* Add to the peg generator a new directive ('&&') that allows to expect
a token and hard fail the parsing if the token is not found. This
allows to quickly emmit syntax errors for missing tokens.
* Use the new grammar element to hard-fail if the ':' is missing before
suites.
* Implement running the parser a second time for the errors messages
The first parser run is only responsible for detecting whether
there is a `SyntaxError` or not. If there isn't the AST gets returned.
Otherwise, the parser is run a second time with all the `invalid_*`
rules enabled so that all the customized error messages get produced.
* Add new capability to the PEG parser to type variable assignments. For instance:
```
| a[asdl_stmt_seq*]=';'.small_stmt+ [';'] NEWLINE { a }
```
* Add new sequence types from the asdl definition (automatically generated)
* Make `asdl_seq` type a generic aliasing pointer type.
* Create a new `asdl_generic_seq` for the generic case using `void*`.
* The old `asdl_seq_GET`/`ast_seq_SET` macros now are typed.
* New `asdl_seq_GET_UNTYPED`/`ast_seq_SET_UNTYPED` macros for dealing with generic sequences.
* Changes all possible `asdl_seq` types to use specific versions everywhere.
This program can segfault the parser by stack overflow:
```
import ast
code = "f(" + ",".join(['a' for _ in range(100000)]) + ")"
print("Ready!")
ast.parse(code)
```
the reason is that the rule for arguments has a simple recursion when collecting args:
args[expr_ty]:
[...]
| a=named_expression b=[',' c=args { c }] {
[...] }
`GET_INVALID_TARGET` might unexpectedly return `NULL`, which if not
caught will cause a SEGFAULT. Therefore, this commit introduces a new
inline function `RAISE_SYNTAX_ERROR_INVALID_TARGET` that always
checks for `GET_INVALID_TARGET` returning NULL and can be used in
the grammar, replacing the long C ternary operation used till now.
The following error messages get produced:
- `cannot delete ...` for invalid `del` targets
- `... is an illegal 'for' target` for invalid targets in for
statements
- `... is an illegal 'with' target` for invalid targets in
with statements
Additionally, a few `cut`s were added in various places before the
invocation of the `invalid_*` rule, in order to speed things
up.
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
This commit removes the old parser, the deprecated parser module, the old parser compatibility flags and environment variables and all associated support code and documentation.
Nicholas Sim
Pablo Galindo
Lysandros Nikolaou