Propertly deserialize three-levels nested structures

In some cases, the "functions" attribute of a RangeFunction to mention
one, the value is a tuple-of-tuples-of-dicts: replace existing
two-levels hardcoded logic with a recursive solution.

This fixes issue #153.

pglast/ast.py

@@ -13,6 +13,20 @@
 SlotTypeInfo = namedtuple('SlotTypeInfo', ['c_type', 'py_type', 'adaptor'])
 
 
+def _deserialize_value(value):
+    if isinstance(value, dict) and '@' in value:
+        G = globals()
+        if len(value) > 1:
+            result = G[value['@']](value)
+        else:
+            result = G[value['@']]()
+    elif isinstance(value, (tuple, list)):
+        result = tuple(_deserialize_value(item) for item in value)
+    else:
+        result = value
+    return result
+
+
 def _serialize_node(n, depth, ellipsis, skip_none):
     d = {'@': n.__class__.__name__}
     for a in n:
@@ -69,19 +83,10 @@ def __init__(self, data):
             raise ValueError(f'Bad argument, wrong "@" value, expected'
                              f' {self.__class__.__name__!r}, got {data["@"]!r}')
 
-        G = globals()
         for a in self:
             v = data.get(a)
             if v is not None:
-                if isinstance(v, dict) and '@' in v:
-                    if len(v) > 1:
-                        v = G[v['@']](v)
-                    else:
-                        v = G[v['@']]()
-                elif isinstance(v, (tuple, list)):
-                    v = tuple((G[i['@']](i) if len(i) > 1 else G[i['@']]())
-                              if isinstance(i, dict) and '@' in i else i
-                              for i in v)
+                v = _deserialize_value(v)
             setattr(self, a, v)
 
     def __iter__(self):

tests/test_ast.py

@@ -3,7 +3,7 @@
 # :Created:   sab 29 mag 2021, 21:25:46
 # :Author:    Lele Gaifax <[email protected]>
 # :License:   GNU General Public License version 3 or later
-# :Copyright: © 2021, 2022, 2023 Lele Gaifax
+# :Copyright: © 2021, 2022, 2023, 2024 Lele Gaifax
 #
 
 import pytest
@@ -104,3 +104,45 @@ def test_issue_97():
 def test_issue_138():
     raw = parse_sql('select * from foo')[0]
     ast.RawStmt(raw())
+
+
+def test_issue_153():
+    selstmt = parse_sql('select t.y from f(5) as t')[0].stmt
+    serialized = selstmt()
+    assert serialized['@'] == 'SelectStmt'
+    clone = ast.SelectStmt(serialized)
+    orig_fromc = selstmt.fromClause[0]
+    orig_fc_funcs = orig_fromc.functions
+    clone_fromc = clone.fromClause[0]
+    clone_fc_funcs = clone_fromc.functions
+    assert orig_fc_funcs == clone_fc_funcs
+    assert selstmt == clone
+
+
+def test_issue_153b():
+    serialized = {
+        '@': 'RangeFunction',
+        'alias': {'@': 'Alias', 'aliasname': 'tmp', 'colnames': None},
+        'coldeflist': None,
+        'functions': (({'@': 'FuncCall',
+                        'agg_distinct': False,
+                        'agg_filter': None,
+                        'agg_order': None,
+                        'agg_star': False,
+                        'agg_within_group': False,
+                        'args': ({'@': 'A_Const',
+                                  'isnull': False,
+                                  'val': {'@': 'Integer', 'ival': 5}},),
+                        'func_variadic': False,
+                        'funcformat': {'#': 'CoercionForm',
+                                       'name': 'COERCE_EXPLICIT_CALL',
+                                       'value': 0},
+                        'funcname': ({'@': 'String', 'sval': 'f'},),
+                        'location': 21,
+                        'over': None},
+                       None),),
+        'is_rowsfrom': False,
+        'lateral': False,
+        'ordinality': False}
+    rf = ast.RangeFunction(serialized)
+    assert isinstance(rf.functions[0][0], ast.FuncCall)

tests/test_printers_roundtrip.py

@@ -150,3 +150,20 @@ def test_pg_regress_corpus(filename):
 
         assert orig_ast == serialized_ast, "Statement “%s” from %s at line %d != %r" % (
             trimmed_stmt, rel_src, lineno, serialized)
+
+
+@pytest.mark.parametrize('src,lineno,statement',
+                         ((src, lineno, statement)
+                          for src in sorted(tests_dir.glob('**/*.sql'))
+                          for (lineno, statement) in statements(src)),
+                         ids=make_id)
+def test_ast_serialization_roundtrip(src, lineno, statement):
+    try:
+        orig_ast = parse_sql(statement)
+    except:  # noqa
+        raise RuntimeError("%s:%d:Could not parse %r" % (src, lineno, statement))
+
+    stmt = orig_ast[0].stmt
+    serialized = stmt()
+    clone = stmt.__class__(serialized)
+    assert stmt == clone