switchy2tire_if.js

function parse_switchy(text){
  return text
    .split("\n")
    .filter(l => l.length && l[0] == '*')
    .map(l => l.split(' '))
}

function switchy2tire_if(text){
  function tree2if(tree){
    function t2i(node, depth, defa){
      if(typeof node === 'number') return node.toString();
      defa = node['.'] || defa
      let keys = Object.keys(node).filter(s => s!='.')
      let sms  = keys.map(k => `t[${depth}]=='${k}'?${t2i(node[k], depth+1, defa)}`)
      if(sms.length){
        sms.push(defa.toString())
        return '('+sms.join(':')+')'
      }else{
        return defa.toString()
      }
    }
    return `function(t){return ${t2i(tree, 0, tree['.'])}}`
  }
  const records = parse_switchy(text)
  const tree = {['.']: 'DIRECT'}
  let proxy_id_counter = 0
  const proxy_id_map = {}
  const proxy_vec = []
  for(let [pat, pro] of records){
    const host = pat.split('.').reverse()
    let   head = tree
    let   part = host.shift()
    while(host.length && part != '*'){
      head = head[part] ? head[part] : (head[part] = {})
      part = host.shift()
    }
    if(proxy_id_map[pro]){
      head['.'] = proxy_id_map[pro]
    }else{
      proxy_id_map[pro] = proxy_id_counter
      head['.'] = proxy_id_counter
      proxy_vec.push(pro)
      proxy_id_counter ++
    }
    
  }
  return `
  function FindProxyForURL(url, host){
    let t = FindProxyForURL.func(host.split('.').reverse())
    return FindProxyForURL.vec[t]
  }
  FindProxyForURL.func = ${tree2if(tree)};
  FindProxyForURL.vec = ${JSON.stringify(proxy_vec)};
  `
}