handle Processing instructions in SimpleXmlParser

common/xml/src/main/java/io/helidon/build/common/xml/SimpleXMLParser.java

@@ -221,6 +221,16 @@ default List<String> readAttributeList(String name, String qName, Map<String, St
             Collections.addAll(values, value.split(","));
             return values;
         }
+
+        /**
+         * Receive notification of content data inside a processing instruction element.
+         *
+         * @param data the content data of a processing instruction
+         * @param target the name of an application to which the instruction is directed
+         * @throws XMLReaderException if any error occurs
+         */
+        default void processingInstruction(String target, String data) {
+        }
     }
 
     private enum STATE {
@@ -236,10 +246,14 @@ private enum STATE {
         ATTRIBUTE_VALUE,
         SINGLE_QUOTED_VALUE,
         DOUBLE_QUOTED_VALUE,
+        PI_TARGET,
+        PI_CONTENT
     }
 
-    private static final String PROLOG_START = "<?";
+    private static final String PROLOG_START = "<?xml";
     private static final String PROLOG_END = "?>";
+    private static final String PI_START = "<?";
+    private static final String PI_END = "?>";
     private static final String COMMENT_START = "<!--";
     private static final String COMMENT_END = "-->";
     private static final String ELEMENT_SELF_CLOSE = "/>";
@@ -367,6 +381,13 @@ private void processElement() throws IOException {
         } else if (hasToken(CLOSE_MARKUP_START)) {
             state = STATE.END_ELEMENT;
             position++;
+        } else if (hasToken(PI_START)) {
+            resumeState = STATE.PI_CONTENT;
+            state = STATE.PI_TARGET;
+            position += PI_START.length();
+        } else if (hasToken(PI_END)) {
+            state = STATE.END_ELEMENT;
+            position += PI_END.length();
         } else if (hasToken(MARKUP_START)) {
             resumeState = STATE.ATTRIBUTES;
             state = STATE.NAME;
@@ -511,6 +532,36 @@ private void processCdata() throws IOException {
         }
     }
 
+    private void processPIContent() throws IOException {
+        if (hasToken(PI_END)) {
+            position += PI_END.length();
+            state = STATE.ELEMENT;
+            String target = nameBuilder.toString();
+            reader.startElement(target, attributes);
+            reader.processingInstruction(target, decode(textBuilder.toString()));
+            reader.endElement(target);
+            nameBuilder = new StringBuilder();
+            textBuilder = new StringBuilder();
+        } else {
+            position++;
+            textBuilder.append(c);
+        }
+    }
+
+    private void processPITarget() throws IOException {
+        if (hasToken(PI_END)) {
+            state = resumeState;
+        } else if (Character.isWhitespace(c)) {
+            position++;
+            state = resumeState;
+        } else {
+            validateNameChar(c, nameBuilder.length() == 0);
+            position++;
+            nameBuilder.append(c);
+        }
+    }
+
+
     /**
      * Start parsing.
      *
@@ -564,6 +615,12 @@ public void parse() throws IOException {
                     case CDATA:
                         processCdata();
                         break;
+                    case PI_TARGET:
+                        processPITarget();
+                        break;
+                    case PI_CONTENT:
+                        processPIContent();
+                        break;
                     default:
                         throw new IllegalStateException(String.format(
                                 "Unknown state: %s, line: %d, char: %d", state, lineNo, charNo));

common/xml/src/test/java/io/helidon/build/common/xml/SimpleMXLParserTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Oracle and/or its affiliates.
+ * Copyright (c) 2021, 2022 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,6 +37,15 @@
  */
 class SimpleMXLParserTest {
 
+    @Test
+    void testParseProcessInstruction() throws IOException {
+        InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("test1.xml");
+        assertThat(inputStream, is(not(nullValue())));
+        Test1Reader reader = new Test1Reader();
+        SimpleXMLParser.parse(inputStream, reader);
+        assertThat(reader.m2e, is("execute onConfiguration,onIncremental"));
+    }
+
     @Test
     void testParse() throws IOException {
         InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("test1.xml");
@@ -117,6 +126,7 @@ private static final class Test1Reader implements Reader {
         String rootQName;
         String foo;
         String bob;
+        String m2e;
 
         @Override
         public void startElement(String name, Map<String, String> attributes) {
@@ -142,5 +152,14 @@ public void elementText(String data) {
                 }
             }
         }
+
+        @Override
+        public void processingInstruction(String target, String data) {
+            if (target != null) {
+                if ("m2e".equals(target)) {
+                    m2e = data;
+                }
+            }
+        }
     }
 }

common/xml/src/test/resources/test1.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-    Copyright (c) 2021 Oracle and/or its affiliates.
+    Copyright (c) 2021, 2022 Oracle and/or its affiliates.
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -19,7 +19,8 @@
 <document xmlns="http://acme.com/1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://acme.com/1.0 http://acme.com/xsd/acme-1.0.xsd">
     <foo>bar</foo>
-    <bob>alice</bob>
+    <bob attribute="name">alice</bob>
+    <?m2e execute onConfiguration,onIncremental?>
     <bar/>
     <booh />
 </document>