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Volodymyr Karpenko 2022-10-23 21:25:33 +02:00
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@ -129,26 +129,19 @@ lines of Java code and this satisfies all the requirements.
We use
\href{https://users.encs.concordia.ca/~nikolaos/pattern\_detection.html}{\textit{Pattern4J}}
as a pattern detection tool. This tool needs compiled \textit{.class} files in
order to perform analysis. Therefore, as \textit{jackson-core} is a standard
Maven project, we compile the sources using the command \textit{mvn clean
compile}. The \textit{pom.xml} of the library specifies Java 1.6 as a
build target, which is not supported by JDK 17 or above. We used JDK 11
instead, as it is the previous LTS version.
as a pattern detection tool. This tool needs to be compiled \textit{.class} files to perform analysis.
Therefore, as \textit{jackson-core} is a standard Maven project, we compile the sources using the command mvn clean compile.
The \textit{pom.xml} of the library specifies Java 1.6 as a build target, which is not supported by JDK 17 or above. We used JDK 11 instead, as it is the previous LTS version.
An XML dump of the \textit{Pattern4j} analysis results are included in the
submission as the file \textit{analysis.xml}.
An XML dump of the \textit{Pattern4j} analysis results is included in the submission as the file \textit{analysis.xml}.
\section{Structural Patterns}
\subsection{TO REWRITE Singleton Pattern}
Ensure a class only has one instance and provide a global point of access to it.
The tool found thirteen instances with the Singleton pattern,
doing a deeper analysis of the found instances we discovered that some of the results are false positives.
Example, com.fasterxml.jackson.core.sym.Name1 has a package private constructor and a
public static final instance of it, but reading the documentation the class
represents (short) JSON string literals and therefore is clearly
initialized by client code.
The tool found thirteen instances with the Singleton pattern.
Doing a deeper analysis of the found instances, we discovered that some results are false positives.
Example, \textit{com.fasterxml.jackson.core.sym.Name1} has a private package constructor and a public static final instance of it, but reading the documentation, the class represents (short) JSON string literals and is initialized by client code.
\begin{lstlisting}[caption=Name1 class,language=java]
public final class Name1 extends Name {
@ -190,13 +183,11 @@ public final class Name1 extends Name {
\begin{description}
\item[sym.Name1, JsonLocation, DefaultIndenter,
util.DefaultPrettyPrinter\$FixedSpaceIndenter] not a singleton (detected
cause of "convenient" default instance given as static final field), the
constructor is not used but the class is extensible
\item[JsonPointer, filter.TokenFilter] like above, but constructors are protected
util.DefaultPrettyPrinter\$FixedSpaceIndenter] is not a singleton (detected cause of "convenient" default instance given as static final field), the constructor is not used, but the class is extensible
\item[JsonPointer, filter.TokenFilter] is like the above, but constructors are protected
\item[JsonpCharacterEscapes, util.DefaultPrettyPrinter\$NopIndenter,
Version] a singleton but with a public constructor that is never called
in the module code, may be called in tests
Version] a singleton but with a public constructor that is never called in the module code,
may be called in tests
\item[io.JsonStringEncoder] like above, but the class is final
\item[util.InternCache, io.CharTypes\$AltEscapes]
actual singleton, thread-unsafe initialization
@ -208,44 +199,21 @@ public final class Name1 extends Name {
\begin{description}
\item[TokenStreamFactory] which indeed is a factory for \textbf{JsonParser} and
\textbf{JsonGenerator} objects, although two overloaded factory methods
exist on this class (one for each class) catering for different combination of
arguments. A concrete implementation of this factory is included in the form
of the \textbf{JsonFactory} class, although other modules may add additional
implementations to cater for different encodings (like the
\textit{jackson-dataformat-xml} module for XML);
\item[TSFBuilder] which is also a factory for concrete implementations of
\textbf{TokenStreamFactory} to allow slight changes in the serialization and
deserialization rules (e.g. changing the quote character used in JSON keys
from \textit{"} to \textit{'}). Like \textbf{TokenStreamFactory}, this class
is only implemented by one class, namely \textbf{JsonFactoryBuilder}, whitin
the scope of this module. And as mentioned previously, this abstract factory
is also likely to be extended by concrete implementations in other
\textit{Jackson} modules.
\textbf{JsonGenerator} is a factory for JsonParser and JsonGenerator objects, although two overloaded factory methods exist on this class (one for each class) catering to a different combination of arguments.
A concrete implementation of this factory is included in the form of the \textbf{JsonFactory} class, although other modules may add additional implementations to cater to different encodings (like the \textit{jackson-dataformat-xml} module for XML);
\item[TSFBuilder] which is also a factory for concrete implementations of \textbf{TokenStreamFactory} allows slight changes in the serialization and deserialization rules (e.g., changing the quote character used in JSON keys from " to '). Like TokenStreamFactory, this class is only implemented by one class, JsonFactoryBuilder, within this module's scope. Moreover, as mentioned previously, this abstract factory will likely be extended by concrete implementations in other Jackson modules.
\end{description}
\subsection{Builder Pattern}
The builder pattern does not seem to be analyzed by
\textit{Pattern4J}, as the analysis output does not mention the pattern, even
just to report that no instances of it have been found (as it is the case with
other patterns, e.g. the observer pattern). A manual search in the source code
produced the following results:
\textit{Pattern4J}, as the analysis output does not mention the pattern, even to report that no instances of it have been found (as is the case with other patterns, e.g., the observer pattern).
A manual search in the source code produced the following results:
\begin{description}
\item[TSFBuilder] is also a builder other than an abstract factory. As mentioned
previously, this class allows to alter slightly the serialization and
deserialization rules used to build outputtting \textbf{JsonFactory}
objects. Each rule is represented by an object or enum instance implementing
the \textbf{util.JacksonFeature} interface. \textit{TSFBuilder} then
provides several overloaded methods to enable and disable features
represented by the interface. Enabled features are stored in several
bitmask \textit{protected int} fields, which are then directly accessed by
the constructor of the \textbf{TokenStreamFactory} concrete implementation
to build;
\item[TSFBuilder] is also a builder other than an abstract factory. As mentioned previously, this class allows slightly altering the serialization and deserialization rules used to build outputting JsonFactory objects. Each rule is represented by an object or enum instance implementing the util.JacksonFeature interface. TSFBuilder then provides several overloaded methods to enable and disable features represented by the interface. Enabled features are stored in several bitmask-protected int fields, which are then directly accessed by the constructor of the TokenStreamFactory concrete implementation to build;
\marginpar[right text]{\color{white}\url{https://youtu.be/72b2nH-kdbU}}
\item[JsonFactoryBuilder] an concrete factory implementation of
\textbf{TSFBuilder} that builds \textbf{JsonFactory} instances;
\item[JsonFactoryBuilder] is a concrete factory implementation of \textbf{TSFBuilder} that builds \textbf{JsonFactory} instances;
\item[util.ByteArrayBuilder] provides facilities to build \textit{byte[]} objects
of varying length, akin to \textbf{StringBuilder} building \textbf{String}
objects. This is not a strict implementation of the builder pattern per se