iot-sol/node_modules/hope-base/lib/to_string.js

Intel(r) IoT Services Orchestration Layer - HTML5 IDE + Node.js middleware to create and host distributed IoT Apps in minutes

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/**
 * Dump to string
 * @module  base
 */

var _ = require("lodash");


function to_short_string(x) {
  if (_.isUndefined(x)) {
    return "<__undefined__>";
  }
  if (_.isNull(x)) {
    return "<__null__>";
  }
  if (_.isString(x.$short_string)) {
    return x.$short_string;
  }
  if (_.isFunction(x.$to_short_string)) {
    return x.$to_short_string();
  }
  if (_.isString(x)) {
    return x;
  }
  if (_.isDate(x)) {
    return "<DATE: " + x.toString() + ">";
  }
  if (_.isError(x)) {
    return "<ERROR: " + x.message + ">";
  }
  if (_.isFunction(x)) {
    return "<FUNCTION: " + (x.name || "anonymous") + ">";
  }
  if (_.isArray(x)) {
    return "<ARRAY of length: " + x.length + ">";
  }
  if (_.isObject(x)) {
    if (x.constructor) {
      return "<OBJECT of TYPE: " + x.constructor.name + ">";
    } else {
      return "<OBJECT of unknown TYPE>";
    }
  }
  return x.toString();
}

function to_string(x, depth, cur_depth, indent) {

  if (_.isUndefined(x) || _.isNull(x)) {
    return to_short_string(x);
  }

  if (_.isFunction(x.$to_string)) {
    return x.$to_string();
  }

  if (_.isString(x)) {
    if (depth > 0) {
      return "\"" + x + "\"";
    } else {
      return x;
    }
  }

  // cannot use instanceof because this would be false if it is TypeError etc.
  if (_.isDate(x) || _.isFunction(x)) {
    return to_short_string(x);
  }

  if (_.isError(x)) {
    return x.stack;
  }


  depth = depth || 3;
  if (depth < 0) {
    depth = 3;
  }
  cur_depth = cur_depth || 0;
  // indent is only used when there is a need to add a new line
  if (_.isUndefined(indent)) {
    indent = "";
  }

  var lines = [], i;
  if (_.isArray(x)) {
    if (cur_depth >= depth) {
      return to_short_string(x);
    }
    for (i = 0; i < x.length; i++) {
      lines.push(to_string(x[i], depth, cur_depth + 1, indent));
    }
    return "[" + lines.join(", ") + "]";
  }


  if (_.isObject(x)) {

    if (cur_depth >= depth) {
      return to_short_string(x);
    }
    var new_indent = indent + "  ";   // indent 2 spaces
    var keys = _.keys(x);
    if (keys.length === 0) {
      return "{}";
    } 
    if (keys.length === 1) {
      return "{ " + keys[0] + ": " + 
        to_string(x[keys[0]], depth, cur_depth + 1, new_indent) + " }";
    }
    for (i = 0; i < keys.length; i++) {
      var k = keys[i];
      lines.push(indent + "  " + k + ": " + to_string(x[k], depth, 
        cur_depth + 1, new_indent));
    }
    return "{\n" + lines.join(",\n") + "\n" + indent + "}";
  }
  return x.toString();
}

/**
 * Dump a value to a formated string
 *
 * The value (or its descendants) may have $to_string() defined to replace
 * the default behavior of this to_string()
 * It may further defines a $short_string member, or a $to_short_string() 
 * function, if it needs to be shown in one line (e.g. when it exceeds depth)
 * 
 * @param  {any} x      Any value, e.g. primitive, array, object, etc.
 * @param  {uint} depth  Max depth that would recrusively dump
 * @return {string}      
 */
exports.to_string = function(x, depth) {
  return to_string(x, depth, 0, "");  
};


/**
 * Dump a value to a formated one line string
 *
 * Users may attach a $short_string member or a $to_short_string() function
 * to the object to overwrite the default short string dumped 
 * 
 * @param {any} x
 * @return {string}      
 */
exports.to_short_string = to_short_string;