DSL is a computer language specialized to a particular application domain, in contrast to a general-purpose language (GPL) that is broadly applicable across domains. There are several common ways to implement a DSL, including using parsers to convert DSL scripts into semantic models or abstract syntax trees that can then be used to generate executable code. DSLs allow expressing solutions to problems in a particular domain in a simpler and more natural way than GPLs.

1. DSL
• " , , ,
, "
赵李挺
WHY
HOW
WHAT

2. WHAT'S DSL

3. 什么是DSL?
•
@Before
public void setUp() throws Exception {
math = context.mock(IMathfun.class);
context.checking(new Expectations() {
{
oneOf(math).abs(-10);
will(returnValue(10));
}
});
}
select name,average(grade) from student
where class = ’01’
and sex = ‘Female’

4. 什么是DSL?
•
• A domain-specific language (DSL) is a computer language specialized to
a particular application domain. This is in contrast to a general-purpose
language (GPL), which is broadly applicable across domains, and lacks
specialized features for a particular domain.
•
•
• " "
• vs
DSL GPL , DSL?

5. DSL的边界
…
… …
,
.

6. DSL的边界
http://www.martinfowler.com/bliki/FluentInterface.html
=
+
DSL

7. DSL的通⽤实现⽅式
computer:
processor:
cores 2
i386
disk:
size 150
disk:
size 75
speed 7200
sata
Processor p = new
Processor(2,
Processor.Type.i386);
Disk d1 = new Disk(150,
Disk.UNKNOWN_SIZE,
null);
Disk d2 = new Disk(75,
7200,
Disk.Interface.SATA);
return new Computer(p,
d1, d2);
Parse
DSL Script Generated Code

8. DSL的分类
• dsl
jmock, linq, ruby on rails, hql, jquery
• dsl
css, sql, ant, make, awk…
1 + 2 - 3 * 4 / 5

9. HOW TO
IMPLEMENTS A DSL

10. L-编程语⾔组成要素
•
• ? AST
•
•
•
• ,

11. 从⼀个最简单的例⼦开始
expr ::= expr + term
| expr - term
| term
term ::= term * factor
| term / factor
| factor
factor ::= digit
• : bnf
:eval

12. DONEC QUIS NUNC
语法树
• 1 + 2 * 3
expr
expr term
term
1 + 2 * 3
term
digit
digit
digit
expr
expr term
term
1 + 2 * 3
term
digit
digit
digit
61
7

13. JAVA中的语法及语义
Statement:
try Block (Catches | [Catches] Finally)
…
Catches:
CatchClause { CatchClause }
CatchClause:
catch ( {VariableModifier} CatchType Identifier ) Block
CatchType:
QualifiedIdentifier { | QualifiedIdentifier }
Finally:
finally Block
https://docs.oracle.com/javase/specs/jls/se7/html/jls-18.html
http://cui.unige.ch/isi/bnf/JAVA/try_statement.html

14. DSL中的语法及语义
Jmock
invocation-count (mock-object).method(argument-constraints);
inSequence(sequence-name);
when(state-machine.is(state-name));
will(action);
then(state-machine.is(new-state-name));
http://www.jmock.org/cheat-sheet.html
http://www.jmock.org/javadoc/jmock-2.6.0/doc/org/jmock/syntax/package-frame.html

15. DSL中的语法及语义
• HTML
dom
• HQL
SQL AST
• make / ant

16. 让我们看的更远⼀点
=
DSL
+

17. DSL的通⽤实现⽅式
computer:
processor:
cores 2
i386
disk:
size 150
disk:
size 75
speed 7200
sata
Processor p = new
Processor(2,
Processor.Type.i386);
Disk d1 = new Disk(150,
Disk.UNKNOWN_SIZE,
null);
Disk d2 = new Disk(75,
7200,
Disk.Interface.SATA);
return new Computer(p,
d1, d2);
Parse Generate
DSL Script Semantic Model Generated Code

18. 语义模型
<li> <ul>

19. WHY DSL

20. DSL的好处
•
•
• …
•
•
DSL DSL

21. 语法糖
min(max(min(max(a,b),c),d),e)
=>
max a b | min c | max d | min e
var ul = document.createElement("ul");
var li1 = document.createElement("li");
var txt1 = document.createTextNode("Treebear");
li1.appendChild(txt1);
...
ul.append(li1);
=>
<ul id="company">
<li tag="NB">treebear</li>
<li tag="liumang"> </li>
<li>aliyeye</li>
</ul>
: ,

22. 计算模型-决策表
Y N Y N
Y Y N N
60% 90% 80% 100%
if else, ?

23. 计算模型-状态机
•
if else, ?

24. 计算模型-依赖⽹络
• ant

25. DSL IN TREEBEAR

26. HOMEWORK
• java
• java future js callback hell

27. Q & A

28. 最后的最后
• , . ,

29. DONEC QUIS NUNC
参考资料
• ( )
• (Martin Fowler, 2013)
• http://taligarsiel.com/Projects/howbrowserswork1.htm