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From: Michel Pawlak <michel.pawlak@gmail.com>
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Date: Sat, 28 Jan 2017 15:51:10 +0100
Subject: What's the correct way to use InputLocationTracker?
Message-Id: <1E1413C8-08C7-4B95-9601-EF4306845756@gmail.com>
To: dev@maven.apache.org
archived-at: Sat, 28 Jan 2017 14:51:32 -0000

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Hi all,

I need some help with issues I=E2=80=99m facing when using =
org.apache.maven.model.InputLocationTracker.

Let=E2=80=99s first have a look at this sample class file (I tried to =
only keep what is relevant to the issue.)

-[snip]=E2=80=94
import java.util.ArrayList;
import java.util.List;
import org.apache.maven.model.Build;
import org.apache.maven.model.InputLocation;
import org.apache.maven.model.InputLocationTracker;
import org.apache.maven.model.Model;
import org.apache.maven.model.Plugin;
import org.codehaus.plexus.util.FileUtils;
import org.codehaus.plexus.util.xml.Xpp3Dom;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Sample check that verifies if Java source version is the ones that is =
expected.
 */
public class JavaSourceVersionCheck {

    private static final Logger LOGGER =3D =
LoggerFactory.getLogger(JavaSourceVersionCheck.class);

    private static final String MAVEN_COMPILER_PLUGIN_GROUPID =3D =
"org.apache.maven.plugins";

    private static final String MAVEN_COMPILER_PLUGIN_ARTIFACTID =3D =
"maven-compiler-plugin";

    /**
     * Default Java source version.
     */
    public static final String EXPECTED_JAVA_SOURCE_VERSION =3D "1.7";

    /**
     * Default Java target version.
     */
    public static final String EXPECTED_JAVA_TARGET_VERSION =3D "1.7";

    /**
     * Executes the check on a Maven Model instance.
     *
     * @param model Maven raw Model (i.e. with unresolved pom =
inheritance)
     */
    public void execute(final Model model) {
        LOGGER.debug("checking Model");
        final Build build =3D model.getBuild();
        if (build !=3D null) {
            for (final Plugin plugin : build.getPlugins()) {
                if (isMavenCompilerPlugin(plugin)) {
                    LOGGER.debug("Maven compiler plugin found!");
                    checkJavaSourceVersion(plugin);
                }
            }
        }
        LOGGER.debug("done");
    }

    private boolean isMavenCompilerPlugin(final Plugin plugin) {
        return MAVEN_COMPILER_PLUGIN_GROUPID.equals(plugin.getGroupId()) =
&& MAVEN_COMPILER_PLUGIN_ARTIFACTID.equals(plugin.getArtifactId());
    }

    private void checkJavaSourceVersion(final Plugin plugin) {
        final Xpp3Dom configuration =3D (Xpp3Dom) =
plugin.getConfiguration();
        final Xpp3Dom sourceDom =3D configuration.getChild("source");
        LOGGER.debug("Configuration DOM: {}", configuration.toString());
        if (sourceDom !=3D null) {
            LOGGER.debug("Found <source> tag, checking its value");
            final String sourceValue =3D sourceDom.getValue();
            if (!sourceValue.equals(EXPECTED_JAVA_SOURCE_VERSION)) {
                final InputLocation location =3D locate(plugin, =
=E2=80=9Cconfiguration", "source");
                // here I should do something else with the location =
instance, but as I want to keep the sample as simple as possible, =
let=E2=80=99s just log a message
                LOGGER.warn(=E2=80=9Cnon compliant value: is {} but =
should be {} (issue was found at {} column {})", sourceValue, =
EXPECTED_JAVA_SOURCE_VERSION, location.getLineNumber(),
                    location.getColumnNumber());
            }
        }
    }

    /**
     * Locates the line in the {@link Model} POM where XML tags below an =
{@link InputLocationTracker} is located.
     *
     * @param locationTracker Maven {@link Model} {@link =
InputLocationTracker} for which the line has to be retrieved.
     * @param tags list of tags to drill down, the last one representing =
the tag for which the line has to be retrieved.
     * @return an IssueLocation representing the line and column in the =
{@link Model} where the last tag of the {@code tags} list below {@link =
InputLocationTracker} is located.
     */
    public final InputLocation locate(final InputLocationTracker =
locationTracker, final String... tags) {
        final List<String> tagsList =3D new ArrayList<>();
        if (tags.length =3D=3D 0) {
            tagsList.add("");
        } else {
            for (final String tag : tags) {
                tagsList.add(tag);
            }
        }
        final InputLocation inputLocation =3D locate(locationTracker, =
tagsList);
        LOGGER.debug("\t<{}> tag located at line {}, column {})", =
tagsList.get(tagsList.size() - 1), inputLocation.getLineNumber(), =
inputLocation.getColumnNumber());
        return inputLocation;

    }

    private final InputLocation locate(final InputLocationTracker =
locationTracker, final List<String> tags) {
        InputLocation inputLocation =3D null;
        for (final String tag : tags) {
            if (inputLocation =3D=3D null) {
                inputLocation =3D locationTracker.getLocation(tag);
            } else {
                // InputLocation is an InputLocationTracker
                final InputLocation tempInputLocation =3D =
inputLocation.getLocation(tag); // (1)=20
                if (tempInputLocation =3D=3D null) {
                    LOGGER.error("InputLocation for tag <{}> is null, =
returning position of last tag that has been found", tag);
                    break;
                } else {
                    inputLocation =3D tempInputLocation;
                }
            }
        }
        return inputLocation;
    }

    public static void main(final String[] args) throws Exception {
        final Model model =3D RawMavenModelFactory.instance()
            =
.buildWith(FileUtils.toFile(JavaSourceVersionCheck.class.getClassLoader()
                .getResource("pom.xml")));
        final JavaSourceVersionCheck check =3D new =
JavaSourceVersionCheck();
        check.execute(model);
    }

}
-[snip]=E2=80=94

Here is the code of the buildWith() method:

-[snip]=E2=80=94
    public Model buildWith(final File pomFile) throws =
MavenModelBuildingException {
        final MavenXpp3ReaderEx reader =3D new MavenXpp3ReaderEx();
        reader.setAddDefaultEntities(false);
        try {
            return reader.read(new FileInputStream(pomFile), true, new =
InputSource());
        } catch (IOException | XmlPullParserException e) {
            throw new MavenModelBuildingException("Could not build Maven =
model.", e);
        }
    }
-[snip]=E2=80=94

The dependencies I=E2=80=99m using here are the following:

-[snip]=E2=80=94
<lib.maven.version>3.3.3</lib.maven.version>
<lib.aether.version>1.0.2.v20150114</lib.aether.version>
-[snip]=E2=80=94

And here is the sample pom.xml file that is used by the main method:

-[snip]=E2=80=94
<project xmlns=3D"http://maven.apache.org/POM/4.0.0" =
xmlns:xsi=3D"http://www.w3.org/2001/XMLSchema-instance" =
xsi:schemaLocation=3D"http://maven.apache.org/POM/4.0.0 =
http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>test</groupId>
  <artifactId>test</artifactId>
  <version>1.0.0-SNAPSHOT</version>
  <properties>
    =
<plugin.maven-compiler-plugin.version>3.3</plugin.maven-compiler-plugin.ve=
rsion>
  </properties>
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>${plugin.maven-compiler-plugin.version}</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>
-[snip]=E2=80=94

When run the code, I get the following output:

-[snip]=E2=80=94
15:21:35.822 [main] DEBUG JavaSourceVersionCheck - checking Model
15:21:35.826 [main] DEBUG JavaSourceVersionCheck - Maven compiler plugin =
found!
15:21:35.830 [main] DEBUG JavaSourceVersionCheck - Configuration DOM: =
<?xml version=3D"1.0" encoding=3D"UTF-8"?>
<configuration>
  <source>1.8</source>
  <target>1.8</target>
</configuration>
15:21:35.831 [main] DEBUG JavaSourceVersionCheck - Found <source> tag, =
checking its value
15:21:35.831 [main] ERROR JavaSourceVersionCheck - InputLocation for tag =
<source> is null, returning position of last tag that has been found
15:21:35.831 [main] DEBUG JavaSourceVersionCheck - 	<source> tag =
located at line 15, column 24)
15:21:35.831 [main] WARN  JavaSourceVersionCheck - non compliant value: =
is 1.8 but should be 1.7 (issue was found at 15 column 24)
15:21:35.832 [main] DEBUG JavaSourceVersionCheck - done
-[snip]=E2=80=94

So I have two problems here:

I cannot retrieve the line and column number for the <source> tag, as =
calling inputLocation.getLocation(tag); is null (see (1) in above source =
code)
getColumnNumber() returns =E2=80=9Cline 15 column 24=E2=80=9D which is =
the last column of the line of the pom.xml where <configuration> is =
located.

My questions are the following:
Is it a bug or am I doing something wrong? (source is reachable from the =
DOM, but when calling getLocation())
How can I retrieve the line and column of the opening <source> tag?
How can I retrieve the line and column of the closing <source> tag?
Why does getColumnNumber() always return the last column of the line?

Thanks a lot in advance for your help and best regards!

Michel


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