Equation.js/dist/index.js

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'use strict';
var _interopRequireWildcard = function (obj) { return obj && obj.__esModule ? obj : { 'default': obj }; };
var _slicedToArray = function (arr, i) { if (Array.isArray(arr)) { return arr; } else if (Symbol.iterator in Object(arr)) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i['return']) _i['return'](); } finally { if (_d) throw _e; } } return _arr; } else { throw new TypeError('Invalid attempt to destructure non-iterable instance'); } };
var _toConsumableArray = function (arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) arr2[i] = arr[i]; return arr2; } else { return Array.from(arr); } };
Object.defineProperty(exports, '__esModule', {
value: true
});
var _ReadStream = require('./readstream');
var _ReadStream2 = _interopRequireWildcard(_ReadStream);
var _operators = require('./operators');
var _operators2 = _interopRequireWildcard(_operators);
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var _constants = require('./constants');
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var _constants2 = _interopRequireWildcard(_constants);
var _import = require('./helpers');
var _ = _interopRequireWildcard(_import);
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var Equation = {
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/**
* Solves the given math expression, following these steps:
* 1. Replace constants in the expression
* 2. parse the expression, separating numbers and operators into
* an array
* 3. Sort the stack by operators' precedence, it actually groups the
* operator with it's arguments n-level deep
* 4. Apply parseFloat to numbers of the array
* 5. Solve groups recursively
*
* @param {String} expression
* The math expression to solve
* @return {Number}
* Result of the expression
*/
solve: function solve(expression) {
// replace constants with their values
expression = replaceConstants(expression);
var stack = parseExpression(expression);
stack = sortStack(stack);
stack = _.parseNumbers(stack);
stack = solveStack(stack);
return stack;
},
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/**
* Creates an equation function which replaces variables
* in the given expression with the values specified in order,
* and solves the new expression
*
* Example:
* equation('x+y+z')(2, 5, 6) => solve('2+5+6')
*
* @param {String} expression
* The expression to create an equation for (containing variables)
* @return {Function}
* The function which replaces variables with values in order
* and solves the expression
*/
equation: function equation(expression) {
var stack = parseExpression(expression);
var variables = [];
stack.forEach(function (a) {
if (typeof a === 'string' && !_.isNumber(a) && !_operators2['default'][a] && a === a.toLowerCase()) {
// grouped variables like (y) need to have their parantheses removed
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variables.push(_.removeSymbols(a));
}
});
return function () {
for (var _len = arguments.length, args = Array(_len), _key = 0; _key < _len; _key++) {
args[_key] = arguments[_key];
}
expression = expression.replace(/[a-z]*/g, function (a) {
var index = variables.indexOf(a);
if (index > -1) {
return args[index] || 0;
}
return a;
});
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return Equation.solve(expression);
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};
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},
registerOperator: function registerOperator(key, options) {
_operators2['default'][key] = options;
},
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registerConstant: function registerConstant(key, options) {
_constants2['default'][key] = options;
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}
};
var solveStack = (function (_solveStack) {
function solveStack(_x) {
return _solveStack.apply(this, arguments);
}
solveStack.toString = function () {
return _solveStack.toString();
};
return solveStack;
})(function (stack) {
if (stack.some(Array.isArray)) {
stack = stack.map(function (group) {
if (!Array.isArray(group)) {
return group;
}
return solveStack(group);
});
return solveStack(stack);
} else {
return evaluate(stack);
}
});
var PRECEDENCES = Object.keys(_operators2['default']).map(function (key) {
return _operators2['default'][key].precedence;
});
var MAX_PRECEDENCE = Math.max.apply(Math, _toConsumableArray(PRECEDENCES));
var MIN_PRECEDENCE = Math.min.apply(Math, _toConsumableArray(PRECEDENCES));
/**
* Parses the given expression into an array of separated
* numbers and operators/functions.
* The result is passed to parseGroups
*
* @param {String} expression
* The expression to parse
* @return {Array}
* The parsed array
*/
var parseExpression = function parseExpression(expression) {
var stream = new _ReadStream2['default'](expression),
stack = [],
record = '';
// Create an array of separated numbers & operators
while (stream.next()) {
var cur = stream.current(),
past = stack.length - 1;
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if (cur === ' ') {
continue;
}
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// it's probably a function with a length more than one
if (!_.isNumber(cur) && !_operators2['default'][cur] && cur !== '.') {
record += cur;
} else if (record.length) {
stack.push(record, cur);
record = '';
} else if (_.isNumber(stack[stack.length - 1]) && (_.isNumber(cur) || cur === '.')) {
stack[stack.length - 1] += cur;
} else if (stack[past] === '-') {
var beforeSign = stack[stack.length - 2];
if (_operators2['default'][beforeSign]) {
stack[past] += cur;
} else if (beforeSign === ')') {
stack[past] = '+';
stack.push('-' + cur);
} else if (_.isNumber(beforeSign)) {
stack.push(cur);
} else {
stack[past] += cur;
}
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} else {
stack.push(cur);
}
}
if (record.length) {
stack.push(record);
}
return parseGroups(stack);
};
/**
* Takes the parsed array from parseExpression and
* groups up expressions in parantheses in deep arrays
*
* Example: 2+(5+4) becomes [2, [5, '+', 4]]
*
* @param {Array} stack
* The parsed expression
* @return {Array}
* Grouped up expression
*/
var parseGroups = function parseGroups(stack) {
// Parantheses become inner arrays which will then be processed first
var sub = 0;
return stack.reduce(function (a, b) {
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if (b.indexOf('(') > -1) {
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if (b.length > 1) {
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_.dive(a, sub).push(b.replace('(', ''), []);
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} else {
_.dive(a, sub).push([]);
}
sub++;
} else if (b === ')') {
sub--;
} else {
_.dive(a, sub).push(b);
}
return a;
}, []);
};
/**
* Gives information about an operator's format
* including number of left and right arguments
*
* @param {String/Object} operator
* The operator object or operator name (e.g. +, -)
* @return {Object}
* An object including the count of left and right arguments
*/
var formatInfo = function formatInfo(operator) {
var op = typeof operator === 'string' ? _operators2['default'][operator] : operator;
if (!op) {
return null;
}
var format = op.format.split('1'),
left = format[0].length,
right = format[1].length;
return { left: left, right: right };
};
/**
* Groups up operators and their arguments based on their precedence
* in deep arrays, the higher the priority, the deeper the group.
* This simplifies the evaluating process, the only thing to do is to
* evaluate from bottom up, evaluating deep groups first
*
* @param {Array} stack
* The parsed and grouped expression
* @return {Array}
* Grouped expression based on precedences
*/
var sortStack = (function (_sortStack) {
function sortStack(_x2) {
return _sortStack.apply(this, arguments);
}
sortStack.toString = function () {
return _sortStack.toString();
};
return sortStack;
})(function (stack) {
var _iteratorNormalCompletion = true;
var _didIteratorError = false;
var _iteratorError = undefined;
try {
for (var _iterator = stack.entries()[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
var _step$value = _slicedToArray(_step.value, 2);
var index = _step$value[0];
var item = _step$value[1];
if (Array.isArray(item)) {
stack.splice(index, 1, sortStack(item));
}
}
} catch (err) {
_didIteratorError = true;
_iteratorError = err;
} finally {
try {
if (!_iteratorNormalCompletion && _iterator['return']) {
_iterator['return']();
}
} finally {
if (_didIteratorError) {
throw _iteratorError;
}
}
}
for (var i = MIN_PRECEDENCE; i <= MAX_PRECEDENCE; i++) {
for (var index = 0; index < stack.length; ++index) {
var item = stack[index];
var op = _operators2['default'][item];
if (!op || op.precedence !== i) {
continue;
}
var _formatInfo = formatInfo(op);
var left = _formatInfo.left;
var right = _formatInfo.right;
var group = stack.splice(index - left, left + right + 1, []);
stack[index - left] = group;
for (var y = 0; y < i; y++) {
group = [group];
}
index -= right;
}
}
return stack;
});
/**
* Evaluates the given math expression.
* The expression is an array with an operator and arguments
*
* Example: evaluate([2, '+', 4]) == 6
*
* @param {Array} stack
* A single math expression
* @return {Number}
* Result of the expression
*/
var evaluate = function evaluate(stack) {
var _operators$op;
var op = findOperator(stack);
if (!op) {
return stack[0];
}
var _formatInfo2 = formatInfo(op);
var left = _formatInfo2.left;
var leftArguments = stack.slice(0, left),
rightArguments = stack.slice(left + 1);
return (_operators$op = _operators2['default'][op]).fn.apply(_operators$op, _toConsumableArray(leftArguments).concat(_toConsumableArray(rightArguments)));
};
/**
* Finds the first operator in an array and returns it
*
* @param {Array} arr
* The array to look for an operator in
* @return {Object}
* The operator object or null if no operator is found
*/
var findOperator = function findOperator(arr) {
var _iteratorNormalCompletion2 = true;
var _didIteratorError2 = false;
var _iteratorError2 = undefined;
try {
for (var _iterator2 = arr[Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
var o = _step2.value;
if (typeof o === 'string') {
return o;
}
}
} catch (err) {
_didIteratorError2 = true;
_iteratorError2 = err;
} finally {
try {
if (!_iteratorNormalCompletion2 && _iterator2['return']) {
_iterator2['return']();
}
} finally {
if (_didIteratorError2) {
throw _iteratorError2;
}
}
}
return null;
};
/**
* Replaces constants in a string with their values
*
* @param {String} expression
* The expression to replace constants in
* @return {String}
* The expression with constants replaced
*/
var replaceConstants = function replaceConstants(expression) {
return expression.replace(/[A-Z]*/g, function (a) {
var c = _constants2['default'][a];
if (!c) {
return a;
}
return typeof c === 'function' ? c() : c;
});
};
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exports['default'] = Equation;
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module.exports = exports['default'];