Expressif

Expressif is the variable substitution syntax, initially designed for NBi.io.

Expressif allows you to define variables and transformation of these variables (functions), in plain text, which can then be interpreted by the engine. The syntax for the definition of the expression transforming the variable is similar to:

@myVariable | text-to-lower | text-to-pad-right(@myCount, *)

About | Quickstart | Installing | Functions and predicates

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Quickstart

Expression

Expressif provides a class named Expression to define a chain of functions applied to a value. The class is expecting the textual representation of the chained functions in its constructor.

var expression = new Expression("lower");
var result = expression.Evaluate("Nikola Tesla");
Assert.That(result, Is.EqualTo("nikola tesla"));

Some functions require parameters, you can specify them between the parenthesis following the function name. Note that literal textual values don't required quotes surronding them.

var expression = new Expression("remove-chars(a)");
var result = expression.Evaluate("Nikola Tesla");
Assert.That(result, Is.EqualTo("Nikol Tesl"));

You can chain the functions with the operator pipe (|). The functions are executed from left to right.

var expression = new Expression("lower | remove-chars(a)");
var result = expression.Evaluate("Nikola Tesla");
Assert.That(result, Is.EqualTo("nikol tesl"));

It's possible to use variables as function parameters. The name of the variables must always start by an arobas (@)

var context = new Context();
context.Variables.Add<char>("myChar", 'k');

var expression = new Expression("lower | remove-chars(@myChar)", context);
var result = expression.Evaluate("Nikola Tesla");
Assert.That(result, Is.EqualTo("niola tesla"));

In addition to the variables that must be scalar values (text, numeric, dateTime ...), you can also add a property-object to the context. A property-object must be a pure C# object, an IDictionnary, an IList, or a DataRow. You can access the properties of the property-object based on the property's name with the syntax [property-name].

var context = new Context();
context.CurrentObject.Set(new { CharToBeRemoved = 't' });

var expression = new Expression("lower | remove-chars([CharToBeRemoved])", context);
var result = expression.Evaluate("Nikola Tesla");
Assert.That(result, Is.EqualTo("nikola esla"));

or based on its position with the syntax #index (where index is positive number).

var context = new Context();
context.CurrentObject.Set(new List<char>() { 'e', 's' });

var expression = new Expression("lower | remove-chars(#1)", context);
var result = expression.Evaluate("Nikola Tesla");
Assert.That(result, Is.EqualTo("nikola tela"));

It's also possible to use the result of function as the value of a parameter for another function. To achieve this the function as a parameter must be surrounded by curly braces {...}.

var context = new Context();
context.Variables.Add<int>("myVar", 6);
context.CurrentObject.Set(new List<int>() { 15, 8, 3 });

var expression = new Expression("lower | skip-last-chars( {@myVar | subtract(#2) })", context);
var result = expression.Evaluate("Nikola Tesla");
Assert.That(result, Is.EqualTo("nikola te"));

Predication

Expressif provides a class named Predication to define a combination of predicates applied to an argument. The class is expecting the textual representation of the predicates in its constructor.

var predication = new Predication("lower-case");
var result = predication.Evaluate("Nikola Tesla");
Assert.That(result, Is.False);

Same than for expressions, some predicates require parameters, you can specify them between the parenthesis immediately following the predicate name. More specifically, some predicates require an interval as parameter. The parameter can be define with the help of square brackets or parenthesis.

var predication = new Predication("within-interval([0;20[)");
var result = predication.Evaluate(15);
Assert.That(result, Is.True);

Other predicates require a culture as parameter. To specify a culture just use the textual representation of the culture composed of the two letter ISO code of the language then the two letters ISO code of the country separated by a dash i.e. fr-be for Belgian French, nl-be for Belgian Dutch or de-de for German.

var predication = new Predication("matches-date(fr-fr)");
var result = predication.Evaluate("28/12/1978");
Assert.That(result, Is.True);

Any predicate can be negated to return the opposite result. To negate a predicate just put the exclamation mark (!) in front of the predicate name.

var predication = new Predication("!starts-with(Nik)");
var result = predication.Evaluate("Nikola Tesla");
Assert.That(result, Is.False);

You can combine the predicates. Each predicate will accept the same argument and will be evaluated separatly. The results of the combination is dependening on the combinational operator used. To specify the name of the combinational operator use the pipe operator (|) immediately followed by the name of the operator. The following operators are valid |AND, |OR, |XOR.

Take into account that when possible, the operators are implementing a short-circuit. If the two predicates are combined with the operator |AND and the first is returning false, the second will not be evaluated. Following the same reasoning, if the two predicates are combined with the operator |OR and the first is returning true, the second will also be ignored.

var predication = new Predication("starts-with(Nik) |AND ends-with(sla)");
var result = predication.Evaluate("Nikola Tesla");
Assert.That(result, Is.True);

By default, the predicates are combined from left to right. If you've three predicates, the two firsts will be combined and then the result of this combination will be combined with the third predicate. To alter this order, you must group the predicates with the help of curly braces {...}. Each predicate inside a group is evaluated from left to right and then the result of the group is combined with another group or predicate also from left to right.

var predication = new Predication("{starts-with(Nik) |AND ends-with(sla)} |OR {starts-with(ola) |AND ends-with(Tes)}");
var result = predication.Evaluate("Nikola Tesla");
Assert.That(result, Is.True);

var withoutGroupsPredication = new Predication("starts-with(Nik) |AND ends-with(sla) |OR starts-with(ola) |AND ends-with(Tes)");
var secondResult = withoutGroupsPredication.Evaluate("Nikola Tesla");
Assert.That(result, Is.Not.EqualTo(secondResult));

Installing

Install in the usual .NET fashion:

Install-Package Expressif

Supported functions and predicates

Functions

Scope	Name	Aliases
IO	creation-datetime	file-to-creation-datetime, file-to-creation-dateTime
IO	creation-datetime-utc	file-to-creation-datetime-utc, file-to-creation-dateTime-utc
IO	directory	path-to-directory
IO	extension	path-to-extension
IO	filename	path-to-filename
IO	filename-without-extension	path-to-filename-without-extension
IO	root	path-to-root
IO	size	file-to-size
IO	update-datetime	file-to-update-datetime, file-to-update-dateTime
IO	update-datetime-utc	file-to-update-datetime-utc, file-to-update-dateTime-utc
Numeric	absolute	numeric-to-absolute
Numeric	add	numeric-to-add
Numeric	ceiling	numeric-to-ceiling
Numeric	clip	numeric-to-clip
Numeric	cube-power	numeric-to-cube-power
Numeric	cube-root	numeric-to-cube-root
Numeric	decrement	numeric-to-decrement
Numeric	divide	numeric-to-divide
Numeric	floor	numeric-to-floor
Numeric	increment	numeric-to-increment
Numeric	integer	numeric-to-integer
Numeric	invert	numeric-to-invert
Numeric	multiply	numeric-to-multiply
Numeric	nth-root	numeric-to-nth-root
Numeric	null-to-zero
Numeric	oppose	numeric-to-oppose
Numeric	power	numeric-to-power
Numeric	round	numeric-to-round
Numeric	sign	numeric-to-sign
Numeric	square-power	numeric-to-square-power
Numeric	square-root	numeric-to-square-root
Numeric	subtract	numeric-to-subtract
Special	any-to-any
Special	neutral	Special-to-neutral
Special	null-to-value
Special	value-to-value
Temporal	age	date-to-age
Temporal	backward	dateTime-to-backward, dateTime-to-subtract
Temporal	ceiling-hour	dateTime-to-ceiling-hour
Temporal	ceiling-minute	dateTime-to-ceiling-minute
Temporal	change-of-hour	dateTime-to-change-of-hour
Temporal	change-of-minute	dateTime-to-change-of-minute
Temporal	change-of-month	dateTime-to-change-of-month
Temporal	change-of-second	dateTime-to-change-of-second
Temporal	change-of-year	dateTime-to-change-of-year
Temporal	clamp	dateTime-to-clamp, dateTime-to-clip
Temporal	datetime-to-date	dateTime-to-date
Temporal	day-of-month	dateTime-to-day-of-month
Temporal	day-of-week	dateTime-to-day-of-week
Temporal	day-of-year	dateTime-to-day-of-year
Temporal	first-in-month	dateTime-to-first-in-month
Temporal	first-of-month	dateTime-to-first-of-month
Temporal	first-of-year	dateTime-to-first-of-year
Temporal	floor-hour	dateTime-to-floor-hour
Temporal	floor-minute	dateTime-to-floor-minute
Temporal	forward	dateTime-to-forward, dateTime-to-add
Temporal	hour	dateTime-to-hour
Temporal	hour-minute	dateTime-to-hour-minute
Temporal	hour-minute-second	dateTime-to-hour-minute-second
Temporal	hour-of-day	dateTime-to-hour-of-day
Temporal	invalid-to-date
Temporal	iso-day-of-year	dateTime-to-iso-day-of-year
Temporal	iso-week-of-year	dateTime-to-iso-week-of-year
Temporal	iso-year-day	dateTime-to-iso-year-day
Temporal	iso-year-week	dateTime-to-iso-year-week
Temporal	iso-year-week-day	dateTime-to-iso-year-week-day
Temporal	last-in-month	dateTime-to-last-in-month
Temporal	last-of-month	dateTime-to-last-of-month
Temporal	last-of-year	dateTime-to-last-of-year
Temporal	length-of-month	dateTime-to-length-of-month
Temporal	length-of-year	dateTime-to-length-of-year
Temporal	local-to-utc
Temporal	minute-of-day	dateTime-to-minute-of-day
Temporal	minute-of-hour	dateTime-to-minute-of-hour
Temporal	month	dateTime-to-month
Temporal	month-day	dateTime-to-month-day
Temporal	month-of-year	dateTime-to-month-of-year
Temporal	next-business-days	temporal-to-next-business-days, next-business-day, add-business-days
Temporal	next-day	dateTime-to-next-day
Temporal	next-month	dateTime-to-next-month
Temporal	next-weekday	dateTime-to-next-weekday
Temporal	next-weekday-or-same	dateTime-to-next-weekday-or-same
Temporal	next-year	dateTime-to-next-year
Temporal	null-to-date
Temporal	previous-business-days	temporal-to-previous-business-days, previous-business-day, subtract-business-days
Temporal	previous-day	dateTime-to-previous-day
Temporal	previous-month	dateTime-to-previous-month
Temporal	previous-weekday	dateTime-to-previous-weekday
Temporal	previous-weekday-or-same	dateTime-to-previous-weekday-or-same
Temporal	previous-year	dateTime-to-previous-year
Temporal	second-of-day	dateTime-to-second-of-day
Temporal	second-of-hour	dateTime-to-second-of-hour
Temporal	second-of-minute	dateTime-to-second-of-minute
Temporal	set-time	dateTime-to-set-time
Temporal	set-to-local
Temporal	set-to-utc
Temporal	utc-to-local
Temporal	year	dateTime-to-year
Temporal	year-of-era	dateTime-to-year-of-era
Text	after-substring	text-to-after-substring
Text	append	text-to-append
Text	append-new-line	text-to-append-new-line
Text	append-space	text-to-append-space
Text	before-substring	text-to-before-substring
Text	clean-whitespace	text-to-clean-whitespace
Text	collapse-whitespace	text-to-collapse-whitespace
Text	count-distinct-chars	text-to-count-distinct-chars
Text	count-substring	text-to-count-substring
Text	empty-to-null
Text	filter-chars	text-to-filter-chars
Text	first-chars	text-to-first-chars
Text	html-to-text
Text	last-chars	text-to-last-chars
Text	length	text-to-length, count-chars
Text	lower	text-to-lower
Text	mask-to-text
Text	null-to-empty
Text	pad-center	text-to-pad-center
Text	pad-left	text-to-pad-left
Text	pad-right	text-to-pad-right
Text	prefix	text-to-prefix
Text	prefix-new-line	text-to-prefix-new-line
Text	prefix-space	text-to-prefix-space
Text	prepend	text-to-prepend
Text	prepend-new-line	text-to-prepend-new-line
Text	prepend-space	text-to-prepend-space
Text	remove-chars	text-to-remove-chars
Text	replace-chars	text-to-replace-chars
Text	replace-slice	text-to-replace-slice
Text	retain-alpha	text-to-retain-alpha
Text	retain-alpha-numeric	text-to-retain-alpha-numeric
Text	retain-numeric	text-to-retain-numeric
Text	retain-numeric-symbol	text-to-retain-numeric-symbol
Text	skip-first-chars	text-to-skip-first-chars
Text	skip-last-chars	text-to-skip-last-chars
Text	suffix	text-to-suffix
Text	suffix-new-line	text-to-suffix-new-line
Text	suffix-space	text-to-suffix-space
Text	text-to-datetime	text-to-dateTime
Text	text-to-html
Text	text-to-mask
Text	token	text-to-token
Text	token-count	text-to-token-count
Text	trim	text-to-trim
Text	upper	text-to-upper
Text	whitespaces-to-empty	blank-to-empty
Text	whitespaces-to-null	blank-to-null
Text	without-diacritics	text-to-without-diacritics
Text	without-whitespaces	text-to-without-whitespaces

Predicates

Scope	Name	Aliases
Boolean	false	boolean-is-false
Boolean	false-or-null	boolean-is-false-or-null
Boolean	identical-to	boolean-is-identical-to
Boolean	true	boolean-is-true
Boolean	true-or-null	boolean-is-true-or-null
Numeric	equal-to	numeric-is-equal-to
Numeric	even	numeric-is-even
Numeric	greater-than	numeric-is-greater-than
Numeric	greater-than-or-equal	numeric-is-greater-than-or-equal
Numeric	integer	numeric-is-integer
Numeric	less-than	numeric-is-less-than
Numeric	less-than-or-equal	numeric-is-less-than-or-equal
Numeric	modulo	numeric-is-modulo
Numeric	negative	numeric-is-negative
Numeric	negative-or-zero	numeric-is-negative-or-zero
Numeric	odd	numeric-is-odd
Numeric	one	numeric-is-one
Numeric	opposite	numeric-is-opposite
Numeric	positive	numeric-is-positive
Numeric	positive-or-zero	numeric-is-positive-or-zero
Numeric	within-interval	numeric-is-within-interval
Numeric	zero	numeric-is-zero
Numeric	zero-or-null	numeric-is-zero-or-null
Special	null	is-null
Temporal	after	dateTime-is-after
Temporal	after-or-same-instant	dateTime-is-after-or-same-instant
Temporal	before	dateTime-is-before
Temporal	before-or-same-instant	dateTime-is-before-or-same-instant
Temporal	business-day	dateTime-is-business-day
Temporal	contained-in	dateTime-is-contained-in
Temporal	in-the-future	dateTime-is-in-the-future
Temporal	in-the-future-or-now	dateTime-is-in-the-future-or-now
Temporal	in-the-future-or-today	dateTime-is-in-the-future-or-today
Temporal	in-the-past	dateTime-is-in-the-past
Temporal	in-the-past-or-now	dateTime-is-in-the-past-or-now
Temporal	in-the-past-or-today	dateTime-is-in-the-past-or-today
Temporal	leap-year	dateTime-is-leap-year
Temporal	on-the-day	dateTime-is-on-the-day
Temporal	on-the-hour	dateTime-is-on-the-hour
Temporal	on-the-minute	dateTime-is-on-the-minute
Temporal	same-instant	dateTime-is-same-instant
Temporal	today	dateTime-is-today
Temporal	tomorrow	dateTime-is-tomorrow
Temporal	weekday	dateTime-is-weekday
Temporal	weekend	dateTime-is-weekend
Temporal	within-current-month	dateTime-is-within-current-month
Temporal	within-current-week	dateTime-is-within-current-week
Temporal	within-current-year	dateTime-is-within-current-year
Temporal	within-last-month	dateTime-is-within-last-month
Temporal	within-last-week	dateTime-is-within-last-week
Temporal	within-last-year	dateTime-is-within-last-year
Temporal	within-next-days	dateTime-is-within-next-days
Temporal	within-previous-days	dateTime-is-within-previous-days
Temporal	within-upcoming-month	dateTime-is-within-upcoming-month
Temporal	within-upcoming-week	dateTime-is-within-upcoming-week
Temporal	within-upcoming-year	dateTime-is-within-upcoming-year
Temporal	yesterday	dateTime-is-yesterday
Text	any-of	text-is-any-of
Text	contains	text-contains
Text	empty	text-is-empty
Text	empty-or-null	text-is-empty-or-null
Text	ends-with	text-ends-with
Text	equivalent-to	text-is-equivalent-to
Text	lower-case	text-is-lower-case
Text	matches-date	text-matches-date
Text	matches-datetime	text-matches-datetime
Text	matches-numeric	text-matches-numeric
Text	matches-regex	text-matches-regex
Text	matches-time	text-matches-time
Text	sorted-after	text-is-sorted-after
Text	sorted-after-or-equivalent-to	text-is-sorted-after-or-equivalent-to
Text	sorted-before	text-is-sorted-before
Text	sorted-before-or-equivalent-to	text-is-sorted-before-or-equivalent-to
Text	starts-with	text-starts-with
Text	upper-case	text-is-upper-case