feat: Add channel encoder (apache#224)

* feat: add channel encoder

* fix: all errors

* fix: test

* feat: complete channel encoder implementation and unit tests

* fix: lint

* fix: address comments

* fix: lint

packages/superset-ui-color/package.json

@@ -26,7 +26,7 @@
     "access": "public"
   },
   "dependencies": {
-    "@types/d3-scale": "^2.0.2",
+    "@types/d3-scale": "^2.1.1",
     "d3-scale": "^3.0.0"
   },
   "peerDependencies": {

packages/superset-ui-encodable/package.json

@@ -27,9 +27,10 @@
   },
   "private": true,
   "dependencies": {
+    "@types/d3-array": "^2.0.0",
     "@types/d3-interpolate": "^1.3.1",
-    "@types/d3-scale": "^2.1.1",
     "@types/d3-time": "^1.0.10",
+    "d3-array": "^2.3.1",
     "d3-interpolate": "^1.3.2",
     "d3-scale": "^3.0.1",
     "d3-time": "^1.0.11",

packages/superset-ui-encodable/src/encoders/ChannelEncoder.ts

@@ -0,0 +1,129 @@
+import { extent as d3Extent } from 'd3-array';
+import { ChannelType, ChannelInput } from '../types/Channel';
+import { PlainObject, Dataset } from '../types/Data';
+import { ChannelDef } from '../types/ChannelDef';
+import createGetterFromChannelDef, { Getter } from '../parsers/createGetterFromChannelDef';
+import completeChannelDef, { CompleteChannelDef } from '../fillers/completeChannelDef';
+import createFormatterFromChannelDef from '../parsers/format/createFormatterFromChannelDef';
+import createScaleFromScaleConfig from '../parsers/scale/createScaleFromScaleConfig';
+import identity from '../utils/identity';
+import { HasToString, IdentityFunction } from '../types/Base';
+import { isTypedFieldDef, isValueDef } from '../typeGuards/ChannelDef';
+import { isX, isY, isXOrY } from '../typeGuards/Channel';
+import { Value } from '../types/VegaLite';
+
+type EncodeFunction<Output> = (value: ChannelInput | Output) => Output | null | undefined;
+
+export default class ChannelEncoder<Def extends ChannelDef<Output>, Output extends Value = Value> {
+  readonly name: string | Symbol | number;
+  readonly channelType: ChannelType;
+  readonly originalDefinition: Def;
+  readonly definition: CompleteChannelDef<Output>;
+  readonly scale: false | ReturnType<typeof createScaleFromScaleConfig>;
+
+  private readonly getValue: Getter<Output>;
+  readonly encodeValue: IdentityFunction<ChannelInput | Output> | EncodeFunction<Output>;
+  readonly formatValue: (value: ChannelInput | HasToString) => string;
+
+  constructor({
+    name,
+    channelType,
+    definition: originalDefinition,
+  }: {
+    name: string;
+    channelType: ChannelType;
+    definition: Def;
+  }) {
+    this.name = name;
+    this.channelType = channelType;
+
+    this.originalDefinition = originalDefinition;
+    this.definition = completeChannelDef(this.channelType, originalDefinition);
+
+    this.getValue = createGetterFromChannelDef(this.definition);
+    this.formatValue = createFormatterFromChannelDef(this.definition);
+
+    const scale = this.definition.scale && createScaleFromScaleConfig(this.definition.scale);
+    this.encodeValue = scale === false ? identity : (value: ChannelInput) => scale(value);
+    this.scale = scale;
+  }
+
+  encodeDatum: {
+    (datum: PlainObject): Output | null | undefined;
+    (datum: PlainObject, otherwise: Output): Output;
+  } = (datum: PlainObject, otherwise?: Output) => {
+    const value = this.getValueFromDatum(datum);
+
+    if (otherwise !== undefined && (value === null || value === undefined)) {
+      return otherwise;
+    }
+
+    return this.encodeValue(value) as Output;
+  };
+
+  formatDatum = (datum: PlainObject): string => this.formatValue(this.getValueFromDatum(datum));
+
+  getValueFromDatum = <T extends ChannelInput | Output>(datum: PlainObject, otherwise?: T) => {
+    const value = this.getValue(datum);
+
+    return otherwise !== undefined && (value === null || value === undefined)
+      ? otherwise
+      : (value as T);
+  };
+
+  getDomain = (data: Dataset) => {
+    if (isValueDef(this.definition)) {
+      const { value } = this.definition;
+
+      return [value];
+    }
+
+    const { type } = this.definition;
+    if (type === 'nominal' || type === 'ordinal') {
+      return Array.from(new Set(data.map(d => this.getValueFromDatum(d)))) as string[];
+    } else if (type === 'quantitative') {
+      const extent = d3Extent(data, d => this.getValueFromDatum<number>(d));
+
+      return typeof extent[0] === 'undefined' ? [0, 1] : (extent as [number, number]);
+    } else if (type === 'temporal') {
+      const extent = d3Extent(data, d => this.getValueFromDatum<number | Date>(d));
+
+      return typeof extent[0] === 'undefined'
+        ? [0, 1]
+        : (extent as [number, number] | [Date, Date]);
+    }
+
+    return [];
+  };
+
+  getTitle() {
+    return this.definition.title;
+  }
+
+  isGroupBy() {
+    if (isTypedFieldDef(this.definition)) {
+      const { type } = this.definition;
+
+      return (
+        this.channelType === 'Category' ||
+        this.channelType === 'Text' ||
+        (this.channelType === 'Color' && (type === 'nominal' || type === 'ordinal')) ||
+        (isXOrY(this.channelType) && (type === 'nominal' || type === 'ordinal'))
+      );
+    }
+
+    return false;
+  }
+
+  isX() {
+    return isX(this.channelType);
+  }
+
+  isXOrY() {
+    return isXOrY(this.channelType);
+  }
+
+  isY() {
+    return isY(this.channelType);
+  }
+}

packages/superset-ui-encodable/src/fillers/completeChannelDef.ts

@@ -1,27 +1,51 @@
-import { ChannelDef } from '../types/ChannelDef';
+import { ChannelDef, NonValueDef } from '../types/ChannelDef';
 import { ChannelType } from '../types/Channel';
-import { isFieldDef } from '../typeGuards/ChannelDef';
+import { isFieldDef, isValueDef, isTypedFieldDef } from '../typeGuards/ChannelDef';
 import completeAxisConfig, { CompleteAxisConfig } from './completeAxisConfig';
 import completeScaleConfig, { CompleteScaleConfig } from './completeScaleConfig';
-import { Value } from '../types/VegaLite';
+import { Value, ValueDef, Type } from '../types/VegaLite';
+import inferFieldType from './inferFieldType';
 
-type CompleteChannelDef<Output extends Value = Value> = Omit<
-  ChannelDef,
+export interface CompleteValueDef<Output extends Value = Value> extends ValueDef<Output> {
+  axis: false;
+  scale: false;
+  title: '';
+}
+
+export type CompleteFieldDef<Output extends Value = Value> = Omit<
+  NonValueDef<Output>,
   'title' | 'axis' | 'scale'
 > & {
+  type: Type;
   axis: CompleteAxisConfig;
   scale: CompleteScaleConfig<Output>;
   title: string;
 };
 
-export default function completeChannelDef<Output extends Value = Value>(
+export type CompleteChannelDef<Output extends Value = Value> =
+  | CompleteValueDef<Output>
+  | CompleteFieldDef<Output>;
+
+export default function completeChannelDef<Output extends Value>(
   channelType: ChannelType,
   channelDef: ChannelDef<Output>,
 ): CompleteChannelDef<Output> {
+  if (isValueDef(channelDef)) {
+    return {
+      ...channelDef,
+      axis: false,
+      scale: false,
+      title: '',
+    };
+  }
+
   // Fill top-level properties
   const copy = {
     ...channelDef,
     title: isFieldDef(channelDef) ? channelDef.title || channelDef.field : '',
+    type: isTypedFieldDef(channelDef)
+      ? channelDef.type
+      : inferFieldType(channelType, channelDef.field),
   };
 
   return {

packages/superset-ui-encodable/src/fillers/completeScaleConfig.ts

@@ -9,7 +9,7 @@ import { Value } from '../types/VegaLite';
 
 export type CompleteScaleConfig<Output extends Value = Value> = false | ScaleConfig<Output>;
 
-export default function completeScaleConfig<Output extends Value = Value>(
+export default function completeScaleConfig<Output extends Value>(
   channelType: ChannelType,
   channelDef: ChannelDef<Output>,
 ): CompleteScaleConfig<Output> {

packages/superset-ui-encodable/src/fillers/inferFieldType.ts

@@ -0,0 +1,13 @@
+import { ChannelType } from '../types/Channel';
+import { isXOrY } from '../typeGuards/Channel';
+import { Type } from '../types/VegaLite';
+
+const temporalFieldNames = new Set(['time', 'date', 'datetime', 'timestamp']);
+
+export default function inferFieldType(channelType: ChannelType, field: string = ''): Type {
+  if (isXOrY(channelType) || channelType === 'Numeric') {
+    return temporalFieldNames.has(field.toLowerCase()) ? 'temporal' : 'quantitative';
+  }
+
+  return 'nominal';
+}

packages/superset-ui-encodable/src/index.ts

@@ -0,0 +1,3 @@
+export { default as ChannelEncoder } from './encoders/ChannelEncoder';
+export { default as completeChannelDef } from './fillers/completeChannelDef';
+export { default as createScaleFromScaleConfig } from './parsers/scale/createScaleFromScaleConfig';

packages/superset-ui-encodable/src/parsers/createGetterFromChannelDef.ts

@@ -1,17 +1,20 @@
 import { get } from 'lodash/fp';
-import identity from '../utils/identity';
 import { ChannelDef } from '../types/ChannelDef';
 import { isValueDef } from '../typeGuards/ChannelDef';
 import { PlainObject } from '../types/Data';
+import { Value } from '../types/VegaLite';
+import { ChannelInput } from '../types/Channel';
 
-export default function createGetterFromChannelDef(
-  definition: ChannelDef,
-): (x?: PlainObject) => any {
+export type Getter<Output extends Value> = (x?: PlainObject) => ChannelInput | Output | undefined;
+
+export default function createGetterFromChannelDef<Output extends Value>(
+  definition: ChannelDef<Output>,
+): Getter<Output> {
   if (isValueDef(definition)) {
     return () => definition.value;
   } else if (typeof definition.field !== 'undefined') {
     return get(definition.field);
   }
 
-  return identity;
+  return () => undefined;
 }

packages/superset-ui-encodable/src/parsers/scale/createScaleFromScaleType.ts

@@ -12,8 +12,7 @@ import {
   scalePoint,
   scaleBand,
 } from 'd3-scale';
-import { HasToString } from '../../types/Base';
-import { ScaleConfig } from '../../types/Scale';
+import { ScaleConfig, CategoricalScaleInput } from '../../types/Scale';
 import { ScaleType, Value } from '../../types/VegaLite';
 
 // eslint-disable-next-line complexity
@@ -44,11 +43,11 @@ export default function createScaleFromScaleType<Output extends Value>(
     case ScaleType.THRESHOLD:
       return scaleThreshold<number | string | Date, Output>();
     case ScaleType.ORDINAL:
-      return scaleOrdinal<HasToString, Output>();
+      return scaleOrdinal<CategoricalScaleInput, Output>();
     case ScaleType.POINT:
-      return scalePoint<HasToString>();
+      return scalePoint<CategoricalScaleInput>();
     case ScaleType.BAND:
-      return scaleBand<HasToString>();
+      return scaleBand<CategoricalScaleInput>();
     case ScaleType.SYMLOG:
       // TODO: d3-scale typings does not include scaleSymlog yet
       // needs to patch the declaration file before continue.

packages/superset-ui-encodable/src/types/Base.ts

@@ -14,3 +14,6 @@ export type RequiredSome<T, RequiredFields extends keyof T> = {
   {
     [Field in RequiredFields]-?: T[Field];
   };
+
+/** Signature of an identity function */
+export type IdentityFunction<T> = (value: T) => T;

packages/superset-ui-encodable/src/types/Scale.ts

@@ -191,6 +191,8 @@ export interface WithScale<Output extends Value = Value> {
 /** Each ScaleCategory contains one or more ScaleType */
 export type ScaleCategory = 'continuous' | 'discrete' | 'discretizing';
 
+export type CategoricalScaleInput = HasToString | null | undefined;
+
 export interface ScaleTypeToD3ScaleType<Output extends Value = Value> {
   [ScaleType.LINEAR]: ScaleLinear<Output, Output>;
   [ScaleType.LOG]: ScaleLogarithmic<Output, Output>;
@@ -202,10 +204,10 @@ export interface ScaleTypeToD3ScaleType<Output extends Value = Value> {
   [ScaleType.QUANTILE]: ScaleQuantile<Output>;
   [ScaleType.QUANTIZE]: ScaleQuantize<Output>;
   [ScaleType.THRESHOLD]: ScaleThreshold<number | string | Date, Output>;
-  [ScaleType.BIN_ORDINAL]: ScaleOrdinal<HasToString, Output>;
-  [ScaleType.ORDINAL]: ScaleOrdinal<HasToString, Output>;
-  [ScaleType.POINT]: ScalePoint<HasToString>;
-  [ScaleType.BAND]: ScaleBand<HasToString>;
+  [ScaleType.BIN_ORDINAL]: ScaleOrdinal<CategoricalScaleInput, Output>;
+  [ScaleType.ORDINAL]: ScaleOrdinal<CategoricalScaleInput, Output>;
+  [ScaleType.POINT]: ScalePoint<CategoricalScaleInput>;
+  [ScaleType.BAND]: ScaleBand<CategoricalScaleInput>;
 }
 
 export type ContinuousD3Scale<Output extends Value = Value> =
@@ -219,6 +221,6 @@ export type D3Scale<Output extends Value = Value> =
   | ScaleQuantile<Output>
   | ScaleQuantize<Output>
   | ScaleThreshold<number | string | Date, Output>
-  | ScaleOrdinal<HasToString, Output>
-  | ScalePoint<HasToString>
-  | ScaleBand<HasToString>;
+  | ScaleOrdinal<CategoricalScaleInput, Output>
+  | ScalePoint<CategoricalScaleInput>
+  | ScaleBand<CategoricalScaleInput>;