- Adjusted Arithmetic example

DHParser/dsl.py

@@ -102,7 +102,7 @@ from DHParser import logging, is_filename, load_if_file, \\
     keep_children, is_one_of, not_one_of, has_content, apply_if, remove_first, remove_last, \\
     remove_anonymous_empty, keep_nodes, traverse_locally, strip, lstrip, rstrip, \\
     replace_content, replace_content_by, forbid, assert_content, remove_infix_operator, \\
-    error_on, recompile_grammar, GLOBALS
+    reduce_anonymous_nodes, error_on, recompile_grammar, GLOBALS
 '''.format(dhparserdir=dhparserdir)
 
 

DHParser/ebnf.py

@@ -562,7 +562,7 @@ class EBNFCompiler(Compiler):
         tt_name = self.grammar_name + '_AST_transformation_table'
         transtable = [tt_name + ' = {',
                       '    # AST Transformations for the ' + self.grammar_name + '-grammar']
-        transtable.append('    "<": eliminate_anonymous_nodes,')
+        transtable.append('    "<": reduce_anonymous_nodes,')
         for name in self.rules:
             transformations = '[]'
             # rule = self.definitions[name]

DHParser/syntaxtree.py

@@ -313,9 +313,10 @@ class Node:  # (collections.abc.Sized): Base class omitted for cython-compatibil
     @result.setter
     def result(self, result: ResultType):
         # # made obsolete by static type checking with mypy
-        # assert ((isinstance(result, tuple) and all(isinstance(child, Node) for child in result))
-        #         or isinstance(result, Node)
-        #         or isinstance(result, str)), str(result)
+        assert ((isinstance(result, tuple) and all(isinstance(child, Node) for child in result))
+                or isinstance(result, Node)
+                or isinstance(result, str)
+                or isinstance(result, StringView)), "%s (%s)" % (str(result), str(type(result)))
         # Possible optimization: Do not allow single nodes as argument:
         # assert not isinstance(result, Node)
         self._len = -1        # lazy evaluation

DHParser/transform.py

@@ -47,7 +47,7 @@ __all__ = ('TransformationDict',
            'traverse',
            'is_named',
            'update_attr',
-           'eliminate_anonymous_nodes',
+           'reduce_anonymous_nodes',
            'replace_by_single_child',
            'reduce_single_child',
            'replace_or_reduce',
@@ -559,8 +559,13 @@ def _reduce_child(node: Node, child: Node):
 #         _reduce_child(context[-1], child)
 
 
-@transformation_factory
-def eliminate_anonymous_nodes(context: List[Node]):
+def reduce_anonymous_nodes(context: List[Node]):
+    """
+    Reduces (non-recursively) all anonymous non-leaf children by adding
+    their result to the result of the last node in the context. If the
+    last node is anonymous itself, it will be replaced by a single child.
+    Also drops any empty anonymous nodes.
+    """
     node = context[-1]
     if node.children:
         new_result = []
@@ -577,11 +582,13 @@ def eliminate_anonymous_nodes(context: List[Node]):
             child = new_result[0]
             if node.is_anonymous():
                 node.tag_name = child.tag_name
-                new_result = [child.result]
+                node.result = child.result
                 update_attr(node, child)
+                return
             elif child.is_anonymous():
-                new_result = [child.result]
+                node.result = child.result
                 update_attr(node, child)
+                return
         node.result = tuple(new_result)
 
 

dhparser.py

@@ -16,7 +16,7 @@ distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 implied.  See the License for the specific language governing
 permissions and limitations under the License.
-"""
+"""3
 
 #  TODO: This is still a stub...
 

examples/Arithmetic/Arithmetic.ebnf

@@ -10,7 +10,7 @@
 @ literalws   = right           # literals have implicit whitespace on the right hand side
 @ comment     = /#.*/           # comments range from a '#'-character to the end of the line
 @ ignorecase  = False           # literals and regular expressions are case-sensitive
-@ drop        = whitespace      # drop anonymous whitespace and tokens
+@ drop        = whitespace      # drop anonymous whitespace
 
 #######################################################################
 #

examples/Arithmetic/ArithmeticCompiler.py

@@ -33,7 +33,7 @@ from DHParser import logging, is_filename, load_if_file, \
     keep_children, is_one_of, not_one_of, has_content, apply_if, remove_first, remove_last, \
     remove_anonymous_empty, keep_nodes, traverse_locally, strip, lstrip, rstrip, \
     replace_content, replace_content_by, forbid, assert_content, remove_infix_operator, \
-    error_on, recompile_grammar, GLOBALS
+    error_on, recompile_grammar, reduce_anonymous_nodes, GLOBALS
 
 
 #######################################################################
@@ -59,7 +59,7 @@ class ArithmeticGrammar(Grammar):
     r"""Parser for an Arithmetic source file.
     """
     expression = Forward()
-    source_hash__ = "d03e397fb4cabd6f20f3ae7c9add4ad5"
+    source_hash__ = "a94242482d508901d1692b82c48ba903"
     parser_initialization__ = ["upon instantiation"]
     resume_rules__ = {}
     COMMENT__ = r'#.*'
@@ -95,10 +95,11 @@ def get_grammar() -> ArithmeticGrammar:
 
 Arithmetic_AST_transformation_table = {
     # AST Transformations for the Arithmetic-grammar
-    "<": remove_empty,
+    "<": reduce_anonymous_nodes,
     "expression": [],
-    "term": [],
-    "factor": [replace_or_reduce],
+    "term": [reduce_single_child],
+    "factor": [reduce_single_child],
+    "group": [remove_tokens('(', ')'), replace_by_single_child],
     "NUMBER": [],
     "VARIABLE": [],
     ":Token": reduce_single_child,

examples/Arithmetic/example.dsl

-Life is but a walking shadow