From 04703f3f4077c7ae3f9aa138c97c9a76b1da4076 Mon Sep 17 00:00:00 2001
From: Kia <kia@special-circumstanc.es>
Date: Thu, 6 Aug 2020 12:15:00 -0600
Subject: [PATCH] continue work on tree manip
---
cfg_utils.py | 36 ++++++++++++++++++++++++++++--------
1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/cfg_utils.py b/cfg_utils.py
index a04bc79..ad2d14c 100644
--- a/cfg_utils.py
+++ b/cfg_utils.py
@@ -17,7 +17,7 @@ def walk_the_tree(tree, level = 1):
if tree == None:
return
- print(" " * (level -1) + "|---" + hex(tree.language_element) + " with " + str(len(tree.subnodes)) + " subnodes")
+ print(" " * (level -1) + "|---" + str(tree.language_element) + " with " + str(len(tree.subnodes)) + " subnodes")
for subnode in tree.subnodes:
walk_the_tree(subnode, level + 1)
@@ -56,6 +56,8 @@ CFG = collections.namedtuple("CFG", "nonterminals terminals rules start")
symbols = Enum("Symbols", "EXPRESSION TERM FACTOR INTEGER ADDOP MULTOP OPENPAREN CLOSEPAREN")
start = symbols.EXPRESSION
+
+
# The rules are a list of tuples, each of which represents a rule, as follows:
# (Nonterminal symbol, [ordered list of symbols (terminal or nonterminal) that are reduced to aforementioned nonterminal])
@@ -69,7 +71,7 @@ rules = [
(symbols.FACTOR, [symbols.INTEGER ])
]
-#print(rules)
+print(rules)
@@ -88,7 +90,7 @@ rules = [
-def apply_rule(tree, location, rule_number, ruleset):
+def apply_rule(tree, location, ruleset, rule_number):
# first, we isolate the place on the tree that we are going to do the graft.
opsite = tree
@@ -99,12 +101,30 @@ def apply_rule(tree, location, rule_number, ruleset):
print(opsite)
walk_the_tree(opsite)
+ # now we verify that we can legitimately apply the given rule here.
+
+ the_rule = ruleset[rule_number]
+
+ print("We will try applying the following rule:", the_rule)
+
+ # We verify that the item at the operation site is:
+ # 1) a leaf (it has no subnodes)
+ # and
+ # 2) has the correct value
+
+ print("Opsite language value", opsite.language_element)
+ print("Rule expects", the_rule[0])
+
+ assert(opsite.language_element == the_rule[0])
+
+
+
-test_tree = TreeNode(0, [
- TreeNode(1,[]),
- TreeNode(2,[
- TreeNode(3,[]), TreeNode(4,[]),TreeNode(5,[])
+test_tree = TreeNode(symbols.EXPRESSION, [
+ TreeNode(symbols.ADDOP,[]),
+ TreeNode(symbols.MULTOP,[
+ TreeNode(symbols.EXPRESSION,[]), TreeNode(symbols.TERM,[]),TreeNode(symbols.FACTOR,[])
])
])
@@ -114,7 +134,7 @@ walk_the_tree(test_tree)
#def next_stage(derivation_tree_with_cached, language_definition):
-apply_rule(test_tree,[1,1],None,None)
+apply_rule(test_tree,[1,2],rules,5)
# Furthermore, we also note that the description of a context-free grammar is *itself* context-free
# so if we take the CFG-description grammar (BNF or something isomorphic to it), and use Boltzmann
--
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