rudeshark.net/src/mfm/parse.ts
2018-11-24 17:10:12 +09:00

83 lines
2.4 KiB
TypeScript

import parser, { Node } from './parser';
import * as A from '../prelude/array';
import * as S from '../prelude/string';
export default (source: string): Node[] => {
if (source == null || source == '') {
return null;
}
let nodes: Node[] = parser.root.tryParse(source);
const combineText = (es: Node[]): Node =>
({ name: 'text', props: { text: S.concat(es.map(e => e.props.text)) } });
const concatText = (nodes: Node[]): Node[] =>
A.concat(A.groupOn(x => x.name, nodes).map(es =>
es[0].name === 'text' ? [combineText(es)] : es
));
const concatTextRecursive = (es: Node[]): void =>
es.filter(x => x.children).forEach(x => {
x.children = concatText(x.children);
concatTextRecursive(x.children);
});
nodes = concatText(nodes);
concatTextRecursive(nodes);
function getBeforeTextNode(node: Node): Node {
if (node == null) return null;
if (node.name == 'text') return node;
if (node.children) return getBeforeTextNode(node.children[node.children.length - 1]);
return null;
}
function getAfterTextNode(node: Node): Node {
if (node == null) return null;
if (node.name == 'text') return node;
if (node.children) return getBeforeTextNode(node.children[0]);
return null;
}
function isBlockNode(node: Node): boolean {
return ['blockCode', 'quote', 'title'].includes(node.name);
}
/**
* ブロック要素の前後にある改行を削除します
* (ブロック要素自体が改行の役割を果たすため、余計に改行されてしまう)
* @param nodes
*/
const removeNeedlessLineBreaks = (nodes: Node[]) => {
nodes.forEach((node, i) => {
if (node.children) removeNeedlessLineBreaks(node.children);
if (isBlockNode(node)) {
const before = getBeforeTextNode(nodes[i - 1]);
const after = getAfterTextNode(nodes[i + 1]);
if (before && before.props.text.endsWith('\n')) {
before.props.text = before.props.text.substring(0, before.props.text.length - 1);
}
if (after && after.props.text.startsWith('\n')) {
after.props.text = after.props.text.substring(1);
}
}
});
};
const removeEmptyTextNodes = (nodes: Node[]) => {
nodes.forEach(n => {
if (n.children) {
n.children = removeEmptyTextNodes(n.children);
}
});
return nodes.filter(n => !(n.name == 'text' && n.props.text == ''));
};
removeNeedlessLineBreaks(nodes);
nodes = removeEmptyTextNodes(nodes);
return nodes;
};