Context Navigation

Syntactic Abstraction Code

Syntactic abstraction is a mechanism to support the Fortress language growth. The design of the system is described in our FOOL'09 paper. This page includes a list of the files implementing the syntactic abstraction mechanism with brief comments.

Parser

Fortress grammar for defining new syntax is defined in: trunk/ProjectFortress/src/com/sun/fortress/parser/Syntax.rats

Template parser is extended to add template nodes and ellipses nodes as follows:

trunk/ProjectFortress/src/com/sun/fortress/parser/templateparser/Symbol.rats:
```
transient void DoubleStar = "**";
```

trunk/ProjectFortress/src/com/sun/fortress/parser/templateparser/Identifier.rats:

Id Id += 
     NameGap
   / IdGap
   / <FIRST> ... ;

List<Id> BindIdOrBindIdTuple +=
     BindIdOrBindIdTupleGap
   / <FIRST> ... ;

trunk/ProjectFortress/src/com/sun/fortress/parser/templateparser/Literal.rats:

Expr LiteralExpr +=
     ExprGap
   / LooseJuxtGap
   / SimpleExprGap
   / PrimaryGap
   / LiteralExprGap
   / <VOID> ...;

Expr VoidLiteralExpr +=
     VoidLiteralExprGap
   / <FIRST> ...;

IntLiteralExpr IntLiteralExpr +=
     NumberLiteralExprGap
   / IntLiteralExprGap
   / <FIRST> ...;

CharLiteralExpr CharLiteralExpr +=
     CharLiteralExprGap
   / <FIRST> ...;

StringLiteralExpr StringLiteralExpr +=
     StringLiteralExprGap
   / <FIRST> ... ;

trunk/ProjectFortress/src/com/sun/fortress/parser/templateparser/Expression.rats

Expr ExprFront +=
     ExprGap
   / LooseJuxtGap
   / FnExprGap
   / <Fn> ... ;

Action<Expr> ExprTail += EllipsesExpr / <As> ...;

constant inline Action<Expr> EllipsesExpr =
        w DoubleStar
        { yyValue = new Action<Expr>() {
                public Expr run(Expr base) {
                    return new _EllipsesExpr(NodeFactory.makeExprInfo(createSpan(yyStart,yyCount)), base);
                }};
        };

trunk/ProjectFortress/src/com/sun/fortress/parser/templateparser/NoNewlineExpr.rats:

Action<Expr> ExprTail += NoNewlineEllipsesExpr / <As> ...;

constant inline Action<Expr> NoNewlineEllipsesExpr =
        s DoubleStar
        { yyValue = new Action<Expr>() {
                public Expr run(Expr base) {
			return new _EllipsesExpr(NodeFactory.makeExprInfo(createSpan(yyStart,yyCount)), base);
                }};
	};

trunk/ProjectFortress/src/com/sun/fortress/parser/templateparser/Gaps.rats

Entry Points

There are two entry points to the syntactic abstraction code:

Parser.macroParse by GraphRepository.syntaxExpand: If a given component imports APIs defining new syntax, use parseWithGrammars. Otherwise, use parseFileConvertExn.
GrammarRewriter.rewriteApis by GrammarPhase.execute: If any API defines new syntax, rewrite them.

Parsing Programs with New Syntax (parseWithGrammars)

ParserMaker.parserForComponent: Create a parser from the grammars.
1. GrammarComposer.pegForComponent: Composes grammars together into a flat PEG.
2. ParserMaker.makeParser: Compile a parser given a set of nonterminals and productions.
  1. Turn PEG into a single new module using ComposingSyntaxDefTranslator. Use ArrayUnpacker to handle ellipses nodes.
  2. RatsParserGenerator.generateParser: Given a set of Rats! modules, generate a new Fortress parser extended with the modifications in the given modules.
RatsUtil.getParserObject: Create a Java parser by invoking Rats! and parse the original component with that parser.
Transform.transform: Macro expander. Traverse a given AST node, replacing transformation nodes with the results of their transformer executions, and return a core Fortress AST.
1. SyntaxEnvironment: Environment used for hygienic transformation

Grammar Rewriting (GrammarRewriter.rewriteApis)

ItemDisambiguator: Disambiguate item symbols and rewrite to either nonterminal, keyword or token symbol.
Disambiguate nonterminal parameters. (Not yet done)
WhitespaceElimination: Remove whitespace where indicated by no-whitespace symbols.
EscapeRewriter: Rewrite escaped symbols.
ExtensionDesugarer: Desugar extensions: fill in unmentioned imported grammars and collect multiple extensions of same nonterminal together.
RewriteTransformerNames: Rewrite transformer names.
TemplateParser: Parse pretemplates and replace with real templates.
1. TemplateVarRewriter: Rewrite all occurrences of variables in a given template to occurrences of gaps using BaseTypeCollector.

Other Code

Utilities