mlgitter / pyone

Python One-liner Helper

PyOne

PyOne is a helper script for a quick and dirty one-liner in Python.

Examples

$ pyone '2+3.4*5'
19.0

$ pyone 'x=3; while 1<x { if(x%2==0) {x//=2} else {x=x*3+1} print(x) }'
10
5
16
8
4
2
1

$ pyone 'EL{(x,_,_)=s.partition("#");x=x.strip();if(x){print(s.split("\t")[1])}}' /etc/fstab
/
/boot
none

$ pyone -f sqlite3 'db=connect("foo.db"); for row in db.execute("SELECT * FROM FOO;"){print(row)}'
(123, 'Alice')
(456, 'Bob')

$ pyone -f urllib.request -f html.parser 'class P(HTMLParser){ \
     z=0; def handle_starttag(self,t,_){ if(t=="tr"){self.r=[]} \
     elif(t=="td"){self.z=1}} def handle_endtag(self,t){ \
     if(t=="tr"){print(",".join(self.r))}elif(t=="td"){self.z=0}} \
     def handle_data(self,s){if(self.z){self.r.append(s)}}} \
     P().feed(urlopen(argv[1]).read().decode("utf-8"))' \
     https://news.ycombinator.com/

Usage

$ pyone [-d] [-i modules] [-f modules] [-F delim] script [args ...]

PyOne converts a given script to properly indented Python code and executes it. When a single expression is given, it simply evals it and displays the return value.

Command Line Options

• -d : Debug mode. (dump the expanded code and exit)
• -i modules : Adds import modules at the beginning of the script.
• -f modules : Adds from modules import * for each module.
• -F delim : Sets the field delimiter (DELIM variable).

Script Syntax

• ; inserts a newline and make proper indentation.

  A; B; C becomes:

    A
    B
    C

• { ... } makes the inner part indented.

  A { B; C } becomes:

    A:
        B
        C

• EL{ ... } wraps the inner part as a loop executed for each line of files specified by the command line (or stdin).

  The following variables are available during the loop:

  • L: Current line number (0-based).
  • S: Current raw text, including "\n".
  • s: Stripped text line.
  • F[]: Split fields with DELIM.
  • I[]: Integer value obtained from each field if any.

  More precisely, the following code is inserted:

    for (L,S) in enumerate(fileinput.input()):
        s = S.strip()
        F = s.split(DELIM)
        I = [ toint(v) for v in F ]
        (... your code here ...)

Special variables

• DELIM : the field separator used in EL { ... } loop.
• argv : command line arguments.