java/12 : java.base/jdk/internal/org/objectweb/asm/AnnotationWriter.java

AnnotationWriter
https://openjdk.java.net/
GPLv2 + Classpath Exception
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 * ASM: a very small and fast Java bytecode manipulation framework
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package jdk.internal.org.objectweb.asm;

An AnnotationVisitor that generates a corresponding 'annotation' or 'type_annotation' structure, as defined in the Java Virtual Machine Specification (JVMS). AnnotationWriter instances can be chained in a doubly linked list, from which Runtime[In]Visible[Type]Annotations attributes can be generated with the putAnnotations method. Similarly, arrays of such lists can be used to generate Runtime[In]VisibleParameterAnnotations attributes. 
Author: Eric Bruneton, Eugene Kuleshov
See Also: JVMS
 *     4.7.16
JVMS
 *     4.7.20/**
 * An {@link AnnotationVisitor} that generates a corresponding 'annotation' or 'type_annotation'
 * structure, as defined in the Java Virtual Machine Specification (JVMS). AnnotationWriter
 * instances can be chained in a doubly linked list, from which Runtime[In]Visible[Type]Annotations
 * attributes can be generated with the {@link #putAnnotations} method. Similarly, arrays of such
 * lists can be used to generate Runtime[In]VisibleParameterAnnotations attributes.
 *
 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.16">JVMS
 *     4.7.16</a>
 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.20">JVMS
 *     4.7.20</a>
 * @author Eric Bruneton
 * @author Eugene Kuleshov
 */
final class AnnotationWriter extends AnnotationVisitor {

    Where the constants used in this AnnotationWriter must be stored. /** Where the constants used in this AnnotationWriter must be stored. */
    private final SymbolTable symbolTable;

    Whether values are named or not. AnnotationWriter instances used for annotation default and
annotation arrays use unnamed values (i.e. they generate an 'element_value' structure for each
value, instead of an element_name_index followed by an element_value).
/**
      * Whether values are named or not. AnnotationWriter instances used for annotation default and
      * annotation arrays use unnamed values (i.e. they generate an 'element_value' structure for each
      * value, instead of an element_name_index followed by an element_value).
      */
    private final boolean useNamedValues;

    The 'annotation' or 'type_annotation' JVMS structure corresponding to the annotation values visited so far. All the fields of these structures, except the last one - the element_value_pairs array, must be set before this ByteVector is passed to the constructor (num_element_value_pairs can be set to 0, it is reset to the correct value in visitEnd()). The element_value_pairs array is filled incrementally in the various visit() methods. Note: as an exception to the above rules, for AnnotationDefault attributes (which contain a single element_value by definition), this ByteVector is initially empty when passed to the constructor, and numElementValuePairsOffset is set to -1. /**
      * The 'annotation' or 'type_annotation' JVMS structure corresponding to the annotation values
      * visited so far. All the fields of these structures, except the last one - the
      * element_value_pairs array, must be set before this ByteVector is passed to the constructor
      * (num_element_value_pairs can be set to 0, it is reset to the correct value in {@link
      * #visitEnd()}). The element_value_pairs array is filled incrementally in the various visit()
      * methods.
      *
      * <p>Note: as an exception to the above rules, for AnnotationDefault attributes (which contain a
      * single element_value by definition), this ByteVector is initially empty when passed to the
      * constructor, and {@link #numElementValuePairsOffset} is set to -1.
      */
    private final ByteVector annotation;

    The offset in annotation where numElementValuePairs must be stored (or -1 for the case of AnnotationDefault attributes). /**
      * The offset in {@link #annotation} where {@link #numElementValuePairs} must be stored (or -1 for
      * the case of AnnotationDefault attributes).
      */
    private final int numElementValuePairsOffset;

    The number of element value pairs visited so far. /** The number of element value pairs visited so far. */
    private int numElementValuePairs;

    The previous AnnotationWriter. This field is used to store the list of annotations of a
Runtime[In]Visible[Type]Annotations attribute. It is unused for nested or array annotations
(annotation values of annotation type), or for AnnotationDefault attributes.
/**
      * The previous AnnotationWriter. This field is used to store the list of annotations of a
      * Runtime[In]Visible[Type]Annotations attribute. It is unused for nested or array annotations
      * (annotation values of annotation type), or for AnnotationDefault attributes.
      */
    private final AnnotationWriter previousAnnotation;

    The next AnnotationWriter. This field is used to store the list of annotations of a
Runtime[In]Visible[Type]Annotations attribute. It is unused for nested or array annotations
(annotation values of annotation type), or for AnnotationDefault attributes.
/**
      * The next AnnotationWriter. This field is used to store the list of annotations of a
      * Runtime[In]Visible[Type]Annotations attribute. It is unused for nested or array annotations
      * (annotation values of annotation type), or for AnnotationDefault attributes.
      */
    private AnnotationWriter nextAnnotation;

    // -----------------------------------------------------------------------------------------------
    // Constructors
    // -----------------------------------------------------------------------------------------------

    Constructs a new AnnotationWriter. 
Params: symbolTable – where the constants used in this AnnotationWriter must be stored.
useNamedValues – whether values are named or not. AnnotationDefault and annotation arrays
    use unnamed values.
annotation – where the 'annotation' or 'type_annotation' JVMS structure corresponding to
    the visited content must be stored. This ByteVector must already contain all the fields of
    the structure except the last one (the element_value_pairs array).
previousAnnotation – the previously visited annotation of the
    Runtime[In]Visible[Type]Annotations attribute to which this annotation belongs, or null in
    other cases (e.g. nested or array annotations)./**
      * Constructs a new {@link AnnotationWriter}.
      *
      * @param symbolTable where the constants used in this AnnotationWriter must be stored.
      * @param useNamedValues whether values are named or not. AnnotationDefault and annotation arrays
      *     use unnamed values.
      * @param annotation where the 'annotation' or 'type_annotation' JVMS structure corresponding to
      *     the visited content must be stored. This ByteVector must already contain all the fields of
      *     the structure except the last one (the element_value_pairs array).
      * @param previousAnnotation the previously visited annotation of the
      *     Runtime[In]Visible[Type]Annotations attribute to which this annotation belongs, or null in
      *     other cases (e.g. nested or array annotations).
      */
    AnnotationWriter(
            final SymbolTable symbolTable,
            final boolean useNamedValues,
            final ByteVector annotation,
            final AnnotationWriter previousAnnotation) {
        super(Opcodes.ASM7);
        this.symbolTable = symbolTable;
        this.useNamedValues = useNamedValues;
        this.annotation = annotation;
        // By hypothesis, num_element_value_pairs is stored in the last unsigned short of 'annotation'.
        this.numElementValuePairsOffset = annotation.length == 0 ? -1 : annotation.length - 2;
        this.previousAnnotation = previousAnnotation;
        if (previousAnnotation != null) {
            previousAnnotation.nextAnnotation = this;
        }
    }

    Constructs a new AnnotationWriter using named values. 
Params: symbolTable – where the constants used in this AnnotationWriter must be stored.
annotation – where the 'annotation' or 'type_annotation' JVMS structure corresponding to
    the visited content must be stored. This ByteVector must already contain all the fields of
    the structure except the last one (the element_value_pairs array).
previousAnnotation – the previously visited annotation of the
    Runtime[In]Visible[Type]Annotations attribute to which this annotation belongs, or null in
    other cases (e.g. nested or array annotations)./**
      * Constructs a new {@link AnnotationWriter} using named values.
      *
      * @param symbolTable where the constants used in this AnnotationWriter must be stored.
      * @param annotation where the 'annotation' or 'type_annotation' JVMS structure corresponding to
      *     the visited content must be stored. This ByteVector must already contain all the fields of
      *     the structure except the last one (the element_value_pairs array).
      * @param previousAnnotation the previously visited annotation of the
      *     Runtime[In]Visible[Type]Annotations attribute to which this annotation belongs, or null in
      *     other cases (e.g. nested or array annotations).
      */
    AnnotationWriter(
            final SymbolTable symbolTable,
            final ByteVector annotation,
            final AnnotationWriter previousAnnotation) {
        this(symbolTable, /* useNamedValues = */ true, annotation, previousAnnotation);
    }

    // -----------------------------------------------------------------------------------------------
    // Implementation of the AnnotationVisitor abstract class
    // -----------------------------------------------------------------------------------------------

    @Override
    public void visit(final String name, final Object value) {
        // Case of an element_value with a const_value_index, class_info_index or array_index field.
        // See https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.16.1.
        ++numElementValuePairs;
        if (useNamedValues) {
            annotation.putShort(symbolTable.addConstantUtf8(name));
        }
        if (value instanceof String) {
            annotation.put12('s', symbolTable.addConstantUtf8((String) value));
        } else if (value instanceof Byte) {
            annotation.put12('B', symbolTable.addConstantInteger(((Byte) value).byteValue()).index);
        } else if (value instanceof Boolean) {
            int booleanValue = ((Boolean) value).booleanValue() ? 1 : 0;
            annotation.put12('Z', symbolTable.addConstantInteger(booleanValue).index);
        } else if (value instanceof Character) {
            annotation.put12('C', symbolTable.addConstantInteger(((Character) value).charValue()).index);
        } else if (value instanceof Short) {
            annotation.put12('S', symbolTable.addConstantInteger(((Short) value).shortValue()).index);
        } else if (value instanceof Type) {
            annotation.put12('c', symbolTable.addConstantUtf8(((Type) value).getDescriptor()));
        } else if (value instanceof byte[]) {
            byte[] byteArray = (byte[]) value;
            annotation.put12('[', byteArray.length);
            for (byte byteValue : byteArray) {
                annotation.put12('B', symbolTable.addConstantInteger(byteValue).index);
            }
        } else if (value instanceof boolean[]) {
            boolean[] booleanArray = (boolean[]) value;
            annotation.put12('[', booleanArray.length);
            for (boolean booleanValue : booleanArray) {
                annotation.put12('Z', symbolTable.addConstantInteger(booleanValue ? 1 : 0).index);
            }
        } else if (value instanceof short[]) {
            short[] shortArray = (short[]) value;
            annotation.put12('[', shortArray.length);
            for (short shortValue : shortArray) {
                annotation.put12('S', symbolTable.addConstantInteger(shortValue).index);
            }
        } else if (value instanceof char[]) {
            char[] charArray = (char[]) value;
            annotation.put12('[', charArray.length);
            for (char charValue : charArray) {
                annotation.put12('C', symbolTable.addConstantInteger(charValue).index);
            }
        } else if (value instanceof int[]) {
            int[] intArray = (int[]) value;
            annotation.put12('[', intArray.length);
            for (int intValue : intArray) {
                annotation.put12('I', symbolTable.addConstantInteger(intValue).index);
            }
        } else if (value instanceof long[]) {
            long[] longArray = (long[]) value;
            annotation.put12('[', longArray.length);
            for (long longValue : longArray) {
                annotation.put12('J', symbolTable.addConstantLong(longValue).index);
            }
        } else if (value instanceof float[]) {
            float[] floatArray = (float[]) value;
            annotation.put12('[', floatArray.length);
            for (float floatValue : floatArray) {
                annotation.put12('F', symbolTable.addConstantFloat(floatValue).index);
            }
        } else if (value instanceof double[]) {
            double[] doubleArray = (double[]) value;
            annotation.put12('[', doubleArray.length);
            for (double doubleValue : doubleArray) {
                annotation.put12('D', symbolTable.addConstantDouble(doubleValue).index);
            }
        } else {
            Symbol symbol = symbolTable.addConstant(value);
            annotation.put12(".s.IFJDCS".charAt(symbol.tag), symbol.index);
        }
    }

    @Override
    public void visitEnum(final String name, final String descriptor, final String value) {
        // Case of an element_value with an enum_const_value field.
        // See https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.16.1.
        ++numElementValuePairs;
        if (useNamedValues) {
            annotation.putShort(symbolTable.addConstantUtf8(name));
        }
        annotation
                .put12('e', symbolTable.addConstantUtf8(descriptor))
                .putShort(symbolTable.addConstantUtf8(value));
    }

    @Override
    public AnnotationVisitor visitAnnotation(final String name, final String descriptor) {
        // Case of an element_value with an annotation_value field.
        // See https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.16.1.
        ++numElementValuePairs;
        if (useNamedValues) {
            annotation.putShort(symbolTable.addConstantUtf8(name));
        }
        // Write tag and type_index, and reserve 2 bytes for num_element_value_pairs.
        annotation.put12('@', symbolTable.addConstantUtf8(descriptor)).putShort(0);
        return new AnnotationWriter(symbolTable, annotation, null);
    }

    @Override
    public AnnotationVisitor visitArray(final String name) {
        // Case of an element_value with an array_value field.
        // https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.16.1
        ++numElementValuePairs;
        if (useNamedValues) {
            annotation.putShort(symbolTable.addConstantUtf8(name));
        }
        // Write tag, and reserve 2 bytes for num_values. Here we take advantage of the fact that the
        // end of an element_value of array type is similar to the end of an 'annotation' structure: an
        // unsigned short num_values followed by num_values element_value, versus an unsigned short
        // num_element_value_pairs, followed by num_element_value_pairs { element_name_index,
        // element_value } tuples. This allows us to use an AnnotationWriter with unnamed values to
        // visit the array elements. Its num_element_value_pairs will correspond to the number of array
        // elements and will be stored in what is in fact num_values.
        annotation.put12('[', 0);
        return new AnnotationWriter(symbolTable, /* useNamedValues = */ false, annotation, null);
    }

    @Override
    public void visitEnd() {
        if (numElementValuePairsOffset != -1) {
            byte[] data = annotation.data;
            data[numElementValuePairsOffset] = (byte) (numElementValuePairs >>> 8);
            data[numElementValuePairsOffset + 1] = (byte) numElementValuePairs;
        }
    }

    // -----------------------------------------------------------------------------------------------
    // Utility methods
    // -----------------------------------------------------------------------------------------------

    Returns the size of a Runtime[In]Visible[Type]Annotations attribute containing this annotation
and all its predecessors (see previousAnnotation. Also adds the attribute name to the constant pool of the class (if not null). 
Params: attributeName – one of "Runtime[In]Visible[Type]Annotations", or null.
Returns: the size in bytes of a Runtime[In]Visible[Type]Annotations attribute containing this
    annotation and all its predecessors. This includes the size of the attribute_name_index and
    attribute_length fields./**
      * Returns the size of a Runtime[In]Visible[Type]Annotations attribute containing this annotation
      * and all its <i>predecessors</i> (see {@link #previousAnnotation}. Also adds the attribute name
      * to the constant pool of the class (if not null).
      *
      * @param attributeName one of "Runtime[In]Visible[Type]Annotations", or null.
      * @return the size in bytes of a Runtime[In]Visible[Type]Annotations attribute containing this
      *     annotation and all its predecessors. This includes the size of the attribute_name_index and
      *     attribute_length fields.
      */
    int computeAnnotationsSize(final String attributeName) {
        if (attributeName != null) {
            symbolTable.addConstantUtf8(attributeName);
        }
        // The attribute_name_index, attribute_length and num_annotations fields use 8 bytes.
        int attributeSize = 8;
        AnnotationWriter annotationWriter = this;
        while (annotationWriter != null) {
            attributeSize += annotationWriter.annotation.length;
            annotationWriter = annotationWriter.previousAnnotation;
        }
        return attributeSize;
    }

    Puts a Runtime[In]Visible[Type]Annotations attribute containing this annotations and all its
predecessors (see previousAnnotation in the given ByteVector. Annotations are put in the same order they have been visited. 
Params: attributeNameIndex – the constant pool index of the attribute name (one of
    "Runtime[In]Visible[Type]Annotations").
output – where the attribute must be put./**
      * Puts a Runtime[In]Visible[Type]Annotations attribute containing this annotations and all its
      * <i>predecessors</i> (see {@link #previousAnnotation} in the given ByteVector. Annotations are
      * put in the same order they have been visited.
      *
      * @param attributeNameIndex the constant pool index of the attribute name (one of
      *     "Runtime[In]Visible[Type]Annotations").
      * @param output where the attribute must be put.
      */
    void putAnnotations(final int attributeNameIndex, final ByteVector output) {
        int attributeLength = 2; // For num_annotations.
        int numAnnotations = 0;
        AnnotationWriter annotationWriter = this;
        AnnotationWriter firstAnnotation = null;
        while (annotationWriter != null) {
            // In case the user forgot to call visitEnd().
            annotationWriter.visitEnd();
            attributeLength += annotationWriter.annotation.length;
            numAnnotations++;
            firstAnnotation = annotationWriter;
            annotationWriter = annotationWriter.previousAnnotation;
        }
        output.putShort(attributeNameIndex);
        output.putInt(attributeLength);
        output.putShort(numAnnotations);
        annotationWriter = firstAnnotation;
        while (annotationWriter != null) {
            output.putByteArray(annotationWriter.annotation.data, 0, annotationWriter.annotation.length);
            annotationWriter = annotationWriter.nextAnnotation;
        }
    }

    Returns the size of a Runtime[In]VisibleParameterAnnotations attribute containing all the
annotation lists from the given AnnotationWriter sub-array. Also adds the attribute name to the
constant pool of the class.
Params: attributeName – one of "Runtime[In]VisibleParameterAnnotations".
annotationWriters – an array of AnnotationWriter lists (designated by their last
    element).
annotableParameterCount – the number of elements in annotationWriters to take into account
    (elements [0..annotableParameterCount[ are taken into account).
Returns: the size in bytes of a Runtime[In]VisibleParameterAnnotations attribute corresponding
    to the given sub-array of AnnotationWriter lists. This includes the size of the
    attribute_name_index and attribute_length fields./**
      * Returns the size of a Runtime[In]VisibleParameterAnnotations attribute containing all the
      * annotation lists from the given AnnotationWriter sub-array. Also adds the attribute name to the
      * constant pool of the class.
      *
      * @param attributeName one of "Runtime[In]VisibleParameterAnnotations".
      * @param annotationWriters an array of AnnotationWriter lists (designated by their <i>last</i>
      *     element).
      * @param annotableParameterCount the number of elements in annotationWriters to take into account
      *     (elements [0..annotableParameterCount[ are taken into account).
      * @return the size in bytes of a Runtime[In]VisibleParameterAnnotations attribute corresponding
      *     to the given sub-array of AnnotationWriter lists. This includes the size of the
      *     attribute_name_index and attribute_length fields.
      */
    static int computeParameterAnnotationsSize(
            final String attributeName,
            final AnnotationWriter[] annotationWriters,
            final int annotableParameterCount) {
        // Note: attributeName is added to the constant pool by the call to computeAnnotationsSize
        // below. This assumes that there is at least one non-null element in the annotationWriters
        // sub-array (which is ensured by the lazy instantiation of this array in MethodWriter).
        // The attribute_name_index, attribute_length and num_parameters fields use 7 bytes, and each
        // element of the parameter_annotations array uses 2 bytes for its num_annotations field.
        int attributeSize = 7 + 2 * annotableParameterCount;
        for (int i = 0; i < annotableParameterCount; ++i) {
            AnnotationWriter annotationWriter = annotationWriters[i];
            attributeSize +=
                    annotationWriter == null ? 0 : annotationWriter.computeAnnotationsSize(attributeName) - 8;
        }
        return attributeSize;
    }

    Puts a Runtime[In]VisibleParameterAnnotations attribute containing all the annotation lists
from the given AnnotationWriter sub-array in the given ByteVector.
Params: attributeNameIndex – constant pool index of the attribute name (one of
    Runtime[In]VisibleParameterAnnotations).
annotationWriters – an array of AnnotationWriter lists (designated by their last
    element).
annotableParameterCount – the number of elements in annotationWriters to put (elements
    [0..annotableParameterCount[ are put).
output – where the attribute must be put./**
      * Puts a Runtime[In]VisibleParameterAnnotations attribute containing all the annotation lists
      * from the given AnnotationWriter sub-array in the given ByteVector.
      *
      * @param attributeNameIndex constant pool index of the attribute name (one of
      *     Runtime[In]VisibleParameterAnnotations).
      * @param annotationWriters an array of AnnotationWriter lists (designated by their <i>last</i>
      *     element).
      * @param annotableParameterCount the number of elements in annotationWriters to put (elements
      *     [0..annotableParameterCount[ are put).
      * @param output where the attribute must be put.
      */
    static void putParameterAnnotations(
            final int attributeNameIndex,
            final AnnotationWriter[] annotationWriters,
            final int annotableParameterCount,
            final ByteVector output) {
        // The num_parameters field uses 1 byte, and each element of the parameter_annotations array
        // uses 2 bytes for its num_annotations field.
        int attributeLength = 1 + 2 * annotableParameterCount;
        for (int i = 0; i < annotableParameterCount; ++i) {
            AnnotationWriter annotationWriter = annotationWriters[i];
            attributeLength +=
                    annotationWriter == null ? 0 : annotationWriter.computeAnnotationsSize(null) - 8;
        }
        output.putShort(attributeNameIndex);
        output.putInt(attributeLength);
        output.putByte(annotableParameterCount);
        for (int i = 0; i < annotableParameterCount; ++i) {
            AnnotationWriter annotationWriter = annotationWriters[i];
            AnnotationWriter firstAnnotation = null;
            int numAnnotations = 0;
            while (annotationWriter != null) {
                // In case user the forgot to call visitEnd().
                annotationWriter.visitEnd();
                numAnnotations++;
                firstAnnotation = annotationWriter;
                annotationWriter = annotationWriter.previousAnnotation;
            }
            output.putShort(numAnnotations);
            annotationWriter = firstAnnotation;
            while (annotationWriter != null) {
                output.putByteArray(
                        annotationWriter.annotation.data, 0, annotationWriter.annotation.length);
                annotationWriter = annotationWriter.nextAnnotation;
            }
        }
    }
}
Author:	Eric Bruneton, Eugene Kuleshov
See Also:	JVMS * 4.7.16 JVMS * 4.7.20
Params:	attributeName – one of "Runtime[In]Visible[Type]Annotations", or null.
Returns:	the size in bytes of a Runtime[In]Visible[Type]Annotations attribute containing this annotation and all its predecessors. This includes the size of the attribute_name_index and attribute_length fields.
/

java/ 12/ java.base/jdk/internal/org/objectweb/asm/AnnotationWriter.java
