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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.

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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)

License

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


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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.

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