Klint, P. (1994). Writing meta-level specifications in ASF+SDF. Technical Note, CWI, Amsterdam.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....to support very general operations. The cost of this generality is a leaky grammar that defines much more sentences than are actually intended; terms over the language have to be type checked to verify their consistency. The following grammar of generic applicative terms (ATerms) is defined by Klint (1994) to represent parse trees and abstract syntax trees over arbitrary grammars. Literal strings are the basic terms, T 1 T 2 ] denotes application of T 1 to T 2 , nil denotes the empty list and T 1 ; T 2 denotes the concatenation of T 1 and T 2 . module ATerms imports Literals sorts ATerm ....

Klint, P. (1994). Writing meta-level specifications in ASF+SDF. Technical Note, CWI, Amsterdam.

.... ] fELEM ; g Elem [0 9 0 ] ELEM equations [1 ] fSet1 ; Elem; Set2 ; Elem; Set3g = fSet1 ; Elem; Set2 ; Set3g [2 ] union(fSet1g; fSet2g) fSet1 ; Set2g [3 ] elem(Elem; fSet1 ; Elem; Set2g) true [4 ] diff(fSet1 ; Elem; Set1 0 g; fElem; Set2g) diff(fSet1 ; Set1 0 g; fElem; Set2g) [5 ] elem(Elem; fSet1g) 6= true diff(fSet1g; fElem; Set2g) diff(fSet1g; fSet2g) 6 ] diff(fSetg; fg) fSetg [7 ] inter(fSet1g; fSet2g) diff(fSet1g; diff(fSet1g; fSet2g) 2.3 Defining vods In order to define the visual appearance of sets, we first define the appropriate graphical tokens. So, ....

....a homomorphism by selecting the appropriate vods from that set based on sort information and number of parameters required. 5 Discussion For the definition of a mapping tool we need to write meta level specifications, where we define a mapping syntax over two language definition modules. AsFix [5] is specifically designed to write meta level specifications for ASF SDF modules. It uses prefix notation for representing the abstract signature of languages. We can define a tool as defined in 4 using AsFix, which defines such mappings using the AsFix representation for the source and target ....

P. Klint. Writing meta-level specifications in asf+sdf. unpublished document, November 1994.

....implementation of the generator. encoding of trees and graphs. This intermediate format is input for the next phase, the kernel, which translates each context free rule in the SDF specification into one or more formatting functions. These functions are in another intermediate format, called AsFix [Klint 1994], which we use for the internal representation of ASF SDF specifications. The next phase, the AsFix2Box unparser, produces the Box representation of the formatting functions. In this phase the AsFix representation is translated to an ASF SDF specification. The last phase is the Box2ascii backend ....

Klint, P. 1994. Writing meta-level specifications in asf+sdf. Unpublished note.

....specifications as well. Generating Asf Sdf specifications created possibilities for tuning a generated pretty printer. The generator has been used to produce pretty printers for, among others, COBOL [Res94] SEAL error messages [Koo94] and PSF [Bru95] The development of the formalism AsFix [Kli94] yielded another application of the pretty printer technology, viz. a pretty printer which could produce the original Asf Sdf specification given an AsFix specification. Furthermore, the introduction of AsFix led to a redesign of the pretty printer generator, because it was easier to generate ....

....This feature was implemented by extending the box language with the following box operators. context free syntax LBL [ BOX STRING ; BOX ] BOX REF [ BOX STRING ; BOX ] BOX An example of a typeset PSF specification can be found in Figure 11. 3. 6 The AsFix pretty printer AsFix [Kli94] is an intermediate format for Asf Sdf, this formalism is developed in order to be able to write specifications which either generate Asf Sdf specifications or transform Asf Sdf specifications. The last and maybe the most important tool developed on top of the box language is the AsFix pretty ....

P. Klint. Writing meta-level specifications in asf+sdf, 1994.

....obtaining concise, readable, descriptions of tools like typecheckers and compilers for Asf Sdf. AsFix (derived from P. Klint [ AndDef ; TrueDef FalseDef Figure 3: Graph representation of the term true false Asf Sdf preFix representation) is a fixed exchange format for Asf Sdf specifications [Kli94] The overall representation of specifications is made very simple by representing a complete Asf Sdf specification as a single term. This representation is sufficiently self contained to specify, for instance, the complete type checking of Asf Sdf specifications. A generic annotation mechanism ....

P. Klint. Writing meta-level specifications in Asf+Sdf. unpublished note, 1994.

....work has been done already to create a new system in which it will be possible to maintain the system with meta level specifications. This means that Asf Sdf specifications manipulate Asf Sdf specifications. A new fixed exchange format for specifications has been designed to make this possible [Kli94]. This format is called AsFix and is totally defined in an Asf Sdf specification (see Appendix E) Now, an Asf Sdf specification is represented as an AsFix term, containing all the information in recursive or annotational form. Processing a specification is done by processing the AsFix ....

P. Klint. Writing meta-level specifications in asf+sdf. unpublished report, Centrum voor Wiskunde en Informatica (CWI), 1994.

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