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Adds support for Ion Schema 2.0 ieee754_float constraint
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ion-schema/src/main/kotlin/com/amazon/ionschema/internal/constraint/Ieee754Float.kt
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| /* | ||
| * Copyright 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"). | ||
| * You may not use this file except in compliance with the License. | ||
| * A copy of the License is located at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * or in the "license" file accompanying this file. This file is distributed | ||
| * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either | ||
| * express or implied. See the License for the specific language governing | ||
| * permissions and limitations under the License. | ||
| */ | ||
|
|
||
| package com.amazon.ionschema.internal.constraint | ||
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| import com.amazon.ion.IonFloat | ||
| import com.amazon.ion.IonSymbol | ||
| import com.amazon.ion.IonValue | ||
| import com.amazon.ionschema.Violation | ||
| import com.amazon.ionschema.Violations | ||
| import com.amazon.ionschema.internal.constraint.Ieee754Float.Ieee754InterchangeFormat.binary16 | ||
| import com.amazon.ionschema.internal.constraint.Ieee754Float.Ieee754InterchangeFormat.binary32 | ||
| import com.amazon.ionschema.internal.constraint.Ieee754Float.Ieee754InterchangeFormat.binary64 | ||
| import com.amazon.ionschema.internal.util.islRequire | ||
| import com.amazon.ionschema.internal.util.islRequireIonTypeNotNull | ||
| import com.amazon.ionschema.internal.util.islRequireNotNull | ||
| import kotlin.math.absoluteValue | ||
|
|
||
| /** | ||
| * Implements the ieee754_float constraint. | ||
| * | ||
| * @see https://amzn.github.io/ion-schema/docs/isl-2-0/spec#ieee754_float | ||
| */ | ||
| internal class Ieee754Float(ion: IonValue) : ConstraintBase(ion) { | ||
|
|
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| /** | ||
| * Represents a range of floating point numbers and the interval between the representable values in that range. | ||
| */ | ||
| private data class PrecisionInfo(val range: ClosedRange<Double>, val interval: Double) | ||
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| companion object { | ||
| /** | ||
| * Available precision can be calculated to produce a table, such as the following table for 16-bit floats. | ||
| * | ||
| * Rather than create a generalized solution, we're going to hardcode some values. This is justifiable because | ||
| * 16-bit floats are small enough that we can do it, this is the only floating point format for which it is | ||
| * needed, and it avoids the complexity of a generalized solution. | ||
| * | ||
| * Technically, there is overlap between the ranges, but that's okay because the overlap is only the boundary | ||
| * value, which will be valid regardless of which interval we test it against. | ||
| */ | ||
| private val BINARY_16_PRECISION_RANGES = listOf( | ||
| PrecisionInfo(0.0..1.0 / 16_384, interval = 1.0 / 16_777_216), // Subnormal numbers | ||
| PrecisionInfo(1.0 / 16_384..1.0 / 8_192, interval = 1.0 / 16_777_216), | ||
| PrecisionInfo(1.0 / 8_192..1.0 / 4_096, interval = 1.0 / 8_388_608), | ||
| PrecisionInfo(1.0 / 4_096..1.0 / 2_048, interval = 1.0 / 4_194_304), | ||
| PrecisionInfo(1.0 / 2_048..1.0 / 1_024, interval = 1.0 / 2_097_152), | ||
| PrecisionInfo(1.0 / 1_024..1.0 / 512, interval = 1.0 / 1_048_576), | ||
| PrecisionInfo(1.0 / 512..1.0 / 256, interval = 1.0 / 524_288), | ||
| PrecisionInfo(1.0 / 256..1.0 / 128, interval = 1.0 / 262_144), | ||
| PrecisionInfo(1.0 / 128..1.0 / 64, interval = 1.0 / 131_072), | ||
| PrecisionInfo(1.0 / 64..1.0 / 32, interval = 1.0 / 65_536), | ||
| PrecisionInfo(1.0 / 32..1.0 / 16, interval = 1.0 / 32_768), | ||
| PrecisionInfo(1.0 / 16..1.0 / 8, interval = 1.0 / 16_384), | ||
| PrecisionInfo(1.0 / 8..1.0 / 4, interval = 1.0 / 8_192), | ||
| PrecisionInfo(1.0 / 4..1.0 / 2, interval = 1.0 / 4_096), | ||
| PrecisionInfo(1.0 / 2..1.0, interval = 1.0 / 2_048), | ||
| PrecisionInfo(1.0..2.0, interval = 1.0 / 1_024), | ||
| PrecisionInfo(2.0..4.0, interval = 1.0 / 512), | ||
| PrecisionInfo(4.0..8.0, interval = 1.0 / 256), | ||
| PrecisionInfo(8.0..16.0, interval = 1.0 / 128), | ||
| PrecisionInfo(16.0..32.0, interval = 1.0 / 64), | ||
| PrecisionInfo(32.0..64.0, interval = 1.0 / 32), | ||
| PrecisionInfo(64.0..128.0, interval = 1.0 / 16), | ||
| PrecisionInfo(128.0..256.0, interval = 1.0 / 8), | ||
| PrecisionInfo(256.0..512.0, interval = 1.0 / 4), | ||
| PrecisionInfo(512.0..1_024.0, interval = 1.0 / 2), | ||
| PrecisionInfo(1_024.0..2_048.0, interval = 1.0), | ||
| PrecisionInfo(2_048.0..4_096.0, interval = 2.0), | ||
| PrecisionInfo(4_096.0..8_192.0, interval = 4.0), | ||
| PrecisionInfo(8_192.0..16_384.0, interval = 8.0), | ||
| PrecisionInfo(16_384.0..32_768.0, interval = 16.0), | ||
| PrecisionInfo(32_768.0..65_504.0, interval = 32.0), | ||
| ) | ||
| } | ||
|
|
||
| /** | ||
| * The possible values for the `ieee754_float` constraint. | ||
| */ | ||
| private enum class Ieee754InterchangeFormat { | ||
| binary16, | ||
| binary32, | ||
| binary64; | ||
| companion object { | ||
| val names = Ieee754InterchangeFormat.values().map { it.name } | ||
| } | ||
| } | ||
|
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||
| private val interchangeFormat = ion.let { | ||
| islRequireIonTypeNotNull<IonSymbol>(it) { "ieee754_float must be a non-null Ion symbol" } | ||
| islRequire(it.typeAnnotations.isEmpty()) { "ieee754_float must not have annotations" } | ||
| islRequire(it.stringValue() in Ieee754InterchangeFormat.names) { "ieee754_float must be one of ${Ieee754InterchangeFormat.names}" } | ||
| return@let Ieee754InterchangeFormat.valueOf(it.stringValue()) | ||
| } | ||
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| override fun validate(value: IonValue, issues: Violations) { | ||
| validateAs<IonFloat>(value, issues) { | ||
| if (!(interchangeFormat losslesslyEncodes it)) { | ||
| issues.add(Violation(ion, "invalid_ieee754_float", "value cannot be losslessly represented by the IEEE-754 $interchangeFormat interchange format.")) | ||
| } | ||
| } | ||
| } | ||
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| private infix fun Ieee754InterchangeFormat.losslesslyEncodes(value: IonFloat): Boolean { | ||
| // +inf, -inf, and nan are always valid | ||
| if (!value.doubleValue().isFinite()) return true | ||
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||
| return when (this) { | ||
| binary16 -> value.doubleValue().isExactHalfValue() | ||
| binary32 -> value.doubleValue().toFloat().toDouble() == value.doubleValue() | ||
| binary64 -> true // All Ion Floats are 64 bits or smaller. | ||
| } | ||
| } | ||
|
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||
| private fun Double.isExactHalfValue(): Boolean { | ||
| if (this.absoluteValue > 65504) return false | ||
| // Find the appropriate interval for the Double value we are testing | ||
| val (_, interval) = BINARY_16_PRECISION_RANGES.first { (range, _) -> absoluteValue in range } | ||
| // If the value is an exact multiple of the interval between two Half values, then we know it | ||
| // is possible to _exactly_ represent the value as a Half precision float. | ||
| return this % interval == 0.0 | ||
| } | ||
| } |
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