Question 52454 in Javascript Question posted in
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How can I get the outer only angle brackets nodes (algorithm) – Javascript

Having this as input '<apple, <pear>>, <orange, <apple>, <cherry>, banana>, <banana, <pear>, <orange>>' having in mind that whatever is inside angle brackets is considered a node, so the output should be:
['<apple, <pear>>', '<orange, <apple>, <cherry>, banana>', '<banana, <pear>, <orange>>']

I’ve tried regex and split like this

const regexBycomma = /([^,<]*(?:<[^>]*>[^,<]*)*),?/g;
str.split(regexBycomma);

with not good results, also many algorithms like this one:

function getParentNodes(input) {
  const nodes = input.match(/<[^<>]+>/g); // Extract all nodes from the input
  const parentNodes = [];
  let currentParentNode = '';

  for (const node of nodes) {
    if (currentParentNode === '') {
      currentParentNode = node;
    } else if (node.startsWith(currentParentNode)) {
      currentParentNode += ',' + node;
    } else {
      parentNodes.push(currentParentNode);
      currentParentNode = node;
    }
  }
  
  if (currentParentNode !== '') {
    parentNodes.push(currentParentNode);
  }

  return parentNodes;
}
Tags:

2

Answers


  1. 0

    Here the idea is to track how deep you are in to the nodes by adding to the depth when encountering a < and reducing it when encounting a >. When the depth becomes zero start a new string.

    const nodes_string = '<apple, <pear>>, <orange, <apple>, <cherry>, banana>, <banana, <pear>, <orange>>';
const nodes_string2 = 'doughnut, <apple, <pear>>, muffin, crumpet, <orange, <apple>, <cherry>, banana>, <banana, <pear>, <orange>>, pie';

const clean_text_nodes = (node) =>
  node.startsWith('<') ?
    node :
    node
      .split(',')
      .map( (str) => str.trim() )
      .filter( (str) => str !== '' );

const get_top_nodes = (nodes_string) => {
  let depth = 0;
  const result = [''];
  
  for(const char of nodes_string) {
    if(char === '<') {
      if(depth === 0) result.push('');
      depth++;
    }
    
    result[result.length - 1] += char;
    
    if(char === '>') {
      depth--;
      if(depth === 0) result.push('');
    }
  }
  
  return result.flatMap(clean_text_nodes);
};

console.log(get_top_nodes(nodes_string));
console.log(get_top_nodes(nodes_string2));
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  2. 0

    You might just naively count opened and closed brackets and push "nodes" to the result:

    const parse = str => {
  const result = [];
  let sub = '',
    opened = 0,
    closed = 0;
  for (const s of str) {
    if (s === '<') ++opened;
    else if (s === '>') ++closed;
    if (opened > 0) {
      sub += s;
      if (opened === closed) {
        opened = closed = 0;
        result.push(sub);
        sub = '';
      }
    }
  }
  return result;
}

console.log(parse('<apple, <pear>>, <orange, <apple>, <cherry>, banana>, <banana, <pear>, <orange>>'))
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