Get rid of the old Node wrappers

Those wrappers were needed in v1 to hide the underlying JSON structures
emitted by libpg_query, making it possible to see them as generic Python
instances.

Version 3 obsoleted that by introducing a set of concrete AST classes,
and the wrappers were kept mainly for their ability to track the
parentship of each node, required by some of the printer functions.

Now they are gone, and everything works directly on AST classes, and the
printers use the new "ancestors" slot attached to each instance.

This implements issue #80.

docs/api.rst

@@ -3,7 +3,7 @@
 .. :Created:   gio 10 ago 2017 10:14:17 CEST
 .. :Author:    Lele Gaifax <lele@metapensiero.it>
 .. :License:   GNU General Public License version 3 or later
-.. :Copyright: © 2017, 2018, 2019, 2021 Lele Gaifax
+.. :Copyright: © 2017, 2018, 2019, 2021, 2022 Lele Gaifax
 ..
 
 ===================
@@ -23,7 +23,6 @@ This chapter briefly explains some implementation detail.
    ast
    enums
    keywords
-   node
    stream
    printers
    sfuncs

docs/printers.rst

@@ -3,7 +3,7 @@
 .. :Created:   gio 10 ago 2017 13:23:18 CEST
 .. :Author:    Lele Gaifax <lele@metapensiero.it>
 .. :License:   GNU General Public License version 3 or later
-.. :Copyright: © 2017, 2018, 2021 Lele Gaifax
+.. :Copyright: © 2017, 2018, 2021, 2022 Lele Gaifax
 ..
 
 ==========================================================
@@ -22,7 +22,7 @@ associated :class:`~.node.Node` will be serialized.
 
 .. autoexception:: PrinterAlreadyPresentError
 
-.. autofunction:: get_printer_for_node_tag
+.. autofunction:: get_printer_for_node
 
 .. autofunction:: node_printer
 

docs/usage.rst

@@ -3,7 +3,7 @@
 .. :Created:   gio 10 ago 2017 10:06:38 CEST
 .. :Author:    Lele Gaifax <lele@metapensiero.it>
 .. :License:   GNU General Public License version 3 or later
-.. :Copyright: © 2017, 2018, 2019, 2021 Lele Gaifax
+.. :Copyright: © 2017, 2018, 2019, 2021, 2022 Lele Gaifax
 ..
 
 .. _usage:
@@ -15,7 +15,7 @@
 Here are some example of how the module can be used.
 
 ---------
-Low level
+AST level
 ---------
 
 The lowest level is a Python wrapper around each *parse node* returned by the ``PostgreSQL``
@@ -181,89 +181,6 @@ This basically means that you can reconstruct a syntax tree from the result of c
    >>> clone == stmt
    True
 
-------------
-Medium level
-------------
-
-Parse an ``SQL`` statement and get its *AST* root node
-======================================================
-
-.. doctest::
-
-   >>> from pglast import Node
-   >>> root = Node(parse_sql('SELECT foo FROM bar'))
-   >>> print(root)
-   None=[1*{RawStmt}]
-
-Get a particular node
-=====================
-
-.. doctest::
-
-   >>> from_clause = root[0].stmt.fromClause
-   >>> print(from_clause)
-   fromClause=[1*{RangeVar}]
-
-Obtain some information about a node
-====================================
-
-.. doctest::
-
-   >>> range_var = from_clause[0]
-   >>> print(range_var.node_tag)
-   RangeVar
-   >>> print(range_var.attribute_names)
-   ('catalogname', 'schemaname', 'relname', 'inh', 'relpersistence', 'alias', 'location')
-   >>> print(range_var.parent_node)
-   stmt={SelectStmt}
-
-Iterate over nodes
-==================
-
-.. doctest::
-
-   >>> for a in from_clause:
-   ...     print(a)
-   ...     for b in a:
-   ...         print(b)
-   ...
-   fromClause[0]={RangeVar}
-   inh=<True>
-   location=<16>
-   relname=<'bar'>
-   relpersistence=<'p'>
-
-Recursively :meth:`traverse <pglast.node.Node.traverse>` the parse tree
-=======================================================================
-
-.. doctest::
-
-   >>> for node in root.traverse():
-   ...   print(node)
-   ...
-   None[0]={RawStmt}
-   stmt={SelectStmt}
-   all=<False>
-   fromClause[0]={RangeVar}
-   inh=<True>
-   location=<16>
-   relname=<'bar'>
-   relpersistence=<'p'>
-   limitOption=<LimitOption.LIMIT_OPTION_DEFAULT: 0>
-   op=<SetOperation.SETOP_NONE: 0>
-   targetList[0]={ResTarget}
-   location=<7>
-   val={ColumnRef}
-   fields[0]={String}
-   val=<'foo'>
-   location=<7>
-   stmt_len=<0>
-   stmt_location=<0>
-
-As you can see, the ``repr``\ esentation of each value is mnemonic: ``{some_tag}`` means a
-``Node`` with tag ``some_tag``, ``[X*{some_tag}]`` is a ``List`` containing `X` nodes of that
-particular kind\ [*]_ and ``<value>`` is a ``Scalar``.
-
 Programmatically :func:`reformat <pglast.prettify>` a ``SQL`` statement
 =======================================================================
 
@@ -318,7 +235,7 @@ that extends :class:`pglast.stream.RawStream` adding a bit a aesthetic sense.
 
 .. doctest::
 
-   >>> print(IndentedStream()(root))
+   >>> print(IndentedStream()('select foo from bar'))
    SELECT foo
    FROM bar
 
@@ -400,7 +317,7 @@ Customize a :func:`node printer <pglast.printers.node_printer>`
    >>> from pglast.printers import node_printer
    >>> @node_printer('ParamRef', override=True)
    ... def replace_param_ref(node, output):
-   ...     output.write(repr(args[node.number.value - 1]))
+   ...     output.write(repr(args[node.number - 1]))
    ...
    >>> args = ['Hello', 'Ciao']
    >>> print(prettify(sql, safety_belt=False))
@@ -542,11 +459,6 @@ Preserve comments
           carry their exact location, so it is not possible to differentiate between
           ``SELECT * /*comment*/ FROM foo`` and ``SELECT * FROM /*comment*/ foo``.
 
----
-
-.. [*] This is an approximation, because in principle a list can contain different kinds of
-       nodes, or even sub-lists in some cases: the ``List`` representation arbitrarily shows
-       the tag of the first object.
 
 Functions vs SQL syntax
 =======================

pglast/__init__.py

@@ -3,12 +3,13 @@
 # :Created:   mer 02 ago 2017 15:11:02 CEST
 # :Author:    Lele Gaifax <lele@metapensiero.it>
 # :License:   GNU General Public License version 3 or later
-# :Copyright: © 2017, 2018, 2019, 2021 Lele Gaifax
+# :Copyright: © 2017, 2018, 2019, 2021, 2022 Lele Gaifax
 #
 
+from collections import namedtuple
+
 from . import enums
 from .error import Error
-from .node import Comment, Missing, Node
 try:
     from .parser import fingerprint, get_postgresql_version, parse_sql, scan, split
 except ModuleNotFoundError:  # pragma: no cover
@@ -31,6 +32,10 @@ def parse_plpgsql(statement):
     return loads(parse_plpgsql_json(statement))
 
 
+Comment = namedtuple('Comment', ('location', 'text', 'at_start_of_line', 'continue_previous'))
+"A structure to carry information about a single SQL comment."
+
+
 def _extract_comments(statement):
     lines = []
     lofs = 0
@@ -81,7 +86,7 @@ def prettify(statement, safety_belt=False, preserve_comments=False, **options):
         options['comments'] = _extract_comments(statement)
 
     orig_pt = parse_sql(statement)
-    prettified = IndentedStream(**options)(Node(orig_pt))
+    prettified = IndentedStream(**options)(orig_pt)
     if safety_belt:
         from logging import getLogger
         import warnings
@@ -109,5 +114,5 @@ def prettify(statement, safety_belt=False, preserve_comments=False, **options):
     return prettified
 
 
-__all__ = ('Error', 'Missing', 'Node', 'enums', 'fingerprint', 'get_postgresql_version',
+__all__ = ('Error', 'enums', 'fingerprint', 'get_postgresql_version',
            'parse_plpgsql', 'parse_sql', 'prettify', 'split')