monasca-api/monasca/expression_parser/alarm_expr_parser.py

#!/usr/bin/python
# -*- coding: utf-8 -*-
# Copyright 2014 Hewlett-Packard
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import itertools
import sys

from pyparsing import CaselessLiteral
from pyparsing import alphanums
from pyparsing import delimitedList
from pyparsing import Forward
from pyparsing import Group
from pyparsing import Literal
from pyparsing import nums
from pyparsing import opAssoc
from pyparsing import operatorPrecedence
from pyparsing import Optional
from pyparsing import stringEnd
from pyparsing import Word


class SubExpr(object):
    def __init__(self, tokens):
        self._sub_expr = tokens
        self._func = tokens.func
        self._metric_name = tokens.metric_name
        self._dimensions = tokens.dimensions.dimensions_list
        self._operator = tokens.relational_op
        self._threshold = tokens.threshold
        self._period = tokens.period
        self._periods = tokens.periods
        self._id = None

    @property
    def sub_expr_str(self):
        """Get the entire sub expression as a string with no spaces."""
        return "".join(list(itertools.chain(*self._sub_expr)))

    @property
    def fmtd_sub_expr_str(self):
        """Get the entire sub expressions as a string with spaces."""
        result = "{}({}".format(self._func.encode('utf8'),
                                self._metric_name.encode('utf8'))

        if self._dimensions:
            result += "{{{}}}".format(self._dimensions.encode('utf8'))

        if self._period:
            result += ", {}".format(self._period.encode('utf8'))

        result += ")"

        result += " {} {}".format(self._operator.encode('utf8'),
                                  self._threshold.encode('utf8'))

        if self._periods:
            result += " times {}".format(self._periods.encode('utf8'))

        return result.decode('utf8')

    @property
    def dimensions_str(self):
        """Get all the dimensions as a single comma delimited string."""
        return self._dimensions

    @property
    def operands_list(self):
        """Get this sub expression as a list."""
        return [self]

    @property
    def func(self):
        """Get the function as it appears in the orig expression."""
        return self._func

    @property
    def normalized_func(self):
        """Get the function upper-cased."""
        return self._func.upper()

    @property
    def metric_name(self):
        """Get the metric name as it appears in the orig expression."""
        return self._metric_name

    @property
    def normalized_metric_name(self):
        """Get the metric name lower-cased."""
        return self._metric_name.lower()

    @property
    def dimensions(self):
        """Get the dimensions."""
        return self._dimensions

    @property
    def dimensions_as_list(self):
        """Get the dimensions as a list."""
        if self._dimensions:
            return self._dimensions.split(",")
        else:
            return []

    @property
    def operator(self):
        """Get the operator."""
        return self._operator

    @property
    def threshold(self):
        """Get the threshold value."""
        return self._threshold

    @property
    def period(self):
        """Get the period. Default is 60 seconds."""
        if self._period:
            return self._period
        else:
            return u'60'

    @property
    def periods(self):
        """Get the periods. Default is 1."""
        if self._periods:
            return self._periods
        else:
            return u'1'

    @property
    def normalized_operator(self):
        """Get the operator as one of LT, GT, LTE, or GTE."""
        if self._operator.lower() == "lt" or self._operator == "<":
            return u"LT"
        elif self._operator.lower() == "gt" or self._operator == ">":
            return u"GT"
        elif self._operator.lower() == "lte" or self._operator == "<=":
            return u"LTE"
        elif self._operator.lower() == "gte" or self._operator == ">=":
            return u"GTE"

    @property
    def id(self):
        """Get the id used to identify this sub expression in the repo."""
        return self._id

    @id.setter
    def id(self, id):
        """Set the d used to identify this sub expression in the repo."""
        self._id = id


class BinaryOp(object):
    def __init__(self, tokens):
        self.op = tokens[0][1]
        self.operands = tokens[0][0::2]

    @property
    def operands_list(self):
        return ([sub_operand for operand in self.operands for sub_operand in
                 operand.operands_list])


class AndSubExpr(BinaryOp):
    """ Expand later as needed.
    """
    pass


class OrSubExpr(BinaryOp):
    """Expand later as needed.
    """
    pass


COMMA = Literal(",")
LPAREN = Literal("(")
RPAREN = Literal(")")
EQUAL = Literal("=")
LBRACE = Literal("{")
RBRACE = Literal("}")

# Initialize non-ascii unicode code points in the Basic Multilingual Plane.
unicode_printables = u''.join(
    unichr(c) for c in xrange(128, 65536) if not unichr(c).isspace())

# Does not like comma. No Literals from above allowed.
valid_identifier_chars = (unicode_printables + alphanums + ".-_#!$%&'*+/:;?@["
                                                           "\\]^`|~")

metric_name = Word(valid_identifier_chars, min=1, max=255)("metric_name")
dimension_name = Word(valid_identifier_chars, min=1, max=255)
dimension_value = Word(valid_identifier_chars, min=1, max=255)

integer_number = Word(nums)
decimal_number = Word(nums + ".")

max = CaselessLiteral("max")
min = CaselessLiteral("min")
avg = CaselessLiteral("avg")
count = CaselessLiteral("count")
sum = CaselessLiteral("sum")
func = (max | min | avg | count | sum)("func")

less_than_op = (CaselessLiteral("<") | CaselessLiteral("lt"))
less_than_eq_op = (CaselessLiteral("<=") | CaselessLiteral("lte"))
greater_than_op = (CaselessLiteral(">") | CaselessLiteral("gt"))
greater_than_eq_op = (CaselessLiteral(">=") | CaselessLiteral("gte"))

# Order is important. Put longer prefix first.
relational_op = (
    less_than_eq_op | less_than_op | greater_than_eq_op | greater_than_op)(
    "relational_op")

AND = CaselessLiteral("and") | CaselessLiteral("&&")
OR = CaselessLiteral("or") | CaselessLiteral("||")
logical_op = (AND | OR)("logical_op")

times = CaselessLiteral("times")

dimension = Group(dimension_name + EQUAL + dimension_value)

# Cannot have any whitespace after the comma delimiter.
dimension_list = Group(Optional(
    LBRACE + delimitedList(dimension, delim=',', combine=True)(
        "dimensions_list") + RBRACE))

metric = metric_name + dimension_list("dimensions")
period = integer_number("period")
threshold = decimal_number("threshold")
periods = integer_number("periods")

expression = Forward()

sub_expression = (func + LPAREN + metric + Optional(
    COMMA + period) + RPAREN + relational_op + threshold + Optional(
    times + periods) | LPAREN + expression + RPAREN)

sub_expression.setParseAction(SubExpr)

expression = operatorPrecedence(sub_expression,
                                [(AND, 2, opAssoc.LEFT, AndSubExpr),
                                 (OR, 2, opAssoc.LEFT, OrSubExpr)])


class AlarmExprParser(object):
    def __init__(self, expr):
        self._expr = expr

    @property
    def sub_expr_list(self):
        parseResult = (expression + stringEnd).parseString(self._expr)
        sub_expr_list = parseResult[0].operands_list
        return sub_expr_list


def main():
    """ Used for development and testing. """
    expr = "max(-_.千幸福的笑脸{घोड़ा=馬,dn2=dv2}, 60) gte 100 times 3 && " \
           "(min(ເຮືອນ{dn3=dv3,家=дом}) < 10 or sum(biz{dn5=dv5}) > 99 and " \
           "count(fizzle) lt 0 or count(baz) > 1)".decode('utf8')
    # expr = "max(foo{hostname=mini-mon,千=千}, 120) > 100 and (max(bar)>100 \
    # or max(biz)>100)".decode('utf8')
    alarmExprParser = AlarmExprParser(expr)
    r = alarmExprParser.sub_expr_list
    for sub_expression in r:
        print sub_expression.sub_expr_str
        print sub_expression.fmtd_sub_expr_str
        print sub_expression.dimensions_str
        print


if __name__ == "__main__":
    sys.exit(main())