Generate operators from unit relations defined in JSON #1329

Muximize · 2023-11-13T12:16:33Z

Related #1200

In the PR adding generic math (#1164) @AndreasLeeb states:

Regarding the operators in the *.extra.cs files, that could be tackled easily by describing the dependencies (operations) between different quantities in the quantity JSON files, and then the operator overloads and the generic math interfaces for the quantity structs could also be automatically generated. But that's a topic for another time 😄

I decided to give this a shot.

UnitRelations.json contains relations extracted from the existing *.extra.cs files. I decided on a new file because multiplication is commutative and I didn't want to duplicate these in the individual quantity JSON files, or risk missing one or the other, so it's best to define them once in one place. The generator handles this by generating two operators for a single multiplication relation.

The relations format uses the quantities method names. This is a bit unfortunate, but it's the best I could come up with without making the CodeGen project depend on UnitsNet, which would create a bit of a chicken/egg problem. This is not unheard of (self-hosted compilers) but I wanted to keep it simple for now.

The generated code enables the removal of 44 *.extra.cs files, and the 17 remaining contain much less code.

Muximize · 2023-12-19T17:48:45Z

@angularsen What's your opinion about this? Is this a worthwhile endeavor in the right direction?

angularsen · 2023-12-20T06:23:17Z

Apologies, I thought this was still being worked on so I haven't looked at it yet.
The PR description sounds very useful, I'm just curious if there are any challenges to this approach or not.

Let me read more through the code and get back to you 👍 Will try to find time the next couple of days.

Muximize · 2023-12-22T10:03:33Z

No worries, I should have been more clear that this is a proposal in need of feedback. God jul! 😄

angularsen

I think this looks very promising and a big improvement on the existing approach.

A few ideas below.

CodeGen/JsonTypes/Relation.cs

CodeGen/Generators/UnitsNetGen/QuantityGenerator.cs

Common/UnitRelations.json

UnitsNet/CustomCode/Quantities/Force.extra.cs

UnitsNet/GeneratedCode/Quantities/MassConcentration.g.cs

Came across this while working on #1329. I'm afraid it's an API-breaking change, so maybe it should wait for v6? Related: #1200

…rder

angularsen

I think this looks solid! This is some impressive work 👏

Some minor suggestions for you to consider.

The biggest one for me is to get some peace of mind that we are not breaking anyone as it is hard to verify by review.

I added a suggestion to maybe use reflection to compare before/after of all quantities and their public members, by outputting to text and diffing that.

angularsen · 2024-01-08T20:55:16Z

CodeGen/Generators/QuantityRelationsParser.cs

@@ -119,7 +112,7 @@ private static QuantityRelation ParseRelation(string relationString, IReadOnlyDi
        {
            var segments = relationString.Split(' ');

-            if (segments.Length != 5 || segments[1] != "=")
+            if (segments is not [_, "=", _, "*" or "/", _])
            {
                throw new Exception($"Invalid relation string: {relationString}");


Exception can give an example of a valid format.

It could, but isn't UnitRelations.json full of valid examples?

Absolutely, but I still think it improves the developer experience a bit.

angularsen · 2024-01-08T21:15:58Z

CodeGen/Generators/QuantityRelationsParser.cs

+                var relationStrings = JsonConvert.DeserializeObject<List<string>>(text) ?? [];
+                relationStrings.Sort();
+
+                var parsedRelations = relationStrings.Select(relationString => ParseRelation(relationString, quantities)).ToList();


Should we throw on duplicates here, with a helpful explanation?

It probably gives compile errors in the generated code anyway, but it would be helpful if codegen failed early on invalid input to make it easier for contributors to find out what they did wrong.

If we eventually do #1354 , then duplicates could also occur implicitly by one explicit definition conflicting with the implicit definition for division operators.

Another option is to remove duplicates with a HashSet or similar, then fix the document when writing it back. But it may be complicated to know what to remove, in particular with the magic division operators, so it is probably better to just throw and have the author fix their mistake.

Good idea, I added a check after all relations are inferred.

Duplicate definitions in UnitRelations.json are automatically removed with a SortedSet.

angularsen · 2024-01-08T21:19:04Z

CodeGen/Generators/QuantityRelationsParser.cs

+        ///     "double" can be used as a unitless operand.
+        ///     "1" can be used as the left operand to define inverse relations.
+        /// </summary>
+        /// <param name="rootDir">Repository root directory.</param>


A few examples with some actual quantities and units in a <example></example> tag could be helpful for the reader

angularsen · 2024-01-08T21:20:55Z

CodeGen/Generators/QuantityRelationsParser.cs

+            var @operator = segments[3];
+            var left = segments[2].Split('.');
+            var right = segments[4].Split('.');
+            var result = segments[0].Split('.');


This is fine, I was just thinking maybe regex was a good fit for this parsing?
Not important at all, just a tip to consider.

I tried that but it wasn't a big improvement, the regex is quite ugly and less comprehensible than the list pattern:

^(\w+)\.?(\w*) = (\w+)\.?(\w*) (\*|\/) (\w+)\.?(\w*)$ [_, "=", _, "*" or "/", _]

angularsen · 2024-01-08T21:26:00Z

CodeGen/Generators/UnitsNetGen/QuantityGenerator.cs

@@ -17,6 +17,8 @@ internal class QuantityGenerator : GeneratorBase
        private readonly string _valueType;
        private readonly Unit _baseUnit;

+        private readonly string[] _decimalTypes = { "BitRate", "Information", "Power" };


If it is not too much hassle, I would rather take a list of all quantities in the ctor to determine the value type from their Quantity type, or a list of all decimal quantities determined from the original list of quantities.

We are not likely to get more decimal types anytime soon, rather changing them to double I think, but it may take some time and this is one less place to maintain when that changes.

This wasn't needed anymore since I reworked the codegen, so I removed it 👍

angularsen · 2024-01-08T21:29:44Z

CodeGen/Generators/UnitsNetGen/QuantityGenerator.cs

+                    var rightParameter = relation.RightQuantity.Name.ToCamelCase();
+                    var rightConversionProperty = relation.RightUnit.PluralName;
+
+                    if (relation.LeftQuantity.Name == "TimeSpan")


Maybe reuse some constants for all these repeating strings

I tried to tidy up a bit, but code generation is always a bit messy and throwing around consts called _double and _value didn't make things better 😅

UnitsNet/CustomCode/Quantities/Area.extra.cs

…lations

In [#1329](#1329 (comment)) this proposal came up: > Another idea: generate division operators based on multiplication. Right now we define: > ``` > ElectricPotential.Volt = ElectricCurrent.Ampere * ElectricResistance.Ohm (and generate the reverse) > ElectricCurrent.Ampere = ElectricPotential.Volt / ElectricResistance.Ohm > ElectricResistance.Ohm = ElectricPotential.Volt / ElectricCurrent.Ampere > ``` > But those last two could also be generated based on the first. This PR is an experiment implementing this. ### Breaking changes: - `TimeSpan = Volume / VolumeFlow` => `Duration = Volume / VolumeFlow`

Muximize changed the title ~~[WIP] Generate operators from defined unit relations in JSON~~ [WIP] Generate operators from unit relations defined in JSON Nov 13, 2023

Muximize force-pushed the relations branch from efd1f1f to e7ba650 Compare November 13, 2023 14:50

Muximize changed the title ~~[WIP] Generate operators from unit relations defined in JSON~~ Generate operators from unit relations defined in JSON Dec 22, 2023

angularsen requested changes Dec 31, 2023

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Muximize mentioned this pull request Jan 2, 2024

Fix typo: Celcius -> Celsius #1347

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angularsen pushed a commit that referenced this pull request Jan 2, 2024

Fix typo: Celcius -> Celsius (#1347)

cff63a6

Came across this while working on #1329. I'm afraid it's an API-breaking change, so maybe it should wait for v6? Related: #1200

Muximize added 3 commits January 4, 2024 14:11

Define unit relations

d93e058

Add relations to CodeGen

ce1a6ff

Generate code, clean up extras

cfefd26

Muximize force-pushed the relations branch from e7ba650 to cfefd26 Compare January 4, 2024 13:30

Muximize mentioned this pull request Jan 7, 2024

Inferred division from defined multiplication relations #1354

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Muximize added 3 commits January 8, 2024 13:26

Separate relation inference and application, add more comments

c7918a3

Sort inferred relations to keep generated operators in a consistent o…

4de9789

…rder

Generated code with re-sorted operators

7046318

Muximize force-pushed the relations branch from 787996d to 7046318 Compare January 8, 2024 12:26

angularsen requested changes Jan 8, 2024

View reviewed changes

Muximize added 6 commits January 9, 2024 01:25

Add examples

59e8f7f

Automatically remove duplicate relation definitions

049eaf9

Throw exception on duplicate inferred relations

7a52a91

Generate code: changed SortString format changes the order of some re…

5c9abed

…lations

Make casting decimal types neater

2b9d456

Clean up GenerateRelationalOperators a bit

f4231c1

Muximize force-pushed the relations branch from 443d8c5 to f4231c1 Compare January 9, 2024 01:48

angularsen changed the base branch from master to release/v6 February 4, 2024 14:10

Merge remote-tracking branch 'origin/release/v6' into relations

5802fb2

angularsen force-pushed the relations branch from 70a4eb7 to 5802fb2 Compare February 4, 2024 14:18

angularsen mentioned this pull request Feb 4, 2024

v6 Wishlist #1200

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13 tasks

angularsen merged commit 2424307 into angularsen:release/v6 Feb 4, 2024
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angularsen added this to the vNext milestone Feb 4, 2024

Muximize mentioned this pull request Feb 26, 2024

Add operator to convert from TemperatureDelta to TemperatureChangeRate. #1370

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Muximize mentioned this pull request Apr 4, 2024

Add operators for ReciprocalLength/-Area #1382

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Generate operators from unit relations defined in JSON #1329

Generate operators from unit relations defined in JSON #1329

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Generate operators from unit relations defined in JSON #1329

Generate operators from unit relations defined in JSON #1329

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