@struktoai/mirage-core/dist/workspace/executor/builtins/shift/shift.js

A Unified Virtual Filesystem For AI Agents

// ========= Copyright 2026 @ Strukto.AI All Rights Reserved. =========
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ========= Copyright 2026 @ Strukto.AI All Rights Reserved. =========
import { IOResult } from "../../../../io/types.js";
import { ExitSignal } from "../../../../shell/errors.js";
import { positionalParams, setPositionalParams } from "../../../session/state.js";
import { ExecutionNode } from "../../../types.js";
import { builtinError, isCountWord, numericOperands } from "../shared.js";
/**
 * Shift positional parameters, with bash's argument checks: a count past
 * `$#` shifts nothing and exits 1 with no message, a negative count is
 * `shift count out of range`, and a non-numeric word is `numeric argument
 * required`; every other case exits 0.
 */
export function handleShift(args, callStack, session) {
    const words = numericOperands(args);
    const first = words[0];
    if (first !== undefined && !isCountWord(first)) {
        const err = builtinError('shift', `${first}: numeric argument required`);
        return [
            null,
            new IOResult({ exitCode: 1, stderr: err }),
            new ExecutionNode({ command: 'shift', exitCode: 1 }),
        ];
    }
    // bash abandons everything still to run, as `exit 1 2` does.
    if (words.length > 1)
        throw new ExitSignal(1, builtinError('shift', 'too many arguments'));
    const n = first !== undefined ? Number(first.trim()) : 1;
    if (n < 0) {
        const err = builtinError('shift', `${first ?? ''}: shift count out of range`);
        return [
            null,
            new IOResult({ exitCode: 1, stderr: err }),
            new ExecutionNode({ command: 'shift', exitCode: 1 }),
        ];
    }
    const params = positionalParams(session, callStack);
    // bash: a count past `$#` shifts nothing and returns 1, silently.
    if (n > params.length) {
        return [
            null,
            new IOResult({ exitCode: 1 }),
            new ExecutionNode({ command: 'shift', exitCode: 1 }),
        ];
    }
    setPositionalParams(session, callStack, params.slice(n));
    return [null, new IOResult(), new ExecutionNode({ command: 'shift', exitCode: 0 })];
}
/** The `shift` arm. */
export function shiftBuiltin(call) {
    return Promise.resolve(handleShift([...call.argv.args], call.callStack, call.context.session));
}
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