javacompat

package
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 Go to latest Published: Aug 11, 2026 License: EPL-2.0 Imports: 2 Imported by: 0

Documentation

Overview

Package javacompat contains the small parts of the Java runtime whose exact behavior is observable in ELK layouts.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func BooleanHashCode 

func BooleanHashCode(value bool) int32

BooleanHashCode implements Boolean.hashCode(boolean).

func DoubleCompare 

func DoubleCompare(a, b float64) int

DoubleCompare implements Double.compare. In particular, -0.0 sorts before +0.0 and every NaN sorts after positive infinity and compares equal to every other NaN.

func DoubleHashCode 

func DoubleHashCode(value float64) int32

DoubleHashCode implements Double.hashCode(double).

func DoubleToInt 

func DoubleToInt(value float64) int32

DoubleToInt and DoubleToLong implement Java's narrowing primitive casts: NaN becomes zero, finite out-of-range values and infinities saturate, and finite in-range values truncate toward zero.

func DoubleToLong 

func DoubleToLong(value float64) int64

func DoubleToLongBits 

func DoubleToLongBits(value float64) uint64

DoubleToLongBits implements Double.doubleToLongBits, including NaN canonicalization. Use math.Float64bits when Java's doubleToRawLongBits is specifically required.

func FloatCompare 

func FloatCompare(a, b float32) int

FloatCompare implements Float.compare.

func FloatHashCode 

func FloatHashCode(value float32) int32

FloatHashCode implements Float.hashCode(float).

func FloatToIntBits 

func FloatToIntBits(value float32) uint32

FloatToIntBits implements Float.floatToIntBits, including NaN canonicalization.

func GWTStableSort added in v0.2.0 

func GWTStableSort[T any](values []T, compare func(T, T) int)

GWTStableSort reproduces the object-array legacy merge sort in GWT 2.11.0's emulated java.util.Arrays. The relevant implementation is unchanged from GWT 2.9.0. Comparator invocation order is observable when a comparator records comparisons or derives transitive state, as ELK's model-order comparators do.

func HashMapSpread 

func HashMapSpread(hash int32) int32

HashMapSpread reproduces the one-step high-bit spread observed by ELK's Java-compatible hash tables. Its behavior is pinned by independent vectors.

func IntCompare 

func IntCompare(a, b int32) int

IntCompare and LongCompare implement Integer.compare and Long.compare.

func IntToByte 

func IntToByte(value int32) int8

Narrowing integral conversions implement Java casts.

func IntToChar 

func IntToChar(value int32) uint16

func IntToShort 

func IntToShort(value int32) int16

func JSMathCos added in v0.2.0 

func JSMathCos(x float64) float64

func JSMathSin added in v0.2.0 

func JSMathSin(x float64) float64

JSMathSin and JSMathCos reproduce the fdlibm implementation used by V8's Math.sin and Math.cos for the medium-size arguments emitted by ELK Radial. The kernels and constants are adapted from Node.js v24.19.0's pinned V8 deps/v8/src/base/ieee754.cc (itself adapted from fdlibm). Very large arguments fall back to Go's math package; layout angles are many orders of magnitude below that boundary.

func LongCompare 

func LongCompare(a, b int64) int

func LongHashCode 

func LongHashCode(value int64) int32

LongHashCode implements Long.hashCode(long).

func MathMaxDouble 

func MathMaxDouble(a, b float64) float64

func MathMinDouble 

func MathMinDouble(a, b float64) float64

MathMinDouble and MathMaxDouble preserve Java's NaN and signed-zero rules.

func MathRoundDouble 

func MathRoundDouble(value float64) int64

MathRoundDouble and MathRoundFloat implement Math.round.

func MathRoundFloat 

func MathRoundFloat(value float32) int32

func StringHashCode 

func StringHashCode(value string) int32

StringHashCode implements String.hashCode over Java UTF-16 code units, not Unicode code points. This distinction matters for supplementary characters.

func UnsignedRightShiftInt 

func UnsignedRightShiftInt(value int32, distance uint) int32

UnsignedRightShiftInt and UnsignedRightShiftLong implement Java's >>>. Java masks the shift distance to five or six bits respectively.

func UnsignedRightShiftLong 

func UnsignedRightShiftLong(value int64, distance uint) int64

Types

type Comparator 

type Comparator[T any] func(a, b T) int

Comparator has the contract of java.util.Comparator.compare: negative when a is less than b, zero when they compare equal, and positive otherwise.

type GWTPriorityQueue 

type GWTPriorityQueue[T any] struct {
	// contains filtered or unexported fields
}

GWTPriorityQueue reproduces GWT 2.11.0's java.util.PriorityQueue implementation linked into elkjs 0.12.0. The relevant GWT source is unchanged from the 2.9.0 runtime used by the former elkjs 0.8.2 baseline. Its bulk-add heapification and equal-item sift-down behavior differ observably from OpenJDK's PriorityQueue.

func NewGWTPriorityQueue 

func NewGWTPriorityQueue[T any](compare Comparator[T]) *GWTPriorityQueue[T]

func (*GWTPriorityQueue[T]) Add 

func (queue *GWTPriorityQueue[T]) Add(item T)

func (*GWTPriorityQueue[T]) AddAll 

func (queue *GWTPriorityQueue[T]) AddAll(items []T) bool

AddAll appends the complete collection and then invokes GWT's recursive makeHeap routine. It does not repeatedly call Offer.

func (*GWTPriorityQueue[T]) IsEmpty 

func (queue *GWTPriorityQueue[T]) IsEmpty() bool

func (*GWTPriorityQueue[T]) Len 

func (queue *GWTPriorityQueue[T]) Len() int

func (*GWTPriorityQueue[T]) Offer 

func (queue *GWTPriorityQueue[T]) Offer(item T) bool

func (*GWTPriorityQueue[T]) Peek 

func (queue *GWTPriorityQueue[T]) Peek() (T, bool)

func (*GWTPriorityQueue[T]) Poll 

func (queue *GWTPriorityQueue[T]) Poll() (T, bool)

type IdentityMap 

type IdentityMap[K comparable, V any] struct {
	// contains filtered or unexported fields
}

IdentityMap provides IdentityHashMap equality semantics for identity-bearing comparable keys. K should be a pointer or an arena handle, never a value object whose == operation represents structural equality. Iteration is made deterministic in first-insertion order; ELK does not rely on the unspecified table order of java.util.IdentityHashMap.

The zero value is ready to use.

func NewIdentityMap 

func NewIdentityMap[K comparable, V any]() *IdentityMap[K, V]

func (*IdentityMap[K, V]) Clear 

func (m *IdentityMap[K, V]) Clear()

func (*IdentityMap[K, V]) ContainsKey 

func (m *IdentityMap[K, V]) ContainsKey(key K) bool

func (*IdentityMap[K, V]) Get 

func (m *IdentityMap[K, V]) Get(key K) (V, bool)

func (*IdentityMap[K, V]) IsEmpty 

func (m *IdentityMap[K, V]) IsEmpty() bool

func (*IdentityMap[K, V]) Keys 

func (m *IdentityMap[K, V]) Keys() []K

func (*IdentityMap[K, V]) Len 

func (m *IdentityMap[K, V]) Len() int

func (*IdentityMap[K, V]) Put 

func (m *IdentityMap[K, V]) Put(key K, value V) (V, bool)

func (*IdentityMap[K, V]) Range 

func (m *IdentityMap[K, V]) Range(visit func(K, V) bool)

func (*IdentityMap[K, V]) Remove 

func (m *IdentityMap[K, V]) Remove(key K) (V, bool)

func (*IdentityMap[K, V]) Values 

func (m *IdentityMap[K, V]) Values() []V

type IdentitySet 

type IdentitySet[K comparable] struct {
	// contains filtered or unexported fields
}

IdentitySet is IdentityMap's set counterpart. K should be a pointer or an arena handle so Go equality is object identity.

func NewIdentitySet 

func NewIdentitySet[K comparable]() *IdentitySet[K]

func (*IdentitySet[K]) Add 

func (s *IdentitySet[K]) Add(value K) bool

func (*IdentitySet[K]) Clear 

func (s *IdentitySet[K]) Clear()

func (*IdentitySet[K]) Contains 

func (s *IdentitySet[K]) Contains(value K) bool

func (*IdentitySet[K]) IsEmpty 

func (s *IdentitySet[K]) IsEmpty() bool

func (*IdentitySet[K]) Len 

func (s *IdentitySet[K]) Len() int

func (*IdentitySet[K]) Range 

func (s *IdentitySet[K]) Range(visit func(K) bool)

func (*IdentitySet[K]) Remove 

func (s *IdentitySet[K]) Remove(value K) bool

func (*IdentitySet[K]) Values 

func (s *IdentitySet[K]) Values() []K

type OrderedMap 

type OrderedMap[K comparable, V any] struct {
	// contains filtered or unexported fields
}

OrderedMap is an insertion-ordered map matching LinkedHashMap's default (accessOrder=false) behavior. Replacing a value does not move its key; removing and reinserting a key appends it at the end.

The zero value is ready to use.

func NewOrderedMap 

func NewOrderedMap[K comparable, V any]() *OrderedMap[K, V]

NewOrderedMap constructs an empty insertion-ordered map.

func (*OrderedMap[K, V]) Clear 

func (m *OrderedMap[K, V]) Clear()

Clear removes all entries.

func (*OrderedMap[K, V]) ContainsKey 

func (m *OrderedMap[K, V]) ContainsKey(key K) bool

ContainsKey reports whether key is present.

func (*OrderedMap[K, V]) First 

func (m *OrderedMap[K, V]) First() (K, V, bool)

First returns the oldest entry.

func (*OrderedMap[K, V]) Get 

func (m *OrderedMap[K, V]) Get(key K) (V, bool)

Get looks up a value.

func (*OrderedMap[K, V]) IsEmpty 

func (m *OrderedMap[K, V]) IsEmpty() bool

IsEmpty reports whether the map has no entries.

func (*OrderedMap[K, V]) Keys 

func (m *OrderedMap[K, V]) Keys() []K

Keys returns keys in insertion order.

func (*OrderedMap[K, V]) Last 

func (m *OrderedMap[K, V]) Last() (K, V, bool)

Last returns the newest entry.

func (*OrderedMap[K, V]) Len 

func (m *OrderedMap[K, V]) Len() int

Len returns the number of entries.

func (*OrderedMap[K, V]) Put 

func (m *OrderedMap[K, V]) Put(key K, value V) (V, bool)

Put inserts or replaces a value. It returns the old value and whether the key was already present.

func (*OrderedMap[K, V]) PutIfAbsent 

func (m *OrderedMap[K, V]) PutIfAbsent(key K, value V) (V, bool)

PutIfAbsent inserts only when key is absent and returns the existing or new value plus whether an existing entry was found.

func (*OrderedMap[K, V]) Range 

func (m *OrderedMap[K, V]) Range(visit func(K, V) bool)

Range visits entries in insertion order until visit returns false. Structural mutation during Range is unsupported, matching Java iterator fail-fast semantics without exposing a concurrent-modification exception.

func (*OrderedMap[K, V]) Remove 

func (m *OrderedMap[K, V]) Remove(key K) (V, bool)

Remove deletes key, preserving the relative order of all remaining keys.

func (*OrderedMap[K, V]) Values 

func (m *OrderedMap[K, V]) Values() []V

Values returns values in key insertion order.

type OrderedSet 

type OrderedSet[T comparable] struct {
	// contains filtered or unexported fields
}

OrderedSet is an insertion-ordered set matching LinkedHashSet. The zero value is ready to use.

func NewOrderedSet 

func NewOrderedSet[T comparable]() *OrderedSet[T]

NewOrderedSet constructs an empty insertion-ordered set.

func (*OrderedSet[T]) Add 

func (s *OrderedSet[T]) Add(value T) bool

Add inserts value and reports whether the set changed.

func (*OrderedSet[T]) Clear 

func (s *OrderedSet[T]) Clear()

Clear removes every value.

func (*OrderedSet[T]) Contains 

func (s *OrderedSet[T]) Contains(value T) bool

Contains reports whether value is present.

func (*OrderedSet[T]) IsEmpty 

func (s *OrderedSet[T]) IsEmpty() bool

IsEmpty reports whether the set is empty.

func (*OrderedSet[T]) Len 

func (s *OrderedSet[T]) Len() int

Len returns the number of values.

func (*OrderedSet[T]) Range 

func (s *OrderedSet[T]) Range(visit func(T) bool)

Range visits values in insertion order until visit returns false.

func (*OrderedSet[T]) Remove 

func (s *OrderedSet[T]) Remove(value T) bool

Remove deletes value and reports whether the set changed.

func (*OrderedSet[T]) Values 

func (s *OrderedSet[T]) Values() []T

Values returns values in insertion order.

type PriorityQueue 

type PriorityQueue[T any] struct {
	// contains filtered or unexported fields
}

PriorityQueue is a clean-room binary min-heap whose tie behavior is pinned by elkjs oracle vectors. Java does not define FIFO ordering for equal elements, but ELK observes the heap-array order, so left-child and strict-comparison choices are part of this compatibility type's tested behavior.

func NewPriorityQueue 

func NewPriorityQueue[T any](compare Comparator[T]) *PriorityQueue[T]

NewPriorityQueue returns an empty Java-compatible min-priority queue.

func NewPriorityQueueCapacity 

func NewPriorityQueueCapacity[T any](capacity int, compare Comparator[T]) *PriorityQueue[T]

NewPriorityQueueCapacity is NewPriorityQueue with a capacity hint. Java's growth policy does not affect heap order, but avoiding reallocations is handy for the larger layered-layout queues.

func (*PriorityQueue[T]) Add 

func (q *PriorityQueue[T]) Add(item T)

Add inserts item. Java's add and offer have identical heap behavior.

func (*PriorityQueue[T]) Clear 

func (q *PriorityQueue[T]) Clear()

Clear removes every element while releasing references held by the backing slice.

func (*PriorityQueue[T]) Elements 

func (q *PriorityQueue[T]) Elements() []T

Elements returns a copy in PriorityQueue iterator order (the heap-array order). This order is deliberately not sorted, just like Java's iterator.

func (*PriorityQueue[T]) IsEmpty 

func (q *PriorityQueue[T]) IsEmpty() bool

IsEmpty reports whether the queue is empty.

func (*PriorityQueue[T]) Len 

func (q *PriorityQueue[T]) Len() int

Len returns the number of queued elements.

func (*PriorityQueue[T]) Offer 

func (q *PriorityQueue[T]) Offer(item T) bool

Offer inserts item and returns true, matching PriorityQueue.offer.

func (*PriorityQueue[T]) Peek 

func (q *PriorityQueue[T]) Peek() (T, bool)

Peek returns the least element without removing it.

func (*PriorityQueue[T]) Poll 

func (q *PriorityQueue[T]) Poll() (T, bool)

Poll removes and returns the least element.

func (*PriorityQueue[T]) RemoveFirst 

func (q *PriorityQueue[T]) RemoveFirst(match func(T) bool) bool

RemoveFirst removes the first element in the queue's internal array for which match returns true. This is PriorityQueue.remove(Object) with equality supplied explicitly, which also supports non-comparable Go values.

type Random 

type Random struct {
	// contains filtered or unexported fields
}

Random is a bit-for-bit implementation of java.util.Random from Java 8.

Random is not safe for concurrent use. ELK owns one instance per layout, as the Java implementation does, so synchronization would only obscure the order in which random values are consumed.

func NewRandom 

func NewRandom(seed int64) *Random

NewRandom constructs a Java-compatible pseudo-random number generator.

func (*Random) NextBoolean 

func (r *Random) NextBoolean() bool

NextBoolean implements Random.nextBoolean().

func (*Random) NextBytes 

func (r *Random) NextBytes(dst []byte)

NextBytes implements Random.nextBytes(byte[]). Java's byte is signed, but assigning its low eight bits to a Go byte gives the same byte sequence.

func (*Random) NextDouble 

func (r *Random) NextDouble() float64

NextDouble implements Random.nextDouble().

func (*Random) NextFloat 

func (r *Random) NextFloat() float32

NextFloat implements Random.nextFloat().

func (*Random) NextGaussian 

func (r *Random) NextGaussian() float64

NextGaussian implements Random.nextGaussian(), including its cached second sample. ELK 0.8.1 does not use this in a layout path, but providing the Java behavior prevents consumers from accidentally substituting math/rand. Math-library results may differ by a final bit across platforms, just as Java's Math implementation may, while the random-value consumption is exact.

func (*Random) NextInt 

func (r *Random) NextInt() int32

NextInt implements Random.nextInt().

func (*Random) NextIntN 

func (r *Random) NextIntN(bound int32) int32

NextIntN implements Random.nextInt(bound). It panics for a non-positive bound, corresponding to Java's IllegalArgumentException.

func (*Random) NextLong 

func (r *Random) NextLong() int64

NextLong implements Random.nextLong(). The low 32 bits are sign-extended before addition, as required by Java's two signed int32 draws.

func (*Random) SetSeed 

func (r *Random) SetSeed(seed int64)

SetSeed implements Random.setSeed(long). It also clears the cached value used by NextGaussian.

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