Struct ScopeMap 

pub struct ScopeMap<V> { /* private fields */ }

A map from a name to a value, in a stack of scopes.

A lookup has to find the innermost binding of a name, and a scope closing has to expose whatever that name meant outside it. Walking a stack of scopes would make every lookup cost the depth, and a compiler looks up every identifier it reads, so the shape is inverted: one map from name to the stack of bindings for that name, innermost last, plus a log of the names bound in each open scope so that closing one knows what to undo.

Implementations

impl<V: Copy> ScopeMap<V>

pub fn new() -> Self

An empty namespace, with the file scope open.

pub fn depth(&self) -> u32

How many scopes are open. The file scope counts, so this is never zero.

pub fn at_file_scope(&self) -> bool

Whether the only open scope is the file scope.

pub fn push(&mut self)

Opens a scope.

pub fn pop(&mut self)

Closes the innermost scope, exposing whatever its names meant outside it.

Panics

Panics on closing the file scope, which nothing in C does and which would leave the namespace unable to hold a declaration.

pub fn declare(&mut self, name: Symbol, value: V) -> Option<V>

Binds name in the innermost scope, and gives back what it was already bound to in that same scope.

A returned value is a redeclaration, which is the caller’s to judge: int x; int x; is fine at file scope and typedef int T; T T; is not, and neither decision belongs here. Shadowing an outer binding is not a redeclaration and gives back None.

pub fn get(&self, name: Symbol) -> Option<V>

What name is bound to in the innermost scope that binds it.

pub fn get_here(&self, name: Symbol) -> Option<V>

What name is bound to in the innermost scope alone, ignoring the ones outside it.

Trait Implementations

impl<V: Debug> Debug for ScopeMap<V>

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

Formats the value using the given formatter.

impl<V> Default for ScopeMap<V>

fn default() -> Self

Returns the “default value” for a type.