From d4e28e67526f1f715198bba3f2dea4dab2fbc20a Mon Sep 17 00:00:00 2001 From: Chris Hanson Date: Tue, 20 Nov 2001 22:27:55 +0000 Subject: [PATCH] Write first draft of parser-macro section. --- v7/doc/ref-manual/scheme.texinfo | 72 +++++++++++++++++++++++++++++--- 1 file changed, 66 insertions(+), 6 deletions(-) diff --git a/v7/doc/ref-manual/scheme.texinfo b/v7/doc/ref-manual/scheme.texinfo index e78522547..472be4518 100644 --- a/v7/doc/ref-manual/scheme.texinfo +++ b/v7/doc/ref-manual/scheme.texinfo @@ -2,7 +2,7 @@ @iftex @finalout @end iftex -@comment $Id: scheme.texinfo,v 1.105 2001/11/20 21:48:04 cph Exp $ +@comment $Id: scheme.texinfo,v 1.106 2001/11/20 22:27:55 cph Exp $ @comment %**start of header (This is for running Texinfo on a region.) @setfilename scheme.info @settitle MIT Scheme Reference @@ -14688,30 +14688,90 @@ language. @node Parser-language Macros, , *Parser, Parser Language @subsection Parser-language Macros +The parser and matcher languages provide a macro facility so that +common patterns can be abstracted. The macro facility allows new +expression types to be independently defined in the two languages. +The macros are defined in heirarchically organized tables, so that +different applications can have private macro bindings. + @deffn {special form} define-*matcher-macro formals expression @deffnx {special form} define-*parser-macro formals expression +These special forms are used to define macros in the matcher and +parser language, respectively. @var{Formals} is like the +@var{formals} list of a @code{define} special form, and +@var{expression} is a Scheme expression. + +If @var{formals} is a list (or improper list) of symbols, the first +symbol in the list is the name of the macro, and the remaining symbols +are interpreted as the @var{formals} of a lambda expression. A lambda +expression is formed by combining the latter @var{formals} with the +@var{expression}, and this lambda expression, when evaluated, becomes +the @dfn{expander}. The defined macro accepts the same number of +operands as the expander. A macro instance is expanded by applying +the expander to the list of operands; the result of the application is +interpreted as a replacement expression for the macro instance. + +If @var{formals} is a symbol, it is the name of the macro. In this +case, the expander is a procedure of no arguments whose body is +@var{expression}. When the @var{formals} symbol appears by itself as +an expression in the language, the expander is called with no +arguments, and the result is interpreted as a replacement expression +for the symbol. @end deffn @deffn procedure define-*matcher-expander identifier expander @deffnx procedure define-*parser-expander identifier expander +These procedures provide a procedural interface to the +macro-definition mechanism. @var{Identifier} must be a symbol, and +@var{expander} must be an expander procedure, as defined above. +Instances of the @code{define-*matcher-macro} and +@code{define-*parser-macro} special forms expand into calls to these +procedures. @end deffn -@deffn procedure make-parser-macros parent-macros +The remaining procedures define the interface to the parser-macros +table abstraction. Each parser-macro table has a separate binding +space for macros in the matcher and parser languages. However, the +table inherits bindings from one specified table; it's not possible to +inherit matcher-language bindings from one table and parser-language +bindings from another. + +@deffn procedure make-parser-macros parent-table +Create and return a new parser-macro table that inherits from +@var{parent-table}. @var{Parent-table} must be either a parser-macro +table, or @code{#f}; usually it is specified as the value of +@code{global-parser-macros}. @end deffn @deffn procedure parser-macros? object +This is a predicate for parser-macro tables. @end deffn -@deffn procedure current-parser-macros +@deffn procedure global-parser-macros +Return the global parser-macro table. This table is predefined and +contains all of the bindings documented here. @end deffn -@deffn procedure global-parser-macros +There is a ``current'' table at all times, and macro definitions are +always placed in this table. By default, the current table is the +global macro table, but the following procedures allow this to be +changed. + +@deffn procedure current-parser-macros +Return the current parser-macro table. @end deffn -@deffn procedure set-current-parser-macros! macros +@deffn procedure set-current-parser-macros! table +Change the current parser-macro table to @var{table}, which must +satisfy @code{parser-macros?}. @end deffn -@deffn procedure with-current-parser-macros macros thunk +@deffn procedure with-current-parser-macros table thunk +Bind the current parser-macro table to @var{table}, call @var{thunk} +with no arguments, then restore the original table binding. The value +returned by @var{thunk} is the returned as the value of this +procedure. @var{Table} must satisfy @code{parser-macros?}, and +@var{thunk} must be a procedure of no arguments. @end deffn @node Operating-System Interface, Error System, Input/Output, Top -- 2.25.1