MemberExpression.ts

import type MagicString from 'magic-string';
import type { AstContext } from '../../Module';
import type { NormalizedTreeshakingOptions } from '../../rollup/types';
import { BLANK, EMPTY_ARRAY } from '../../utils/blank';
import { errorIllegalImportReassignment, errorMissingExport } from '../../utils/error';
import type { NodeRenderOptions, RenderOptions } from '../../utils/renderHelpers';
import type { DeoptimizableEntity } from '../DeoptimizableEntity';
import type { HasEffectsContext, InclusionContext } from '../ExecutionContext';
import type {
	NodeInteraction,
	NodeInteractionAccessed,
	NodeInteractionAssigned,
	NodeInteractionCalled
} from '../NodeInteractions';
import { INTERACTION_ACCESSED, INTERACTION_ASSIGNED } from '../NodeInteractions';
import {
	EMPTY_PATH,
	type ObjectPath,
	type ObjectPathKey,
	type PathTracker,
	SHARED_RECURSION_TRACKER,
	SymbolToStringTag,
	UNKNOWN_PATH,
	UnknownKey,
	UnknownNonAccessorKey
} from '../utils/PathTracker';
import { UNDEFINED_EXPRESSION } from '../values';
import ExternalVariable from '../variables/ExternalVariable';
import type NamespaceVariable from '../variables/NamespaceVariable';
import type Variable from '../variables/Variable';
import Identifier from './Identifier';
import Literal from './Literal';
import type * as NodeType from './NodeType';
import type PrivateIdentifier from './PrivateIdentifier';
import type SpreadElement from './SpreadElement';
import type Super from './Super';
import {
	deoptimizeInteraction,
	type ExpressionEntity,
	type LiteralValueOrUnknown,
	UNKNOWN_RETURN_EXPRESSION,
	UnknownValue
} from './shared/Expression';
import type { ChainElement, ExpressionNode, IncludeChildren } from './shared/Node';
import { NodeBase } from './shared/Node';

// To avoid infinite recursions
const MAX_PATH_DEPTH = 7;

function getResolvablePropertyKey(memberExpression: MemberExpression): string | null {
	return memberExpression.computed
		? getResolvableComputedPropertyKey(memberExpression.property)
		: (memberExpression.property as Identifier).name;
}

function getResolvableComputedPropertyKey(propertyKey: ExpressionNode): string | null {
	if (propertyKey instanceof Literal) {
		return String(propertyKey.value);
	}
	return null;
}

type PathWithPositions = { key: string; pos: number }[];

function getPathIfNotComputed(memberExpression: MemberExpression): PathWithPositions | null {
	const nextPathKey = memberExpression.propertyKey;
	const object = memberExpression.object;
	if (typeof nextPathKey === 'string') {
		if (object instanceof Identifier) {
			return [
				{ key: object.name, pos: object.start },
				{ key: nextPathKey, pos: memberExpression.property.start }
			];
		}
		if (object instanceof MemberExpression) {
			const parentPath = getPathIfNotComputed(object);
			return (
				parentPath && [...parentPath, { key: nextPathKey, pos: memberExpression.property.start }]
			);
		}
	}
	return null;
}

function getStringFromPath(path: PathWithPositions): string {
	let pathString = path[0].key;
	for (let index = 1; index < path.length; index++) {
		pathString += '.' + path[index].key;
	}
	return pathString;
}

export default class MemberExpression
	extends NodeBase
	implements DeoptimizableEntity, ChainElement
{
	declare computed: boolean;
	declare object: ExpressionNode | Super;
	declare optional: boolean;
	declare property: ExpressionNode | PrivateIdentifier;
	declare propertyKey: ObjectPathKey | null;
	declare type: NodeType.tMemberExpression;
	variable: Variable | null = null;
	protected declare assignmentInteraction: NodeInteractionAssigned;
	private declare accessInteraction: NodeInteractionAccessed;
	private assignmentDeoptimized = false;
	private bound = false;
	private expressionsToBeDeoptimized: DeoptimizableEntity[] = [];
	private isUndefined = false;

	bind(): void {
		this.bound = true;
		const path = getPathIfNotComputed(this);
		const baseVariable = path && this.scope.findVariable(path[0].key);
		if (baseVariable?.isNamespace) {
			const resolvedVariable = resolveNamespaceVariables(
				baseVariable,
				path!.slice(1),
				this.context
			);
			if (!resolvedVariable) {
				super.bind();
			} else if (resolvedVariable === 'undefined') {
				this.isUndefined = true;
			} else {
				this.variable = resolvedVariable;
				this.scope.addNamespaceMemberAccess(getStringFromPath(path!), resolvedVariable);
			}
		} else {
			super.bind();
		}
	}

	deoptimizeArgumentsOnInteractionAtPath(
		interaction: NodeInteraction,
		path: ObjectPath,
		recursionTracker: PathTracker
	): void {
		if (this.variable) {
			this.variable.deoptimizeArgumentsOnInteractionAtPath(interaction, path, recursionTracker);
		} else if (!this.isUndefined) {
			if (path.length < MAX_PATH_DEPTH) {
				this.object.deoptimizeArgumentsOnInteractionAtPath(
					interaction,
					[this.getPropertyKey(), ...path],
					recursionTracker
				);
			} else {
				deoptimizeInteraction(interaction);
			}
		}
	}

	deoptimizeCache(): void {
		const { expressionsToBeDeoptimized, object } = this;
		this.expressionsToBeDeoptimized = EMPTY_ARRAY as unknown as DeoptimizableEntity[];
		this.propertyKey = UnknownKey;
		object.deoptimizePath(UNKNOWN_PATH);
		for (const expression of expressionsToBeDeoptimized) {
			expression.deoptimizeCache();
		}
	}

	deoptimizePath(path: ObjectPath): void {
		if (path.length === 0) this.disallowNamespaceReassignment();
		if (this.variable) {
			this.variable.deoptimizePath(path);
		} else if (!this.isUndefined && path.length < MAX_PATH_DEPTH) {
			const propertyKey = this.getPropertyKey();
			this.object.deoptimizePath([
				propertyKey === UnknownKey ? UnknownNonAccessorKey : propertyKey,
				...path
			]);
		}
	}

	getLiteralValueAtPath(
		path: ObjectPath,
		recursionTracker: PathTracker,
		origin: DeoptimizableEntity
	): LiteralValueOrUnknown {
		if (this.variable) {
			return this.variable.getLiteralValueAtPath(path, recursionTracker, origin);
		}
		if (this.isUndefined) {
			return undefined;
		}
		if (this.propertyKey !== UnknownKey && path.length < MAX_PATH_DEPTH) {
			this.expressionsToBeDeoptimized.push(origin);
			return this.object.getLiteralValueAtPath(
				[this.getPropertyKey(), ...path],
				recursionTracker,
				origin
			);
		}
		return UnknownValue;
	}

	getReturnExpressionWhenCalledAtPath(
		path: ObjectPath,
		interaction: NodeInteractionCalled,
		recursionTracker: PathTracker,
		origin: DeoptimizableEntity
	): [expression: ExpressionEntity, isPure: boolean] {
		if (this.variable) {
			return this.variable.getReturnExpressionWhenCalledAtPath(
				path,
				interaction,
				recursionTracker,
				origin
			);
		}
		if (this.isUndefined) {
			return [UNDEFINED_EXPRESSION, false];
		}
		if (this.propertyKey !== UnknownKey && path.length < MAX_PATH_DEPTH) {
			this.expressionsToBeDeoptimized.push(origin);
			return this.object.getReturnExpressionWhenCalledAtPath(
				[this.getPropertyKey(), ...path],
				interaction,
				recursionTracker,
				origin
			);
		}
		return UNKNOWN_RETURN_EXPRESSION;
	}

	hasEffects(context: HasEffectsContext): boolean {
		if (!this.deoptimized) this.applyDeoptimizations();
		return (
			this.property.hasEffects(context) ||
			this.object.hasEffects(context) ||
			this.hasAccessEffect(context)
		);
	}

	hasEffectsAsAssignmentTarget(context: HasEffectsContext, checkAccess: boolean): boolean {
		if (checkAccess && !this.deoptimized) this.applyDeoptimizations();
		if (!this.assignmentDeoptimized) this.applyAssignmentDeoptimization();
		return (
			this.property.hasEffects(context) ||
			this.object.hasEffects(context) ||
			(checkAccess && this.hasAccessEffect(context)) ||
			this.hasEffectsOnInteractionAtPath(EMPTY_PATH, this.assignmentInteraction, context)
		);
	}

	hasEffectsOnInteractionAtPath(
		path: ObjectPath,
		interaction: NodeInteraction,
		context: HasEffectsContext
	): boolean {
		if (this.variable) {
			return this.variable.hasEffectsOnInteractionAtPath(path, interaction, context);
		}
		if (this.isUndefined) {
			return true;
		}
		if (path.length < MAX_PATH_DEPTH) {
			return this.object.hasEffectsOnInteractionAtPath(
				[this.getPropertyKey(), ...path],
				interaction,
				context
			);
		}
		return true;
	}

	include(context: InclusionContext, includeChildrenRecursively: IncludeChildren): void {
		if (!this.deoptimized) this.applyDeoptimizations();
		this.includeProperties(context, includeChildrenRecursively);
	}

	includeAsAssignmentTarget(
		context: InclusionContext,
		includeChildrenRecursively: IncludeChildren,
		deoptimizeAccess: boolean
	): void {
		if (!this.assignmentDeoptimized) this.applyAssignmentDeoptimization();
		if (deoptimizeAccess) {
			this.include(context, includeChildrenRecursively);
		} else {
			this.includeProperties(context, includeChildrenRecursively);
		}
	}

	includeCallArguments(
		context: InclusionContext,
		parameters: readonly (ExpressionEntity | SpreadElement)[]
	): void {
		if (this.variable) {
			this.variable.includeCallArguments(context, parameters);
		} else {
			super.includeCallArguments(context, parameters);
		}
	}

	initialise(): void {
		this.propertyKey = getResolvablePropertyKey(this);
		this.accessInteraction = { args: [this.object], type: INTERACTION_ACCESSED };
	}

	isSkippedAsOptional(origin: DeoptimizableEntity): boolean {
		return (
			!this.variable &&
			!this.isUndefined &&
			((this.object as ExpressionNode).isSkippedAsOptional?.(origin) ||
				(this.optional &&
					this.object.getLiteralValueAtPath(EMPTY_PATH, SHARED_RECURSION_TRACKER, origin) == null))
		);
	}

	render(
		code: MagicString,
		options: RenderOptions,
		{
			renderedParentType,
			isCalleeOfRenderedParent,
			renderedSurroundingElement
		}: NodeRenderOptions = BLANK
	): void {
		if (this.variable || this.isUndefined) {
			const {
				snippets: { getPropertyAccess }
			} = options;
			let replacement = this.variable ? this.variable.getName(getPropertyAccess) : 'undefined';
			if (renderedParentType && isCalleeOfRenderedParent) replacement = '0, ' + replacement;
			code.overwrite(this.start, this.end, replacement!, {
				contentOnly: true,
				storeName: true
			});
		} else {
			if (renderedParentType && isCalleeOfRenderedParent) {
				code.appendRight(this.start, '0, ');
			}
			this.object.render(code, options, { renderedSurroundingElement });
			this.property.render(code, options);
		}
	}

	setAssignedValue(value: ExpressionEntity) {
		this.assignmentInteraction = {
			args: [this.object, value],
			type: INTERACTION_ASSIGNED
		};
	}

	protected applyDeoptimizations(): void {
		this.deoptimized = true;
		const { propertyReadSideEffects } = this.context.options
			.treeshake as NormalizedTreeshakingOptions;
		if (
			// Namespaces are not bound and should not be deoptimized
			this.bound &&
			propertyReadSideEffects &&
			!(this.variable || this.isUndefined)
		) {
			const propertyKey = this.getPropertyKey();
			this.object.deoptimizeArgumentsOnInteractionAtPath(
				this.accessInteraction,
				[propertyKey],
				SHARED_RECURSION_TRACKER
			);
			this.context.requestTreeshakingPass();
		}
	}

	private applyAssignmentDeoptimization(): void {
		this.assignmentDeoptimized = true;
		const { propertyReadSideEffects } = this.context.options
			.treeshake as NormalizedTreeshakingOptions;
		if (
			// Namespaces are not bound and should not be deoptimized
			this.bound &&
			propertyReadSideEffects &&
			!(this.variable || this.isUndefined)
		) {
			this.object.deoptimizeArgumentsOnInteractionAtPath(
				this.assignmentInteraction,
				[this.getPropertyKey()],
				SHARED_RECURSION_TRACKER
			);
			this.context.requestTreeshakingPass();
		}
	}

	private disallowNamespaceReassignment() {
		if (this.object instanceof Identifier) {
			const variable = this.scope.findVariable(this.object.name);
			if (variable.isNamespace) {
				if (this.variable) {
					this.context.includeVariableInModule(this.variable);
				}
				this.context.warn(
					errorIllegalImportReassignment(this.object.name, this.context.module.id),
					this.start
				);
			}
		}
	}

	private getPropertyKey(): ObjectPathKey {
		if (this.propertyKey === null) {
			this.propertyKey = UnknownKey;
			const value = this.property.getLiteralValueAtPath(EMPTY_PATH, SHARED_RECURSION_TRACKER, this);
			return (this.propertyKey =
				value === SymbolToStringTag
					? value
					: typeof value === 'symbol'
					? UnknownKey
					: String(value));
		}
		return this.propertyKey;
	}

	private hasAccessEffect(context: HasEffectsContext) {
		const { propertyReadSideEffects } = this.context.options
			.treeshake as NormalizedTreeshakingOptions;
		return (
			!(this.variable || this.isUndefined) &&
			propertyReadSideEffects &&
			(propertyReadSideEffects === 'always' ||
				this.object.hasEffectsOnInteractionAtPath(
					[this.getPropertyKey()],
					this.accessInteraction,
					context
				))
		);
	}

	private includeProperties(
		context: InclusionContext,
		includeChildrenRecursively: IncludeChildren
	) {
		if (!this.included) {
			this.included = true;
			if (this.variable) {
				this.context.includeVariableInModule(this.variable);
			}
		}
		this.object.include(context, includeChildrenRecursively);
		this.property.include(context, includeChildrenRecursively);
	}
}

function resolveNamespaceVariables(
	baseVariable: Variable,
	path: PathWithPositions,
	astContext: AstContext
): Variable | 'undefined' | null {
	if (path.length === 0) return baseVariable;
	if (!baseVariable.isNamespace || baseVariable instanceof ExternalVariable) return null;
	const exportName = path[0].key;
	const variable = (baseVariable as NamespaceVariable).context.traceExport(exportName);
	if (!variable) {
		if (path.length === 1) {
			const fileName = (baseVariable as NamespaceVariable).context.fileName;
			astContext.warn(errorMissingExport(exportName, astContext.module.id, fileName), path[0].pos);
			return 'undefined';
		}
		return null;
	}
	return resolveNamespaceVariables(variable, path.slice(1), astContext);
}