Struct SymbolTable

pub struct SymbolTable<'a> { /* private fields */ }

Symbol binding table that keeps track of symbol resolution and scoping.

Nodes may introduce a symbol so that other parts of the IR can refer to the node. Symbols have an associated name and are scoped via regions. A symbol can shadow another symbol with the same name from an outer region, but within any single region each symbol name must be unique.

When a symbol is referred to directly by the id of the node, the symbol must be in scope at the point of reference as if the reference was by name. This guarantees that transformations between directly indexed and named formats are always valid.

Examples

let mut symbols = SymbolTable::new();
symbols.enter(RegionId(0));
symbols.insert("foo", NodeId(0)).unwrap();
assert_eq!(symbols.resolve("foo").unwrap(), NodeId(0));
symbols.enter(RegionId(1));
assert_eq!(symbols.resolve("foo").unwrap(), NodeId(0));
symbols.insert("foo", NodeId(1)).unwrap();
assert_eq!(symbols.resolve("foo").unwrap(), NodeId(1));
assert!(!symbols.is_visible(NodeId(0)));
symbols.exit();
assert_eq!(symbols.resolve("foo").unwrap(), NodeId(0));
assert!(symbols.is_visible(NodeId(0)));
assert!(!symbols.is_visible(NodeId(1)));

Implementations

impl<'a> SymbolTable<'a>

pub fn new() -> Self

Create a new symbol table.

pub fn enter(&mut self, region: RegionId)

Enter a new scope for the given region.

pub fn exit(&mut self)

Exit a previously entered scope.

Panics

Panics if there are no remaining open scopes.

pub fn insert( &mut self, name: &'a str, node: NodeId, ) -> Result<(), DuplicateSymbolError<'_>>

Insert a new symbol into the current scope.

Errors

Returns an error if the symbol is already defined in the current scope. In the case of an error the table remains unchanged.

Panics

Panics if there is no current scope.

pub fn is_visible(&self, node: NodeId) -> bool

Check whether a symbol is currently visible in the current scope.

pub fn resolve(&self, name: &'a str) -> Result<NodeId, UnknownSymbolError<'_>>

Tries to resolve a symbol name in the current scope.

pub fn region_to_depth(&self, region: RegionId) -> Option<u16>

Returns the depth of the given region, if it corresponds to a currently open scope.

pub fn depth_to_region(&self, depth: u16) -> Option<RegionId>

Returns the region corresponding to the scope at the given depth.

pub fn clear(&mut self)

Resets the symbol table to its initial state while maintaining its allocated memory.

Trait Implementations

impl<'a> Clone for SymbolTable<'a>

fn clone(&self) -> SymbolTable<'a>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'a> Debug for SymbolTable<'a>

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

Formats the value using the given formatter.

impl<'a> Default for SymbolTable<'a>

fn default() -> SymbolTable<'a>

Returns the “default value” for a type.