Merge branch 'graphivz_dot_output' of https://github.com/omega16/lark into omega16-graphivz_dot_output

README.md

@@ -81,7 +81,7 @@ Lark is great at handling ambiguity. Here is the result of parsing the phrase "f
 
 ![fruitflies.png](examples/fruitflies.png)
 
-See the code and more [examples here](https://github.com/lark-parser/lark/tree/master/examples)
+See the code to make [this image](https://github.com/lark-parser/lark/tree/master/examples/fruitflies.py) and more [examples here](https://github.com/lark-parser/lark/tree/master/examples)
 
 
 ## List of main features

docs/features.md

@@ -26,6 +26,8 @@
   - Support for external regex module ([see here](classes.md#using-unicode-character-classes-with-regex))
   - Import grammars from Nearley.js ([read more](nearley.md))
   - CYK parser
+  - Transform your parse tree to dot or png files  for better visualization ([see_example](https://github.com/lark-parser/lark/blob/master/examples/fruitflies.py))
+
 
 ### Experimental features
   - Automatic reconstruction of input from parse-tree (see examples)

examples/fruitflies.py

@@ -33,9 +33,13 @@ sentence = 'fruit flies like bananas'
 def make_png(filename):
     tree.pydot__tree_to_png( parser.parse(sentence), filename)
 
+def make_dot(filename):
+    tree.pydot__tree_to_dot( parser.parse(sentence), filename)
+
 if __name__ == '__main__':
     print(parser.parse(sentence).pretty())
     # make_png(sys.argv[1])
+    # make_dot(sys.argv[1])
 
 # Output:
 #

lark/tree.py

@@ -160,6 +160,15 @@ class SlottedTree(Tree):
 
 
 def pydot__tree_to_png(tree, filename, rankdir="LR", **kwargs):
+    graph = pydot__tree_to_graph(tree, rankdir, **kwargs)
+    graph.write_png(filename)
+
+
+def pydot__tree_to_dot(tree, filename, rankdir="LR", **kwargs):
+    graph = pydot__tree_to_graph(tree, rankdir, **kwargs)
+    graph.write(filename)
+
+def pydot__tree_to_graph(tree, rankdir="LR", **kwargs):
     """Creates a colorful image that represents the tree (data+children, without meta)
 
     Possible values for `rankdir` are "TB", "LR", "BT", "RL", corresponding to
@@ -197,5 +206,5 @@ def pydot__tree_to_png(tree, filename, rankdir="LR", **kwargs):
         return node
 
     _to_pydot(tree)
-    graph.write_png(filename)
-
+    return graph
+