pepasflo

Using graphviz to visualize abstract syntax trees

• Take the above ast.dot file
• Paste it into http://www.webgraphviz.com/
• It will generate a diagram like this:

• After you've written your first lexer and parser, write a function which walks the AST and "compiles" it into graphviz notation like the above

pepasflo

jpepas@radium$ cat do-md5.py 
#!/usr/bin/env python
import sys
import hashlib
h = hashlib.md5()
with open(sys.argv[1], 'rb') as f:
    # thanks to https://stackoverflow.com/a/3431838/7543271
    for chunk in iter(lambda: f.read(4096 * 64), b""):
        h.update(chunk)
print h.hexdigest()

pepasflo

#!/usr/bin/env python

class LinkedListNode(object):
    def __init__(self, value, next=None):
        self.value = value
        self.next = None

class Queue(object):
    def __init__(self):
        self.head = None

pepasflo

#!/usr/bin/env python

# Intervie Cake problem: verify a binary search tree.
# See https://www.interviewcake.com/question/python/bst-checker

class BinarySearchTree(object):

    def __init__(self, value):
        self.value = value
        self.left = None

pepasflo

#!/usr/bin/env python

class BinaryTreeNode(object):

    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None

    def insert_left(self, value):

pepasflo

#!/usr/bin/env python

# does this linked list have a cycle?
# https://www.interviewcake.com/question/python/linked-list-cycles?__s=rf71cpqpqpezb7dgts5r

class ListNode:
    next = None

def has_loop(l):
    seen = set()

pepasflo

[
    [1,1],
    [2,1],
    [3,3]
]

pepasflo

#!/usr/bin/env python

# generate a "Units.js" file for quickqwerty.
# see https://github.com/susam/quickqwerty

import sys
import random

def gen_subunit_str(chars):
    words = []

pepasflo

./charfreq.py c linux-4.19.5
' ' 9.38%
e 5.59%
t 4.79%
_ 4.57%
\t 4.30%
r 3.82%
\n 3.68%
i 3.64%
s 3.41%

pepasflo

$ gcc -O3 -std=c99 -Wall parens.c

$ ./a.out parens-tests/100k.txt 
answer: 1
elapsed time: 13.773000ms

$ ./a.out parens-tests/1million.txt 
answer: 1
elapsed time: 125.703000ms