2016-09-12 10:58:50 -04:00
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var Color = require('../util/color');
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2016-08-11 18:47:34 -04:00
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function Cast () {}
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/**
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* @fileoverview
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* Utilities for casting and comparing Scratch data-types.
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* Scratch behaves slightly differently from JavaScript in many respects,
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* and these differences should be encapsulated below.
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* For example, in Scratch, add(1, join("hello", world")) -> 1.
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* This is because "hello world" is cast to 0.
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* In JavaScript, 1 + Number("hello" + "world") would give you NaN.
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* Use when coercing a value before computation.
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*/
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/**
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* Scratch cast to number.
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* Treats NaN as 0.
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* In Scratch 2.0, this is captured by `interp.numArg.`
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* @param {*} value Value to cast to number.
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* @return {number} The Scratch-casted number value.
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*/
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Cast.toNumber = function (value) {
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var n = Number(value);
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if (isNaN(n)) {
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// Scratch treats NaN as 0, when needed as a number.
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// E.g., 0 + NaN -> 0.
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return 0;
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}
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return n;
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};
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/**
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* Scratch cast to boolean.
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* In Scratch 2.0, this is captured by `interp.boolArg.`
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* Treats some string values differently from JavaScript.
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* @param {*} value Value to cast to boolean.
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* @return {boolean} The Scratch-casted boolean value.
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*/
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Cast.toBoolean = function (value) {
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// Already a boolean?
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if (typeof value === 'boolean') {
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return value;
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}
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if (typeof value === 'string') {
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// These specific strings are treated as false in Scratch.
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if ((value == '') ||
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(value == '0') ||
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(value.toLowerCase() == 'false')) {
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return false;
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}
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// All other strings treated as true.
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return true;
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}
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// Coerce other values and numbers.
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return Boolean(value);
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};
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/**
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* Scratch cast to string.
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* @param {*} value Value to cast to string.
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* @return {string} The Scratch-casted string value.
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*/
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Cast.toString = function (value) {
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return String(value);
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};
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2016-09-12 10:58:50 -04:00
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/**
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* Cast any Scratch argument to an RGB color object to be used for the renderer.
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* @param {*} value Value to convert to RGB color object.
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* @return {Array.<number>} [r,g,b], values between 0-255.
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*/
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Cast.toRgbColorList = function (value) {
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var color;
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if (typeof value == 'string' && value.substring(0, 1) == '#') {
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color = Color.hexToRgb(value);
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} else {
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color = Color.decimalToRgb(Cast.toNumber(value));
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}
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return [color.r, color.g, color.b];
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};
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2016-08-11 18:47:34 -04:00
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/**
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* Compare two values, using Scratch cast, case-insensitive string compare, etc.
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* In Scratch 2.0, this is captured by `interp.compare.`
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* @param {*} v1 First value to compare.
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* @param {*} v2 Second value to compare.
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* @returns {Number} Negative number if v1 < v2; 0 if equal; positive otherwise.
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*/
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Cast.compare = function (v1, v2) {
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var n1 = Number(v1);
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var n2 = Number(v2);
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if (isNaN(n1) || isNaN(n2)) {
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// At least one argument can't be converted to a number.
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// Scratch compares strings as case insensitive.
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var s1 = String(v1).toLowerCase();
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var s2 = String(v2).toLowerCase();
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return s1.localeCompare(s2);
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} else {
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// Compare as numbers.
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return n1 - n2;
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}
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};
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module.exports = Cast;
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