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read: Support R7RS |...| symbol notation.

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* libguile/private-options.h (SCM_R7RS_SYMBOLS_P): New macro.
  (SCM_N_READ_OPTIONS): Increment.

* libguile/read.c (scm_read_opts): Add entry for 'r7rs-symbols'.
  (t_read_opts): Add field for 'r7rs_symbols_p'.
  (scm_read_string_like_syntax): New function based on earlier
  'scm_read_string' that handles either string literals or R7RS quoted
  symbols (delimited by vertical bars), depending on the value of 'chr'.
  (scm_read_string): Reimplement based on 'scm_read_string_like_syntax'.
  (scm_read_r7rs_symbol): New static function.

* doc/ref/api-data.texi (Symbol Read Syntax): Briefly describe the R7RS
  symbol syntax, mention the 'r7rs-symbols' read option, and give some
  examples.

* doc/ref/api-evaluation.texi (Scheme Read): Mention the 'r7rs-symbols'
  read option.

* test-suite/tests/reader.test ("reading"): Add test.
This commit is contained in:
Mark H Weaver 2014-01-12 07:55:22 -05:00
parent b306fae0ab
commit dc59631d30
5 changed files with 58 additions and 10 deletions
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10
doc/ref/api-data.texi
View file

@ -5575,6 +5575,16 @@ Although Guile provides this extended read syntax for symbols,
widespread usage of it is discouraged because it is not portable and not
very readable.
Alternatively, if you enable the @code{r7rs-symbols} read option (see
@pxref{Scheme Read}), you can write arbitrary symbols using the same
notation used for strings, except delimited by vertical bars instead of
double quotes.
@example
|foo bar|
|\x3BB; is a greek lambda|
|\| is a vertical bar|
@end example
@node Symbol Uninterned
@subsubsection Uninterned Symbols

8
doc/ref/api-evaluation.texi
View file

@ -1,7 +1,7 @@
@c -*-texinfo-*-
@c This is part of the GNU Guile Reference Manual.
@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2009, 2010, 2011, 2012, 2013
@c Free Software Foundation, Inc.
@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2009,
@c 2010, 2011, 2012, 2013, 2014 Free Software Foundation, Inc.
@c See the file guile.texi for copying conditions.
@node Read/Load/Eval/Compile
@ -340,6 +340,7 @@ square-brackets yes Treat `[' and `]' as parentheses, for R6RS compatibility
hungry-eol-escapes no In strings, consume leading whitespace after an
escaped end-of-line.
curly-infix no Support SRFI-105 curly infix expressions.
r7rs-symbols no Support R7RS |...| symbol notation.
@end smalllisp
Note that Guile also includes a preliminary mechanism for setting read
@ -377,6 +378,9 @@ For example, to make @code{read} fold all symbols to their lower case
For more information on the effect of the @code{r6rs-hex-escapes} and
@code{hungry-eol-escapes} options, see (@pxref{String Syntax}).
For more information on the @code{r7rs-symbols} option, see
(@pxref{Symbol Read Syntax}).
@node Scheme Write
@subsection Writing Scheme Values

5
libguile/private-options.h
View file

@ -4,7 +4,7 @@
* We put this in a private header, since layout of data structures
* is an implementation detail that we want to hide.
*
* Copyright (C) 2007, 2009, 2010, 2011 Free Software Foundation, Inc.
* Copyright (C) 2007, 2009, 2010, 2011, 2014 Free Software Foundation, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
@ -68,7 +68,8 @@ SCM_INTERNAL scm_t_option scm_read_opts[];
#define SCM_SQUARE_BRACKETS_P scm_read_opts[5].val
#define SCM_HUNGRY_EOL_ESCAPES_P scm_read_opts[6].val
#define SCM_CURLY_INFIX_P scm_read_opts[7].val
#define SCM_R7RS_SYMBOLS_P scm_read_opts[8].val
#define SCM_N_READ_OPTIONS 8
#define SCM_N_READ_OPTIONS 9
#endif /* PRIVATE_OPTIONS */

40
libguile/read.c
View file

@ -88,6 +88,8 @@ scm_t_option scm_read_opts[] =
"In strings, consume leading whitespace after an escaped end-of-line."},
{ SCM_OPTION_BOOLEAN, "curly-infix", 0,
"Support SRFI-105 curly infix expressions."},
{ SCM_OPTION_BOOLEAN, "r7rs-symbols", 0,
"Support R7RS |...| symbol notation."},
{ 0, },
};
@ -113,6 +115,7 @@ struct t_read_opts
unsigned int hungry_eol_escapes_p : 1;
unsigned int curly_infix_p : 1;
unsigned int neoteric_p : 1;
unsigned int r7rs_symbols_p : 1;
};
typedef struct t_read_opts scm_t_read_opts;
@ -588,8 +591,11 @@ skip_intraline_whitespace (SCM port)
scm_ungetc (c, port);
}
/* Read either a double-quoted string or an R7RS-style symbol delimited
by vertical lines, depending on the value of 'chr' ('"' or '|').
Regardless, the result is always returned as a string. */
static SCM
scm_read_string (int chr, SCM port, scm_t_read_opts *opts)
scm_read_string_like_syntax (int chr, SCM port, scm_t_read_opts *opts)
#define FUNC_NAME "scm_lreadr"
{
/* For strings smaller than C_STR, this function creates only one Scheme
@ -603,13 +609,16 @@ scm_read_string (int chr, SCM port, scm_t_read_opts *opts)
long line = SCM_LINUM (port);
int column = SCM_COL (port) - 1;
while ('"' != (c = scm_getc (port)))
while (chr != (c = scm_getc (port)))
{
if (c == EOF)
{
str_eof:
scm_i_input_error (FUNC_NAME, port,
"end of file in string constant", SCM_EOL);
(chr == '|'
? "end of file in symbol"
: "end of file in string constant"),
SCM_EOL);
}
if (c_str_len + 1 >= READER_STRING_BUFFER_SIZE)
@ -624,7 +633,6 @@ scm_read_string (int chr, SCM port, scm_t_read_opts *opts)
{
case EOF:
goto str_eof;
case '"':
case '|':
case '\\':
break;
@ -657,7 +665,7 @@ scm_read_string (int chr, SCM port, scm_t_read_opts *opts)
c = '\010';
break;
case 'x':
if (opts->r6rs_escapes_p)
if (opts->r6rs_escapes_p || chr == '|')
SCM_READ_HEX_ESCAPE (10, ';');
else
SCM_READ_HEX_ESCAPE (2, '\0');
@ -675,6 +683,8 @@ scm_read_string (int chr, SCM port, scm_t_read_opts *opts)
break;
}
default:
if (c == chr)
break;
bad_escaped:
scm_i_input_error (FUNC_NAME, port,
"illegal character in escape sequence: ~S",
@ -700,6 +710,17 @@ scm_read_string (int chr, SCM port, scm_t_read_opts *opts)
}
#undef FUNC_NAME
static SCM
scm_read_string (int chr, SCM port, scm_t_read_opts *opts)
{
return scm_read_string_like_syntax (chr, port, opts);
}
static SCM
scm_read_r7rs_symbol (int chr, SCM port, scm_t_read_opts *opts)
{
return scm_string_to_symbol (scm_read_string_like_syntax (chr, port, opts));
}
static SCM
scm_read_number (scm_t_wchar chr, SCM port, scm_t_read_opts *opts)
@ -1788,6 +1809,11 @@ read_inner_expression (SCM port, scm_t_read_opts *opts)
return (scm_read_sexp (chr, port, opts));
case '"':
return (scm_read_string (chr, port, opts));
case '|':
if (opts->r7rs_symbols_p)
return scm_read_r7rs_symbol (chr, port, opts);
else
return scm_read_mixed_case_symbol (chr, port, opts);
case '\'':
case '`':
case ',':
@ -2204,9 +2230,10 @@ SCM_SYMBOL (sym_port_read_options, "port-read-options");
#define READ_OPTION_SQUARE_BRACKETS_P 10
#define READ_OPTION_HUNGRY_EOL_ESCAPES_P 12
#define READ_OPTION_CURLY_INFIX_P 14
#define READ_OPTION_R7RS_SYMBOLS_P 16
/* The total width in bits of the per-port overrides */
#define READ_OPTIONS_NUM_BITS 16
#define READ_OPTIONS_NUM_BITS 18
#define READ_OPTIONS_INHERIT_ALL ((1UL << READ_OPTIONS_NUM_BITS) - 1)
#define READ_OPTIONS_MAX_VALUE READ_OPTIONS_INHERIT_ALL
@ -2304,6 +2331,7 @@ init_read_options (SCM port, scm_t_read_opts *opts)
RESOLVE_BOOLEAN_OPTION (SQUARE_BRACKETS_P, square_brackets_p);
RESOLVE_BOOLEAN_OPTION (HUNGRY_EOL_ESCAPES_P, hungry_eol_escapes_p);
RESOLVE_BOOLEAN_OPTION (CURLY_INFIX_P, curly_infix_p);
RESOLVE_BOOLEAN_OPTION (R7RS_SYMBOLS_P, r7rs_symbols_p);
#undef RESOLVE_BOOLEAN_OPTION

5
test-suite/tests/reader.test
View file

@ -238,6 +238,11 @@
(with-read-options '(case-insensitive)
(lambda ()
(read-string "GuiLe")))))
(pass-if-equal "r7rs-symbols"
(list 'a (string->symbol "Hello, this is | a \"test\"") 'b)
(with-read-options '(r7rs-symbols)
(lambda ()
(read-string "(a |H\\x65;llo, this is \\| a \"test\"| b)"))))
(pass-if "prefix keywords"
(eq? #:keyword
(with-read-options '(keywords prefix case-insensitive)