mathjs/lib/esm/expression/transform/utils/compileInlineExpression.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

import { isSymbolNode } from '../../../utils/is.js';
import { PartitionedMap } from '../../../utils/map.js';

/**
 * Compile an inline expression like "x > 0"
 * @param {Node} expression
 * @param {Object} math
 * @param {Map} scope
 * @return {function} Returns a function with one argument which fills in the
 *                    undefined variable (like "x") and evaluates the expression
 */
export function compileInlineExpression(expression, math, scope) {
  // find an undefined symbol
  var symbol = expression.filter(function (node) {
    return isSymbolNode(node) && !(node.name in math) && !scope.has(node.name);
  })[0];
  if (!symbol) {
    throw new Error('No undefined variable found in inline expression "' + expression + '"');
  }

  // create a test function for this equation
  var name = symbol.name; // variable name
  var argsScope = new Map();
  var subScope = new PartitionedMap(scope, argsScope, new Set([name]));
  var eq = expression.compile();
  return function inlineExpression(x) {
    argsScope.set(name, x);
    return eq.evaluate(subScope);
  };
}