com.google.inject.spi.ElementSource Maven / Gradle / Ivy
package com.google.inject.spi;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.inject.internal.util.StackTraceElements;
import com.google.inject.internal.util.StackTraceElements.InMemoryStackTraceElement;
import java.util.List;
/**
* Contains information about where and how an {@link Element element} was bound.
*
* The {@link #getDeclaringSource() declaring source} refers to a location in source code that
* defines the Guice {@link Element element}. For example, if the element is created from a method
* annotated by {@literal @Provides}, the declaring source of element would be the method itself.
*
* The {@link #getStackTrace()} refers to the sequence of calls ends at one of {@link Binder}
* {@code bindXXX()} methods and eventually defines the element. Note that {@link #getStackTrace()}
* lists {@link StackTraceElement StackTraceElements} in reverse chronological order. The first
* element (index zero) is the last method call and the last element is the first method invocation.
* By default, the stack trace is not collected. The default behavior can be changed by setting the
* {@code guice_include_stack_traces} flag value. The value can be either {@code OFF}, {@code
* ONLY_FOR_DECLARING_SOURCE} or {@code COMPLETE}. Note that collecting stack traces for every
* binding can cause a performance hit when the injector is created.
*
* The sequence of class names of {@link Module modules} involved in the element creation can be
* retrieved by {@link #getModuleClassNames()}. Similar to {@link #getStackTrace()}, the order is
* reverse chronological. The first module (index 0) is the module that installs the {@link Element
* element}. The last module is the root module.
*
* In order to support the cases where a Guice {@link Element element} is created from another
* Guice {@link Element element} (original) (e.g., by {@link Element#applyTo()}), it also
* provides a reference to the original element source ({@link #getOriginalElementSource()}).
*/
public final class ElementSource {
/**
* The {@link ElementSource source} of element that this element created from (if there is any),
* otherwise {@code null}.
*/
final ElementSource originalElementSource;
/** The {@link ModuleSource source} of module creates the element. */
final ModuleSource moduleSource;
/**
* The partial call stack that starts at the last module {@link Module#Configure(Binder)
* configure(Binder)} call. The value is empty if stack trace collection is off.
*/
final InMemoryStackTraceElement[] partialCallStack;
/**
* Refers to a single location in source code that causes the element creation. It can be any
* object such as {@link Constructor}, {@link Method}, {@link Field}, {@link StackTraceElement},
* etc. For example, if the element is created from a method annotated by {@literal @Provides},
* the declaring source of element would be the method itself.
*/
final Object declaringSource;
/**
* Creates a new {@ElementSource} from the given parameters.
* @param originalElementSource The source of element that this element created from (if there is
* any), otherwise {@code null}.
* @param declaringSource the source (in)directly declared the element.
* @param moduleSource the moduleSource when the element is bound
* @param partialCallStack the partial call stack from the top module to where the element is
* bound
*/
ElementSource(/* @Nullable */ ElementSource originalSource, Object declaringSource,
ModuleSource moduleSource, StackTraceElement[] partialCallStack) {
Preconditions.checkNotNull(declaringSource, "declaringSource cannot be null.");
Preconditions.checkNotNull(moduleSource, "moduleSource cannot be null.");
Preconditions.checkNotNull(partialCallStack, "partialCallStack cannot be null.");
this.originalElementSource = originalSource;
this.declaringSource = declaringSource;
this.moduleSource = moduleSource;
this.partialCallStack = StackTraceElements.convertToInMemoryStackTraceElement(partialCallStack);
}
/**
* Returns the {@link ElementSource} of the element this was created or copied from. If this was
* not created or copied from another element, returns {@code null}.
*/
public ElementSource getOriginalElementSource() {
return originalElementSource;
}
/**
* Returns a single location in source code that defines the element. It can be any object
* such as {@link Constructor}, {@link Method}, {@link Field}, {@link StackTraceElement}, etc. For
* example, if the element is created from a method annotated by {@literal @Provides}, the
* declaring source of element would be the method itself.
*/
public Object getDeclaringSource() {
return declaringSource;
}
/**
* Returns the class names of modules involved in creating this {@link Element}. The first
* element (index 0) is the class name of module that defined the element, and the last element
* is the class name of root module.
*/
public List getModuleClassNames() {
return moduleSource.getModuleClassNames();
}
/**
* Returns the position of {@link Module#configure(Binder) configure(Binder)} method call in the
* {@link #getStackTrace() stack trace} for modules that their classes returned by
* {@link #getModuleClassNames()}. For example, if the stack trace looks like the following:
*
* {@code
* 0 - Binder.bind(),
* 1 - ModuleTwo.configure(),
* 2 - Binder.install(),
* 3 - ModuleOne.configure(),
* 4 - theRest().
* }
*
* 1 and 3 are returned.
*
* In the cases where stack trace is not available (i.e., the stack trace was not collected),
* it returns -1 for all module positions.
*/
public List getModuleConfigurePositionsInStackTrace() {
int size = moduleSource.size();
Integer[] positions = new Integer[size];
int chunkSize = partialCallStack.length;
positions[0] = chunkSize - 1;
ModuleSource current = moduleSource;
for (int cursor = 1; cursor < size; cursor++) {
chunkSize = current.getPartialCallStackSize();
positions[cursor] = positions[cursor - 1] + chunkSize;
current = current.getParent();
}
return ImmutableList.copyOf(positions);
}
/**
* Returns the sequence of method calls that ends at one of {@link Binder} {@code bindXXX()}
* methods and eventually defines the element. Note that {@link #getStackTrace()} lists {@link
* StackTraceElement StackTraceElements} in reverse chronological order. The first element (index
* zero) is the last method call and the last element is the first method invocation. In the cases
* where stack trace is not available (i.e.,the stack trace was not collected), it returns an
* empty array.
*/
public StackTraceElement[] getStackTrace() {
int modulesCallStackSize = moduleSource.getStackTraceSize();
int chunkSize = partialCallStack.length;
int size = moduleSource.getStackTraceSize() + chunkSize;
StackTraceElement[] callStack = new StackTraceElement[size];
System.arraycopy(
StackTraceElements.convertToStackTraceElement(partialCallStack), 0, callStack, 0,
chunkSize);
System.arraycopy(moduleSource.getStackTrace(), 0, callStack, chunkSize, modulesCallStackSize);
return callStack;
}
/**
* Returns {@code getDeclaringSource().toString()} value.
*/
@Override
public String toString() {
return getDeclaringSource().toString();
}
}