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jsonpath.py
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jsonpath.py
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"""
An XPath for JSON
A port of the Perl, and JavaScript versions of JSONPath
see http://goessner.net/articles/JsonPath/
Based on on JavaScript version by Stefan Goessner at:
http://code.google.com/p/jsonpath/
and Perl version by Kate Rhodes at:
http://github.com/masukomi/jsonpath-perl/tree/master
"""
__author__ = "Phil Budne"
__revision__ = "$Revision: 1.13 $"
__version__ = '0.54'
# Copyright (c) 2007 Stefan Goessner (goessner.net)
# Copyright (c) 2008 Kate Rhodes (masukomi.org)
# Copyright (c) 2008-2012 Philip Budne (ultimate.com)
# Licensed under the MIT licence:
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
import re
import sys
# XXX BUGS:
# evalx is generally a crock:
# handle !@.name.name???
# there are probably myriad unexpected ways to get an exception:
# wrap initial "trace" call in jsonpath body in a try/except??
# XXX TODO:
# internally keep paths as lists to preserve integer types
# (instead of as ';' delimited strings)
__all__ = [ 'jsonpath' ]
# XXX precompile RE objects on load???
# re_1 = re.compile(.....)
# re_2 = re.compile(.....)
def normalize(x):
"""normalize the path expression; outside jsonpath to allow testing"""
subx = []
# replace index/filter expressions with placeholders
# Python anonymous functions (lambdas) are cryptic, hard to debug
def f1(m):
n = len(subx) # before append
g1 = m.group(1)
subx.append(g1)
ret = "[#%d]" % n
# print "f1:", g1, ret
return ret
x = re.sub(r"[\['](\??\(.*?\))[\]']", f1, x)
# added the negative lookbehind -krhodes
x = re.sub(r"'?(?<!@)\.'?|\['?", ";", x)
x = re.sub(r";;;|;;", ";..;", x)
x = re.sub(r";$|'?\]|'$", "", x)
# put expressions back
def f2(m):
g1 = m.group(1)
# print "f2:", g1
return subx[int(g1)]
x = re.sub(r"#([0-9]+)", f2, x)
return x
def jsonpath(obj, expr, result_type='VALUE', debug=0, use_eval=True):
"""traverse JSON object using jsonpath expr, returning values or paths"""
def s(x,y):
"""concatenate path elements"""
return str(x) + ';' + str(y)
def isint(x):
"""check if argument represents a decimal integer"""
return x.isdigit()
def as_path(path):
"""convert internal path representation to
"full bracket notation" for PATH output"""
p = '$'
for piece in path.split(';')[1:]:
# make a guess on how to index
# XXX need to apply \ quoting on '!!
if isint(piece):
p += "[%s]" % piece
else:
p += "['%s']" % piece
return p
def store(path, object):
if result_type == 'VALUE':
result.append(object)
elif result_type == 'IPATH': # Index format path (Python ext)
# return list of list of indices -- can be used w/o "eval" or split
result.append(path.split(';')[1:])
else: # PATH
result.append(as_path(path))
return path
def trace(expr, obj, path):
if debug: print "trace", expr, "/", path
if expr:
x = expr.split(';')
loc = x[0]
x = ';'.join(x[1:])
if debug: print "\t", loc, type(obj)
if loc == "*":
def f03(key, loc, expr, obj, path):
if debug > 1: print "\tf03", key, loc, expr, path
trace(s(key, expr), obj, path)
walk(loc, x, obj, path, f03)
elif loc == "..":
trace(x, obj, path)
def f04(key, loc, expr, obj, path):
if debug > 1: print "\tf04", key, loc, expr, path
if isinstance(obj, dict):
if key in obj:
trace(s('..', expr), obj[key], s(path, key))
else:
if key < len(obj):
trace(s('..', expr), obj[key], s(path, key))
walk(loc, x, obj, path, f04)
elif loc == "!":
# Perl jsonpath extension: return keys
def f06(key, loc, expr, obj, path):
if isinstance(obj, dict):
trace(expr, key, path)
walk(loc, x, obj, path, f06)
elif isinstance(obj, dict) and loc in obj:
trace(x, obj[loc], s(path, loc))
elif isinstance(obj, list) and isint(loc):
iloc = int(loc)
if len(obj) >= iloc:
trace(x, obj[iloc], s(path, loc))
else:
# [(index_expression)]
if loc.startswith("(") and loc.endswith(")"):
if debug > 1: print "index", loc
e = evalx(loc, obj)
trace(s(e,x), obj, path)
return
# ?(filter_expression)
if loc.startswith("?(") and loc.endswith(")"):
if debug > 1: print "filter", loc
def f05(key, loc, expr, obj, path):
if debug > 1: print "f05", key, loc, expr, path
if isinstance(obj, dict):
eval_result = evalx(loc, obj[key])
else:
eval_result = evalx(loc, obj[int(key)])
if eval_result:
trace(s(key, expr), obj, path)
loc = loc[2:-1]
walk(loc, x, obj, path, f05)
return
m = re.match(r'(-?[0-9]*):(-?[0-9]*):?(-?[0-9]*)$', loc)
if m:
if isinstance(obj, (dict, list)):
def max(x,y):
if x > y:
return x
return y
def min(x,y):
if x < y:
return x
return y
objlen = len(obj)
s0 = m.group(1)
s1 = m.group(2)
s2 = m.group(3)
# XXX int("badstr") raises exception
start = int(s0) if s0 else 0
end = int(s1) if s1 else objlen
step = int(s2) if s2 else 1
if start < 0:
start = max(0, start+objlen)
else:
start = min(objlen, start)
if end < 0:
end = max(0, end+objlen)
else:
end = min(objlen, end)
for i in xrange(start, end, step):
trace(s(i, x), obj, path)
return
# after (expr) & ?(expr)
if loc.find(",") >= 0:
# [index,index....]
for piece in re.split(r"'?,'?", loc):
if debug > 1: print "piece", piece
trace(s(piece, x), obj, path)
else:
store(path, obj)
def walk(loc, expr, obj, path, funct):
if isinstance(obj, list):
for i in xrange(0, len(obj)):
funct(i, loc, expr, obj, path)
elif isinstance(obj, dict):
for key in obj:
funct(key, loc, expr, obj, path)
def evalx(loc, obj):
"""eval expression"""
if debug: print "evalx", loc
# a nod to JavaScript. doesn't work for @.name.name.length
# Write len(@.name.name) instead!!!
loc = loc.replace("@.length", "len(__obj)")
loc = loc.replace("&&", " and ").replace("||", " or ")
# replace !@.name with 'name' not in obj
# XXX handle !@.name.name.name....
def notvar(m):
return "'%s' not in __obj" % m.group(1)
loc = re.sub("!@\.([a-zA-Z@_]+)", notvar, loc)
# replace @.name.... with __obj['name']....
# handle @.name[.name...].length
def varmatch(m):
def brackets(elts):
ret = "__obj"
for e in elts:
if isint(e):
ret += "[%s]" % e # ain't necessarily so
else:
ret += "['%s']" % e # XXX beware quotes!!!!
return ret
g1 = m.group(1)
elts = g1.split('.')
if elts[-1] == "length":
return "len(%s)" % brackets(elts[1:-1])
return brackets(elts[1:])
loc = re.sub(r'(?<!\\)(@\.[a-zA-Z@_.]+)', varmatch, loc)
# removed = -> == translation
# causes problems if a string contains =
# replace @ w/ "__obj", but \@ means a literal @
loc = re.sub(r'(?<!\\)@', "__obj", loc).replace(r'\@', '@')
if not use_eval:
if debug: print "eval disabled"
raise Exception("eval disabled")
if debug: print "eval", loc
try:
# eval w/ caller globals, w/ local "__obj"!
v = eval(loc, caller_globals, {'__obj': obj})
except Exception, e:
if debug: print e
return False
if debug: print "->", v
return v
# body of jsonpath()
# Get caller globals so eval can pick up user functions!!!
caller_globals = sys._getframe(1).f_globals
result = []
if expr and obj:
cleaned_expr = normalize(expr)
if cleaned_expr.startswith("$;"):
cleaned_expr = cleaned_expr[2:]
# XXX wrap this in a try??
trace(cleaned_expr, obj, '$')
if len(result) > 0:
return result
return False
if __name__ == '__main__':
try:
import json # v2.6
except ImportError:
import simplejson as json
import sys
# XXX take options for output format, output file, debug level
if len(sys.argv) < 3 or len(sys.argv) > 4:
sys.stdout.write("Usage: jsonpath.py FILE PATH [OUTPUT_TYPE]\n")
sys.exit(1)
object = json.load(file(sys.argv[1]))
path = sys.argv[2]
format = 'VALUE'
if len(sys.argv) > 3:
# XXX verify?
format = sys.argv[3]
value = jsonpath(object, path, format)
if not value:
sys.exit(1)
f = sys.stdout
json.dump(value, f, sort_keys=True, indent=1)
f.write("\n")
sys.exit(0)