color-math/src/index.js

expressions to manipulate colors

import * as Utils from './utils'
import * as Evaluators from './evaluators'
import * as Nodes from './nodes'
import * as Parser from './parser'
import ColorScale from './ColorScale'
import ValueType from './ValueType'
import BlendMode from './BlendMode'

Parser.parser.yy = Nodes

export function evaluate(expr, options) {
  options = Object.assign({
    evaluator: Evaluators.CoreEvaluator.instance,
    withAst: false,
    astWithLocs: false,
  }, options)

  let program
  let value
  let error

  try {
    program = Parser.parse(expr)
    value = program.evaluate(options.evaluator)
  } catch (e) {
    error = e.message || String(e)
  }

  return {
    withAst: options.withAst,
    astWithLocs: options.astWithLocs,
    evaluator: options.evaluator.$type,
    expr,
    program,
    result: error != null ? null : value,
    resultStr: error != null ? null : formatValue(value),
    astStr: error != null || !options.withAst || !program ? null : JSON.stringify(program.getDto(options.astWithLocs), null, '  '),
    error: error != null ? error : null,
  }
}

function formatValue(value) {
  if (Utils.isColor(value)) {
    return Utils.formatColor(value)
  } else if (typeof value === 'number') {
    const s = value % 1 === 0 ? String(value) : value.toFixed(4).replace(/0+$/, '')
    return s
  } else if (typeof value === 'string') {
    return value
  } else if (Array.isArray(value)) {
    let s = '['
    for (let i = 0; i < value.length; i++) {
      s += formatValue(value[i]) + (i < value.length - 1 ? ', ' : '')
    }
    s += ']'
    return s
  } else if (value instanceof ColorScale) {
    return String(value)
  } else {
    return JSON.stringify(value, null, '  ')
  }
}

export {
  Nodes,
  Evaluators,
  ColorScale,
  BlendMode,
  ValueType,
  Utils,
}