symtable
— Acesso a tabela de símbolos do compilador¶
Código-fonte: Lib/symtable.py
Symbol tables are generated by the compiler from AST just before bytecode is
generated. The symbol table is responsible for calculating the scope of every
identifier in the code. symtable
provides an interface to examine these
tables.
Generating Symbol Tables¶
- symtable.symtable(code, filename, compile_type)¶
Return the toplevel
SymbolTable
for the Python source code. filename is the name of the file containing the code. compile_type is like the mode argument tocompile()
.
Examining Symbol Tables¶
- class symtable.SymbolTableType¶
An enumeration indicating the type of a
SymbolTable
object.- MODULE = "module"¶
Used for the symbol table of a module.
- FUNCTION = "function"¶
Used for the symbol table of a function.
- CLASS = "class"¶
Used for the symbol table of a class.
The following members refer to different flavors of annotation scopes.
- ANNOTATION = "annotation"¶
Used for annotations if
from __future__ import annotations
is active.
- TYPE_PARAMETERS = "type parameters"¶
Used for the symbol table of generic functions or generic classes.
- TYPE_VARIABLE = "type variable"¶
Used for the symbol table of the bound, the constraint tuple or the default value of a single type variable in the formal sense, i.e., a TypeVar, a TypeVarTuple or a ParamSpec object (the latter two do not support a bound or a constraint tuple).
Adicionado na versão 3.13.
- class symtable.SymbolTable¶
A namespace table for a block. The constructor is not public.
- get_type()¶
Return the type of the symbol table. Possible values are members of the
SymbolTableType
enumeration.Alterado na versão 3.12: Added
'annotation'
,'TypeVar bound'
,'type alias'
, and'type parameter'
as possible return values.Alterado na versão 3.13: Return values are members of the
SymbolTableType
enumeration.The exact values of the returned string may change in the future, and thus, it is recommended to use
SymbolTableType
members instead of hard-coded strings.
- get_id()¶
Return the table’s identifier.
- get_name()¶
Return the table’s name. This is the name of the class if the table is for a class, the name of the function if the table is for a function, or
'top'
if the table is global (get_type()
returns'module'
). For type parameter scopes (which are used for generic classes, functions, and type aliases), it is the name of the underlying class, function, or type alias. For type alias scopes, it is the name of the type alias. ForTypeVar
bound scopes, it is the name of theTypeVar
.
- get_lineno()¶
Return the number of the first line in the block this table represents.
- is_optimized()¶
Return
True
if the locals in this table can be optimized.
- is_nested()¶
Return
True
if the block is a nested class or function.
- has_children()¶
Return
True
if the block has nested namespaces within it. These can be obtained withget_children()
.
- get_identifiers()¶
Return a view object containing the names of symbols in the table. See the documentation of view objects.
- get_children()¶
Return a list of the nested symbol tables.
- class symtable.Function¶
A namespace for a function or method. This class inherits from
SymbolTable
.- get_parameters()¶
Return a tuple containing names of parameters to this function.
- get_locals()¶
Return a tuple containing names of locals in this function.
- get_globals()¶
Return a tuple containing names of globals in this function.
- get_nonlocals()¶
Return a tuple containing names of explicitly declared nonlocals in this function.
- get_frees()¶
Return a tuple containing names of free (closure) variables in this function.
- class symtable.Class¶
A namespace of a class. This class inherits from
SymbolTable
.- get_methods()¶
Return a tuple containing the names of method-like functions declared in the class.
Here, the term ‘method’ designates any function defined in the class body via
def
orasync def
.Functions defined in a deeper scope (e.g., in an inner class) are not picked up by
get_methods()
.Por exemplo:
>>> import symtable >>> st = symtable.symtable(''' ... def outer(): pass ... ... class A: ... def f(): ... def w(): pass ... ... def g(self): pass ... ... @classmethod ... async def h(cls): pass ... ... global outer ... def outer(self): pass ... ''', 'test', 'exec') >>> class_A = st.get_children()[1] >>> class_A.get_methods() ('f', 'g', 'h')
Although
A().f()
raisesTypeError
at runtime,A.f
is still considered as a method-like function.
- class symtable.Symbol¶
An entry in a
SymbolTable
corresponding to an identifier in the source. The constructor is not public.- get_name()¶
Return the symbol’s name.
- is_referenced()¶
Return
True
if the symbol is used in its block.
- is_imported()¶
Return
True
if the symbol is created from an import statement.
- is_parameter()¶
Return
True
if the symbol is a parameter.
- is_global()¶
Return
True
if the symbol is global.
- is_nonlocal()¶
Return
True
if the symbol is nonlocal.
- is_declared_global()¶
Return
True
if the symbol is declared global with a global statement.
- is_local()¶
Return
True
if the symbol is local to its block.
- is_annotated()¶
Return
True
if the symbol is annotated.Adicionado na versão 3.6.
- is_free()¶
Return
True
if the symbol is referenced in its block, but not assigned to.
- is_assigned()¶
Return
True
if the symbol is assigned to in its block.
- is_namespace()¶
Return
True
if name binding introduces new namespace.If the name is used as the target of a function or class statement, this will be true.
Por exemplo:
>>> table = symtable.symtable("def some_func(): pass", "string", "exec") >>> table.lookup("some_func").is_namespace() True
Note that a single name can be bound to multiple objects. If the result is
True
, the name may also be bound to other objects, like an int or list, that does not introduce a new namespace.
- get_namespaces()¶
Return a list of namespaces bound to this name.
- get_namespace()¶
Return the namespace bound to this name. If more than one or no namespace is bound to this name, a
ValueError
is raised.
Uso na linha de comando¶
Adicionado na versão 3.13.
O módulo symtable
pode ser invocado como um script na linha de comando:
python -m symtable [infile...]
Symbol tables are generated for the specified Python source files and dumped to stdout. If no input file is specified, the content is read from stdin.