titus.pfaast.SymbolTable¶

class titus.pfaast.SymbolTable(parent, symbols, cells, pools, sealedAbove, sealedWithin)[source]¶

Bases: object

Represents the symbols (variables) and their data types in a lexical scope.

__init__(parent, symbols, cells, pools, sealedAbove, sealedWithin)¶

Parameters:

parent (titus.pfaast.SymbolTable or None) – enclosing scope; symbol lookup defers to the parent scope if not found here symbols (dict from symbol name to titus.datatype.AvroType) – initial symbol names and their types cells (dict from cell name to titus.datatype.AvroType) – initial cell names and their types pools (dict from pool name to titus.datatype.AvroType) – initial pool names and their types sealedAbove (bool) – if True, symbols in the parent scope cannot be modified (but can be accessed); if False, this scope does not restrict access (but a parent might) sealedWithin (bool) – if True, new symbols cannot be created in this scope

allInScope¶

All symbols (and their types) that are defined in this scope and all parents.

Return type:	dict from symbol name to titus.datatype.AvroType
Returns:	symbols and their types

static blank()¶

Create a blank symbol table.

Return type:	titus.pfaast.SymbolTable
Returns:	a symbol table containing nothing

cell(name)¶

Get a cell’s type from this scope or a parent’s.

Parameters:	name (string) – name of the cell
Return type:	titus.datatype.AvroType or None
Returns:	the cell’s type if defined, None otherwise

get(name)¶

Get a symbol’s type from this scope or a parent’s.

Parameters:	name (string) – name of the symbol
Return type:	titus.datatype.AvroType or None
Returns:	the symbol’s type if defined, None otherwise

getAbove(name)¶

Get a symbol’s type specifically from a parent’s scope, not this one.

Parameters:	name (string) – name of the symbol
Return type:	titus.datatype.AvroType or None
Returns:	the symbol’s type if defined in a parent’s scope, None otherwise

getLocal(name)¶

Get a symbol’s type specifically from this scope.

Parameters:	name (string) – name of the symbol
Return type:	titus.datatype.AvroType or None
Returns:	the symbol’s type if defined in this scope, None otherwise

inThisScope¶

All symbols (and their types) that are defined in this scope (not in any parents).

Return type:	dict from symbol name to titus.datatype.AvroType
Returns:	symbols and their types

newScope(sealedAbove, sealedWithin)¶

Create a new scope with this as parent.

Parameters:	sealedAbove (bool) – if True, symbols in the parent scope cannot be modified (but can be accessed); if False, this scope does not restrict access (but a parent might) sealedWithin (bool) – if True, new symbols cannot be created in this scope
Return type:	titus.pfaast.SymbolTable
Returns:	a new scope, linked to this one

pool(name)¶

Get a pool’s type from this scope or a parent’s.

Parameters:	name (string) – name of the pool
Return type:	titus.datatype.AvroType or None
Returns:	the pool’s type if defined, None otherwise

put(name, avroType)¶

Create or overwrite a symbol’s type in the table.

Parameters:	name (string) – name of the symbol avroType (titus.datatype.AvroType) – the data type to associate with this symbol
Return type:	None
Returns:	nothing; changes table in-place

writable(name)¶

Determine if a symbol can be modified in this scope.

Parameters:	name (string) – name of the symbol
Return type:	bool
Returns:	True if the symbol can be modified; False otherwise