tiny-symbol-solver

A symbol solver.

• Define symbols and expressions.
• Solve a symbol.
• Get dependencies and effects of a symbol.

Install

npm install tiny-symbol-solver --save

Usage

import { Solver } from 'tiny-symbol-solver';

const solver = new Solver();
solver.define('a = 1');
solver.define('b = 2');
solver.define('c = a + b');

console.log(solver.solve('c')); // 3

API

Solver

A class that represents a symbol solver.

import { Solver } from 'tiny-symbol-solver';
const solver = new Solver();

solver.define()

Defines a symbol or an expression.

solver.define('a = 1');
solver.define('power2(x) = x * x');
solver.define('c = a + power2(3)');

console.log(solver.solve('c')); // 10

You can also define symbols with a native number or function.

solver.define('a', 1); // a = 1
solver.define('power2', x => x * x);
solver.define('sin', Math.sin);

solver.solve()

Solves a symbol.

const result = solver.solve('c');

NOTE: If the symbol is not defined, it will throw an error.

solver.deps(), solver.effects()

• solver.deps(sym): Returns a list of dependencies for a symbol.
• solver.effects(sym): Returns a list of symbols that depend on a symbol.

/**
 * make a dependency graph
 * a
 * | \
 * b  c
 * | \| \
 * d  e  f
 */
solver.define('a = 1');
solver.define('b = a + 1');
solver.define('c = a + 2');
solver.define('d = b + 3');
solver.define('e = b + c');
solver.define('f = c + 4');

solver.deps('a'); // []
solver.deps('b'); // ['a']
solver.deps('c'); // ['a']
solver.deps('d'); // ['a', 'b']
solver.deps('e'); // ['a', 'b', 'c']
solver.deps('f'); // ['a', 'c']

solver.effects('a'); // ['b', 'c', 'd', 'e', 'f']
solver.effects('b'); // ['d', 'e']
solver.effects('c'); // ['e', 'f']
solver.effects('d'); // []
solver.effects('e'); // []
solver.effects('f'); // []

solver.events

Listen to events.

event types:

• solve: when a symbol is solved.
  • ev.sym: the symbol key.

solver.events.listen('solve', ev => {
  console.log(`solved: ${ev.sym}`);
});