Module interpreter 

Interpreter module for kaish.

This module provides expression evaluation, variable scope management, and the structured result type ($?) that every command returns.

Architecture

The interpreter is built in layers:

• ExecResult: The structured result of every command, accessible as $?
• Scope: Variable bindings with nested frames and path resolution
• Evaluator: Reduces expressions to values

Command Substitution

The evaluator supports $(pipeline) expressions through the Executor trait. Higher layers (L6: Pipes & Jobs) implement this trait to provide actual command execution. For standalone expression evaluation, use NoOpExecutor.

Example

use kaish_kernel::interpreter::{Scope, eval_expr};
use kaish_kernel::ast::{Expr, Value};

let mut scope = Scope::new();
scope.set("X", Value::Int(42));

let expr = Expr::VarRef(kaish_kernel::ast::VarPath::simple("X"));
let result = eval_expr(&expr, &mut scope).unwrap();
assert_eq!(result, Value::Int(42));

Structs

Evaluator

Expression evaluator.

ExecResult

The result of executing a command or pipeline.

NoOpExecutor

A stub executor that always returns an error.

OutputData

Structured output data from a command.

OutputNode

A node in the output tree.

Scope

Variable scope with nested frames and last-result tracking.

Enums

ControlFlow

Control flow signal from statement execution.

EntryType

Entry type for rendering hints (colors, icons).

EvalError

Errors that can occur during expression evaluation.

OutputFormat

Output serialization format, requested via global flags.

Traits

Executor

Trait for executing pipelines (command substitution).

Functions

apply_output_format

Transform an ExecResult into the requested output format.

eval_expr

Convenience function to evaluate an expression with a scope.

expand_tilde

Expand tilde (~) to home directory.

json_to_value

Convert serde_json::Value to our AST Value.

value_to_bool

Convert a Value to its boolean representation.

value_to_json

Convert our AST Value to serde_json::Value for serialization.

value_to_string

Convert a Value to its string representation for interpolation.

value_to_string_with_tilde

Convert a Value to its string representation, with tilde expansion for paths.

Type Aliases

EvalResult

Result type for evaluation.