forked from Fediversity/fediversity.eu
457 lines
13 KiB
JavaScript
457 lines
13 KiB
JavaScript
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'use strict';
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const internals = {
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operators: ['!', '^', '*', '/', '%', '+', '-', '<', '<=', '>', '>=', '==', '!=', '&&', '||', '??'],
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operatorCharacters: ['!', '^', '*', '/', '%', '+', '-', '<', '=', '>', '&', '|', '?'],
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operatorsOrder: [['^'], ['*', '/', '%'], ['+', '-'], ['<', '<=', '>', '>='], ['==', '!='], ['&&'], ['||', '??']],
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operatorsPrefix: ['!', 'n'],
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literals: {
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'"': '"',
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'`': '`',
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'\'': '\'',
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'[': ']'
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},
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numberRx: /^(?:[0-9]*(\.[0-9]*)?){1}$/,
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tokenRx: /^[\w\$\#\.\@\:\{\}]+$/,
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symbol: Symbol('formula'),
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settings: Symbol('settings')
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};
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exports.Parser = class {
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constructor(string, options = {}) {
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if (!options[internals.settings] &&
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options.constants) {
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for (const constant in options.constants) {
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const value = options.constants[constant];
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if (value !== null &&
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!['boolean', 'number', 'string'].includes(typeof value)) {
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throw new Error(`Formula constant ${constant} contains invalid ${typeof value} value type`);
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}
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}
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}
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this.settings = options[internals.settings] ? options : Object.assign({ [internals.settings]: true, constants: {}, functions: {} }, options);
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this.single = null;
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this._parts = null;
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this._parse(string);
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}
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_parse(string) {
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let parts = [];
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let current = '';
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let parenthesis = 0;
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let literal = false;
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const flush = (inner) => {
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if (parenthesis) {
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throw new Error('Formula missing closing parenthesis');
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}
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const last = parts.length ? parts[parts.length - 1] : null;
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if (!literal &&
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!current &&
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!inner) {
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return;
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}
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if (last &&
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last.type === 'reference' &&
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inner === ')') { // Function
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last.type = 'function';
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last.value = this._subFormula(current, last.value);
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current = '';
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return;
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}
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if (inner === ')') { // Segment
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const sub = new exports.Parser(current, this.settings);
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parts.push({ type: 'segment', value: sub });
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}
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else if (literal) {
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if (literal === ']') { // Reference
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parts.push({ type: 'reference', value: current });
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current = '';
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return;
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}
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parts.push({ type: 'literal', value: current }); // Literal
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}
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else if (internals.operatorCharacters.includes(current)) { // Operator
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if (last &&
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last.type === 'operator' &&
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internals.operators.includes(last.value + current)) { // 2 characters operator
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last.value += current;
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}
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else {
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parts.push({ type: 'operator', value: current });
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}
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}
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else if (current.match(internals.numberRx)) { // Number
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parts.push({ type: 'constant', value: parseFloat(current) });
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}
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else if (this.settings.constants[current] !== undefined) { // Constant
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parts.push({ type: 'constant', value: this.settings.constants[current] });
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}
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else { // Reference
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if (!current.match(internals.tokenRx)) {
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throw new Error(`Formula contains invalid token: ${current}`);
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}
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parts.push({ type: 'reference', value: current });
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}
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current = '';
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};
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for (const c of string) {
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if (literal) {
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if (c === literal) {
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flush();
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literal = false;
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}
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else {
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current += c;
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}
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}
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else if (parenthesis) {
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if (c === '(') {
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current += c;
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++parenthesis;
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}
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else if (c === ')') {
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--parenthesis;
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if (!parenthesis) {
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flush(c);
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}
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else {
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current += c;
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}
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}
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else {
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current += c;
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}
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}
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else if (c in internals.literals) {
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literal = internals.literals[c];
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}
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else if (c === '(') {
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flush();
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++parenthesis;
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}
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else if (internals.operatorCharacters.includes(c)) {
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flush();
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current = c;
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flush();
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}
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else if (c !== ' ') {
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current += c;
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}
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else {
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flush();
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}
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}
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flush();
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// Replace prefix - to internal negative operator
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parts = parts.map((part, i) => {
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if (part.type !== 'operator' ||
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part.value !== '-' ||
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i && parts[i - 1].type !== 'operator') {
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return part;
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}
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return { type: 'operator', value: 'n' };
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});
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// Validate tokens order
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let operator = false;
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for (const part of parts) {
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if (part.type === 'operator') {
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if (internals.operatorsPrefix.includes(part.value)) {
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continue;
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}
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if (!operator) {
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throw new Error('Formula contains an operator in invalid position');
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}
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if (!internals.operators.includes(part.value)) {
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throw new Error(`Formula contains an unknown operator ${part.value}`);
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}
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}
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else if (operator) {
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throw new Error('Formula missing expected operator');
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}
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operator = !operator;
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}
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if (!operator) {
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throw new Error('Formula contains invalid trailing operator');
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}
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// Identify single part
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if (parts.length === 1 &&
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['reference', 'literal', 'constant'].includes(parts[0].type)) {
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this.single = { type: parts[0].type === 'reference' ? 'reference' : 'value', value: parts[0].value };
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}
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// Process parts
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this._parts = parts.map((part) => {
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// Operators
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if (part.type === 'operator') {
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return internals.operatorsPrefix.includes(part.value) ? part : part.value;
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}
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// Literals, constants, segments
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if (part.type !== 'reference') {
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return part.value;
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}
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// References
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if (this.settings.tokenRx &&
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!this.settings.tokenRx.test(part.value)) {
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throw new Error(`Formula contains invalid reference ${part.value}`);
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}
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if (this.settings.reference) {
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return this.settings.reference(part.value);
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}
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return internals.reference(part.value);
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});
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}
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_subFormula(string, name) {
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const method = this.settings.functions[name];
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if (typeof method !== 'function') {
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throw new Error(`Formula contains unknown function ${name}`);
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}
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let args = [];
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if (string) {
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let current = '';
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let parenthesis = 0;
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let literal = false;
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const flush = () => {
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if (!current) {
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throw new Error(`Formula contains function ${name} with invalid arguments ${string}`);
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}
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args.push(current);
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current = '';
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};
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for (let i = 0; i < string.length; ++i) {
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const c = string[i];
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if (literal) {
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current += c;
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if (c === literal) {
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literal = false;
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}
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}
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else if (c in internals.literals &&
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!parenthesis) {
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current += c;
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literal = internals.literals[c];
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}
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else if (c === ',' &&
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!parenthesis) {
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flush();
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}
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else {
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current += c;
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if (c === '(') {
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++parenthesis;
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}
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else if (c === ')') {
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--parenthesis;
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}
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}
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}
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flush();
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}
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args = args.map((arg) => new exports.Parser(arg, this.settings));
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return function (context) {
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const innerValues = [];
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for (const arg of args) {
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innerValues.push(arg.evaluate(context));
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}
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return method.call(context, ...innerValues);
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};
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}
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evaluate(context) {
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const parts = this._parts.slice();
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// Prefix operators
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for (let i = parts.length - 2; i >= 0; --i) {
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const part = parts[i];
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if (part &&
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part.type === 'operator') {
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const current = parts[i + 1];
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parts.splice(i + 1, 1);
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const value = internals.evaluate(current, context);
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parts[i] = internals.single(part.value, value);
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}
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}
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// Left-right operators
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internals.operatorsOrder.forEach((set) => {
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for (let i = 1; i < parts.length - 1;) {
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if (set.includes(parts[i])) {
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const operator = parts[i];
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const left = internals.evaluate(parts[i - 1], context);
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const right = internals.evaluate(parts[i + 1], context);
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parts.splice(i, 2);
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const result = internals.calculate(operator, left, right);
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parts[i - 1] = result === 0 ? 0 : result; // Convert -0
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}
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else {
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i += 2;
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}
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}
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});
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return internals.evaluate(parts[0], context);
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}
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};
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exports.Parser.prototype[internals.symbol] = true;
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internals.reference = function (name) {
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return function (context) {
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return context && context[name] !== undefined ? context[name] : null;
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};
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};
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internals.evaluate = function (part, context) {
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if (part === null) {
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return null;
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}
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if (typeof part === 'function') {
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return part(context);
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}
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if (part[internals.symbol]) {
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return part.evaluate(context);
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}
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return part;
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};
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internals.single = function (operator, value) {
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if (operator === '!') {
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return value ? false : true;
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}
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// operator === 'n'
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const negative = -value;
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if (negative === 0) { // Override -0
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return 0;
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}
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return negative;
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};
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internals.calculate = function (operator, left, right) {
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if (operator === '??') {
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return internals.exists(left) ? left : right;
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}
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if (typeof left === 'string' ||
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typeof right === 'string') {
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if (operator === '+') {
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left = internals.exists(left) ? left : '';
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right = internals.exists(right) ? right : '';
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return left + right;
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}
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}
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else {
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switch (operator) {
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case '^': return Math.pow(left, right);
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case '*': return left * right;
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case '/': return left / right;
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case '%': return left % right;
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case '+': return left + right;
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case '-': return left - right;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
switch (operator) {
|
||
|
|
case '<': return left < right;
|
||
|
|
case '<=': return left <= right;
|
||
|
|
case '>': return left > right;
|
||
|
|
case '>=': return left >= right;
|
||
|
|
case '==': return left === right;
|
||
|
|
case '!=': return left !== right;
|
||
|
|
case '&&': return left && right;
|
||
|
|
case '||': return left || right;
|
||
|
|
}
|
||
|
|
|
||
|
|
return null;
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
internals.exists = function (value) {
|
||
|
|
|
||
|
|
return value !== null && value !== undefined;
|
||
|
|
};
|