planning

node_modules/@mapbox/mapbox-gl-style-spec/expression/index.js

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+// @flow
+
+import assert from 'assert';
+
+import extend from '../util/extend.js';
+import ParsingError from './parsing_error.js';
+import ParsingContext from './parsing_context.js';
+import EvaluationContext from './evaluation_context.js';
+import CompoundExpression from './compound_expression.js';
+import Step from './definitions/step.js';
+import Interpolate from './definitions/interpolate.js';
+import Coalesce from './definitions/coalesce.js';
+import Let from './definitions/let.js';
+import definitions from './definitions/index.js';
+import * as isConstant from './is_constant.js';
+import RuntimeError from './runtime_error.js';
+import {success, error} from '../util/result.js';
+import {supportsPropertyExpression, supportsZoomExpression, supportsInterpolation} from '../util/properties.js';
+
+import type {Type, EvaluationKind} from './types.js';
+import type {Value} from './values.js';
+import type {Expression} from './expression.js';
+import type {StylePropertySpecification} from '../style-spec.js';
+import type {Result} from '../util/result.js';
+import type {InterpolationType} from './definitions/interpolate.js';
+import type {PropertyValueSpecification} from '../types.js';
+import type {FormattedSection} from './types/formatted.js';
+import type Point from '@mapbox/point-geometry';
+import type {CanonicalTileID} from '../../source/tile_id.js';
+import type {FeatureDistanceData} from '../feature_filter/index.js';
+
+export type Feature = {
+    +type: 1 | 2 | 3 | 'Unknown' | 'Point' | 'LineString' | 'Polygon',
+    +id?: number | null,
+    +properties: {[_: string]: any},
+    +patterns?: {[_: string]: string},
+    +geometry?: Array<Array<Point>>
+};
+
+export type FeatureState = {[_: string]: any};
+
+export type GlobalProperties = $ReadOnly<{
+    zoom: number,
+    pitch?: number,
+    heatmapDensity?: number,
+    lineProgress?: number,
+    skyRadialProgress?: number,
+    isSupportedScript?: (_: string) => boolean,
+    accumulated?: Value
+}>;
+
+export class StyleExpression {
+    expression: Expression;
+
+    _evaluator: EvaluationContext;
+    _defaultValue: Value;
+    _warningHistory: {[key: string]: boolean};
+    _enumValues: ?{[_: string]: any};
+
+    constructor(expression: Expression, propertySpec: ?StylePropertySpecification) {
+        this.expression = expression;
+        this._warningHistory = {};
+        this._evaluator = new EvaluationContext();
+        this._defaultValue = propertySpec ? getDefaultValue(propertySpec) : null;
+        this._enumValues = propertySpec && propertySpec.type === 'enum' ? propertySpec.values : null;
+    }
+
+    evaluateWithoutErrorHandling(globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>, formattedSection?: FormattedSection, featureTileCoord?: Point, featureDistanceData?: FeatureDistanceData): any {
+        this._evaluator.globals = globals;
+        this._evaluator.feature = feature;
+        this._evaluator.featureState = featureState;
+        this._evaluator.canonical = canonical || null;
+        this._evaluator.availableImages = availableImages || null;
+        this._evaluator.formattedSection = formattedSection;
+        this._evaluator.featureTileCoord = featureTileCoord || null;
+        this._evaluator.featureDistanceData = featureDistanceData || null;
+
+        return this.expression.evaluate(this._evaluator);
+    }
+
+    evaluate(globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>, formattedSection?: FormattedSection, featureTileCoord?: Point, featureDistanceData?: FeatureDistanceData): any {
+        this._evaluator.globals = globals;
+        this._evaluator.feature = feature || null;
+        this._evaluator.featureState = featureState || null;
+        this._evaluator.canonical = canonical || null;
+        this._evaluator.availableImages = availableImages || null;
+        this._evaluator.formattedSection = formattedSection || null;
+        this._evaluator.featureTileCoord = featureTileCoord || null;
+        this._evaluator.featureDistanceData = featureDistanceData || null;
+
+        try {
+            const val = this.expression.evaluate(this._evaluator);
+            // eslint-disable-next-line no-self-compare
+            if (val === null || val === undefined || (typeof val === 'number' && val !== val)) {
+                return this._defaultValue;
+            }
+            if (this._enumValues && !(val in this._enumValues)) {
+                throw new RuntimeError(`Expected value to be one of ${Object.keys(this._enumValues).map(v => JSON.stringify(v)).join(', ')}, but found ${JSON.stringify(val)} instead.`);
+            }
+            return val;
+        } catch (e) {
+            if (!this._warningHistory[e.message]) {
+                this._warningHistory[e.message] = true;
+                if (typeof console !== 'undefined') {
+                    console.warn(e.message);
+                }
+            }
+            return this._defaultValue;
+        }
+    }
+}
+
+export function isExpression(expression: mixed): boolean {
+    return Array.isArray(expression) && expression.length > 0 &&
+        typeof expression[0] === 'string' && expression[0] in definitions;
+}
+
+/**
+ * Parse and typecheck the given style spec JSON expression.  If
+ * options.defaultValue is provided, then the resulting StyleExpression's
+ * `evaluate()` method will handle errors by logging a warning (once per
+ * message) and returning the default value.  Otherwise, it will throw
+ * evaluation errors.
+ *
+ * @private
+ */
+export function createExpression(expression: mixed, propertySpec: ?StylePropertySpecification): Result<StyleExpression, Array<ParsingError>> {
+    const parser = new ParsingContext(definitions, [], propertySpec ? getExpectedType(propertySpec) : undefined);
+
+    // For string-valued properties, coerce to string at the top level rather than asserting.
+    const parsed = parser.parse(expression, undefined, undefined, undefined,
+        propertySpec && propertySpec.type === 'string' ? {typeAnnotation: 'coerce'} : undefined);
+
+    if (!parsed) {
+        assert(parser.errors.length > 0);
+        return error(parser.errors);
+    }
+
+    return success(new StyleExpression(parsed, propertySpec));
+}
+
+export class ZoomConstantExpression<Kind: EvaluationKind> {
+    kind: Kind;
+    isStateDependent: boolean;
+    _styleExpression: StyleExpression;
+
+    constructor(kind: Kind, expression: StyleExpression) {
+        this.kind = kind;
+        this._styleExpression = expression;
+        this.isStateDependent = kind !== ('constant': EvaluationKind) && !isConstant.isStateConstant(expression.expression);
+    }
+
+    evaluateWithoutErrorHandling(globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>, formattedSection?: FormattedSection): any {
+        return this._styleExpression.evaluateWithoutErrorHandling(globals, feature, featureState, canonical, availableImages, formattedSection);
+    }
+
+    evaluate(globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>, formattedSection?: FormattedSection): any {
+        return this._styleExpression.evaluate(globals, feature, featureState, canonical, availableImages, formattedSection);
+    }
+}
+
+export class ZoomDependentExpression<Kind: EvaluationKind> {
+    kind: Kind;
+    zoomStops: Array<number>;
+    isStateDependent: boolean;
+
+    _styleExpression: StyleExpression;
+    interpolationType: ?InterpolationType;
+
+    constructor(kind: Kind, expression: StyleExpression, zoomStops: Array<number>, interpolationType?: InterpolationType) {
+        this.kind = kind;
+        this.zoomStops = zoomStops;
+        this._styleExpression = expression;
+        this.isStateDependent = kind !== ('camera': EvaluationKind) && !isConstant.isStateConstant(expression.expression);
+        this.interpolationType = interpolationType;
+    }
+
+    evaluateWithoutErrorHandling(globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>, formattedSection?: FormattedSection): any {
+        return this._styleExpression.evaluateWithoutErrorHandling(globals, feature, featureState, canonical, availableImages, formattedSection);
+    }
+
+    evaluate(globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>, formattedSection?: FormattedSection): any {
+        return this._styleExpression.evaluate(globals, feature, featureState, canonical, availableImages, formattedSection);
+    }
+
+    interpolationFactor(input: number, lower: number, upper: number): number {
+        if (this.interpolationType) {
+            return Interpolate.interpolationFactor(this.interpolationType, input, lower, upper);
+        } else {
+            return 0;
+        }
+    }
+}
+
+export type ConstantExpression = {
+    kind: 'constant',
+    +evaluate: (globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>) => any,
+}
+
+export type SourceExpression = {
+    kind: 'source',
+    isStateDependent: boolean,
+    +evaluate: (globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>, formattedSection?: FormattedSection) => any,
+};
+
+export type CameraExpression = {
+    kind: 'camera',
+    +evaluate: (globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>) => any,
+    +interpolationFactor: (input: number, lower: number, upper: number) => number,
+    zoomStops: Array<number>,
+    interpolationType: ?InterpolationType
+};
+
+export type CompositeExpression = {
+    kind: 'composite',
+    isStateDependent: boolean,
+    +evaluate: (globals: GlobalProperties, feature?: Feature, featureState?: FeatureState, canonical?: CanonicalTileID, availableImages?: Array<string>, formattedSection?: FormattedSection) => any,
+    +interpolationFactor: (input: number, lower: number, upper: number) => number,
+    zoomStops: Array<number>,
+    interpolationType: ?InterpolationType
+};
+
+export type StylePropertyExpression =
+    | ConstantExpression
+    | SourceExpression
+    | CameraExpression
+    | CompositeExpression;
+
+export function createPropertyExpression(expression: mixed, propertySpec: StylePropertySpecification): Result<StylePropertyExpression, Array<ParsingError>> {
+    expression = createExpression(expression, propertySpec);
+    if (expression.result === 'error') {
+        return expression;
+    }
+
+    const parsed = expression.value.expression;
+
+    const isFeatureConstant = isConstant.isFeatureConstant(parsed);
+    if (!isFeatureConstant && !supportsPropertyExpression(propertySpec)) {
+        return error([new ParsingError('', 'data expressions not supported')]);
+    }
+
+    const isZoomConstant = isConstant.isGlobalPropertyConstant(parsed, ['zoom', 'pitch', 'distance-from-center']);
+    if (!isZoomConstant && !supportsZoomExpression(propertySpec)) {
+        return error([new ParsingError('', 'zoom expressions not supported')]);
+    }
+
+    const zoomCurve = findZoomCurve(parsed);
+    if (!zoomCurve && !isZoomConstant) {
+        return error([new ParsingError('', '"zoom" expression may only be used as input to a top-level "step" or "interpolate" expression.')]);
+    } else if (zoomCurve instanceof ParsingError) {
+        return error([zoomCurve]);
+    } else if (zoomCurve instanceof Interpolate && !supportsInterpolation(propertySpec)) {
+        return error([new ParsingError('', '"interpolate" expressions cannot be used with this property')]);
+    }
+
+    if (!zoomCurve) {
+        return success(isFeatureConstant ?
+            (new ZoomConstantExpression('constant', expression.value): ConstantExpression) :
+            (new ZoomConstantExpression('source', expression.value): SourceExpression));
+    }
+
+    const interpolationType = zoomCurve instanceof Interpolate ? zoomCurve.interpolation : undefined;
+
+    return success(isFeatureConstant ?
+        (new ZoomDependentExpression('camera', expression.value, zoomCurve.labels, interpolationType): CameraExpression) :
+        (new ZoomDependentExpression('composite', expression.value, zoomCurve.labels, interpolationType): CompositeExpression));
+}
+
+import {isFunction, createFunction} from '../function/index.js';
+import {Color} from './values.js';
+
+// serialization wrapper for old-style stop functions normalized to the
+// expression interface
+export class StylePropertyFunction<T> {
+    _parameters: PropertyValueSpecification<T>;
+    _specification: StylePropertySpecification;
+
+    kind: EvaluationKind;
+    evaluate: (globals: GlobalProperties, feature?: Feature) => any;
+    interpolationFactor: ?(input: number, lower: number, upper: number) => number;
+    zoomStops: ?Array<number>;
+
+    constructor(parameters: PropertyValueSpecification<T>, specification: StylePropertySpecification) {
+        this._parameters = parameters;
+        this._specification = specification;
+        extend(this, createFunction(this._parameters, this._specification));
+    }
+
+    static deserialize(serialized: {_parameters: PropertyValueSpecification<T>, _specification: StylePropertySpecification}): StylePropertyFunction<T> {
+        return new StylePropertyFunction(serialized._parameters, serialized._specification);
+    }
+
+    static serialize(input: StylePropertyFunction<T>): {_parameters: PropertyValueSpecification<T>, _specification: StylePropertySpecification} {
+        return {
+            _parameters: input._parameters,
+            _specification: input._specification
+        };
+    }
+}
+
+export function normalizePropertyExpression<T>(value: PropertyValueSpecification<T>, specification: StylePropertySpecification): StylePropertyExpression {
+    if (isFunction(value)) {
+        return (new StylePropertyFunction(value, specification): any);
+
+    } else if (isExpression(value)) {
+        const expression = createPropertyExpression(value, specification);
+        if (expression.result === 'error') {
+            // this should have been caught in validation
+            throw new Error(expression.value.map(err => `${err.key}: ${err.message}`).join(', '));
+        }
+        return expression.value;
+
+    } else {
+        let constant: any = value;
+        if (typeof value === 'string' && specification.type === 'color') {
+            constant = Color.parse(value);
+        }
+        return {
+            kind: 'constant',
+            evaluate: () => constant
+        };
+    }
+}
+
+// Zoom-dependent expressions may only use ["zoom"] as the input to a top-level "step" or "interpolate"
+// expression (collectively referred to as a "curve"). The curve may be wrapped in one or more "let" or
+// "coalesce" expressions.
+function findZoomCurve(expression: Expression): Step | Interpolate | ParsingError | null {
+    let result = null;
+    if (expression instanceof Let) {
+        result = findZoomCurve(expression.result);
+
+    } else if (expression instanceof Coalesce) {
+        for (const arg of expression.args) {
+            result = findZoomCurve(arg);
+            if (result) {
+                break;
+            }
+        }
+
+    } else if ((expression instanceof Step || expression instanceof Interpolate) &&
+        expression.input instanceof CompoundExpression &&
+        expression.input.name === 'zoom') {
+
+        result = expression;
+    }
+
+    if (result instanceof ParsingError) {
+        return result;
+    }
+
+    expression.eachChild((child) => {
+        const childResult = findZoomCurve(child);
+        if (childResult instanceof ParsingError) {
+            result = childResult;
+        } else if (!result && childResult) {
+            result = new ParsingError('', '"zoom" expression may only be used as input to a top-level "step" or "interpolate" expression.');
+        } else if (result && childResult && result !== childResult) {
+            result = new ParsingError('', 'Only one zoom-based "step" or "interpolate" subexpression may be used in an expression.');
+        }
+    });
+
+    return result;
+}
+
+import {ColorType, StringType, NumberType, BooleanType, ValueType, FormattedType, ResolvedImageType, array} from './types.js';
+
+function getExpectedType(spec: StylePropertySpecification): Type {
+    const types = {
+        color: ColorType,
+        string: StringType,
+        number: NumberType,
+        enum: StringType,
+        boolean: BooleanType,
+        formatted: FormattedType,
+        resolvedImage: ResolvedImageType
+    };
+
+    if (spec.type === 'array') {
+        return array(types[spec.value] || ValueType, spec.length);
+    }
+
+    return types[spec.type];
+}
+
+function getDefaultValue(spec: StylePropertySpecification): Value {
+    if (spec.type === 'color' && (isFunction(spec.default) || Array.isArray(spec.default))) {
+        // Special case for heatmap-color: it uses the 'default:' to define a
+        // default color ramp, but createExpression expects a simple value to fall
+        // back to in case of runtime errors
+        return new Color(0, 0, 0, 0);
+    } else if (spec.type === 'color') {
+        return Color.parse(spec.default) || null;
+    } else if (spec.default === undefined) {
+        return null;
+    } else {
+        return spec.default;
+    }
+}