UAST Role assignment example for a == b == c

example.py

a = b = c 
var1 == var2 == var3
var4 < var5 < var6

output

//*[@roleIdentifier] :
<a>:            [(6, 'LEFT'), (1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<b>:            [(6, 'LEFT'), (1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<c>:            [(7, 'RIGHT'), (1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<var2>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<var3>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<var1>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION'), (18, 'EXPRESSION'), (4, 'BINARY'), (6, 'LEFT')]
<var5>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<var6>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<var4>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION'), (18, 'EXPRESSION'), (4, 'BINARY'), (6, 'LEFT')]

//*[@roleLeft] :
<a>:            [(6, 'LEFT'), (1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<b>:            [(6, 'LEFT'), (1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<var1>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION'), (18, 'EXPRESSION'), (4, 'BINARY'), (6, 'LEFT')]
<var4>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION'), (18, 'EXPRESSION'), (4, 'BINARY'), (6, 'LEFT')]

//*[@roleRight] :
<c>:            [(7, 'RIGHT'), (1, 'IDENTIFIER'), (18, 'EXPRESSION')]
<>:             [(18, 'EXPRESSION'), (4, 'BINARY'), (7, 'RIGHT')]
<>:             [(18, 'EXPRESSION'), (4, 'BINARY'), (7, 'RIGHT')]

//*[@roleBinary] :
<>:             [(4, 'BINARY'), (105, 'THIS'), (18, 'EXPRESSION')]
<>:             [(18, 'EXPRESSION'), (4, 'BINARY')]
<>:             [(18, 'EXPRESSION'), (4, 'BINARY'), (7, 'RIGHT')]
<var1>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION'), (18, 'EXPRESSION'), (4, 'BINARY'), (6, 'LEFT')]
<>:             [(18, 'EXPRESSION'), (4, 'BINARY'), (3, 'OPERATOR')]
<==>:           [(4, 'BINARY'), (3, 'OPERATOR'), (20, 'EQUAL')]
<==>:           [(4, 'BINARY'), (3, 'OPERATOR'), (20, 'EQUAL')]
<>:             [(18, 'EXPRESSION'), (4, 'BINARY')]
<>:             [(18, 'EXPRESSION'), (4, 'BINARY'), (7, 'RIGHT')]
<var4>:         [(1, 'IDENTIFIER'), (18, 'EXPRESSION'), (18, 'EXPRESSION'), (4, 'BINARY'), (6, 'LEFT')]
<>:             [(18, 'EXPRESSION'), (4, 'BINARY'), (3, 'OPERATOR')]
<<>:            [(4, 'BINARY'), (3, 'OPERATOR'), (22, 'LESS_THAN')]
<<>:            [(4, 'BINARY'), (3, 'OPERATOR'), (22, 'LESS_THAN')]

//*[@roleThis] :

run_me.py

import bblfsh
from bblfsh import BblfshClient
import importlib
DESCRIPTOR = importlib.import_module(
        "bblfsh.gopkg.in.bblfsh.sdk.%s.uast.generated_pb2" % bblfsh.sdkversion.VERSION).DESCRIPTOR
Node = importlib.import_module(
        "bblfsh.gopkg.in.bblfsh.sdk.%s.uast.generated_pb2" % bblfsh.sdkversion.VERSION).Node

def _role_id(role_name):
    return DESCRIPTOR.enum_types_by_name["Role"].values_by_name[role_name].number

def _role_name(role_id):
    return DESCRIPTOR.enum_types_by_name["Role"].values_by_number[role_id].name

def get_token_roles_list(response, xpath):
    tokens = []
    for node in bblfsh.filter(response.uast, xpath):
        tokens.append((node.token, [(k, _role_name(k)) for k in node.roles]))
    print('\n'.join("<{}>:{} {}".format(t, " "* (12 - len(t)), r) for t, r in tokens))
    
client = BblfshClient("0.0.0.0:9432")
filepath = "./example.py"
response = client.parse(filepath)

# Get all Simple Identifiers in UAST
for xpath in ["//*[@roleIdentifier]", "//*[@roleLeft]", "//*[@roleRight]", "//*[@roleBinary]", "//*[@roleThis]"]:
    print(xpath, ":")
    get_token_roles_list(response, xpath)
    print()