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|53.41.79E+308|0 is falseany non-0 number is true| |Boolean|truefalse|true is truefalse 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') == 50Number('hello') is invalid| |Boolean|0: number or string|boolean of input value|Boolean('123') == trueBoolean('') == falseBoolean(583) == trueBoolean(0) == false| |round|0: number|rounded number|round(1.3) == 1round(1.95) == 2| |floor|0: number|number rounded to floor|floor(1.3) == 1floor(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 string1: string - substring to find2: 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 string1: string - index to start2: 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 string1: string - string to search for|whether a search string is found inside the main string|includes("codefresh", "odef") == true| |indexOf|0: string - main string1: 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 string1: string - regular expression string, JS style2: boolean - ignore case|search for a regular expression inside a string, ignoring or not ignoring case|match("hello there you", "..ll.", false) == truematch("hello there you", "..LL.", false) == falsematch("hello there you", "hell$", true) == falsematch("hello there you", "^hell", true) == truematch("hello there you", "bye", false) == false| |Variable|string|Lookup the value of a variable|Variable('someVariable')| |Member|0: string - variable name1: 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.