:mod:!token --- Constants used with Python parse trees

.. module:: token :synopsis: Constants representing terminal nodes of the parse tree.

Source code: :source:Lib/token.py

This module provides constants which represent the numeric values of leaf nodes of the parse tree (terminal tokens). Refer to the file :file:Grammar/Tokens in the Python distribution for the definitions of the names in the context of the language grammar. The specific numeric values which the names map to may change between Python versions.

The module also provides a mapping from numeric codes to names and some functions. The functions mirror definitions in the Python C header files.

Note that a token's value may depend on tokenizer options. For example, a "+" token may be reported as either :data:PLUS or :data:OP, or a "match" token may be either :data:NAME or :data:SOFT_KEYWORD.

.. data:: tok_name

Dictionary mapping the numeric values of the constants defined in this module back to name strings, allowing more human-readable representation of parse trees to be generated.

.. function:: ISTERMINAL(x)

Return True for terminal token values.

.. function:: ISNONTERMINAL(x)

Return True for non-terminal token values.

.. function:: ISEOF(x)

Return True if x is the marker indicating the end of input.

The token constants are:

.. data:: NAME

Token value that indicates an :ref:identifier or keyword <identifiers>.

.. data:: NUMBER

Token value that indicates a :ref:numeric literal <numbers>

.. data:: STRING

Token value that indicates a :ref:string or byte literal <strings>, excluding :ref:formatted string literals <f-strings>. The token string is not interpreted: it includes the surrounding quotation marks and the prefix (if given); backslashes are included literally, without processing escape sequences.

.. data:: OP

A generic token value that indicates an :ref:operator <operators> or :ref:delimiter <delimiters>.

.. impl-detail::

  This value is only reported by the :mod:`tokenize` module.
  Internally, the tokenizer uses
  :ref:`exact token types <token_operators_delimiters>` instead.

.. data:: COMMENT

Token value used to indicate a comment. The parser ignores :data:!COMMENT tokens.

.. data:: NEWLINE

Token value that indicates the end of a :ref:logical line <logical-lines>.

.. data:: NL

Token value used to indicate a non-terminating newline. :data:!NL tokens are generated when a logical line of code is continued over multiple physical lines. The parser ignores :data:!NL tokens.

.. data:: INDENT

Token value used at the beginning of a :ref:logical line <logical-lines> to indicate the start of an :ref:indented block <indentation>.

.. data:: DEDENT

Token value used at the beginning of a :ref:logical line <logical-lines> to indicate the end of an :ref:indented block <indentation>.

.. data:: FSTRING_START

Token value used to indicate the beginning of an :ref:f-string literal <f-strings>.

.. impl-detail::

  The token string includes the prefix and the opening quote(s), but none
  of the contents of the literal.

.. data:: FSTRING_MIDDLE

Token value used for literal text inside an :ref:f-string literal <f-strings>, including format specifications.

.. impl-detail::

  Replacement fields (that is, the non-literal parts of f-strings) use
  the same tokens as other expressions, and are delimited by
  :data:`LBRACE`, :data:`RBRACE`, :data:`EXCLAMATION` and :data:`COLON`
  tokens.

.. data:: FSTRING_END

Token value used to indicate the end of a :ref:f-string <f-strings>.

.. impl-detail::

  The token string contains the closing quote(s).

.. data:: TSTRING_START

Token value used to indicate the beginning of a template string literal.

.. impl-detail::

  The token string includes the prefix and the opening quote(s), but none
  of the contents of the literal.

.. versionadded:: 3.14

.. data:: TSTRING_MIDDLE

Token value used for literal text inside a template string literal including format specifications.

.. impl-detail::

  Replacement fields (that is, the non-literal parts of t-strings) use
  the same tokens as other expressions, and are delimited by
  :data:`LBRACE`, :data:`RBRACE`, :data:`EXCLAMATION` and :data:`COLON`
  tokens.

.. versionadded:: 3.14

.. data:: TSTRING_END

Token value used to indicate the end of a template string literal.

.. impl-detail::

  The token string contains the closing quote(s).

.. versionadded:: 3.14

.. data:: ENDMARKER

Token value that indicates the end of input. Used in :ref:top-level grammar rules <top-level>.

.. data:: ENCODING

Token value that indicates the encoding used to decode the source bytes into text. The first token returned by :func:tokenize.tokenize will always be an ENCODING token.

.. impl-detail::

  This token type isn't used by the C tokenizer but is needed for
  the :mod:`tokenize` module.

The following token types are not produced by the :mod:tokenize module, and are defined for special uses in the tokenizer or parser:

.. data:: TYPE_IGNORE

Token value indicating that a type: ignore comment was recognized. Such tokens are produced instead of regular :data:COMMENT tokens only with the :data:~ast.PyCF_TYPE_COMMENTS flag.

.. data:: TYPE_COMMENT

Token value indicating that a type comment was recognized. Such tokens are produced instead of regular :data:COMMENT tokens only with the :data:~ast.PyCF_TYPE_COMMENTS flag.

.. data:: SOFT_KEYWORD

Token value indicating a :ref:soft keyword <soft-keywords>.

The tokenizer never produces this value. To check for a soft keyword, pass a :data:NAME token's string to :func:keyword.issoftkeyword.

.. data:: ERRORTOKEN

Token value used to indicate wrong input.

The :mod:tokenize module generally indicates errors by raising exceptions instead of emitting this token. It can also emit tokens such as :data:OP or :data:NAME with strings that are later rejected by the parser.

.. _token_operators_delimiters:

The remaining tokens represent specific :ref:operators <operators> and :ref:delimiters <delimiters>. (The :mod:tokenize module reports these as :data:OP; see exact_type in the :mod:tokenize documentation for details.)

.. include:: token-list.inc

The following non-token constants are provided:

.. data:: N_TOKENS

The number of token types defined in this module.

.. NT_OFFSET is deliberately undocumented; if you need it you should be reading the source

.. data:: EXACT_TOKEN_TYPES

A dictionary mapping the string representation of a token to its numeric code.

.. versionadded:: 3.8

.. versionchanged:: 3.5 Added :data:!AWAIT and :data:!ASYNC tokens.

.. versionchanged:: 3.7 Added :data:COMMENT, :data:NL and :data:ENCODING tokens.

.. versionchanged:: 3.7 Removed :data:!AWAIT and :data:!ASYNC tokens. "async" and "await" are now tokenized as :data:NAME tokens.

.. versionchanged:: 3.8 Added :data:TYPE_COMMENT, :data:TYPE_IGNORE, :data:COLONEQUAL. Added :data:!AWAIT and :data:!ASYNC tokens back (they're needed to support parsing older Python versions for :func:ast.parse with feature_version set to 6 or lower).

.. versionchanged:: 3.12 Added :data:EXCLAMATION.

.. versionchanged:: 3.13 Removed :data:!AWAIT and :data:!ASYNC tokens again.