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# Author: John MacFarlane <jgm@berkeley.edu>
# Copyright: (C) 2013 John MacFarlane
# License: GPL version 2 or higher
"""
Functions to aid writing python scripts that process the pandoc
AST serialized as JSON.
"""
import sys
import json
def walk(x, action, format = ""):
"""Walk a tree, applying an action to every object.
Returns a modified tree.
"""
if isinstance(x, list):
array = []
for item in x:
if isinstance(item, dict):
if item == {}:
array.append(walk(item, action, format))
else:
for k in item:
res = action(k, item[k], format)
if res is None:
array.append(walk(item, action, format))
elif isinstance(res, list):
for z in res:
array.append(walk(z, action, format))
else:
array.append(walk(res, action, format))
else:
array.append(walk(item, action, format))
return array
elif isinstance(x, dict):
obj = {}
for k in x:
obj[k] = walk(x[k], action, format)
return obj
else:
return x
def toJSONFilter(action):
"""Converts an action into a filter that reads a JSON-formatted
pandoc document from stdin, transforms it by walking the tree
with the action, and returns a new JSON-formatted pandoc document
to stdout. The argument is a function action(key, value, format),
where key is the type of the pandoc object (e.g. 'Str', 'Para'),
value is the contents of the object (e.g. a string for 'Str',
a list of inline elements for 'Para'), and format is the target
output format (which will be taken for the first command line
argument if present). If the function returns None, the object
to which it applies will remain unchanged. If it returns an
object, the object will be replaced. If it returns a list, the
list will be spliced in to the list to which the target object
belongs. (So, returning an empty list deletes the object.)
"""
doc = json.loads(sys.stdin.read())
if len(sys.argv) > 1:
format = sys.argv[1]
else:
format = ""
altered = walk(doc, action, format)
json.dump(altered, sys.stdout)
def attributes(attrs):
"""Returns an attribute list, constructed from the
dictionary attrs.
"""
attrs = attrs or []
ident = attrs["id"] or ""
classes = attrs["classes"] or []
keyvals = [x for x in attrs and x != "classes" and x != "id"]
return [ident, classes, keyvals]
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