stylus/lib/utils.js

/*!
 * Stylus - utils
 * Copyright(c) 2010 LearnBoost <dev@learnboost.com>
 * MIT Licensed
 */

/**
 * Module dependencies.
 */

var nodes = require('./nodes')
  , inspect = require('sys').inspect
  , fs = require('fs');

/**
 * Attempt to lookup `path` within `paths` from tail to head.
 * Optionally a path to `ignore` may be passed.
 *
 * @param {String} path
 * @param {String} paths
 * @param {String} ignore
 * @return {String}
 * @api private
 */

exports.lookup = function(path, paths, ignore){
  var lookup
    , i = paths.length;

  // Absolute
  if ('/' == path[0]) {
    try {
      fs.statSync(path);
      return path;
    } catch (err) {
      // Ignore, continue on
      // to trying relative lookup.
      // Needed for url(/images/foo.png)
      // for example
    }
  }

  // Relative
  while (i--) {
    try {
      lookup = paths[i] + '/' + path;
      if (ignore == lookup) continue;
      fs.statSync(lookup);
      return lookup;
    } catch (err) {
      // Ignore
    }
  }
};

/**
 * Format the given `err` in context to `renderer`.
 *
 * @param {Renderer} renderer
 * @param {Error} err
 * @param {Object} options
 * @return {Error}
 * @api private
 */

exports.formatException = function(renderer, err, options){
  var lineno = renderer.evaluator
      ? renderer.evaluator.lineno
      : renderer.parser.lexer.lineno
    , contextLineno = lineno - 2
    , contextLines = options.context || 8
    , lastWidth = (contextLineno + contextLines).toString().length;

  var src = (err.str || renderer.str).split('\n')
    .slice(contextLineno, contextLineno + contextLines)
    .map(function(line){
      var n = ++contextLineno
        , width = n.toString().length
        , pad = Array(lastWidth - width + 1).join(' ');
      return '  ' + pad + n + ': ' + inspect(line);
    }).join('\n');

  err.message = renderer.options.filename
    + ':' + lineno
    + '\n' + src
    + '\n\n' + err.message + '\n'
    + (err.stylusStack ? err.stylusStack + '\n' : '');

  return err;
};

/**
 * Assert that `node` is of the given `type`, or throw.
 *
 * @param {Node} node
 * @param {Function} type
 * @param {String} param
 * @api public
 */

exports.assertType = function(node, type, param){
  exports.assertPresent(node, param);
  if (node instanceof type) return;
  var actual = node.constructor.name
    , msg = 'expected ' + type.name + ', but got ' + actual + ':' + node;
  throw new Error('TypeError: ' + msg);
};

/**
 * Assert that `node` is a `String` or `Ident`.
 *
 * @param {Node} node
 * @param {String} param
 * @api public
 */

exports.assertString = function(node, param){
  exports.assertPresent(node, param);
  if (node instanceof nodes.String) return;
  if (node instanceof nodes.Ident) return;
  var actual = node.constructor.name
    , msg = 'expected String or Ident, but got ' + actual + ':' + node;
  throw new Error('TypeError: ' + msg);
};

/**
 * Assert that `node` is a `Color` or `HSLA`.
 *
 * @param {Node} node
 * @param {String} param
 * @api public
 */

exports.assertColor = function(node, param){
  exports.assertPresent(node, param);
  if (node instanceof nodes.Color) return;
  if (node instanceof nodes.HSLA) return;
  var actual = node.constructor.name
    , msg = 'expected Color or HSLA, but got ' + actual + ':' + node;
  throw new Error('TypeError: ' + msg);
};

/**
 * Assert that param `name` is given, aka the `node` is passed.
 *
 * @param {Node} node
 * @param {String} name
 * @api public
 */

exports.assertPresent = function(node, name){
  if (node) return;
  if (name) throw new Error('ArgumentError: argument ' + name + ' required');
  throw new Error('ArgumentError: argument missing');
};

/**
 * Unwrap `expr`.
 *
 * Takes an expressions with length of 1
 * such as `(1 2 3)` and unwraps it to `1 2 3`.
 *
 * @param {Expression} expr
 * @return {Node}
 * @api public
 */

exports.unwrap = function(expr){
  if ('expression' != expr.nodeName) return expr;
  if (1 != expr.nodes.length) return expr;
  if ('expression' != expr.nodes[0].nodeName) return expr;
  return expr.nodes[0];
};