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src/java.base/share/classes/java/lang/invoke/MethodType.java
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rev 58769 : imported patch type-descriptor-name
rev 58770 : [mq]: svc-spec-update
@@ -97,10 +97,40 @@
* <p>
* When the JVM materializes a {@code MethodType} from a descriptor string,
* all classes named in the descriptor must be accessible, and will be loaded.
* (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.)
* This loading may occur at any time before the {@code MethodType} object is first derived.
+ * <p>
+ * <b><a id="descriptor">Nominal Descriptors</a></b>
+ * <p>
+ * A {@code MethodType} can be described in {@linkplain MethodTypeDesc nominal form}
+ * if and only if all of the parameter types and return type can be described
+ * with a {@link Class#describeConstable() nominal descriptor} represented by
+ * {@link ClassDesc}. If a method type can be described norminally, then:
+ * <ul>
+ * <li>The method type has a {@link MethodTypeDesc nominal descriptor}
+ * returned by {@link #describeConstable() MethodType::describeConstable}.</li>
+ * <li>The descriptor string returned by
+ * {@link #descriptorString() MethodType::descriptorString} or
+ * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString}
+ * for the method type is a valid type descriptor (JVMS {@jvms 4.3.3}).</li>
+ * </ul>
+ * <p>
+ * If any of the parameter types or return type cannot be described
+ * nominally, i.e. {@link Class#describeConstable() Class::describeConstable}
+ * returns an empty optional for that type,
+ * then the method type cannot be described in nominal form:
+ * <ul>
+ * <li>The method type has no {@link MethodTypeDesc nominal descriptor} and
+ * {@link #describeConstable() MethodType::describeConstable} returns
+ * an empty optional.</li>
+ * <li>The descriptor string returned by
+ * {@link #descriptorString() MethodType::descriptorString} or
+ * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString}
+ * for the method type is not a valid type descriptor string.</li>
+ * </ul>
+ *
* @author John Rose, JSR 292 EG
* @since 1.7
*/
public final
class MethodType
@@ -1137,21 +1167,25 @@
Class<?>[] ptypes = listToArray(types);
return makeImpl(rtype, ptypes, true);
}
/**
- * Produces a bytecode descriptor representation of the method type.
+ * Returns a descriptor string for the method type. This method
+ * is equivalent to calling {@link #descriptorString() MethodType::descriptorString}.
+ *
* <p>
* Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}.
* Two distinct classes which share a common name but have different class loaders
* will appear identical when viewed within descriptor strings.
* <p>
* This method is included for the benefit of applications that must
* generate bytecodes that process method handles and {@code invokedynamic}.
* {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString},
* because the latter requires a suitable class loader argument.
- * @return the bytecode type descriptor representation
+ * @return the descriptor string for this method type
+ * @jvms 4.3.3 Method Descriptors
+ * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
*/
public String toMethodDescriptorString() {
String desc = methodDescriptor;
if (desc == null) {
desc = BytecodeDescriptor.unparseMethod(this.rtype, this.ptypes);
@@ -1159,15 +1193,32 @@
}
return desc;
}
/**
- * Return a field type descriptor string for this type
+ * Returns a descriptor string for this method type.
+ *
+ * <p>
+ * If this method type can be <a href="#descriptor">described nominally</a>,
+ * then the result is a method type descriptor string (JVMS {@jvms 4.3.3}).
+ * {@link MethodTypeDesc MethodTypeDesc} for this method type
+ * can be produced by calling {@link MethodTypeDesc#ofDescriptor(String)
+ * MethodTypeDesc::ofDescriptor} with the result descriptor string.
+ * <p>
+ * If this method type cannot be <a href="#descriptor">described nominally</a>
+ * and the result is a string of the form:
+ * <blockquote>{@code "(<parameter-descriptors>)<return-descriptor>"}</blockquote>
+ * where {@code <parameter-descriptors>} is the concatenation of the
+ * {@linkplain Class#descriptorString() descriptor string} of all
+ * of the parameter types and the {@linkplain Class#descriptorString() descriptor string}
+ * of the return type. No {@link java.lang.constant.MethodTypeDesc MethodTypeDesc}
+ * can be produced from the result string.
*
- * @return the descriptor string
- * @jvms 4.3.2 Field Descriptors
+ * @return the descriptor string for this method type
* @since 12
+ * @jvms 4.3.3 Method Descriptors
+ * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
*/
@Override
public String descriptorString() {
return toMethodDescriptorString();
}
@@ -1176,16 +1227,17 @@
static String toFieldDescriptorString(Class<?> cls) {
return BytecodeDescriptor.unparse(cls);
}
/**
- * Return a nominal descriptor for this instance, if one can be
+ * Returns a nominal descriptor for this instance, if one can be
* constructed, or an empty {@link Optional} if one cannot be.
*
* @return An {@link Optional} containing the resulting nominal descriptor,
* or an empty {@link Optional} if one cannot be constructed.
* @since 12
+ * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
*/
@Override
public Optional<MethodTypeDesc> describeConstable() {
try {
return Optional.of(MethodTypeDesc.of(returnType().describeConstable().orElseThrow(),
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