Method parseExpression

scripts/rubi/wl-parser.ts:213–277

(minPrec = 0)

  }

  parseExpression(minPrec = 0): Json {
    let lhs = this.parsePrefix();
    for (;;) {
      const t = this.peek();
      if (!t) break;
      if (t.kind === 'punct') {
        const bin = BINARY_OPS[t.value];
        if (bin && bin.prec >= minPrec) {
          this.next();
          const rhs = this.parseExpression(bin.right ? bin.prec : bin.prec + 1);
          lhs = bin.flat ? flatBinaryOp(bin.op, lhs, rhs) : [bin.op, lhs, rhs];
          continue;
        }
        if (t.value === '+' && PREC_PLUS >= minPrec) {
          this.next();
          lhs = flatBinary('Add', lhs, this.parseExpression(PREC_PLUS + 1));
          continue;
        }
        if (t.value === '-' && PREC_PLUS >= minPrec) {
          this.next();
          lhs = ['Subtract', lhs, this.parseExpression(PREC_PLUS + 1)];
          continue;
        }
        if (t.value === '*' && PREC_TIMES >= minPrec) {
          this.next();
          lhs = flatBinary(
            'Multiply',
            lhs,
            this.parseExpression(PREC_TIMES + 1)
          );
          continue;
        }
        if (t.value === '/' && PREC_TIMES >= minPrec) {
          this.next();
          lhs = divide(lhs, this.parseExpression(PREC_TIMES + 1));
          continue;
        }
        if (t.value === '^' && PREC_POWER >= minPrec) {
          this.next();
          // right-associative
          lhs = ['Power', lhs, this.parseExpression(PREC_POWER)];
          continue;
        }
        if (t.value === '!' && PREC_FACTORIAL >= minPrec) {
          this.next();
          lhs = ['Factorial', lhs];
          continue;
        }
      }
      // Juxtaposition = multiplication: `2 x`, `a (b + c)` — an operand
      // token follows directly. Only when we can still bind at Times level.
      if (
        PREC_TIMES >= minPrec &&
        (t.kind === 'number' ||
          t.kind === 'symbol' ||
          t.kind === 'pattern' ||
          (t.kind === 'punct' && t.value === '('))
      ) {