Don't fail catastrophically when range is zero

bokeh · Apr 30, 2024 · 2535273 · 2535273
1 parent 43a141b
commit 2535273
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Showing 4 changed files with 27 additions and 6 deletions.
diff --git a/bokehjs/src/lib/core/kinds.ts b/bokehjs/src/lib/core/kinds.ts
@@ -329,6 +329,16 @@ export namespace Kinds {
     }
   }
 
+  export class NonEmptyList<ItemType> extends List<ItemType> {
+    override valid(value: unknown): value is ItemType[] {
+      return super.valid(value) && value.length != 0
+    }
+
+    override toString(): string {
+      return `NonEmptyList(${this.item_type.toString()})`
+    }
+  }
+
   export class Null extends Primitive<null> {
     valid(value: unknown): value is null {
       return value === null
@@ -639,6 +649,7 @@ export const PartialStruct = <T extends {[key: string]: unknown}>(struct_type: K
 export const Iterable = <ItemType>(item_type: Kind<ItemType>) => new Kinds.Iterable(item_type)
 export const Arrayable = <ItemType>(item_type: Kind<ItemType>) => new Kinds.Arrayable(item_type)
 export const List = <ItemType>(item_type: Kind<ItemType>) => new Kinds.List(item_type)
+export const NonEmptyList = <ItemType>(item_type: Kind<ItemType>) => new Kinds.NonEmptyList(item_type)
 export const Dict = <V>(item_type: Kind<V>) => new Kinds.Dict(item_type)
 export const Mapping = <K, V>(key_type: Kind<K>, item_type: Kind<V>) => new Kinds.Mapping(key_type, item_type)
 export const Set = <V>(item_type: Kind<V>) => new Kinds.Set(item_type)

diff --git a/bokehjs/src/lib/models/tickers/composite_ticker.ts b/bokehjs/src/lib/models/tickers/composite_ticker.ts
@@ -24,8 +24,8 @@ export class CompositeTicker extends ContinuousTicker {
   }
 
   static {
-    this.define<CompositeTicker.Props>(({List, Ref}) => ({
-      tickers: [ List(Ref(ContinuousTicker)), [] ],
+    this.define<CompositeTicker.Props>(({NonEmptyList, Ref}) => ({
+      tickers: [ NonEmptyList(Ref(ContinuousTicker)) ],
     }))
   }
 
@@ -52,6 +52,10 @@ export class CompositeTicker extends ContinuousTicker {
 
   get_best_ticker(data_low: number, data_high: number, desired_n_ticks: number): ContinuousTicker {
     const data_range = data_high - data_low
+    if (data_range == 0) {
+      return this.tickers[0]
+    }
+
     const ideal_interval = this.get_ideal_interval(data_low, data_high, desired_n_ticks)
     const ticker_ndxs = [
       sorted_index(this.min_intervals, ideal_interval) - 1,

diff --git a/src/bokeh/models/tickers.py b/src/bokeh/models/tickers.py
@@ -31,6 +31,7 @@
     Float,
     Instance,
     Int,
+    NonEmpty,
     Nullable,
     Override,
     Required,
@@ -169,10 +170,12 @@ class CompositeTicker(ContinuousTicker):
     def __init__(self, *args, **kwargs) -> None:
         super().__init__(*args, **kwargs)
 
-    tickers = Seq(Instance(Ticker), default=[], help="""
-    A list of Ticker objects to combine at different scales in order
+    tickers = NonEmpty(Seq(Instance(Ticker)), help="""
+    A list of ``Ticker`` objects to combine at different scales in order
     to generate tick values. The supplied tickers should be in order.
-    Specifically, if S comes before T, then it should be the case that::
+    Specifically, if S comes before T, then it should be the case that:
+
+    .. code-block:: javascript
 
         S.get_max_interval() < T.get_min_interval()
 

diff --git a/tests/baselines/defaults.json5 b/tests/baselines/defaults.json5
@@ -5654,7 +5654,10 @@
   },
   CompositeTicker: {
     __extends__: "ContinuousTicker",
-    tickers: [],
+    tickers: {
+      type: "symbol",
+      name: "unset",
+    },
   },
   ContinuousTicker: {
     __extends__: "Ticker",