Converters

tip

Converters — scripts that are used to interpret the values ​​of the text in each token.

Converters allow you to convert data tokens placed in $parseTree.

Declaration

Converter declaration:

• when declaring a pattern;

patterns:
  $four = four|| converter = function() {return 4}

• under init tags;

init:
    function amountConverter(pt) {
        var ret = pt.Number[0].value;
        return ret
    }

• in the .js-library file, for example converters.js.

    function amountConverter(pt) {
        var ret = pt.Number[0].value;
        return ret
    }

Functions of the converters get $parseTree as the first argument.

You can use inside a converter the variable refering to $parseTree. To do this, set its name as the first argument of the function; the second argument is the context.

Usage

Using converters:

• Get value ​​from the text.

Script:

$Digit = $regexp<\d+> || converter = numberConverterDigit

.js-file:

function numberConverterDigit(parseTree) {
        return parseInt(parseTree.text);
        }

• Convert value from mapping.

Script:

$Numeral = (one:1|...) || converter = valueToNumberConverter

.js-file:

function valueToNumberConverter(parseTree) {
        return parseInt(parseTree.value);
        }

• Get value from nested tokens.

Script:

$Numeral = (one:1|...)
$Minutes = $Numeral || converter = minutesConverter

.js-file:

function minutesConverter(parseTree) {
         return parseInt(parseTree.Numeral.value)
        };

• Get value ​​from dictionaries.

Script:

$City = $entity<Cities> || converter = cityConverter

.js-file:

function cityConverter(parseTree) {
        var id = parseTree.City[0].value;
        return Cities[id].value;
    }

caution

The $entity rule stores as a value only the entity identifier. The list of associated values ​​is contained in the dictionary.