Better access to children semantic action results

SemanticActionResults instance is now passed in first_pass in the place
of children parameter. This enables dot access operation similar to
parse tree dot navigation.

arpeggio/__init__.py

@@ -798,6 +798,41 @@ class SemanticAction(object):
         return retval
 
 
+class SemanticActionResults(object):
+    """
+    Used in first_pass call to supply results of semantic analysis
+    of children parse tree nodes.
+    Enables dot access by the name of the rule similar to NonTerminal
+    tree navigation.
+    Enables index access as well as iteration.
+    """
+    def __init__(self):
+        self.results = {}
+        self.results_list = []
+
+    def append_result(self, name, result):
+        if name:
+            if not name in self.results:
+                self.results[name] = []
+            self.results[name].append(result)
+
+        self.results_list.append(result)
+
+    def __getitem__(self, key):
+        return self.results_list[key]
+
+    def __iter__(self):
+        return iter(self.results_list)
+
+    def __len__(self):
+        return len(self.results_list)
+
+    def __getattr__(self, attr_name):
+        if attr_name in ['results', 'results_list']:
+            raise AttributeError
+
+        return self.results.get(attr_name, [])
+
 # ----------------------------------------------------
 # Parsers
 
@@ -884,12 +919,12 @@ class Parser(object):
                 print("Walking down ", node.name, "  type:",
                       type(node).__name__, "str:", str(node))
 
-            children = []
+            children = SemanticActionResults()
             if isinstance(node, NonTerminal):
                 for n in node:
                     child = tree_walk(n)
                     if child is not None:
-                        children.append(child)
+                        children.append_result(n.rule, child)
 
             if self.debug:
                 print("Processing ", node.name, "= '", str(node),

arpeggio/peg.py

@@ -127,7 +127,7 @@ class SemRule(PEGSemanticAction):
 class SemSequence(PEGSemanticAction):
     def first_pass(self, parser, node, children):
         if len(children) > 1:
-            return Sequence(nodes=children)
+            return Sequence(nodes=children[:])
         else:
             # If only one child rule exists reduce.
             return children[0]
@@ -136,7 +136,7 @@ class SemSequence(PEGSemanticAction):
 class SemOrderedChoice(PEGSemanticAction):
     def first_pass(self, parser, node, children):
         if len(children) > 1:
-            retval = OrderedChoice(nodes=children)
+            retval = OrderedChoice(nodes=children[:])
         else:
             # If only one child rule exists reduce.
             retval = children[0]

tests/unit/test_semantic_action_results.py

+# -*- coding: utf-8 -*-
+#######################################################################
+# Name: test_semantic_action_results
+# Purpose: Tests semantic action results passed to first_pass call
+# Author: Igor R. Dejanović <igor DOT dejanovic AT gmail DOT com>
+# Copyright: (c) 2014 Igor R. Dejanović <igor DOT dejanovic AT gmail DOT com>
+# License: MIT License
+#######################################################################
+
+import pytest
+
+# Grammar
+from arpeggio import ZeroOrMore, OneOrMore, ParserPython, Terminal, NonTerminal,\
+    SemanticAction, SemanticActionResults
+from arpeggio.export import PTDOTExporter
+from arpeggio import RegExMatch as _
+
+def grammar():      return first, "a", second
+def first():        return [fourth, third], ZeroOrMore(third)
+def second():       return OneOrMore(third), "b"
+def third():        return [third_str, fourth]
+def third_str():    return "3"
+def fourth():       return _(r'\d+')
+
+
+first_sar = None
+third_sar = None
+
+class FirstSA(SemanticAction):
+    def first_pass(self, parser, node, children):
+        global first_sar
+        first_sar = children
+
+
+class ThirdSA(SemanticAction):
+    def first_pass(self, parser, node, children):
+        global third_sar
+        third_sar = children
+
+        return 1
+
+
+first.sem = FirstSA()
+third.sem = ThirdSA()
+
+def test_semantic_action_results():
+
+    global first_sar, third_sar
+
+    input = "4 3 3 3 a 3 3 b"
+
+    parser = ParserPython(grammar, reduce_tree=False)
+    result = parser.parse(input)
+
+    PTDOTExporter().exportFile(result, 'test_semantic_action_results_pt.dot')
+
+    parser.getASG()
+
+    assert isinstance(first_sar, SemanticActionResults)
+    assert len(first_sar.third) == 3
+    assert third_sar.third_str[0] == '3'
+