Struct VarTable

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

Table for keeping track of node parameters.

Variables refer to the parameters of a node which introduces a symbol. Variables have an associated name and are scoped via nodes. The types of parameters of a node may only refer to earlier parameters in the same node in the order they are defined. A variable name must be unique within a single node. Each node that introduces a symbol introduces a new isolated scope for variables.

Examples

let mut vars = VarTable::new();
vars.enter(NodeId(0));
vars.insert("foo").unwrap();
assert_eq!(vars.resolve("foo").unwrap(), VarId(NodeId(0), 0));
assert!(!vars.is_visible(VarId(NodeId(0), 1)));
vars.insert("bar").unwrap();
assert!(vars.is_visible(VarId(NodeId(0), 1)));
assert_eq!(vars.resolve("bar").unwrap(), VarId(NodeId(0), 1));
vars.enter(NodeId(1));
assert!(vars.resolve("foo").is_err());
assert!(!vars.is_visible(VarId(NodeId(0), 0)));
vars.exit();
assert_eq!(vars.resolve("foo").unwrap(), VarId(NodeId(0), 0));
assert!(vars.is_visible(VarId(NodeId(0), 0)));

Implementations

impl<'a> VarTable<'a>

pub fn new() -> Self

Create a new empty variable table.

pub fn enter(&mut self, node: NodeId)

Enter a new scope for the given node.

pub fn exit(&mut self)

Exit a previously entered scope.

Panics

Panics if there are no open scopes.

pub fn resolve(&self, name: &'a str) -> Result<VarId, UnknownVarError<'a>>

Resolve a variable name to a node and variable index.

Errors

Returns an error if the variable is not defined in the current scope.

Panics

Panics if there are no open scopes.

pub fn is_visible(&self, var: VarId) -> bool

Check if a variable is visible in the current scope.

Panics

Panics if there are no open scopes.

pub fn insert(&mut self, name: &'a str) -> Result<VarId, DuplicateVarError<'a>>

Insert a new variable into the current scope.

Errors

Returns an error if the variable is already defined in the current scope.

Panics

Panics if there are no open scopes.

pub fn clear(&mut self)

Reset the variable table to an empty state while preserving the allocations.

Trait Implementations

impl<'a> Clone for VarTable<'a>

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'a> Debug for VarTable<'a>

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

Formats the value using the given formatter.

impl<'a> Default for VarTable<'a>

fn default() -> VarTable<'a>

Returns the “default value” for a type.