forked from GitHub/gf-core
58cd043fa8
This patch fixes a problem introduced last year when the GF shell was
refactored to allow more commands to be treated uniformly and be part
of pipes. The cc command was one of those commands, but unfortunately this
introduced a parsing problem, e.g.
> cc "last"
constant not found: last
> cc "last"++"year"
command not parsed: cc "last"++"year"
This happened because the generic command line parser in
GF.Command.{Abstract,Parse} assumes that all commands have an argument of
type PGF.Expr. Commands that expect other types of arguments have to
use PGF.showExpr combined with other conversion to the argument type they
expect. The cc command excpets a GF.Grammar.Term, and unfortunately not
all terms survice the roundtrip through PGF.Expr, in part because of
an additional hack to allow strings to be roundtripped through PGF.Expr
without adding superfluous double quotes.
To solve the problem, this patch
+ makes room for arguments of type Term in the Argument type in
GF.Command.Abstract.
+ makes a special case for the cc command in GF.Command.Parse, by
calling the partial parser 'runPartial pTerm' recently added in
GF.Grammar.Lexer and GF.Grammar.Parser. Care was taken so that
that "|" and ";" can be used both inside terms and as separators between
commands in the shell, e.g. things like the following now work:
> cc ("a"|"b") | ps -lexcode
variants { "a" ; "b" }
+ introduces a type CommandArgument that replaces [Expr] as the
type of values passed between commands in pipes. It has room for
values of type [Expr], [String] and Term, thus eliminating the need
to roundtrip through the Expr type all the time.
The hack to avoid adding superfluous quotes when strings are
roundtripped through Expr has been left in place for now,
but can probably be removed.
DESCRIPTION
The Grammatical Framework (=GF) is a grammar formalism based on type theory.
It consists of
* a special-purpose programming language
* a compiler of the language
* a generic grammar processor
The compiler reads GF grammars from user-provided files, and the
generic grammar processor performs various tasks with the grammars:
* generation
* parsing
* translation
* type checking
* computation
* paraphrasing
* random generation
* syntax editing
GF particularly addresses four aspects of grammars:
* multilinguality (parallel grammars for different languages)
* semantics (semantic conditions of well-formedness, semantic
properties of expressions)
* grammar engineering (modularity, abstractions, libraries)
* embeddability in programs written in other languages (C,C++,
Haskell, Java, JavaScript)
COMPILATION and INSTALLATION of source distribution:
See download/index.html for installation instructions.
(More details can be found in doc/gf-developers.html.)