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author zaaarf <me@zaaarf.foo>2024-01-24 17:16:50 +0100
committer zaaarf <me@zaaarf.foo>2024-01-24 17:16:50 +0100
commitd06b6211bc0815c36d44c65312c097058901b1c5 (patch)
tree1a942f8d9dfd08ff8f06c576f63ba0663ce051b0 /src/main/java/ftbsc/lll/utils/DescriptorBuilder.java
parent660730086dc6b8895eb871a3df98956041453983 (diff)
chore: internal reorganisation (breaking)0.5.0
Diffstat (limited to 'src/main/java/ftbsc/lll/utils/DescriptorBuilder.java')
-rw-r--r--src/main/java/ftbsc/lll/utils/DescriptorBuilder.java141
1 files changed, 141 insertions, 0 deletions
diff --git a/src/main/java/ftbsc/lll/utils/DescriptorBuilder.java b/src/main/java/ftbsc/lll/utils/DescriptorBuilder.java
new file mode 100644
index 0000000..541497b
--- /dev/null
+++ b/src/main/java/ftbsc/lll/utils/DescriptorBuilder.java
@@ -0,0 +1,141 @@
+package ftbsc.lll.utils;
+
+import org.objectweb.asm.Type;
+
+import java.util.ArrayList;
+
+/**
+ * Builds a method descriptor for you.
+ * See the <a href="https://asm.ow2.io/asm4-guide.pdf">documentation</a> to better understand what this is.
+ * Parameters must be given in a specific order.
+ * Return type should always be specified for clarity, but defaults to void.
+ */
+public class DescriptorBuilder {
+ /**
+ * The descriptor of the return type.
+ */
+ private String returnType;
+
+ /**
+ * The descriptors of the parameters.
+ */
+ private final ArrayList<String> params;
+
+ /**
+ * Public constructor.
+ * Initialises default values.
+ */
+ public DescriptorBuilder() {
+ this.returnType = Type.getDescriptor(void.class);
+ this.params = new ArrayList<>();
+ }
+
+ /**
+ * Sets the return type to the given type.
+ * Passing a {@link Class} may cause problems if used with objects outside the Java
+ * SDK. Pass the fully qualified name as a {@link String} rather than the {@link Class}
+ * object for non-standard types.
+ * @param returnType the Class object corresponding to the return type
+ * @return the builder's state after the change
+ */
+ public DescriptorBuilder setReturnType(Class<?> returnType) {
+ this.returnType = Type.getDescriptor(returnType);
+ return this;
+ }
+
+ /**
+ * Sets the return type to the Object specified here as a fully
+ * qualified name. Example: java.lang.String.
+ * No validity checks are performed: it's up to the user to ensure the name is correct.
+ * @param returnType the fully qualified name of the desired Object.
+ * @return the builder's state after the change
+ */
+ public DescriptorBuilder setReturnType(String returnType) {
+ return this.setReturnType(returnType, 0);
+ }
+
+ /**
+ * Sets the return type to the Object specified here as a fully
+ * qualified name (example: java.lang.String), with the specified array level.
+ * No validity checks are performed: it's up to the user to ensure the name is correct.
+ * @param returnType the fully qualified name of the desired Object.
+ * @param arrayLevel how many levels of array are there
+ * (example: String is 0, String[] is 1, String[][] is 2, etc.)
+ * @return the builder's state after the change
+ */
+ public DescriptorBuilder setReturnType(String returnType, int arrayLevel) {
+ this.returnType = nameToDescriptor(returnType, arrayLevel);
+ return this;
+ }
+
+ /**
+ * Adds a parameter of the given class type to the method.
+ * Parameter order matters.
+ * Passing a {@link Class} may cause problems if used with objects outside the Java
+ * SDK. Pass the fully qualified name as a {@link String} rather than the {@link Class}
+ * object for non-standard types.
+ * @param param the Class object corresponding to the parameter
+ * @return the builder's state after the change
+ */
+ public DescriptorBuilder addParameter(Class<?> param) {
+ this.params.add(Type.getDescriptor(param));
+ return this;
+ }
+
+ /**
+ * Adds a parameter with the type specified by the given fully
+ * qualified name to the method. Example: java.lang.String.
+ * Parameter order matters.
+ * No validity checks are performed: it's up to the user to ensure the name is correct.
+ * @param param the fully qualified name of the parameter type
+ * @return the builder's state after the change
+ */
+ public DescriptorBuilder addParameter(String param) {
+ return this.addParameter(param, 0);
+ }
+
+ /**
+ * Adds a parameter with the type specified by the given fully
+ * qualified name (example: java.lang.String) to the method, with
+ * the specified array level.
+ * Parameter order matters.
+ * No validity checks are performed: it's up to the user to ensure the name is correct.
+ * @param param the fully qualified name of the parameter type
+ * @param arrayLevel how many levels of array are there
+ * (example: String is 0, String[] is 1, String[][] is 2, etc.)
+ * @return the builder's state after the change
+ */
+ public DescriptorBuilder addParameter(String param, int arrayLevel) {
+ this.params.add(nameToDescriptor(param, arrayLevel));
+ return this;
+ }
+
+ /**
+ * Builds the descriptor into a string.
+ * Example result: {@code int m(Object[] o)} becomes {@code ([Ljava/lang/Object;)I}
+ * @return the resulting descriptor
+ */
+ public String build() {
+ StringBuilder sb = new StringBuilder();
+ sb.append('(');
+ for(String p : params)
+ sb.append(p);
+ sb.append(')').append(returnType);
+ return sb.toString();
+ }
+
+ /**
+ * Converts a fully qualified name and array level to a descriptor.
+ * @param name the fully qualified name of the object type
+ * @param arrayLevel how many levels of array are there
+ * (example: String is 0, String[] is 1, String[][] is 2, etc.)
+ * @return object descriptor
+ */
+ public static String nameToDescriptor(String name, int arrayLevel) {
+ StringBuilder sb = new StringBuilder();
+ for(int i = 0; i < arrayLevel; i++)
+ sb.append('[');
+ sb.append('L').append(name.replace('.', '/')).append(';');
+ return sb.toString();
+ }
+}