Package convex.core.data

Class Syntax

java.lang.Object

convex.core.data.AObject

convex.core.data.ACell

convex.core.data.Syntax

All Implemented Interfaces:

IValidated, IWriteable

public final class Syntax
extends ACell

Class representing a Syntax Object. A Syntax Object wraps:

• A Form (which may contain nested Syntax Objects)
• Metadata for the Syntax Object, which may be any arbitrary hashmap

Syntax Objects may not wrap another Syntax Object directly, but may contain nested Syntax Objects within data structures. Inspired by Racket.

Field Summary

Fields

Modifier and Type	Field	Description
static final Syntax	EMPTY
static final AString	EMPTY_META_PREFIX
static final int	MAX_ENCODING_LENGTH	Max encoding size is a Map (with substituted tag) plus an embedded datum

Fields inherited from class convex.core.data.ACell

cachedRef, memorySize

Fields inherited from class convex.core.data.AObject

encoding

Method Summary

Modifier and Type	Method	Description
static Syntax	create(ACell value)	Wraps a value as a Syntax Object with empty metadata.
static Syntax	create(ACell value, AHashMap<ACell,ACell> meta)	Wraps a value as a Syntax Object, adding the given new metadata
static Syntax	createUnchecked(ACell value, AHashMap<ACell,ACell> meta)
int	encode(byte[] bs, int pos)	Writes this Cell's encoding to a byte array, including a tag byte which will be written first.
int	encodeRaw(byte[] bs, int pos)	Writes this Cell's encoding to a byte array, excluding the tag byte.
boolean	equals(ACell o)	Checks for equality with another Cell.
int	estimatedEncodingSize()	Estimate the encoded data size for this Cell.
Long	getEnd()
AHashMap<ACell,ACell>	getMeta()	Gets the metadata for this syntax object.
<R extends ACell> Ref<R>	getRef(int i)	Gets a numbered child Ref from within this Cell.
int	getRefCount()	Gets the number of Refs contained within this Cell.
String	getSource()
Long	getStart()
byte	getTag()	Gets the tag byte for this cell.
AType	getType()	Gets the most specific known runtime Type for this Cell.
<R> R	getValue()	Gets the value datum from this Syntax Object
boolean	isCanonical()	Returns true if this Cell is in a canonical representation.
final boolean	isCVMValue()	Returns true if this cell is a first class CVM Value allowable in the CVM state Sub-structural cells that are not themselves first class values should return false Records and types that are not permissible on the CVM should return false.
final boolean	isDataValue()	Returns true if this cell instance is a first class value, i.e.
static Syntax	mergeMeta(ACell original, Syntax additional)	Merge metadata into a Cell, after wrapping as a Syntax Object
Syntax	mergeMeta(AHashMap<ACell,ACell> additionalMetadata)	Merges metadata into this syntax object, overriding existing metadata
static Syntax	of(ACell value)	Wraps a value as a Syntax Object with empty metadata.
static Syntax	of(Object value)	Create a Syntax Object with the given value.
boolean	print(BlobBuilder bb, long limit)	Prints this Object to a readable String Representation.
static Syntax	read(Blob b, int pos)	Decodes a Syntax object from a Blob encoding
ACell	toCanonical()	Converts this Cell to a canonical version.
static <R> R	unwrap(ACell x)	Unwraps a Syntax Object to get the underlying value.
static <R extends ACell> R	unwrapAll(ACell maybeSyntax)	Recursively unwraps a Syntax object
Syntax	updateRefs(IRefFunction func)	Updates all Refs in this object using the given function.
void	validate()	Validates the complete structure of this object.
void	validateCell()	Validates the local structure and invariants of this cell.
Syntax	withMeta(AHashMap<ACell,ACell> newMetadata)	Replaces metadata on this Syntax Object.
Syntax	withoutMeta()	Removes all metadata from this Syntax Object

Methods inherited from class convex.core.data.ACell

attachMemorySize, attachRef, cachedEncoding, cachedHash, calcMemorySize, createEncoding, createRef, equals, genericEquals, getCanonical, getChildRefs, getEncoding, getEncodingLength, getHash, getMemorySize, getMemorySize, getRef, hashCode, isEmbedded, toCVMString, toString

Methods inherited from class convex.core.data.AObject

attachEncoding, print, print

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

EMPTY

public static final Syntax EMPTY

EMPTY_META_PREFIX

public static final AString EMPTY_META_PREFIX

MAX_ENCODING_LENGTH

public static final int MAX_ENCODING_LENGTH

Max encoding size is a Map (with substituted tag) plus an embedded datum

Method Details

getType

public AType getType()

Description copied from class: ACell

Gets the most specific known runtime Type for this Cell.

Overrides:

getType in class ACell

Returns:

The Type of this Call

createUnchecked

public static Syntax createUnchecked(ACell value,
 AHashMap<ACell,ACell> meta)

create

public static Syntax create(ACell value,
 AHashMap<ACell,ACell> meta)

Wraps a value as a Syntax Object, adding the given new metadata

Parameters:

value - Value to wrap in Syntax Object

meta - Metadata to merge, may be null

Returns:

Syntax instance

create

public static Syntax create(ACell value)

Wraps a value as a Syntax Object with empty metadata. Does not change existing Syntax objects.

Parameters:

value - Any CVM value

Returns:

Syntax instance

of

public static Syntax of(ACell value)

Wraps a value as a Syntax Object with empty metadata. Does not change existing Syntax objects.

Parameters:

value - Any value, will be converted to valid CVM type

Returns:

Syntax instance

of

public static Syntax of(Object value)

Create a Syntax Object with the given value. Converts to appropriate CVM type as a convenience

Parameters:

value - Value to wrap

Returns:

Syntax instance

getValue

public <R> R getValue()

Gets the value datum from this Syntax Object

Type Parameters:

R - Expected datum type from Syntax object

Returns:

Value datum

getMeta

public AHashMap<ACell,ACell> getMeta()

Gets the metadata for this syntax object. May be empty, but never null.

Returns:

Metadata for this Syntax Object as a hashmap

getStart

public Long getStart()

getEnd

public Long getEnd()

getSource

public String getSource()

isCanonical

public boolean isCanonical()

Description copied from class: ACell

Returns true if this Cell is in a canonical representation. Non-canonical objects may be used on a temporary internal basis, they should be converted to canonical representations for general purpose use.

Specified by:

isCanonical in class ACell

Returns:

true if the object is in canonical format, false otherwise

isCVMValue

public final boolean isCVMValue()

Description copied from class: ACell

Returns true if this cell is a first class CVM Value allowable in the CVM state Sub-structural cells that are not themselves first class values should return false Records and types that are not permissible on the CVM should return false. Pretty much everything else should return true. Note: CVM values might not be in a canonical format, e.g. temporary data structures

Specified by:

isCVMValue in class ACell

Returns:

true if the object is a CVM Value, false otherwise

isDataValue

public final boolean isDataValue()

Description copied from class: ACell

Returns true if this cell instance is a first class value, i.e. not a component of a larger data structure Sub-structural cells that are not themselves first class values should return false Everything else should return true.

Specified by:

isDataValue in class ACell

Returns:

true if the object is a Value, false otherwise

read

public static Syntax read(Blob b,
 int pos)
                   throws BadFormatException

Decodes a Syntax object from a Blob encoding

Parameters:

b - Blob to read from

pos - Start position in Blob (location of tag byte)

Returns:

New decoded instance

Throws:

BadFormatException - In the event of any encoding error

encode

public int encode(byte[] bs,
 int pos)

Description copied from class: ACell

Writes this Cell's encoding to a byte array, including a tag byte which will be written first. Cell must be canonical, or else an error may occur.

Specified by:

encode in interface IWriteable

Specified by:

encode in class ACell

Parameters:

bs - A byte array to which to write the encoding

pos - The offset into the byte array

Returns:

New position after writing

encodeRaw

public int encodeRaw(byte[] bs,
 int pos)

Description copied from class: ACell

Writes this Cell's encoding to a byte array, excluding the tag byte.

Specified by:

encodeRaw in class ACell

Parameters:

bs - A byte array to which to write the encoding

pos - The offset into the byte array

Returns:

New position after writing

print

public boolean print(BlobBuilder bb,
 long limit)

Description copied from class: AObject

Prints this Object to a readable String Representation. SECURITY: Must halt and return false in O(1) time when limit of printing is exceeded otherwise DoS attacks may be possible.

Specified by:

print in class AObject

Parameters:

bb - BlobBuilder to append to. May be partially written if print limit exceeded

limit - Limit of printing in string bytes

Returns:

True if fully printed within limit, false otherwise

validateCell

public void validateCell()
                  throws InvalidDataException

Description copied from class: ACell

Validates the local structure and invariants of this cell. Called by validate() super implementation. Should validate directly contained data, but should not validate all other structure of this cell. In particular, should not traverse potentially missing child Refs.

Specified by:

validateCell in class ACell

Throws:

InvalidDataException - If the Cell is invalid

validate

public void validate()
              throws InvalidDataException

Description copied from interface: IValidated

Validates the complete structure of this object. It is necessary to ensure all child Refs are validated, so the general contract for validate is:

1. Call super.validate() - which will indirectly call validateCell()
2. Call validate() on any contained cells in this class

Specified by:

validate in interface IValidated

Overrides:

validate in class ACell

Throws:

InvalidDataException - If the data Value is invalid in any way

estimatedEncodingSize

public int estimatedEncodingSize()

Description copied from interface: IWriteable

Estimate the encoded data size for this Cell. Used for quickly sizing buffers. Implementations should try to return a size that is highly likely to contain the entire object when encoded, including the tag byte. Should not traverse soft Refs, i.e. must be usable on arbitrary partial data structures

Returns:

The estimated size for the binary representation of this object.

getRefCount

public int getRefCount()

Description copied from class: ACell

Gets the number of Refs contained within this Cell. This number is final / immutable for any given instance and is defined by the Cell encoding rules. Contained Refs may be either external or embedded.

Overrides:

getRefCount in class ACell

Returns:

The number of Refs in this Cell

getRef

public <R extends ACell> Ref<R> getRef(int i)

Description copied from class: ACell

Gets a numbered child Ref from within this Cell. WARNING: May need to convert to a canonical instance

Overrides:

getRef in class ACell

Type Parameters:

R - Type of referenced Cell

Parameters:

i - Index of ref to get

Returns:

The Ref at the specified index

updateRefs

public Syntax updateRefs(IRefFunction func)

Description copied from class: ACell

Updates all Refs in this object using the given function. The function *must not* change the hash value of Refs, in order to ensure structural integrity of modified data structures. The implementation *should* re-attach any original encoding in order to prevent re-encoding or surplus hashing This is a building block for a very sneaky trick that enables use to do a lot of efficient operations on large trees of smart references. Must return the same object if no Refs are altered.

Overrides:

updateRefs in class ACell

Parameters:

func - Ref update function

Returns:

Cell with updated Refs

mergeMeta

public Syntax mergeMeta(AHashMap<ACell,ACell> additionalMetadata)

Merges metadata into this syntax object, overriding existing metadata

Parameters:

additionalMetadata - Extra metadata to merge

Returns:

Syntax Object with updated metadata

mergeMeta

public static Syntax mergeMeta(ACell original,
 Syntax additional)

Merge metadata into a Cell, after wrapping as a Syntax Object

Parameters:

original - Cell to enhance with merged metadata

additional - Syntax Object containing additional metadata. Any value will be ignored.

Returns:

Syntax object with merged metadata

withMeta

public Syntax withMeta(AHashMap<ACell,ACell> newMetadata)

Replaces metadata on this Syntax Object. Old metadata is discarded.

Parameters:

newMetadata - New metadata map

Returns:

Syntax Object with updated metadata

withoutMeta

public Syntax withoutMeta()

Removes all metadata from this Syntax Object

Returns:

Syntax Object with empty metadata

unwrap

public static <R> R unwrap(ACell x)

Unwraps a Syntax Object to get the underlying value. If the argument is not a Syntax object, return it unchanged (already unwrapped)

Type Parameters:

R - Expected type of value

Parameters:

x - Any Object, which may be a Syntax Object

Returns:

The unwrapped value

unwrapAll

public static <R extends ACell> R unwrapAll(ACell maybeSyntax)

Recursively unwraps a Syntax object

Parameters:

maybeSyntax - Syntax Object to unwrap

Returns:

Unwrapped object

getTag

public byte getTag()

Description copied from class: ACell

Gets the tag byte for this cell. The tag byte is always equal to the first byte of the Cell's canonical Encoding, and is sufficient to distinguish how to read the rest of the encoding.

Specified by:

getTag in class ACell

Returns:

Tag byte for this Cell

toCanonical

public ACell toCanonical()

Description copied from class: ACell

Converts this Cell to a canonical version. Must return this Cell if already canonical, may be O(n) in size of value otherwise. Callers should usually use getCanonical(), which caches canonical instances once created

Specified by:

toCanonical in class ACell

Returns:

Canonical version of Cell

equals

public boolean equals(ACell o)

Description copied from class: ACell

Checks for equality with another Cell. In general, Cells are considered equal if they have the same canonical representation, i.e. an identical encoding with the same hash value. Subclasses SHOULD override this if they have a more efficient equals implementation. MUST NOT require reads from Store.

Specified by:

equals in class ACell

Parameters:

o - Cell to compare with. May be null.

Returns:

True if this cell is equal to the other object