A DSTL to bridge concrete and abstract syntax
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A DSTL To Bridge Concrete and Abstract Syntax Adolfo Sánchez-Barbudo Herrera, Edward D. Willink and Richard F. Paige
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Transcript of A DSTL to bridge concrete and abstract syntax
A DSTL ToBridge Concrete and
Abstract SyntaxAdolfo Sánchez-Barbudo Herrera, Edward D. Willink and
Richard F. Paige
Agenda
● Scope● Problem● Solution● Comparative Study
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Scope● Complex Textual Modeling Languages
○ CS is textual (particularly, defined by a grammar)○ AS is model-based (particularly, defined by a meta-model)○ Complex Language = AS definition can not be directly inferred from CS definition
● Examples○ Languages specified by OMG, such as OCL and QVT languages.○ OCL specification defines the CS via a grammar (Clause 9.3)○ OCL specification defines the AS via a meta-model (Clause 8) ○ OCL specification describes how to obtain AS from CS (Clause 9.4)
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Agenda
● Scope● Problem● Solution● Comparative Study
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Problem● Related works (e.g. Xtext) allow to map CS grammars to AS meta-models, but...● let … in x.y -- an OCL expression
○ ‘y’ is a navigation (i.e. a PropertyCallExp in the AS)○ ‘x’ ? → It depends on the context
y:PropertyCallExp
x:VariableExp
ownedSource
x:PropertyCallExp
self:VariableExp
y:PropertyCallExp
ownedSource ownedSource
‘x’ is a variable name
‘x’ is aproperty name (i.e self.x.y)
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Problem II
CallExpCS:PrimaryExpCS ( ('.' | '->') NameExpCS)*
NameExpCS:SimpleNameCS (RoundedBracketClauseCS)?
SimpleNameCS:ID;
RoundedBracketClauseCS:'(' (ExpCS (',' ExpCS)* )? ')'
OCLExpression
OperationCallExp
VariableExp
PropertyCallExp
Problem: Syntactically, it can not be determined if a simple name corresponds to a PropertyCallExp or VariableExp
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Problem III● Support to non-simple (i.e. 1-1) CS2AS mappings
○ e.g. a NameExpCS may map to a VariableExp and PropertyCallExp (output pattern)
● Support to cross-references computation○ e.g. an OCLExpression is a TypedElement: it requires a type cross-reference to be computed
● Name resolution○ Special case of cross-reference computation○ e.g. a VariableExp requires to refer to a Variable.
● CS Disambiguation○ e.g. a NameExpCS may map to either an OperationCallExp, or a PropertyCallExp, or a
VariableExp
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Agenda
● Scope● Problem● Solution● Comparative Study
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Solution
Generates
Manual artefactGenerated artefact
ASMM
conformsTo
ASModel
conformsTo
TextualInput
CSGrammar
CSMM
Parser
CS Model
conformsTo
(e.g. like Xtext)
M2M tx
from toCS2ASBridge
(modelware)
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Solution II● (External) DSTL to bridge CS and AS (meta-models).● Why is domain-specific
○ Just one input domain and one output domain (no in-place tx)○ Specific constructs for name resolution○ Specific guards semantics for disambiguation rules
● Features:○ Declarative (M2M) language○ Resuses Essential OCL as expressions language○ Currently, four sections
■ helpers■ mappings■ disambiguation rules■ name resolution
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DSTL: Helpers● To define contextual operations
helpers {NameExpCS::parentAsCallExpCS() : CallExpCS =
let container = self.oclContainer()in if container.oclIsKindOf(CallExpCS) then container.oclAsType(CallExpCS) else null endif
NameExpCS::isNameExpOfACallExpCS() : Boolean =let parentCallExpCS = parentAsCallExpCS()in parentCallExpCS <> null and parentCallExpCS.nameExp = self }
body
resultcontext
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DSTL: Mappings● To define mappings between CS and AS (meta-)classes
mappings {map PropertyCallExp from NameExpCS
when isPropCallExpWithImplicitSource {ownedSource := let referredVar = trace.lookup(Variable, 'self')
in VariableExp {referredVariable = referredVar,type = referredVar.type }
referredProperty := trace.lookupExported(Property,trace.ownedSource.type, expName),
type := trace.referredProperty?.type}}
Mapping guard
AS property initialization
To access AS domain from the CS one Lookup
expressions
Target AS term
Source CS term
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DSTL: Mappings II● Multi-way mappings (same NameExpCS mapped to different outcomes)
mappings {map PropertyCallExp from NameExpCS
when isPropCallExpWithImplicitSource { … }map PropertyCallExp from NameExpCS
when isPropCallExpWithExplicitSource { … }map OperationCallExp from NameExpCS
when isOpCallExpWithExplicitSource { … }map OperationCallExp from NameExpCS
when isOpCallExpWithExplicitSource { … }map VariableExp from NameExpCS
when isVariableExp { … } }
Same source (CS)
Differenttargets (AS)
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DSTL: Disambiguation Rules● To define disambiguation rules
disambiguation {NameExpCS {
isOpCallExpWithImplicitSource := roundedBrackets <> nulland not isNameExpOfACallExpCS()
isOpCallExpWithExplicitSource := roundedBrackets <> nulland isNameExpOfACallExpCS()
isPropCallExpWithExplicitSource := roundedBrackets = nulland isNameExpOfACallExpCS()
isVariableExp := … isPropCallExpWithImplicitSource := …
} }
CS element to disambiguate
Disambiguation rule name
Boolean-valued expression
Important: Order matters14
Name Resolution● Activity to solve AS cross-references, which involve a name-based lookup
○ From an AS element another named AS element needs to be found in the model.○ Declaratively, it’s matter of how named elements are contributed to lookup scopes.○ Scopes are key data structures that keep all visible named element within that scope.
● Scopes:○ Current Scope ○ Exported Scope○ Nested Scopes
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Name Resolution II● Current Scope
class C1 {prop p1 : String;op getP1(): String = p1;
}
:ExpressionInOCL
:PropertyCallExp
class C2 {op getP1() : String = p1;
}
:ExpressionInOCL
:PropertyCallExp
C1:Class
p1:Property
getP1:Operation
referredProperty
C2:Class
getP1:Operation
referredProperty
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Name Resolution III● Exported Scope
class C1 {prop p1 : String;op getP1(): String
= p1;}
class C2 {prop c1 : C1;op getP1() : String
= c1.p1;}
:ExpressionInOCL
:PropertyCallExp
:ExpressionInOCL
:PropertyCallExp
C1:Class
p1:Property
getP1:Operation
referredProperty
getP1:Operation
referredProperty
:PropertyCallExp
referredProperty
C2:Class
c1:Property
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Name Resolution IV● Nested Scope (name oclusssion)
-- valid expression which -- evaluates to falselet v = ‘foo’in let v = ‘bar’ in v = ‘foo’
‘foo’:StringLiteralExp
:LetExp
:LetExp
v:Variable
v:Variable
‘bar’:StringLiteralExp
‘foo’:StringLiteralExp
‘=’:OperationCallExp
:VariableExp
‘v’ -> Variable (‘foo’)
‘v’ -> Variable (‘bar’)parent
nested
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DSTL: Name Resolution● To define name resolution
targets {NamedElement using name; -- ’name’: property used to identify ’targets’Property; -- ’using’ is optional: extends a fully defined ’target’ element }
inputs {SimpleNameCS using name; -- ’name’: property used to match ’targets’ }
providers {Class {
in current-scope provides occluding ownedProperties;
in exported-scope provides ownedProperties; } } 19
DSTL: Name Resolution II● Slightly more complex name resolution
providers {Class {
in current-scope providesoccluding ownedPropertiesoccluding getAllSuperClasses().ownedProperties;
in exported-scope providesownedPropertiesoccluding getAllSuperClasses().ownedProperties;
} }
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DSTL: Name Resolution III● Expressions to perform name-based lookups
trace.lookup(Variable, 'self')
Kind of target to look up
trace.lookupExported(Property,trace.ownedSource.type, expName)
The lookup input (a String)Lookup in current scope
Lookup in a exported scope
Kind of target to look up
Actual element providing the exported scope
The lookup input (a SimpleNameCS)
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Agenda
● Scope● Problem● Solution● Comparative Study
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Comparative Study: Gra2Mol● Gra2Mol
○ DSTL can be used for the same purpose: bridging CS and AS syntax
○ Map arbitrary grammars to arbitrary AS meta-models
Source Target Nature Query Language
Gra2Mol GrammarTerms
AS MMTerms
Declarative Structure-Shy (Xpath Like)
CS2ASDSTL
CS MMTerms
AS MMTerms
Declarative Statically Typed(Essent. OCL)
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Qualitative Study● Gra2Mol pros:
○ Query Language is more concise (few and effort-saving navigation operators)
○ Provides a language extensibility mechanism
● CS2AS DSTL pros:○ OCL has more expressive power (beyond simple model navigation)
○ AS model can be navigated (Gra2Mol QL only operates at CS level)
○ No coupling with a parsing technology
○ Declarative name resolution section saves encoding lookup algorithms
■ to resolve name-based cross-references
○ Ordering-based disambiguation rules description
■ to overcome their admitted limitation of having to define exclusive rule guards.
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Quantitative Study: Examplecompany :
’company’ STRING ’{’ department* ’}’ EOF;department :
’department’ STRING ’{’ department_manager department_employees department* ’}’;department_manager : ’manager’ employee;department_employees :
(’employee’ employee)*;employee :
STRING ’{’ ’address’ STRING’salary’ FLOAT(’mentor’ STRING)? ’}’; 25
Quantitative Study: Gra2Molrule 'mapDepartment'
from department dto Departmentqueries mElem : /d/department_manager/#employee; eElem : /d/department_employees/#employee; dElem : /d/#department;mappings name = removeQuotes d.STRING; manager = mElem; employees = eElem; subdepts = dElem; end_rule 26
Quantitative Study: CS2AS DSTLmappings {
map Department from department {name := name;manager := department_manager.employee.trace;employees := department_employees.employee.trace; subdepts := deparment.trace;
} }
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Quantitative Study: Inputs Generator
● Nd: No of (top level) departments● Ns: No of subdeparments
○ per departement/subdepartment
● Ne: No of employees○ per departement/subdepartment
● Ds: Depth level of (sub)departments
ID Size (bytes)
Elements Nd Ns Ne Ds
1 1,238 22 3 0 3 1
2 6,105 97 3 3 4 2
3 149,951 701 1 1 3 100
4 42,805 708 1 100 3 2
5 223,848 3061 4 4 5 4
6 1,018,254 11901 10 4 10 4
7 9,794,276 109341 10 5 10 5 28
Quantitative Study: Results
● CS2AS tx execution measured● Overall: 10-fold improvement● Input topology does not impact to
our solution
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