private evaluateSliceExpression()

in packages/jinja/src/runtime.ts [1104:1133]

27 lines of code
10 McCabe index (conditional complexity)


	private evaluateSliceExpression(
		object: AnyRuntimeValue,
		expr: SliceExpression,
		environment: Environment
	): ArrayValue | StringValue {
		if (!(object instanceof ArrayValue || object instanceof StringValue)) {
			throw new Error("Slice object must be an array or string");
		}

		const start = this.evaluate(expr.start, environment);
		const stop = this.evaluate(expr.stop, environment);
		const step = this.evaluate(expr.step, environment);

		// Validate arguments
		if (!(start instanceof IntegerValue || start instanceof UndefinedValue)) {
			throw new Error("Slice start must be numeric or undefined");
		}
		if (!(stop instanceof IntegerValue || stop instanceof UndefinedValue)) {
			throw new Error("Slice stop must be numeric or undefined");
		}
		if (!(step instanceof IntegerValue || step instanceof UndefinedValue)) {
			throw new Error("Slice step must be numeric or undefined");
		}

		if (object instanceof ArrayValue) {
			return new ArrayValue(slice(object.value, start.value, stop.value, step.value));
		} else {
			return new StringValue(slice(Array.from(object.value), start.value, stop.value, step.value).join(""));
		}
	}