vega-expression/src/functions.js

Vega expression parser and code generator.

import {error} from 'vega-util';

export default function(codegen) {

  function fncall(name, args, cast, type) {
    let obj = codegen(args[0]);
    if (cast) {
      obj = cast + '(' + obj + ')';
      if (cast.lastIndexOf('new ', 0) === 0) obj = '(' + obj + ')';
    }
    return obj + '.' + name + (type < 0 ? '' : type === 0 ?
      '()' :
      '(' + args.slice(1).map(codegen).join(',') + ')');
  }

  function fn(name, cast, type) {
    return args => fncall(name, args, cast, type);
  }

  const DATE = 'new Date',
        STRING = 'String',
        REGEXP = 'RegExp';

  return {
    // MATH functions
    isNaN:    'Number.isNaN',
    isFinite: 'Number.isFinite',
    abs:      'Math.abs',
    acos:     'Math.acos',
    asin:     'Math.asin',
    atan:     'Math.atan',
    atan2:    'Math.atan2',
    ceil:     'Math.ceil',
    cos:      'Math.cos',
    exp:      'Math.exp',
    floor:    'Math.floor',
    hypot:    'Math.hypot',
    log:      'Math.log',
    max:      'Math.max',
    min:      'Math.min',
    pow:      'Math.pow',
    random:   'Math.random',
    round:    'Math.round',
    sin:      'Math.sin',
    sqrt:     'Math.sqrt',
    tan:      'Math.tan',

    clamp: function(args) {
      if (args.length < 3) error('Missing arguments to clamp function.');
      if (args.length > 3) error('Too many arguments to clamp function.');
      const a = args.map(codegen);
      return 'Math.max('+a[1]+', Math.min('+a[2]+','+a[0]+'))';
    },

    // DATE functions
    now:             'Date.now',
    utc:             'Date.UTC',
    datetime:        DATE,
    date:            fn('getDate', DATE, 0),
    day:             fn('getDay', DATE, 0),
    year:            fn('getFullYear', DATE, 0),
    month:           fn('getMonth', DATE, 0),
    hours:           fn('getHours', DATE, 0),
    minutes:         fn('getMinutes', DATE, 0),
    seconds:         fn('getSeconds', DATE, 0),
    milliseconds:    fn('getMilliseconds', DATE, 0),
    time:            fn('getTime', DATE, 0),
    timezoneoffset:  fn('getTimezoneOffset', DATE, 0),
    utcdate:         fn('getUTCDate', DATE, 0),
    utcday:          fn('getUTCDay', DATE, 0),
    utcyear:         fn('getUTCFullYear', DATE, 0),
    utcmonth:        fn('getUTCMonth', DATE, 0),
    utchours:        fn('getUTCHours', DATE, 0),
    utcminutes:      fn('getUTCMinutes', DATE, 0),
    utcseconds:      fn('getUTCSeconds', DATE, 0),
    utcmilliseconds: fn('getUTCMilliseconds', DATE, 0),

    // sequence functions
    length:      fn('length', null, -1),

    // STRING functions
    parseFloat:  'parseFloat',
    parseInt:    'parseInt',
    upper:       fn('toUpperCase', STRING, 0),
    lower:       fn('toLowerCase', STRING, 0),
    substring:   fn('substring', STRING),
    split:       fn('split', STRING),
    trim:        fn('trim', STRING, 0),
    // base64 encode/decode
    btoa:        'btoa',
    atob:        'atob',

    // REGEXP functions
    regexp:  REGEXP,
    test:    fn('test', REGEXP),

    // Control Flow functions
    if: function(args) {
        if (args.length < 3) error('Missing arguments to if function.');
        if (args.length > 3) error('Too many arguments to if function.');
        const a = args.map(codegen);
        return '('+a[0]+'?'+a[1]+':'+a[2]+')';
      }
  };
}