allow targets to deal with missing extension points. PR 49473. Submitted by Danny Yates.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@957170 13f79535-47bb-0310-9956-ffa450edef68

CONTRIBUTORS

@@ -70,6 +70,7 @@ Daniel Henrique
 Daniel Ribagnac
 Daniel Spilker
 Danno Ferrin
+Danny Yates
 Dante Briones
 Davanum Srinivas
 Dave Brondsema

WHATSNEW

@@ -27,6 +27,11 @@ Changes that could break older environments:
    formatter where ampersands will now always get encoded.
    Bugzilla Report 49404.
 
+ * The list elements returned by ProjectHelper#getExtensionStack are
+   now String arrays of length 3 rather than 2 in order to support the
+   onMissingExtensionPoint attribute.
+   Bugzilla Report 49473.   
+
 Fixed bugs:
 -----------
 
@@ -100,6 +105,13 @@ Other changes:
    when used in any other way than a CLASSPATH for a forked Java VM. 
    Bugzilla Report 46842.
 
+ * A new attribute allows targets to deal with non-existant extensions
+   points, i.e. they can extend and extension-point if it has been
+   defined or silently work as plain targets if it hasn't.  This is
+   useful for targets that get included/imported in different
+   scenarios where a given extension-point may or may not exist.
+   Bugzilla Report 49473.   
+
 Changes from Ant 1.8.0 TO Ant 1.8.1 
 ===================================
 

contributors.xml

@@ -303,6 +303,10 @@
     <first>Danno</first>
     <last>Ferrin</last>
   </name>
+  <name>
+    <first>Danny</first>
+    <last>Yates</last>
+  </name>
   <name>
     <first>Dante</first>
     <last>Briones</last>

docs/manual/targets.html

@@ -205,6 +205,17 @@
         <em>since Ant 1.8.0.</em></td>
       <td align="center" valign="top">No</td>
     </tr>
+    <tr>
+      <td valign="top">onMissingExtensionPoint</td>
+      <td valign="top">What to do if this target tries to extend a
+        missing
+        <a href="#extension-points">extension-point</a>. ("fail",
+        "warn", "ignore").
+        <em>since Ant 1.8.2.</em></td>
+      <td align="center" valign="top">No. Not allowed unless
+        <code>extensionOf</code> is present. Defaults to <code>fail</code>. 
+      </td>
+    </tr>
   </table>
 
   <p>A target name can be any alphanumeric string valid in the

src/main/org/apache/tools/ant/ProjectHelper.java

@@ -82,6 +82,23 @@ public class ProjectHelper {
         helper.parse(project, buildFile);
     }
 
+    /**
+     * Possible value for target's onMissingExtensionPoint attribute:
+     * fail if the extension-point is not defined.
+     */
+    public static final String MISSING_EP_FAIL = "fail";
+    /**
+     * Possible value for target's onMissingExtensionPoint attribute:
+     * warn if the extension-point is not defined.
+     */
+    public static final String MISSING_EP_WARN = "warn";
+    /**
+     * Possible value for target's onMissingExtensionPoint attribute:
+     * ignore the extensionOf attribute if the extension-point is not
+     * defined.
+     */
+    public static final String MISSING_EP_IGNORE = "ignore";
+
     /** Default constructor */
     public ProjectHelper() {
     }
@@ -108,9 +125,11 @@ public class ProjectHelper {
      * Extension stack.
      * Used to keep track of targets that extend extension points.
      *
-     * @return a list of two element string arrays where the first
-     * element is the name of the extensionpoint and the second the
-     * name of the target
+     * @return a list of three element string arrays where the first
+     * element is the name of the extensionpoint, the second the name
+     * of the target and the third one of the MISSINS_EP constants
+     * defined inside this class - it determines how to deal with
+     * targets that want to extend missing extension-points.
      */
     public List getExtensionStack() {
         return extensionStack;

src/main/org/apache/tools/ant/helper/ProjectHelper2.java

@@ -59,6 +59,7 @@ import java.util.Stack;
  *
  */
 public class ProjectHelper2 extends ProjectHelper {
+
     /** Reference holding the (ordered) target Vector */
     public static final String REFID_TARGETS = "ant.targets";
 
@@ -183,21 +184,29 @@ public class ProjectHelper2 extends ProjectHelper {
                 String[] extensionInfo = (String[]) i.next();
                 String tgName = extensionInfo[0];
                 String name = extensionInfo[1];
+                String missingBehaviour = extensionInfo[2];
                 Hashtable projectTargets = project.getTargets();
                 if (!projectTargets.containsKey(tgName)) {
-                    throw new BuildException("can't add target "
-                                             + name + " to extension-point "
-                                             + tgName
-                                             + " because the extension-point"
-                                             + " is unknown.");
-                }
-                Target t = (Target) projectTargets.get(tgName);
-                if (!(t instanceof ExtensionPoint)) {
-                    throw new BuildException("referenced target "
-                                             + tgName
-                                             + " is not an extension-point");
+                    String message = "can't add target " + name
+                        + " to extension-point " + tgName
+                        + " because the extension-point is unknown.";
+                    if (missingBehaviour.equals(MISSING_EP_FAIL)) {
+                        throw new BuildException(message);
+                    } else if (missingBehaviour.equals(MISSING_EP_WARN)) {
+                        Target target = (Target) projectTargets.get(name);
+                        context.getProject().log(target,
+                                                 "Warning: " + message,
+                                                 Project.MSG_WARN);
+                    }
+                } else {
+                    Target t = (Target) projectTargets.get(tgName);
+                    if (!(t instanceof ExtensionPoint)) {
+                        throw new BuildException("referenced target "
+                                                 + tgName
+                                                 + " is not an extension-point");
+                    }
+                    t.addDependency(name);
                 }
-                t.addDependency(name);
             }
         }
     }
@@ -250,7 +259,7 @@ public class ProjectHelper2 extends ProjectHelper {
             buildFileName = url.toString();
         } else {
             throw new BuildException("Source " + source.getClass().getName()
-                    + " not supported by this plugin");
+                                     + " not supported by this plugin");
         }
         InputStream inputStream = null;
         InputSource inputSource = null;
@@ -297,7 +306,7 @@ public class ProjectHelper2 extends ProjectHelper {
             parser.parse(inputSource);
         } catch (SAXParseException exc) {
             Location location = new Location(exc.getSystemId(), exc.getLineNumber(), exc
-                    .getColumnNumber());
+                                             .getColumnNumber());
 
             Throwable t = exc.getException();
             if (t instanceof BuildException) {
@@ -317,11 +326,11 @@ public class ProjectHelper2 extends ProjectHelper {
         } catch (FileNotFoundException exc) {
             throw new BuildException(exc);
         } catch (UnsupportedEncodingException exc) {
-              throw new BuildException("Encoding of project file " + buildFileName + " is invalid.",
-                    exc);
+            throw new BuildException("Encoding of project file " + buildFileName + " is invalid.",
+                                     exc);
         } catch (IOException exc) {
             throw new BuildException("Error reading project file " + buildFileName + ": "
-                    + exc.getMessage(), exc);
+                                     + exc.getMessage(), exc);
         } finally {
             FileUtils.close(inputStream);
             ZipFile.closeQuietly(zf);
@@ -440,7 +449,7 @@ public class ProjectHelper2 extends ProjectHelper {
         public AntHandler onStartChild(String uri, String tag, String qname, Attributes attrs,
                                        AntXMLContext context) throws SAXParseException {
             throw new SAXParseException("Unexpected element \"" + qname + " \"", context
-                    .getLocator());
+                                        .getLocator());
         }
 
         /**
@@ -453,7 +462,7 @@ public class ProjectHelper2 extends ProjectHelper {
          * @exception SAXParseException if an error occurs
          */
         public void onEndChild(String uri, String tag, String qname, AntXMLContext context)
-                throws SAXParseException {
+            throws SAXParseException {
         }
 
         /**
@@ -480,7 +489,7 @@ public class ProjectHelper2 extends ProjectHelper {
          *                              case of error in an overridden version
          */
         public void characters(char[] buf, int start, int count, AntXMLContext context)
-                throws SAXParseException {
+            throws SAXParseException {
             String s = new String(buf, start, count).trim();
 
             if (s.length() > 0) {
@@ -548,9 +557,9 @@ public class ProjectHelper2 extends ProjectHelper {
                 if (!file.isAbsolute()) {
                     file = FILE_UTILS.resolveFile(context.getBuildFileParent(), path);
                     context.getProject().log(
-                            "Warning: '" + systemId + "' in " + context.getBuildFile()
-                                    + " should be expressed simply as '" + path.replace('\\', '/')
-                                    + "' for compliance with other XML tools", Project.MSG_WARN);
+                                             "Warning: '" + systemId + "' in " + context.getBuildFile()
+                                             + " should be expressed simply as '" + path.replace('\\', '/')
+                                             + "' for compliance with other XML tools", Project.MSG_WARN);
                 }
                 context.getProject().log("file=" + file, Project.MSG_DEBUG);
                 try {
@@ -559,7 +568,7 @@ public class ProjectHelper2 extends ProjectHelper {
                     return inputSource;
                 } catch (FileNotFoundException fne) {
                     context.getProject().log(file.getAbsolutePath() + " could not be found",
-                            Project.MSG_WARN);
+                                             Project.MSG_WARN);
                 }
 
             }
@@ -583,7 +592,7 @@ public class ProjectHelper2 extends ProjectHelper {
          *                              <code>"project"</code>
          */
         public void startElement(String uri, String tag, String qname, Attributes attrs)
-                throws SAXParseException {
+            throws SAXParseException {
             AntHandler next = currentHandler.onStartChild(uri, tag, qname, attrs, context);
             antHandlers.push(currentHandler);
             currentHandler = next;
@@ -678,10 +687,10 @@ public class ProjectHelper2 extends ProjectHelper {
             }
             if (name.equals(qname)) {
                 throw new SAXParseException("Unexpected element \"{" + uri
-                    + "}" + name + "\" {" + ANT_CORE_URI + "}" + name, context.getLocator());
+                                            + "}" + name + "\" {" + ANT_CORE_URI + "}" + name, context.getLocator());
             }
             throw new SAXParseException("Unexpected element \"" + qname
-                    + "\" " + name, context.getLocator());
+                                        + "\" " + name, context.getLocator());
         }
     }
 
@@ -774,7 +783,7 @@ public class ProjectHelper2 extends ProjectHelper {
                 } else {
                     // XXX ignore attributes in a different NS ( maybe store them ? )
                     throw new SAXParseException("Unexpected attribute \"" + attrs.getQName(i)
-                            + "\"", context.getLocator());
+                                                + "\"", context.getLocator());
                 }
             }
 
@@ -805,8 +814,8 @@ public class ProjectHelper2 extends ProjectHelper {
 
                 if (context.isIgnoringProjectTag() && !dupFile.equals(contextFile)) {
                     project.log("Duplicated project name in import. Project "
-                            + context.getCurrentProjectName() + " defined first in " + dup
-                            + " and again in " + contextFile, Project.MSG_WARN);
+                                + context.getCurrentProjectName() + " defined first in " + dup
+                                + " and again in " + contextFile, Project.MSG_WARN);
                 }
             }
             if (nameAttributeSet) {
@@ -839,7 +848,7 @@ public class ProjectHelper2 extends ProjectHelper {
                         project.setBasedir(baseDir);
                     } else {
                         project.setBaseDir(FILE_UTILS.resolveFile(context.getBuildFileParent(),
-                                baseDir));
+                                                                  baseDir));
                     }
                 }
             }
@@ -905,6 +914,7 @@ public class ProjectHelper2 extends ProjectHelper {
             String name = null;
             String depends = "";
             String extensionPoint = null;
+            String extensionPointMissing = null;
 
             Project project = context.getProject();
             Target target = "target".equals(tag)
@@ -940,15 +950,17 @@ public class ProjectHelper2 extends ProjectHelper {
                     target.setDescription(value);
                 } else if (key.equals("extensionOf")) {
                     extensionPoint = value;
+                } else if (key.equals("onMissingExtensionPoint")) {
+                    extensionPointMissing = value;
                 } else {
                     throw new SAXParseException("Unexpected attribute \"" + key + "\"", context
-                            .getLocator());
+                                                .getLocator());
                 }
             }
 
             if (name == null) {
                 throw new SAXParseException("target element appears without a name attribute",
-                        context.getLocator());
+                                            context.getLocator());
             }
 
             String prefix = null;
@@ -978,7 +990,7 @@ public class ProjectHelper2 extends ProjectHelper {
             // If the name has not already been defined define it
             if (projectTargets.containsKey(name)) {
                 project.log("Already defined in main or a previous import, ignore " + name,
-                        Project.MSG_VERBOSE);
+                            Project.MSG_VERBOSE);
             } else {
                 target.setName(name);
                 context.getCurrentTargets().put(name, target);
@@ -1008,10 +1020,16 @@ public class ProjectHelper2 extends ProjectHelper {
                 context.getCurrentTargets().put(newName, newTarget);
                 project.addOrReplaceTarget(newName, newTarget);
             }
+            if (extensionPointMissing != null && extensionPoint == null) {
+                throw new BuildException("onMissingExtensionPoint attribute cannot " +
+                                         "be specified unless extensionOf is specified", 
+                                         target.getLocation());
+
+            }
             if (extensionPoint != null) {
                 ProjectHelper helper =
                     (ProjectHelper) context.getProject().
-                        getReference(ProjectHelper.PROJECTHELPER_REFERENCE);
+                    getReference(ProjectHelper.PROJECTHELPER_REFERENCE);
                 for (Iterator iter =
                          Target.parseDepends(extensionPoint, name, "extensionOf")
                          .iterator();
@@ -1020,12 +1038,26 @@ public class ProjectHelper2 extends ProjectHelper {
                     if (isInIncludeMode()) {
                         tgName = prefix + sep + tgName;
                     }
-
-                    // defer extensionpoint resolution until the full
-                    // import stack has been processed
-                    helper.getExtensionStack().add(new String[] {
-                            tgName, name
-                        });
+                    if (extensionPointMissing == null) {
+                        extensionPointMissing = MISSING_EP_FAIL;
+                    }
+                    if (extensionPointMissing.equals(MISSING_EP_FAIL) ||
+                        extensionPointMissing.equals(MISSING_EP_IGNORE) ||
+                        extensionPointMissing.equals(MISSING_EP_WARN)) {
+                        // defer extensionpoint resolution until the full
+                        // import stack has been processed
+                        helper.getExtensionStack().add(new String[] {
+                                tgName, name, extensionPointMissing
+                            });
+                    } else {
+                        throw new BuildException("onMissingExtensionPoint"
+                                                 + " attribute can only be '"
+                                                 + MISSING_EP_FAIL
+                                                 + "', '" + MISSING_EP_WARN
+                                                 + "' or '" + MISSING_EP_IGNORE
+                                                 + "'", 
+                                                 target.getLocation());
+                    }
                 }
             }
         }
@@ -1128,7 +1160,7 @@ public class ProjectHelper2 extends ProjectHelper {
             task.setTaskName(qname);
 
             Location location = new Location(context.getLocator().getSystemId(), context
-                    .getLocator().getLineNumber(), context.getLocator().getColumnNumber());
+                                             .getLocator().getLineNumber(), context.getLocator().getColumnNumber());
             task.setLocation(location);
             task.setOwningTarget(context.getCurrentTarget());
 
@@ -1159,8 +1191,8 @@ public class ProjectHelper2 extends ProjectHelper {
                 // be namespaced, need to extract the name
                 // and convert from qualified name to uri/name
                 if (ANT_TYPE.equals(name)
-                        || (ANT_CORE_URI.equals(attrUri)
-                            && ANT_TYPE.equals(attrs.getLocalName(i)))) {
+                    || (ANT_CORE_URI.equals(attrUri)
+                        && ANT_TYPE.equals(attrs.getLocalName(i)))) {
                     name = ANT_TYPE;
                     int index = value.indexOf(":");
                     if (index >= 0) {
@@ -1168,10 +1200,10 @@ public class ProjectHelper2 extends ProjectHelper {
                         String mappedUri = context.getPrefixMapping(prefix);
                         if (mappedUri == null) {
                             throw new BuildException("Unable to find XML NS prefix \"" + prefix
-                                    + "\"");
+                                                     + "\"");
                         }
                         value = ProjectHelper.genComponentName(mappedUri, value
-                                .substring(index + 1));
+                                                               .substring(index + 1));
                     }
                 }
                 wrapper.setAttribute(name, value);

src/main/org/apache/tools/ant/taskdefs/AntStructure.java

@@ -106,8 +106,8 @@ public class AntStructure extends Task {
             while (dataTypes.hasNext()) {
                 String typeName = (String) dataTypes.next();
                 printer.printElementDecl(
-                    out, getProject(), typeName,
-                    (Class) getProject().getDataTypeDefinitions().get(typeName));
+                                         out, getProject(), typeName,
+                                         (Class) getProject().getDataTypeDefinitions().get(typeName));
             }
 
             Iterator tasks = getProject().getCopyOfTaskDefinitions().keySet()
@@ -266,13 +266,14 @@ public class AntStructure extends Task {
         private void printTargetAttrs(PrintWriter out, String tag) {
             out.print("<!ATTLIST ");
             out.println(tag);
-            out.println("          id          ID    #IMPLIED");
-            out.println("          name        CDATA #REQUIRED");
-            out.println("          if          CDATA #IMPLIED");
-            out.println("          unless      CDATA #IMPLIED");
-            out.println("          depends     CDATA #IMPLIED");
-            out.println("          extensionOf CDATA #IMPLIED");
-            out.println("          description CDATA #IMPLIED>");
+            out.println("          id                      ID    #IMPLIED");
+            out.println("          name                    CDATA #REQUIRED");
+            out.println("          if                      CDATA #IMPLIED");
+            out.println("          unless                  CDATA #IMPLIED");
+            out.println("          depends                 CDATA #IMPLIED");
+            out.println("          extensionOf             CDATA #IMPLIED");
+            out.println("          onMissingExtensionPoint CDATA #IMPLIED");
+            out.println("          description             CDATA #IMPLIED>");
             out.println("");
         }
 

src/tests/antunit/core/extension-point-test.xml

@@ -88,4 +88,49 @@
     <au:assertLogContains text="in target prepare"/>
   </target>
 
+  <target name="testMissingExtensionPointCausesError">
+    <mkdir dir="${output}"/>
+    <echo file="${output}/build.xml"><![CDATA[
+<project default="bar">
+  <target name="bar" extensionOf="foo"/>
+</project>]]></echo>
+    <au:expectfailure
+        expectedMessage="can't add target bar to extension-point foo because the extension-point is unknown">
+      <ant dir="${output}" target="bar"/>
+    </au:expectfailure>
+  </target>
+
+  <target name="testMissingExtensionPointCausesWarningWhenConfigured">
+    <mkdir dir="${output}"/>
+    <echo file="${output}/build.xml"><![CDATA[
+<project default="bar">
+  <target name="bar" extensionOf="foo" onMissingExtensionPoint="warn"/>
+</project>]]></echo>
+    <ant dir="${output}" target="bar"/>
+    <au:assertLogContains level="warning"
+        text="can't add target bar to extension-point foo because the extension-point is unknown" />
+  </target>
+
+  <target name="testMissingExtensionPointIgnoredWhenConfigured">
+    <mkdir dir="${output}"/>
+    <echo file="${output}/build.xml"><![CDATA[
+<project default="bar">
+  <target name="bar" extensionOf="foo" onMissingExtensionPoint="ignore"/>
+</project>]]></echo>
+    <ant dir="${output}" target="bar"/>
+    <au:assertLogDoesntContain level="warning"
+        text="can't add target bar to extension-point foo because the extension-point is unknown" />
+  </target>
+
+  <target name="testOnlyAllowsExtensionPointMissingAttributeWhenExtensionOfPresent">
+    <mkdir dir="${output}"/>
+    <echo file="${output}/build.xml"><![CDATA[
+<project default="bar">
+  <target name="bar" onMissingExtensionPoint="ignore"/>
+</project>]]></echo>
+    <au:expectfailure
+        expectedMessage="onMissingExtensionPoint attribute cannot be specified unless extensionOf is specified">
+      <ant dir="${output}" target="bar"/>
+    </au:expectfailure>
+  </target>
 </project>