Class ClassReader

🏭 Constructors

constructor

new ClassReader(buffer: Uint8Array, classFileOffset: number= 0, len: number= buffer.length): ClassReader

Constructs a new ClassReader object.

Parameters

• buffer: Uint8Array
• classFileOffset: number
• len: number the length of the class data.

Return Type

• ClassReader

Defined in: packages/asm/libs/ClassReader.ts:178

🏷️ Properties

buf

buf: Uint8Array

The class to be parsed. <i>The content of this array must not be modified. This field is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Defined in: packages/asm/libs/ClassReader.ts:141

header

header: number

Start index of the class header information (access, name...) in #b b.

Defined in: packages/asm/libs/ClassReader.ts:169

items

items: number[]

The start index of each constant pool item in #b b, plus one. The one byte offset skips the constant pool item tag that indicates its type.

Defined in: packages/asm/libs/ClassReader.ts:147

maxStringLength

maxStringLength: number

Maximum length of the strings contained in the constant pool of the class.

Defined in: packages/asm/libs/ClassReader.ts:163

strings

strings: string[]

The String objects corresponding to the CONSTANT_Utf8 items. This cache avoids multiple parsing of a given CONSTANT_Utf8 constant pool item, which GREATLY improves performances (by a factor 2 to 3). This caching strategy could be extended to all constant pool items, but its benefit would not be so great for these items (because they are much less expensive to parse than CONSTANT_Utf8 items).

Defined in: packages/asm/libs/ClassReader.ts:157

ANNOTATIONS

ANNOTATIONS: boolean = true

True to enable annotations support.

Defined in: packages/asm/libs/ClassReader.ts:68

EXPAND_ASM_INSNS

EXPAND_ASM_INSNS: number = 256

Flag to expand the ASM pseudo instructions into an equivalent sequence of standard bytecode instructions. When resolving a forward jump it may happen that the signed 2 bytes offset reserved for it is not sufficient to store the bytecode offset. In this case the jump instruction is replaced with a temporary ASM pseudo instruction using an unsigned 2 bytes offset (see Label#resolve). This internal flag is used to re-read classes containing such instructions, in order to replace them with standard instructions. In addition, when this flag is used, GOTO_W and JSR_W are <i>not</i> converted into GOTO and JSR, to make sure that infinite loops where a GOTO_W is replaced with a GOTO in ClassReader and converted back to a GOTO_W in ClassWriter cannot occur.

Defined in: packages/asm/libs/ClassReader.ts:134

EXPAND_FRAMES

EXPAND_FRAMES: number = 8

Flag to expand the stack map frames. By default stack map frames are visited in their original format (i.e. "expanded" for classes whose version is less than V1_6, and "compressed" for the other classes). If this flag is set, stack map frames are always visited in expanded format (this option adds a decompression/recompression step in ClassReader and ClassWriter which degrades performances quite a lot).

Defined in: packages/asm/libs/ClassReader.ts:119

FRAMES

FRAMES: boolean = true

True to enable stack map frames support.

Defined in: packages/asm/libs/ClassReader.ts:73

RESIZE

RESIZE: boolean = true

True to enable JSR_W and GOTO_W support.

Defined in: packages/asm/libs/ClassReader.ts:83

SIGNATURES

SIGNATURES: boolean = true

True to enable signatures support.

Defined in: packages/asm/libs/ClassReader.ts:63

SKIP_CODE

SKIP_CODE: number = 1

Flag to skip method code. If this class is set <code>CODE</code> attribute won't be visited. This can be used, for example, to retrieve annotations for methods and method parameters.

Defined in: packages/asm/libs/ClassReader.ts:90

SKIP_DEBUG

SKIP_DEBUG: number = 2

Flag to skip the debug information in the class. If this flag is set the debug information of the class is not visited, i.e. the visitLocalVariable and visitLineNumber methods will not be called.

Defined in: packages/asm/libs/ClassReader.ts:99

SKIP_FRAMES

SKIP_FRAMES: number = 4

Flag to skip the stack map frames in the class. If this flag is set the stack map frames of the class is not visited, i.e. the visitFrame method will not be called. This flag is useful when the [ClassWriter#COMPUTE_FRAMES] option is used: it avoids visiting frames that will be ignored and recomputed from scratch in the class writer.

Defined in: packages/asm/libs/ClassReader.ts:109

WRITER

WRITER: boolean = true

True to enable bytecode writing support.

Defined in: packages/asm/libs/ClassReader.ts:78

🔧 Methods

accept

accept(classVisitor: ClassVisitor, attrs: Attribute[]= [], flags: number= 0): void

Makes the given visitor visit the Java class of this ClassReader. This class is the one specified in the constructor (see #ClassReader(byte[]) ClassReader).

Parameters

• classVisitor: ClassVisitor the visitor that must visit this class.
• attrs: Attribute[] prototypes of the attributes that must be parsed during the visit of the class. Any attribute whose type is not equal to the type of one the prototypes will not be parsed: its byte array value will be passed unchanged to the ClassWriter. <i>This may corrupt it if this value contains references to the constant pool, or has syntactic or semantic links with a class element that has been transformed by a class adapter between the reader and the writer</i>.
• flags: number option flags that can be used to modify the default behavior of this class. See #SKIP_DEBUG, #EXPAND_FRAMES , #SKIP_FRAMES, #SKIP_CODE.

Return Type

• void

Defined in: packages/asm/libs/ClassReader.ts:301

getAccess

getAccess(): number

Returns the class's access flags (see Opcodes). This value may not reflect Deprecated and Synthetic flags when bytecode is before 1.5 and those flags are represented by attributes.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:233

getAttributes

getAttributes(): number

Returns the start index of the attribute_info structure of this class.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1689

getClassName

getClassName(): string

Returns the internal name of the class (see [Type#getInternalName() getInternalName]).

Return Type

• string

Defined in: packages/asm/libs/ClassReader.ts:244

getImplicitFrame

getImplicitFrame(frame: Context): void

Computes the implicit frame of the method currently being parsed (as defined in the given [Context]) and stores it in the given context.

Parameters

• frame: Context information about the class being parsed.

Return Type

• void

Defined in: packages/asm/libs/ClassReader.ts:1483

getInterfaces

getInterfaces(): string[]

Returns the internal names of the class's interfaces (see [Type#getInternalName() getInternalName]).

Return Type

• string[]

Defined in: packages/asm/libs/ClassReader.ts:269

getItem

getItem(item: number): number

Returns the start index of the constant pool item in #b b, plus one. <i>This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Parameters

• item: number the index a constant pool item.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1760

getItemCount

getItemCount(): number

Returns the number of constant pool items in #b b.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1747

getMaxStringLength

getMaxStringLength(): number

Returns the maximum length of the strings contained in the constant pool of the class.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1771

getSuperName

getSuperName(): string

Returns the internal of name of the super class (see [Type#getInternalName() getInternalName]). For interfaces, the super class is [Object].

Return Type

• string

Defined in: packages/asm/libs/ClassReader.ts:257

readAnnotationTarget

readAnnotationTarget(context: Context, u: number): number

Parses the header of a type annotation to extract its target_type and target_path (the result is stored in the given context), and returns the start offset of the rest of the type_annotation structure (i.e. the offset to the type_index field, which is followed by num_element_value_pairs and then the name,value pairs).

Parameters

• context: Context information about the class being parsed. This is where the extracted target_type and target_path must be stored.
• u: number the start offset of a type_annotation structure.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1210

readAnnotationValue

readAnnotationValue(v: number, buf: number[], name: null | string, av: null | AnnotationVisitor): number

Reads a value of an annotation and makes the given visitor visit it.

Parameters

• v: number the start offset in #b b of the value to be read (<i>not including the value name constant pool index</i>).
• buf: number[] buffer to be used to call #readUTF8 readUTF8, #readClass(int, int[]) readClass or #readConst readConst.
• name: null | string the name of the value to be read.
• av: null | AnnotationVisitor the visitor that must visit the value.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1337

readAnnotationValues

readAnnotationValues(v: number, buf: number[], named: boolean, av: null | AnnotationVisitor): number

Reads the values of an annotation and makes the given visitor visit them.

Parameters

• v: number the start offset in #b b of the values to be read (including the unsigned short that gives the number of values).
• buf: number[] buffer to be used to call #readUTF8 readUTF8, #readClass(int, int[]) readClass or #readConst readConst.
• named: boolean if the annotation values are named or not.
• av: null | AnnotationVisitor the visitor that must visit the values.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1307

readAttribute

readAttribute(attrs: Attribute[], type: null | string, off: number, len: number, buf: number[], codeOff: number, labels: null | Label[]): Attribute

Reads an attribute in #b b.

Parameters

• attrs: Attribute[] prototypes of the attributes that must be parsed during the visit of the class. Any attribute whose type is not equal to the type of one the prototypes is ignored (i.e. an empty Attribute instance is returned).
• type: null | string the type of the attribute.
• off: number index of the first byte of the attribute's content in #b b. The 6 attribute header bytes, containing the type and the length of the attribute, are not taken into account here (they have already been read).
• len: number the length of the attribute's content.
• buf: number[] buffer to be used to call #readUTF8 readUTF8, #readClass(int, int[]) readClass or #readConst readConst.
• codeOff: number index of the first byte of code's attribute content in #b b, or -1 if the attribute to be read is not a code attribute. The 6 attribute header bytes, containing the type and the length of the attribute, are not taken into account here.
• labels: null | Label[] the labels of the method's code, or <tt>null</tt> if the attribute to be read is not a code attribute.

Return Type

• Attribute

Defined in: packages/asm/libs/ClassReader.ts:1733

readByte

readByte(index: number): number

Reads a byte value in #b b. <i>This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Parameters

• index: number the start index of the value to be read in #b b.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1783

readClass

readClass(index: number, buf: number[]): string

Reads a class constant pool item in #b b. <i>This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Parameters

• index: number the start index of an unsigned short value in #b b, whose value is the index of a class constant pool item.
• buf: number[] buffer to be used to read the item. This buffer must be sufficiently large. It is not automatically resized.

Return Type

• string

Defined in: packages/asm/libs/ClassReader.ts:1919

readCode

readCode(mv: MethodVisitor, context: Context, u: number): void

Reads the bytecode of a method and makes the given visitor visit it.

Parameters

• mv: MethodVisitor the visitor that must visit the method's code.
• context: Context information about the class being parsed.
• u: number the start offset of the code attribute in the class file.

Return Type

• void

Defined in: packages/asm/libs/ClassReader.ts:674

readConst

readConst(item: number, buf: number[]): any

Reads a numeric or string constant pool item in #b b. <i>This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Parameters

• item: number the index of a constant pool item.
• buf: number[] buffer to be used to read the item. This buffer must be sufficiently large. It is not automatically resized.

Return Type

• any

Defined in: packages/asm/libs/ClassReader.ts:1935

readField

readField(classVisitor: ClassVisitor, context: Context, u: number): number

Reads a field and makes the given visitor visit it.

Parameters

• classVisitor: ClassVisitor the visitor that must visit the field.
• context: Context information about the class being parsed.
• u: number the start offset of the field in the class file.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:434

readFrame

readFrame(stackMap: number, zip: boolean, unzip: boolean, frame: Context): number

Reads a stack map frame and stores the result in the given [Context] object.

Parameters

• stackMap: number the start offset of a stack map frame in the class file.
• zip: boolean if the stack map frame at stackMap is compressed or not.
• unzip: boolean if the stack map frame must be uncompressed.
• frame: Context where the parsed stack map frame must be stored.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1550

readFrameType

readFrameType(frame: any[], index: number, v: number, buf: number[], labels: Label[]): number

Reads a stack map frame type and stores it at the given index in the given array.

Parameters

• frame: any[] the array where the parsed type must be stored.
• index: number the index in 'frame' where the parsed type must be stored.
• v: number the start offset of the stack map frame type to read.
• buf: number[] a buffer to read strings.
• labels: Label[] the labels of the method currently being parsed, indexed by their offset. If the parsed type is an Uninitialized type, a new label for the corresponding NEW instruction is stored in this array if it does not already exist.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1631

readInt

readInt(index: number): number

Reads a signed int value in #b b. <i>This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Parameters

• index: number the start index of the value to be read in #b b.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1823

readLabel

readLabel(offset: number, labels: Label[]): Label

Returns the label corresponding to the given offset. The default implementation of this method creates a label for the given offset if it has not been already created.

Parameters

• offset: number a bytecode offset in a method.
• labels: Label[] the already created labels, indexed by their offset. If a label already exists for offset this method must not create a new one. Otherwise it must store the new label in this array.

Return Type

• Label

Defined in: packages/asm/libs/ClassReader.ts:1677

readLong

readLong(index: number): bigint

Reads a signed long value in #b b. <i>This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Parameters

• index: number the start index of the value to be read in #b b.

Return Type

• bigint

Defined in: packages/asm/libs/ClassReader.ts:1837

readMethod

readMethod(classVisitor: ClassVisitor, context: Context, u: number): number

Reads a method and makes the given visitor visit it.

Parameters

• classVisitor: ClassVisitor the visitor that must visit the method.
• context: Context information about the class being parsed.
• u: number the start offset of the method in the class file.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:521

readParameterAnnotations

readParameterAnnotations(mv: MethodVisitor, context: Context, v: number, visible: boolean): void

Reads parameter annotations and makes the given visitor visit them.

Parameters

• mv: MethodVisitor the visitor that must visit the annotations.
• context: Context information about the class being parsed.
• v: number start offset in #b b of the annotations to be read.
• visible: boolean <tt>true</tt> if the annotations to be read are visible at runtime.

Return Type

• void

Defined in: packages/asm/libs/ClassReader.ts:1272

readShort

readShort(index: number): number

Reads a signed short value in #b b. <i>This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Parameters

• index: number the start index of the value to be read in #b b.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1810

readTypeAnnotations

readTypeAnnotations(mv: MethodVisitor, context: Context, u: number, visible: boolean): number[]

Parses a type annotation table to find the labels, and to visit the try catch block annotations.

Parameters

• mv: MethodVisitor the method visitor to be used to visit the try catch block annotations.
• context: Context information about the class being parsed.
• u: number the start offset of a type annotation table.
• visible: boolean if the type annotation table to parse contains runtime visible annotations.

Return Type

• number[]

Defined in: packages/asm/libs/ClassReader.ts:1146

readUTF

readUTF(index: number, utfLen: number, buf: number[]): string

Reads UTF8 string in #b b.

Parameters

• index: number start offset of the UTF8 string to be read.
• utfLen: number length of the UTF8 string to be read.
• buf: number[] buffer to be used to read the string. This buffer must be sufficiently large. It is not automatically resized.

Return Type

• string

Defined in: packages/asm/libs/ClassReader.ts:1873

readUTF8

readUTF8(index: number, buf: number[]): string

Reads an UTF8 string constant pool item in #b b. <i>This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Parameters

• index: number the start index of an unsigned short value in #b b, whose value is the index of an UTF8 constant pool item.
• buf: number[] buffer to be used to read the item. This buffer must be sufficiently large. It is not automatically resized.

Return Type

• string

Defined in: packages/asm/libs/ClassReader.ts:1854

readUnsignedShort

readUnsignedShort(index: number): number

Reads an unsigned short value in #b b. <i>This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.</i>

Parameters

• index: number the start index of the value to be read in #b b.

Return Type

• number

Defined in: packages/asm/libs/ClassReader.ts:1796