Visit Python Abstract Syntax Tree

maxme (Maxime Biais) — Wed, 24 Jan 2007 13:03:54 GMT

Simplest AST visitor. More on this blog post :
http://www.biais.org/blog/index.php/2007/01/10/9-visit-python-abstract-syntax-tree



import compiler

 

class CodePrinter:

    def __init__(self):

        self.src = ''

 

    def visitName(self,t):

        self.src += t.name

 

    def visitConst(self,t):

        self.src += str(t.value)

 

    def visitStmt(self, t):

        for i in t:

            a = pretty_print(i)

            self.src += a + "\n"

 

    def visitAssName(self, t):

        self.src += t.name + " = "

 

def pretty_print(node):

    myvisitor = CodePrinter()

    # compiler.walk return the visitor instance : 2nd arg

    return compiler.walk(node, myvisitor).src

Ruby Client for Amazon Alexa Site Thumbnail (AST) Service

peter (Peter Cooperx) — Tue, 05 Dec 2006 18:31:27 GMT

It's scrappy, but it does the job.



require 'cgi'

require 'openssl'

require 'base64'

require 'open-uri'



access_id = 'YOUR_ACCESS_ID'

secret_id = 'YOUR_SECRET_ID'



source_url = ARGV.first



timestamp = Time.now.strftime("%Y-%m-%dT%H:%M:%SZ")

sig = Base64.encode64(OpenSSL::HMAC::digest(OpenSSL::Digest::Digest.new('SHA1'), secret_id, 'Thumbnail' + timestamp)).strip



url = "http://ast.amazonaws.com/Xino?Action=Thumbnail&AWSAccessKeyId=" + access_id

url << "&Signature=" + CGI.escape(sig)

url << "&Timestamp=" + CGI.escape(timestamp)

url << "&Url=" +  source_url



begin

  doc = open(url).read

rescue

  puts "Could not access AWS"

  exit

end



m = doc.match(/\]+exists=\"true\"\>(.+?)\<\//i)



if m && m[1]

  thumb_url = m[1]

  thumb_url.gsub!(/\&/, '&')

  File.open("#{source_url}.jpg", "w") { |f| f.write open(thumb_url).read }

  puts "Saved to #{source_url}.jpg"

elsif m && m.match(/exists=\"false\"/)

  puts "No thumbnail for #{source_url}"

else

  puts "Error"

end

DZone Snippets: ast code

Visit Python Abstract Syntax Tree

Ruby Client for Amazon Alexa Site Thumbnail (AST) Service