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import {array, ValueType, NumberType} from '../types';
import RuntimeError from '../runtime_error';
import type {Expression} from '../expression';
import type ParsingContext from '../parsing_context';
import type EvaluationContext from '../evaluation_context';
import type {Type, ArrayType} from '../types';
import type {Value} from '../values';
class At implements Expression {
type: Type;
index: Expression;
input: Expression;
constructor(type: Type, index: Expression, input: Expression) {
this.type = type;
this.index = index;
this.input = input;
}
static parse(args: $ReadOnlyArray<mixed>, context: ParsingContext) {
if (args.length !== 3)
return context.error(`Expected 2 arguments, but found ${args.length - 1} instead.`);
const index = context.parse(args[1], 1, NumberType);
const input = context.parse(args[2], 2, array(context.expectedType || ValueType));
if (!index || !input) return null;
const t: ArrayType = (input.type: any);
return new At(t.itemType, index, input);
}
evaluate(ctx: EvaluationContext) {
const index = ((this.index.evaluate(ctx): any): number);
const array = ((this.input.evaluate(ctx): any): Array<Value>);
if (index < 0) {
throw new RuntimeError(`Array index out of bounds: ${index} < 0.`);
}
if (index >= array.length) {
throw new RuntimeError(`Array index out of bounds: ${index} > ${array.length - 1}.`);
}
if (index !== Math.floor(index)) {
throw new RuntimeError(`Array index must be an integer, but found ${index} instead.`);
}
return array[index];
}
eachChild(fn: (_: Expression) => void) {
fn(this.index);
fn(this.input);
}
outputDefined() {
return false;
}
serialize() {
return ["at", this.index.serialize(), this.input.serialize()];
}
}
export default At;
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