Struct Evaluation

pub struct Evaluation<'co, 'ro, 'env, IO> {
    pub(crate) source_map: SourceCode,
    pub(crate) globals: Rc<GlobalsMap>,
    pub(crate) env: Option<&'env FxHashMap<SmolStr, Value>>,
    pub(crate) io_handle: IO,
    pub(crate) mode: EvalMode,
    pub(crate) nix_path: Option<String>,
    pub(crate) compiler_observer: Option<&'co mut dyn CompilerObserver>,
    pub(crate) runtime_observer: Option<&'ro mut dyn RuntimeObserver>,
}

An Evaluation represents how a piece of Nix code is evaluated. It can be instantiated and configured directly, or it can be accessed through the various simplified helper methods available below.

Public fields are intended to be set by the caller. Setting all fields is optional.

Fields

source_map: SourceCode

Source code map used for error reporting.

globals: Rc<GlobalsMap>

Set of all global values available at the top-level scope

env: Option<&'env FxHashMap<SmolStr, Value>>

Top-level variables to define in the evaluation

io_handle: IO

Implementation of file-IO to use during evaluation, e.g. for impure builtins.

Defaults to DummyIO if not set explicitly.

mode: EvalMode

Specification for how to handle top-level values returned by evaluation

See the documentation for EvalMode for more information.

nix_path: Option<String>

(optional) Nix search path, e.g. the value of NIX_PATH used for resolving items on the search path (such as <nixpkgs>).

compiler_observer: Option<&'co mut dyn CompilerObserver>

(optional) compiler observer for reporting on compilation details, like the emitted bytecode.

runtime_observer: Option<&'ro mut dyn RuntimeObserver>

(optional) runtime observer, for reporting on execution steps of Nix code.

Implementations

impl<'co, 'ro, 'env, IO> Evaluation<'co, 'ro, 'env, IO>

pub fn builder(io_handle: IO) -> EvaluationBuilder<'co, 'ro, 'env, IO>

Make a new builder for configuring an evaluation

pub fn globals(&self) -> Rc<GlobalsMap>

Clone the reference to the map of Nix globals for this evaluation. If Values are shared across subsequent Evaluations, it is important that those evaluations all have the same underlying globals map.

pub fn source_map(&self) -> SourceCode

Clone the reference to the contained source code map. This is used after an evaluation for pretty error printing. Also, if Values are shared across subsequent Evaluations, it is important that those evaluations all have the same underlying source code map.

impl<'co, 'ro, 'env> Evaluation<'co, 'ro, 'env, Box<dyn EvalIO>>

pub fn builder_impure() -> EvaluationBuilder<'co, 'ro, 'env, Box<dyn EvalIO>>

pub fn builder_pure() -> EvaluationBuilder<'co, 'ro, 'env, Box<dyn EvalIO>>

impl<IO> Evaluation<'_, '_, '_, IO>

where IO: AsRef<dyn EvalIO> + 'static,

pub fn compile_only( self, code: impl AsRef<str>, location: Option<PathBuf>, ) -> EvaluationResult

Only compile the provided source code, at an optional location of the source code (i.e. path to the file it was read from; used for error reporting, and for resolving relative paths in impure functions) This does not run the code, it only provides analysis (errors and warnings) of the compiler.

pub fn evaluate( self, code: impl AsRef<str>, location: Option<PathBuf>, ) -> EvaluationResult

Evaluate the provided source code, at an optional location of the source code (i.e. path to the file it was read from; used for error reporting, and for resolving relative paths in impure functions)