Struct FieldRoute 

pub struct FieldRoute { /* private fields */ }

Where a field sits, from the root of the view that declares it.

Ordered and hashable, so a set of findings or changed locations can be keyed on one without a string in the middle.

Implementations

impl FieldRoute

pub fn new(steps: Vec<RouteStep>) -> Self

Builds a route from its steps.

pub fn steps(&self) -> &[RouteStep]

The steps this route takes, in order.

pub fn is_empty(&self) -> bool

Whether this route names nothing.

pub fn holes(&self) -> usize

How many list indices Self::at wants.

pub fn then(&self, step: RouteStep) -> Self

Extends this route by one step, which is how a walk builds one.

pub fn at(&self, indices: &[usize]) -> Result<GffPath, RouteError>

Turns this route into an address in one file.

indices supplies one element index per RouteStep::Element, in the order they appear. A route through no list takes an empty slice.

Errors

RouteError::IndexCount when the count does not match. Taking a slice rather than one index is what lets a route through two nested lists work, and mismatching the count is the mistake that makes.

pub fn field_in<T: HasSchema>(&self) -> Result<&'static Field, RouteError>

The field this route names in T’s schema.

What turns a route from a claim into an anchor. A route naming a label no view declares is a typo that would otherwise point at nothing and say nothing, and the field it hands back carries the entry a caller needs anyway: what the field holds, whether the engine reads it, and what its absence means.

Errors

RouteError naming how far the walk got, so a long route says which step was wrong rather than that the whole thing was.

pub fn entries_in<T: HasSchema>( &self, ) -> Result<Vec<&'static Field>, RouteError>

Every entry declared for the field this route names.

One, ordinarily. Two when the route ends inside a split and both arms declare the label: List[].TemplateResRef is declared by the templated arm and by the saved one, with different write rules, and which applies depends on the selector’s value in a given file. The address is the same either way, so a tree, a diff row and a write-back can use the route while only a consumer wanting the entry has to choose.

Errors

RouteError naming how far the walk got.

pub fn field_under( &self, parts: &[&'static [Field]], ) -> Result<Vec<&'static Field>, RouteError>

The field this route names under an explicit set of schema parts.

Parts rather than one slice throughout, because that is how a schema holds a type that flattens a shared block: the block stays one declaration and the container points at it.

A list’s elements are looked up across the element schema and both arms of a Split together. Which arm a file takes depends on a sibling’s value, which a route does not carry, so a label declared by one arm resolves and one declared by both is refused.

Errors

RouteError::NoSuchField when parts declares no such label at that point, RouteError::NotAList when the route indexes something that is not one, RouteError::NotAStruct when it descends into something with no fields under it, and RouteError::NamesNoField when the route ends at a list element rather than at something the element holds. An empty route is that last one.

RouteError::AmbiguousArm when both arms of a Split declare the label. Which arm a file takes turns on a sibling’s value, which a route does not carry, so this is refused rather than guessed.

RouteError::IndexCount when the route’s index count does not match what its steps need. That is a malformed route rather than a schema that disagrees with it.

Trait Implementations

impl Clone for FieldRoute

fn clone(&self) -> FieldRoute

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FieldRoute

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for FieldRoute

fn default() -> FieldRoute

Returns the “default value” for a type.

impl Display for FieldRoute

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Dot notation with empty brackets: Creature List[].HitPoints.

The empty bracket is the point. A reader seeing [0] would take it for one element rather than every one.

impl From<&GffPath> for FieldRoute

fn from(path: &GffPath) -> Self

The route a path in one file takes through every file.

The inverse of FieldRoute::at, and lossy in the direction it has to be: Creature List[3].HitPoints becomes Creature List[].HitPoints, because which element was in hand is a fact about the file and a route carries only facts about the format.

Total, and there is nothing here that could fail. Every segment maps to exactly one step, so a path that addresses nothing at all still projects to the route it would have taken. Whether the schema declares anything there is the separate question FieldRoute::field_in answers, and keeping the two apart is what lets a caller ask about a node the file carries and no view models.

impl FromStr for FieldRoute

fn from_str(route: &str) -> Result<Self, Self::Err>

Parses what Display renders.

A bracket has to be empty. Creature List[0].HitPoints is a GffPath and naming one element is what a route does not do, so it is refused rather than read as if the index were decoration.

type Err = RouteParseError

The associated error which can be returned from parsing.

impl Hash for FieldRoute

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for FieldRoute

fn cmp(&self, other: &FieldRoute) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for FieldRoute

fn eq(&self, other: &FieldRoute) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for FieldRoute

fn partial_cmp(&self, other: &FieldRoute) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Eq for FieldRoute

impl StructuralPartialEq for FieldRoute