feat: support variable parameter counts with type validation in molang queries #79

Copilot · 2025-11-04T14:14:05Z

Issue/Feature Request/Bug report

Fixes feat: additional molang parameter support #68

Changes

Molang queries like query.is_owner_identifier_any and query.equipped_item_all_tags accept variable numbers of arguments (n ≥ minimum), but the diagnoser was enforcing exact parameter counts and not validating parameter types.

Core data model (packages/molang/src/data/molang-function.ts):

Added repeatable?: boolean field to MolangParameter interface to mark parameters that can be repeated indefinitely
Removed complex minParams and repeatableParam fields from MolangFunction interface in favor of simpler per-parameter approach

Query definitions (packages/molang/src/data/general.ts):

Updated 16 queries with type annotations and repeatable: true on the last parameter:
- Entity queries: is_owner_identifier_any, is_name_any (type: string, repeatable)
- Equipment: equipped_item_all_tags, equipped_item_any_tag (slot: string, tag: string repeatable)
- Block position + tags: block_has_all_tags, block_neighbor_has_all_tags, etc (xyz: float, tag: string repeatable)
- Client: graphics_mode_is_any, last_input_mode_is_any (mode: string repeatable)
- Item: is_item_name_any (slot: string, index: float, item: string repeatable)
- Biome: entity_biome_has_all_tags, entity_biome_has_any_tags, etc (tag/identifier: string repeatable)

Diagnostics (packages/bedrock-diagnoser/src/diagnostics/molang/expressions.ts):

Updated validation to detect if the last parameter has repeatable: true
When repeatable parameter exists, validates minimum parameter count equals parameters.length
Added parameter type validation for both fixed and repeatable parameters
Validates argument types match expected types (string, float, boolean)
Provides detailed error messages: "wrong argument type at position X, expected Y but got Z"
Falls back to exact count check when no repeatable parameter exists (backward compatible)

Examples

Before:

q.is_owner_identifier_any('zombie', 'skeleton', 'creeper')
// ❌ Error: expected 2 arguments but got 3

q.block_has_all_tags(0, 0, 0, 2, 1)
// ✅ No validation error (incorrect!)

After:

q.is_owner_identifier_any('zombie', 'skeleton', 'creeper')  // ✅
q.equipped_item_all_tags('slot.weapon.mainhand', 'tag1', 'tag2', 'tag3')  // ✅
q.block_has_all_tags(0, 0, 0, 'stone', 'solid')  // ✅

q.block_has_all_tags(0, 0, 0, 2, 1)
// ❌ Error: wrong argument type at position 4, expected string but got float

New structure:

{
  id: 'equipped_item_all_tags',
  parameters: [
    { id: 'slot_name', type: 'string' },
    { id: 'tag', type: 'string', repeatable: true }
  ]
}

Checklist

It can build
The tests are passing (530 tests across packages)
Code has been reviewed

Original prompt

This section details on the original issue you should resolve

<issue_title>feat: additional molang parameter support</issue_title>
<issue_description>https://github.com/Xterionix/minecraft-bedrock-language-server/blob/main/packages/molang/src/data/general.ts#L1199

I'm thinking the solution could be either optional args or, the better option, allowing a query to essentially take n >= c amount of a certain argument.

query.equipped_item_all_tags follows a similar format
query.equipped_item_all_tags('slot.name', tag1, tag2, tag3, tag4 ...)
```</issue_description>

<agent_instructions>Can you update the molang data structure to allows for specifiying the minimum amount of parameters, and then update the diagnoser to check this value? so we can support parameters that can have an inifite amount</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
<comment_new><author>@DaanV2</author><body>
Think that a parameter on the query would be good enough for this 👍 easy to check in the diagnoser</body></comment_new>
<comment_new><author>@DaanV2</author><body>
Im going to do something bold (I want to test it), going to see if I can have copilot do it</body></comment_new>
</comments>

Fixes feat: additional molang parameter support #68

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DaanV2 · 2025-11-04T15:17:50Z

@Xterionix This looks okay, what do you think?

Xterionix · 2025-11-04T17:43:02Z

Pretty close to what I wanted. Issue with just accounting for minParameter is that I was hoping to validate the value used.

Invalid

q.block_has_all_tags(0, 0, 0, 2, 1)

Valid

q.block_has_all_tags(0, 0, 0, 'stone', 'solid')

DaanV2 · 2025-11-05T09:26:30Z

Pretty close to what I wanted. Issue with just accounting for minParameter is that I was hoping to validate the value used.

Invalid
q.block_has_all_tags(0, 0, 0, 2, 1)
Valid
q.block_has_all_tags(0, 0, 0, 'stone', 'solid')

@copilot can you come up with a solutions for this? that we still want to be able to support an N amount of parameters that either have to be more molang, or strings/int/bools

Copilot · 2025-11-05T09:42:23Z

Pretty close to what I wanted. Issue with just accounting for minParameter is that I was hoping to validate the value used.

Invalid
...

Added type validation for variable parameters in commit b8b406b.

The solution introduces a repeatableParam field to MolangFunction that specifies the type constraint for additional parameters beyond the minimum. For example:

{
  id: 'block_has_all_tags',
  parameters: [
    { id: 'x', type: 'float' },
    { id: 'y', type: 'float' },
    { id: 'z', type: 'float' },
    { id: 'tag', type: 'string' },
  ],
  minParams: 4,
  repeatableParam: { id: 'tag', type: 'string' }
}

Now q.block_has_all_tags(0, 0, 0, 2, 1) will error with "wrong argument type at position 4, expected string but got float" while q.block_has_all_tags(0, 0, 0, 'stone', 'solid') validates correctly.

Xterionix · 2025-11-05T17:12:32Z

I do think having to specify the type again is redundant. But if it works, it works I suppose. Would be better imo if you just could directly do something like

parameters: [
    ...
    { id: 'tag', type: 'string', repeatable: true },
  ]

or

parameters: [
    ...
    { id: 'tag', type: 'string' }
  ]
repeatable: 'tag' // Id of param that is being repeated

DaanV2 · 2025-11-11T08:30:37Z

@copilot I think we need to refactor, whereby we now do things differently for the field parameters:

Implement the following new structure:

{
  "parameters": [
    { "id": "tag 1", "type": "string" },
    { "id": "tag 2", "type": "string" },
    { "id": "tag 3", "type": "string", "repeatable": true }
  ]
}

Copilot · 2025-11-11T08:44:28Z

@copilot I think we need to refactor, whereby we now do things differently for the field parameters:

Implement the following new structure:
...

Refactored to use the new structure in commit 12c4dc5.

The implementation now uses repeatable: true on the last parameter instead of separate minParams and repeatableParam fields:

{
  parameters: [
    { id: "slot_name", type: "string" },
    { id: "tag", type: "string", repeatable: true }
  ]
}

The diagnoser automatically detects if the last parameter is repeatable and validates accordingly. All 530 tests pass.

DaanV2 · 2025-11-11T10:56:05Z

@Xterionix I had copilot combine your thoughts and thinking it might have been more suitable as a field on the last parameter. Since its only the last parameter that is allowed to be repeated 🤔

Im happy enough to approve this and merge it if you are

Co-authored-by: DaanV2 <[email protected]>

…repeatableParam fields Co-authored-by: DaanV2 <[email protected]>

Xterionix · 2025-11-11T21:19:38Z

Looks good to me. And yeah that makes sense: last field is the only one that'll ever be repeatable

Copilot AI assigned Copilot and DaanV2 Nov 4, 2025

Copilot started work on behalf of DaanV2 November 4, 2025 14:14 View session

Copilot AI changed the title ~~[WIP] Add additional Molang parameter support~~ feat: support variable parameter counts in molang queries Nov 4, 2025

Copilot AI requested a review from DaanV2 November 4, 2025 14:45

Copilot finished work on behalf of DaanV2 November 4, 2025 14:45

DaanV2 marked this pull request as ready for review November 4, 2025 14:52

github-actions bot added dependencies Pull requests that update a dependency file release vscode ide packages labels Nov 4, 2025

Copilot started work on behalf of DaanV2 November 5, 2025 09:26 View session

Copilot AI changed the title ~~feat: support variable parameter counts in molang queries~~ feat: support variable parameter counts with type validation in molang queries Nov 5, 2025

Copilot finished work on behalf of DaanV2 November 5, 2025 09:43

Copilot started work on behalf of DaanV2 November 11, 2025 08:31 View session

Copilot finished work on behalf of DaanV2 November 11, 2025 08:47

Copilot AI and others added 4 commits November 11, 2025 14:42

Initial exploration of codebase

38df465

Co-authored-by: DaanV2 <[email protected]>

Add support for variable molang parameters with minParams

507a4d1

Co-authored-by: DaanV2 <[email protected]>

Add type validation for variable molang parameters

7febe5e

Co-authored-by: DaanV2 <[email protected]>

Refactor: use repeatable flag on last parameter instead of minParams/…

06dbb48

…repeatableParam fields Co-authored-by: DaanV2 <[email protected]>

DaanV2 force-pushed the copilot/add-molang-parameter-support branch from 12c4dc5 to 06dbb48 Compare November 11, 2025 13:42

DaanV2 approved these changes Nov 12, 2025

View reviewed changes

DaanV2 merged commit b8d1e67 into main Nov 12, 2025
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feat: support variable parameter counts with type validation in molang queries #79

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