svelte/src/generators/server-side-rendering/Block.ts

import deindent from '../../utils/deindent';
import flattenReference from '../../utils/flattenReference';
import { SsrGenerator } from './index';
import { Node } from '../../interfaces';

interface BlockOptions {
	// TODO
}

export default class Block {
	generator: SsrGenerator;
	conditions: string[];

	contexts: Map<string, string>;
	indexes: Map<string, string>;
	contextDependencies: Map<string, string[]>;

	constructor(options: BlockOptions) {
		Object.assign(this, options);
	}

	addBinding(binding: Node, name: string) {
		const conditions = [`!( '${binding.name}' in state )`].concat(
			// TODO handle contextual bindings...
			this.conditions.map(c => `(${c})`)
		);

		const { keypath } = flattenReference(binding.value);

		this.generator.bindings.push(deindent`
			if ( ${conditions.join('&&')} ) {
				tmp = ${name}.data();
				if ( '${keypath}' in tmp ) {
					state.${binding.name} = tmp.${keypath};
					settled = false;
				}
			}
		`);
	}

	child(options: BlockOptions) {
		return new Block(Object.assign({}, this, options, { parent: this }));
	}

	contextualise(expression: Node, context?: string, isEventHandler?: boolean) {
		return this.generator.contextualise(
			this,
			expression,
			context,
			isEventHandler
		);
	}
}