/streams.ts

@@ -8,9 +8,14 @@ export interface XmlToJsonLinesTransformStreamOptions {
 class XmlToJsonLinesTransformStream extends Transform {
   private charactersToParse?: string;
 
-  constructor(private readonly options: XmlToJsonLinesTransformStreamOptions) {
+  private readonly openTag: string;
+
+  private readonly closeTag: string;
+
+  constructor(options: XmlToJsonLinesTransformStreamOptions) {
     super();
-    // noop
+    this.openTag = `<${options.entryTagName}>`;
+    this.closeTag = `</${options.entryTagName}>`;
   }
 
   // eslint-disable-next-line no-underscore-dangle
@@ -18,26 +23,29 @@ class XmlToJsonLinesTransformStream extends Transform {
     try {
       const chunkStr = chunk.toString('utf-8');
       if (typeof this.charactersToParse !== 'string') {
-        const firstEntryIndex = chunkStr.indexOf(`<${this.options.entryTagName}>`);
+        const firstEntryIndex = chunkStr.indexOf(this.openTag);
         this.charactersToParse = chunkStr.slice(firstEntryIndex);
       } else {
         this.charactersToParse += chunkStr;
       }
 
       let theCharacters = `${this.charactersToParse}`;
-      let nextOpenTagIndex = theCharacters.indexOf(`<${this.options.entryTagName}>`);
-      let nextCloseTagIndex = theCharacters.indexOf(`</${this.options.entryTagName}>`);
-      const closeTagLength = this.options.entryTagName.length + 3;
+      let nextOpenTagIndex = theCharacters.indexOf(this.openTag);
+      let nextCloseTagIndex = theCharacters.indexOf(this.closeTag);
+      let sliceEnd = nextCloseTagIndex + this.closeTag.length;
       do {
-        const xml = theCharacters
-          .slice(nextOpenTagIndex, nextCloseTagIndex + closeTagLength)
-          .replace(/&(.+?);/g, '$1'); // FIXME better handling of XML entities??? This makes the pipe hang for some reason
-        const json = xml2json(xml, { compact: true });
-        this.push(`${json}\n`);
-        theCharacters = theCharacters.slice(nextCloseTagIndex + closeTagLength);
-        nextOpenTagIndex = theCharacters.indexOf(`<${this.options.entryTagName}>`);
-        nextCloseTagIndex = theCharacters.indexOf(`</${this.options.entryTagName}>`);
-      } while (nextOpenTagIndex !== -1 && nextCloseTagIndex !== -1);
+        if (nextOpenTagIndex > -1 && nextCloseTagIndex > -1) {
+          const xml = theCharacters
+            .slice(nextOpenTagIndex, sliceEnd)
+            .replace(/&(.+?);/g, '$1'); // FIXME better handling of XML entities??? This makes the pipe hang for some reason
+          const json = xml2json(xml, { compact: true });
+          this.push(`${json}\n`);
+          theCharacters = theCharacters.slice(sliceEnd);
+        }
+        nextOpenTagIndex = theCharacters.indexOf(this.openTag);
+        nextCloseTagIndex = theCharacters.indexOf(this.closeTag);
+        sliceEnd = nextCloseTagIndex + this.closeTag.length;
+      } while (nextOpenTagIndex > -1 && nextCloseTagIndex > -1);
       this.charactersToParse = theCharacters;
       callback(null, '');
     } catch (err) {