Created
March 6, 2021 09:48
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pour itrooz
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| const operators = [ | |
| { | |
| op: '!', | |
| precedence: 5, | |
| associativity: 'left', | |
| function: (a) => { | |
| let acc = 1; | |
| for (let i = 1; i < a + 1; i++) acc *= i; | |
| return acc; | |
| } | |
| }, | |
| { | |
| op: '^', | |
| precedence: 4, | |
| associativity: 'right', | |
| }, | |
| { | |
| op: '*', | |
| precedence: 3, | |
| associativity: 'left', | |
| }, | |
| { | |
| op: '/', | |
| precedence: 3, | |
| associativity: 'left', | |
| }, | |
| { | |
| op: '+', | |
| precedence: 2, | |
| associativity: 'left', | |
| }, | |
| { | |
| op: '-', | |
| precedence: 2, | |
| associativity: 'left', | |
| }, | |
| { | |
| op: 'sqrt', | |
| precedence: 5, | |
| associativity: 'right', | |
| function: (a) => { | |
| return Math.sqrt(a) | |
| }, | |
| } | |
| ]; | |
| operators.get = function(op) { | |
| return this.find((x) => x.op === op); | |
| } | |
| function tokenize(str) { | |
| return str.split(/\s+/g); | |
| } | |
| function isNumber(el) { | |
| return !isNaN(Number(el)); | |
| } | |
| const calculus = '( 5 + 5 ) * 3 + 2 * 5'; | |
| const tokens = tokenize(calculus); | |
| function parse(tokens) { | |
| const stack = []; | |
| const queue = []; | |
| for (const token of tokens) { | |
| if (isNumber(token)) { | |
| queue.push(token); | |
| } else if (operators.get(token) !== undefined) { | |
| const op = operators.get(token); | |
| while ((stack.length > 0) && | |
| ((stack[stack.length - 1].precedence > op.precedence) | |
| || (stack[stack.length - 1].precedence === op.precedence && token.associativity === 'left')) | |
| && (stack[stack.length - 1].op !== '(') | |
| ) { | |
| const popOp = stack.pop(); | |
| queue.push(popOp.op); | |
| } | |
| stack.push(op); | |
| } else if (token === '(') { | |
| stack.push({ op: '(' }); | |
| } else if (token === ')') { | |
| while (stack[stack.length - 1] && stack[stack.length - 1].op !== '(') { | |
| const popOp = stack.pop(); | |
| queue.push(popOp.op); | |
| } | |
| stack.pop(); | |
| if (stack[stack.length - 1] && stack[stack.length - 1].function) { | |
| //console.log('FONCTION') | |
| } | |
| } | |
| } | |
| while (stack.length > 0) { | |
| const popOp = stack.pop(); | |
| queue.push(popOp.op); | |
| } | |
| return queue; | |
| } | |
| function postfixEvaluator(expr) { | |
| const stack = []; | |
| for (const tok of expr) { | |
| if (isNumber(tok)) { | |
| stack.push(Number(tok)) | |
| } else if (operators.get(tok) !== undefined) { | |
| const op = operators.get(tok); | |
| if (op.function) { | |
| const args = []; | |
| while (args.length !== op.function.length) { | |
| args.push(stack.pop()); | |
| } | |
| stack.push(op.function(...args)); | |
| } else { | |
| const a = stack.pop(); | |
| const b = stack.pop(); | |
| stack.push(eval(`${b} ${tok} ${a}`)); | |
| } | |
| } | |
| } | |
| return stack[0]; | |
| } | |
| const postfix = parse(tokens); | |
| console.log(postfixEvaluator(postfix)) |
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