constructor() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/scope.js lines 257–596

	constructor(scope, expression, values) {
		current_evaluations.set(expression, this);

		this.values = values;

		switch (expression.type) {
			case 'Literal': {
				this.values.add(expression.value);
				break;
			}

			case 'Identifier': {
				const binding = scope.get(expression.name);

				if (binding) {
					if (
						binding.initial?.type === 'CallExpression' &&
						get_rune(binding.initial, scope) === '$props.id'
					) {
						this.values.add(STRING);
						break;
					}

					const is_prop =
						binding.kind === 'prop' ||
						binding.kind === 'rest_prop' ||
						binding.kind === 'bindable_prop';

					if (binding.initial?.type === 'EachBlock' && binding.initial.index === expression.name) {
						this.values.add(NUMBER);
						break;
					}

					if (binding.initial?.type === 'SnippetBlock') {
						this.is_defined = true;
						this.is_known = false;
						this.values.add(UNKNOWN);
						break;
					}

					if (!binding.updated && binding.initial !== null && !is_prop) {
						binding.scope.evaluate(/** @type {Expression} */ (binding.initial), this.values);
						break;
					}
				} else if (expression.name === 'undefined') {
					this.values.add(undefined);
					break;
				}

				// TODO glean what we can from reassignments
				// TODO one day, expose props and imports somehow

				this.values.add(UNKNOWN);
				break;
			}

			case 'BinaryExpression': {
				const a = scope.evaluate(/** @type {Expression} */ (expression.left)); // `left` cannot be `PrivateIdentifier` unless operator is `in`
				const b = scope.evaluate(expression.right);

				if (a.is_known && b.is_known) {
					this.values.add(binary[expression.operator](a.value, b.value));
					break;
				}

				switch (expression.operator) {
					case '!=':
					case '!==':
					case '<':
					case '<=':
					case '>':
					case '>=':
					case '==':
					case '===':
					case 'in':
					case 'instanceof':
						this.values.add(true);
						this.values.add(false);
						break;

					case '%':