tevale

Tevale is the tiny evaluator of expressions, which accepts a set of variables (named objects with properties) and an expression, validates its syntax and evaluates the expression.

Developed in Codefresh.

Its goal is to allow the evaluations of expressions (in a variable context) so as to generate a boolean true/false result. It was designed to be embeded into scripts that contain various entities and require the evaluation of an expression to make a yes/no decision.

Features

• Validation and evaluation of expressions
• Supports variables in expressions, including object variables (nesting)
• Supports popular functions and operators for number and string manipulation
• Supports string searching and regexp matching functions

Installation

$ npm install cf-expression-evaluator --save

Usage

const tevale = require('tevale');
const variables = {
    "author": {
        "name": "Alon Diamant",
        "homepage": "http://www.alondiamant.com",
        "github": {
            "repositories": 12,
            "url": "http://www.github.com/advance512"
        },
    },
    "company": {
        "name": "Codefresh",
        "homepage": "http://www.codefresh.io",
        "phoneNumber": "+972-99-999-9999"
    }
}

console.log(
    tevale.evaluateExpression(
        'match(author.name, "alon", true) && ' +
        'author.github.repositories > 10 && ' +
        'Number(substring(company.phoneNumber, 1, 4)) / 2 == 486',
        variables
    )
);

Reference

Types

Type	Example	True/False
String	"hello" 'there'	Empty string is false: '' Non-empty string is true: 'something' String comparison is lexicographic
Number	5 3.4 1.79E+308	0 is false any non-0 number is true
Boolean	true false	true is true false is false
null	Null	always false

Variables and Members

• You can then use the members of each variable.
• To access variables that have a non-standard (i.e. only alphanumeric and _ characters) names, use the Variable() function.
• To access variable members that have a non-standard (i.e. only alphanumeric and _ characters) names, use the Member() function.

Unary Operators

Operator	Operation
-	Negation of numbers
!	Logical NOT

Binary Operators

Operator	Operation
+	Add, String Concatenation
-	Subtract
*	Multiply
/	Divide
%	Modulus
&&	Logical AND
||	Logical OR

Comparisons

Operator	Operation
==	Equal
!=	Not equal
>	Greater than
>=	Greater than or equal
<	Less than
>=	Less than or equal

Functions

Function Name	Parameters	Return value	Example
String	0: number or string	string of input value	String(40) == '40'
Number	0: number or string	number of input value	Number('50') == 50 Number('hello') is invalid
Boolean	0: number or string	boolean of input value	Boolean('123') == true Boolean('') == false Boolean(583) == true Boolean(0) == false
round	0: number	rounded number	round(1.3) == 1 round(1.95) == 2
floor	0: number	number rounded to floor	floor(1.3) == 1 floor(1.95) == 1
upper	0: string	string in upper case	upper('hello') == 'HELLO'
lower	0: string	string in lower case	lower('BYE BYE') == 'bye bye'
trim	0: string	trimmed string	trim(" abc ") == "abc"
trimLeft	0: string	left trimmed string	trimLeft(" abc ") == "abc "
trimRight	0: string	right trimmed string	trimRight(" abc ") == " abc"
replace	0: string - main string 1: string - substring to find 2: string - substring to replace	replace all instances of the substring (1) in the main string (0) with the substring (2)	replace('hello there', 'e', 'a') == 'hallo thara'
substring	0: string - main string 1: string - index to start 2: string - index to end	returns a substring of a string	substring("hello world", 6, 11) == "world"
length	string	length of a string	length("gump") == 4
includes	0: string - main string 1: string - string to search for	whether a search string is found inside the main string	includes("codefresh", "odef") == true
indexOf	0: string - main string 1: string - string to search for	index of a search string if it is found inside the main string	indexOf("codefresh", "odef") == 1
match	0: string - main string 1: string - regular expression string, JS style 2: boolean - ignore case	search for a regular expression inside a string, ignoring or not ignoring case	match("hello there you", "..ll.", false) == true match("hello there you", "..LL.", false) == false match("hello there you", "hell$", true) == false match("hello there you", "^hell", true) == true match("hello there you", "bye", false) == false
Variable	string	Lookup the value of a variable	Variable('someVariable')
Member	0: string - variable name 1: string - member name	Lookup the value of a member of a variable	Member('someVariable', 'workingDirectory')

Examples

Using the variables:

const exampleVariables = {
    'somePositiveNumericValue': 123,
    'someZeroValue': 0,
    'someNegativeNumericValue': -50,
    'stringValue': 'hello',
    'emptyStringValue': '',
    'longStringValue': 'mA26EKMPupgvp6XYlGAVJZKv6yvaD3aobXMyExvyMBa2Hi9LlJXTUaBveMR9ErHtSfXNHHW5xAKbz2DVfBOqQ8CaSMNMQRBrJRpEpsO7FygKZmKpKHvvtPviOTfyUE0HGhnSPYHb9Hbz1CMxab4T0iQxPLCwrg57Qi0sTW1sJhVSygD9ivCfhJwJmD9PNb8bV0rJJ9aWp84LeaC7PDkj5hAozkrrJVA5hozLSXGZb0A4JLKiPOe9ITvxcIqvPNaMPA2SF4AQasE01TeGyuHQICuAMTGFFAP9y0HJBm7N0XmU',
    'trueBooleanValue': true,
    'falseBooleanValue': false,
    'nullBooleanValue': null,
    'simpleObjectValue': {
        'someNumericValue': 123,
        'someStringValue': 'hello there',
        'someNullValue': null,
        'someBooleanValue': false,
    },
    'complexObjectValue': {
        'internalObjectValue': {
            'someNumericValue': 123,
            'someStringValue': 'hello there',
            'someNullValue': null,
            'someBooleanValue': false,
        },
    },
    'superComplexObjectValue': {
        'internalObjectValue': {
            'moreInternalObjectValue': {
                'someNumericValue': 123,
                'someStringValue': 'hello there',
                'someNullValue': null,
                'someBooleanValue': false,
            },
        },
    },
    'typicalObjectValue': {
        'branch_name': 'master',
        'working_dir': '/tmp/whatever',
        'success': true,
    },
    'emptyObjectValue': {},

    'author': {
        'name': 'Alon Diamant',
        'homepage': 'http://www.alondiamant.com',
        'github': {
            'repositories': 12,
            'url': 'http://www.github.com/advance512',
        },
    },
    'company': {
        'name': 'Codefresh',
        'homepage': 'http://www.codefresh.io',
        'phoneNumber': '+972-99-999-9999',
    },
};

The result for the following expressions is:

Expression	Result or Error Message
''	false
'null'	false
'false'	false
'1234'	true
'-1234'	true
'0000000'	false
'""'	false
'"asdasd"'	true
''asdasd''	true
'asdasd'	Unexpected "`" at character 0
'somePositiveNumericValue'	true
'someZeroValue'	false
'someNegativeNumericValue'	true
'stringValue'	true
'emptyStringValue'	false
'longStringValue'	true
'trueBooleanValue'	true
'falseBooleanValue'	false
'!falseBooleanValue'	true
'nullBooleanValue'	false
'invalidIdentifer'	Invalid identifier: 'invalidIdentifer'
'somePositiveNumericValue > someZeroValue'	true
'somePositiveNumericValue < someZeroValue'	false
'somePositiveNumericValue >= someZeroValue'	true
'somePositiveNumericValue <= someZeroValue'	false
'somePositiveNumericValue >= somePositiveNumericValue'	true
'somePositiveNumericValue <= somePositiveNumericValue'	true
'longStringValue > emptyStringValue'	true
'longStringValue < emptyStringValue'	false
'longStringValue == longStringValue'	true
'longStringValue === longStringValue'	Invalid binary operator: ===
'longStringValue > stringValue'	true
'longStringValue < stringValue'	false
'simpleObjectValue.someNumericValue == 123'	true
'simpleObjectValue.someNumericValue'	true
'simpleObjectValue.someNullValue'	false
'simpleObjectValue.someBooleanValue'	false
'simpleObjectValue.someBooleanValue == false'	true
'complexObjectValue.internalObjectValue.someNumericValue == 123'	true
'complexObjectValue.internalObjectValue.someNumericValue'	true
'complexObjectValue.internalObjectValue.someNullValue'	false
'complexObjectValue.internalObjectValue.someBooleanValue'	false
'complexObjectValue.internalObjectValue.someBooleanValue == false'	true
'superComplexObjectValue.internalObjectValue.moreInternalObjectValue.someNumericValue == 123'	true
'superComplexObjectValue.internalObjectValue.moreInternalObjectValue.someNumericValue'	true
'superComplexObjectValue.internalObjectValue.moreInternalObjectValue.someNullValue'	false
'superComplexObjectValue.internalObjectValue.moreInternalObjectValue.someBooleanValue'	false
'superComplexObjectValue.internalObjectValue.moreInternalObjectValue.someBooleanValue == false'	true
'typicalObjectValue.branch_name == "master"'	true
'typicalObjectValue.working_dir == "/var/tmp"'	false
'!!typicalObjectValue.success'	true
'typicalObjectValue.success == true'	true
'typicalObjectValue.nonExistant'	Undefined identifier member: 'nonExistant'
'typicalObjectValue'	Cannot evaluate object variable directly
'emptyObjectValue.someBooleanValue == false'	Undefined identifier member: 'someBooleanValue'
'emptyObjectValue.someBooleanValue'	Undefined identifier member: 'someBooleanValue'
'emptyObjectValue'	Cannot evaluate object variable directly
'superComplexObjectValue.'	Unexpected at character 24
'superComplexObjectValue..'	Unexpected . at character 24
'superComplexObjectValue.internalObjectValue'	Cannot evaluate object variable directly
'superComplexObjectValue.internalObjectValue.'	Unexpected at character 44
'superComplexObjectValue.internalObjectValue.moreInternalObjectValue'	Cannot evaluate object variable directly
'superComplexObjectValue.internalObjectValue.moreInternalObjectValue.'	Unexpected at character 68
'superComplexObjectValue.internalObjectValue.moreInternalObjectValue.nonExistant'	Undefined identifier member: 'nonExistant'
'superComplexObjectValue.internal Object Value.moreInternalObjectValue.someNumericValue'	Cannot handle compound expressions.
'superComplexObjectValue.internalObject.Value.moreInternalObjectValue.someNumericValue'	Undefined identifier member: 'internalObject'
'somePositiveNumericValue > null'	The operator > cannot be used with number,null. It can only be used with the types: number,string
'somePositiveNumericValue < stringValue'	The operator < cannot be used with number,string. It can only be used with the types: number,string
'somePositiveNumericValue > true'	The operator > cannot be used with number,boolean. It can only be used with the types: number,string
'somePositiveNumericValue > simpleObjectValue'	The operator > cannot be used with number,object. It can only be used with the types: number,string
'complexObjectValue > simpleObjectValue'	The operator > cannot be used with object,object. It can only be used with the types: number,string
'false > null'	The operator > cannot be used with boolean,null. It can only be used with the types: number,string
'false > true'	The operator > cannot be used with boolean,boolean. It can only be used with the types: number,string
'someStringValue > null'	Invalid identifier: 'someStringValue'
'internalObjectValue.someNumericValue > null'	Invalid identifier: 'internalObjectValue'
'typicalObjectValue.working_dir > 82'	The operator > cannot be used with string,number. It can only be used with the types: number,string
'typicalObjectValue.working_dir > complexObjectValue.internalObjectValue.someNumericValue'	The operator > cannot be used with string,number. It can only be used with the types: number,string
'(somePositiveNumericValue > someZeroValue)'	true
'(somePositiveNumericValue >= someZeroValue) && true'	true
'(longStringValue > emptyStringValue) && (longStringValue >= emptyStringValue)'	true
'((longStringValue > emptyStringValue) && (longStringValue >= emptyStringValue))'	true
'(longStringValue > emptyStringValue && (longStringValue >= emptyStringValue))'	true
'60 > 35 && (50 > 22 && ((90 > 33) && ((26 > 10) && 15 > 30)) || (80 > 32))'	true
'60 > 35 && (50 > 22 && ((90 > 33) && ((26 > 10) && 15 > 30)) || (80 < 32))'	false
'60 > 35 && (50 > 22 && ((90 > 33) && ((26 > 10) && 15 > 30)) || (somePositiveNumericValue > 32))'	true
'60 > 35 && (50 > 22 && ((90 > 33) && ((26 > 10) && 15 > 30)) || (somePositiveNumericValue < 32))'	false
'somePositiveNumericValue / someZeroValue'	Division of 123 by 0
'somePositiveNumericValue % someZeroValue'	Modulo of 123 by 0
'somePositiveNumericValue / somePositiveNumericValue'	true
'9007199254740991 * 9007199254740991'	true
'1.231 * 5.2342'	true
'+true'	The operator + cannot be used with boolean. It can only be used with the types: number
'+234'	true
'~234'	Invalid unary operator: ~
'555+true'	The operator + cannot be used with number,boolean. It can only be used with the types: number,string
'23423-223'	true
'123-123'	false
'!true'	false
'!!true'	true
'!!!!!!!!!!true'	true
'!33'	false
'!!33'	true
'!0'	true
'!!0'	false
'55 % 10 == 5'	true
'1.79E+308 * 1.79E+308'	Numeric overflow
'15 | 33'	Invalid binary operator: |
'5555 @ 33333'	Unexpected "@" at character 5
'5555 $ 33333'	Cannot handle compound expressions.
'5555 \ 33333'	Unexpected "" at character 5
'5555 : 33333'	Unexpected ":" at character 5
'5555 :::: 33333'	Unexpected ":" at character 5
'stringValue / 5'	The operator / cannot be used with string,number. It can only be used with the types: number
'stringValue / stringValue'	The operator / cannot be used with string,string. It can only be used with the types: number
'stringValue + 5'	The operator + cannot be used with string,number. It can only be used with the types: number,string
'stringValue + 5'	The operator + cannot be used with string,number. It can only be used with the types: number,string
'this'	keyword 'this' not supported.
'5 > 2 ? 4 : 1'	Trinary operator (?:) currently not supported.
'[1, 2, 3]'	Array literals ([1, 2, 3]) currently not supported.
'upper(stringValue)'	true
'substring(stringValue, 2, 4)'	true
'substring(stringValue, 20, 40)'	false
'upper()'	Expected 1 arguments for function 'upper'.
'lower(123)'	Invalid argument #0 of type number for function 'lower': expected string
'lower("asd", 3, 5)'	Expected 1 arguments for function 'lower'.
'trim(null)'	Invalid argument #0 of type null for function 'trim': expected string
'Number(false)'	Invalid argument #0 of type boolean for function 'Number': expected number,string
'hello(false)'	Unknown function: 'hello'
'123(false)'	Cannot handle compound expressions.
'String("123")'	true
'String(123)'	true
'String("0")'	true
'String(0)'	true
'Number("123")'	true
'Number(123)'	true
'Number("0")'	false
'Number(0)'	false
'Number("hello there")'	Error converting value 'hello there' to number
'Boolean("123")'	true
'Boolean(123)'	true
'Boolean("0")'	true
'Boolean(0)'	false
'Boolean("hello there")'	true
'Boolean("")'	false
'Boolean(Number(String(0)))'	false
'Boolean(Number(String(1)))'	true
'round("asd")'	Invalid argument #0 of type string for function 'round': expected number
'round("13")'	Invalid argument #0 of type string for function 'round': expected number
'round(13)'	true
'round(13) == round(13.1222)'	true
'round(13) != round(13.9922)'	true
'round(13) == floor(13.9922)'	true
'floor(13E8)'	true
'floor(1359 / 342)'	true
'upper("alon") == "ALON"'	true
'upper("asd") != "ALON"'	true
'upper("asd") != 333'	The operator != cannot be used with string,number. It can only be used with the types: number,string,boolean
'lower("DIAMANT") == "diamant"'	true
'lower("asd") != "ALON"'	true
'lower("ASD") == "asd"'	true
'trim(" ASD ") == "ASD"'	true
'trim(lower(" ASD ")) == "asd"'	true
'lower(trim(" ASD ")) == "asd"'	true
'trimLeft(" ASD ") == "ASD "'	true
'trimRight(" ASD ") == " ASD"'	true
'replace("test me and you", "me", "her") == "test her and you"'	true
'replace("test ME and you", "me", "her") == "test ME and you"'	true
'replace("test ME and you", 123, "her") == "test ME and you"'	Invalid argument #1 of type number for function 'replace': expected string
'replace("test ME and you", 123) == "test ME and you"'	Expected 3 arguments for function 'replace'.
'replace("test ME and you", 123, 234, "her") == "test ME and you"'	Expected 3 arguments for function 'replace'.
'substring("test ME and you", 0, 4) == "test"'	true
'substring("test ME and you", 4, 8) == " ME "'	true
'substring("test ME and you", 4, null) == " ME and you"'	Invalid argument #2 of type null for function 'substring': expected number
'substring("test ME and you", 4, -1) == " ME and you"'	true
'length("hello") == 5'	true
'length(12345) == 5'	Invalid argument #0 of type number for function 'length': expected string
'includes("team", "i")'	false
'includes("team", "ea")'	true
'includes("team", 456)'	Invalid argument #1 of type number for function 'includes': expected string
'indexOf("team", "i") == -1'	true
'indexOf("team", "ea") == 1'	true
'indexOf("team", 456)'	Invalid argument #1 of type number for function 'indexOf': expected string
'indexOf(234234, "234")'	Invalid argument #0 of type number for function 'indexOf': expected string
'indexOf(String(999234234.23423), "234")'	true
'match("hello there you", "..ll.", false)'	true
'match("hello there you", "..LL.", false)'	false
'match("hello there you", "hell$", true)'	false
'match("hello there you", "^hell", true)'	true
'match("hello there you", "bye", false)'	false
'match("hello there you", 123, false)'	Invalid argument #1 of type number for function 'match': expected string
'match(457457, 123, false)'	Invalid argument #0 of type number for function 'match': expected string
'match("hello there you", "^hell", null)'	Invalid argument #2 of type null for function 'match': expected boolean
'match(123, false)'	Expected 3 arguments for function 'match'.
'match()'	Expected 3 arguments for function 'match'.
'match( lower(String(round(99.234234)) + " is the number to call") + " in case of emergencies", "100", true) == ( 99 * 2000 > 99 * 999 && trueBooleanValue && somePositiveNumericValue < someNegativeNumericValue) '	true
'match(author.name, "alon", true) && author.github.repositories > 10 && Number(substring(company.phoneNumber, 1, 4)) / 2 == 486'	true
'hello there.testVariable == 567'	Cannot handle compound expressions.
'hello there.badly-named-variable == 890'	Cannot handle compound expressions.
'Variable("hello there").testVariable == 567'	Invalid identifier: 'hello there'
'Member(Variable("hello there"), "badly-named-variable") == 890'	Invalid identifier: 'hello there'
'Variable("author").name == "Alon Diamant"'	true
'Member(author.github, "repositories") == 12'	true
'author.toString'	Undefined identifier member: 'toString'
'author.eval("")'	Invalid function name type: 'MemberExpression'

Available gulp tasks

• gulp lint - runs eslint
• gulp test:unit - runs mocha unit tests
• gulp coverage - runs unit tests and generates coverage report
• gulp test:integration - runs karma tests
• gulp test - runs unit and integration tests and generates code coverage report
• gulp - default task, runs lint and test

Running tests

Install dev dependencies and run the test:

$ npm install -d && gulp

Author

Alon Diamant (advance512)

• github/advance512
• Homepage

License

Copyright © 2016, Codefresh. Released under the MIT license.

---