이 콘텐츠는 선택한 언어로 제공되지 않습니다.

14.8. Adding Constraints to Facts

Expand

Table 14.3. Adding Constraints to Facts
Name	Description	Example
Expressing LHS conditions	The DSL facility allows you to add constraints to a pattern by a simple convention: if your DSL expression starts with a hyphen (minus character, "-") it is assumed to be a field constraint and, consequently, is is added to the last pattern line preceding it. In the example, the class `Cheese`, has these fields: type, price, age and country. You can express some LHS condition in normal DRL.	`Cheese(age < 5, price == 20, type=="stilton", country=="ch")` Copy to Clipboard Toggle word wrap
DSL definitions	The DSL definitions given in this example result in three DSL phrases which may be used to create any combination of constraint involving these fields.	`[when]There is a Cheese with=Cheese() [when]- age is less than {age}=age<{age} [when]- type is '{type}'=type=='{type}' [when]- country equal to '{country}'=country=='{country}'` Copy to Clipboard Toggle word wrap
"-"	The parser will pick up a line beginning with "-" and add it as a constraint to the preceding pattern, inserting a comma when it is required.	`There is a Cheese with - age is less than 42 - type is 'stilton'` Copy to Clipboard Toggle word wrap `Cheese(age<42, type=='stilton')` Copy to Clipboard Toggle word wrap
Defining DSL phrases	Defining DSL phrases for various operators and even a generic expression that handles any field constraint reduces the amount of DSL entries.	`[when][]is less than or equal to=<= [when][]is less than=< [when][]is greater than or equal to=>= [when][]is greater than=> [when][]is equal to=== [when][]equals=== [when][]There is a Cheese with=Cheese()` Copy to Clipboard Toggle word wrap [when][]- {field:\w} {operator} {value:\d}={field} {operator} {value}
DSL definition rule	n/a	`There is a Cheese with - age is less than 42 - rating is greater than 50 - type equals 'stilton'` Copy to Clipboard Toggle word wrap In this specific case, a phrase such as "is less than" is replaced by `<`, and then the line matches the last DSL entry. This removes the hyphen, but the final result is still added as a constraint to the preceding pattern. After processing all of the lines, the resulting DRL text is: `Cheese(age<42, rating > 50, type=='stilton')` Copy to Clipboard Toggle word wrap

Note

The order of the entries in the DSL is important if separate DSL expressions are intended to match the same line, one after the other.

맨 위로 이동

자세한 정보

평가판, 구매 및 판매

커뮤니티

Red Hat 문서 정보

Red Hat을 사용하는 고객은 신뢰할 수 있는 콘텐츠가 포함된 제품과 서비스를 통해 혁신하고 목표를 달성할 수 있습니다. 최신 업데이트를 확인하세요.

보다 포괄적 수용을 위한 오픈 소스 용어 교체

Red Hat은 코드, 문서, 웹 속성에서 문제가 있는 언어를 교체하기 위해 최선을 다하고 있습니다. 자세한 내용은 다음을 참조하세요.Red Hat 블로그.

Red Hat 소개

Red Hat은 기업이 핵심 데이터 센터에서 네트워크 에지에 이르기까지 플랫폼과 환경 전반에서 더 쉽게 작업할 수 있도록 강화된 솔루션을 제공합니다.

Theme

© 2025 Red Hat