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Compact path notation now expands correctly

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Simon Brooke 2021-08-18 18:48:05 +01:00
parent 5c6ac7f75d
commit c63c262b74
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GPG key ID: A7A4F18D1D4DF987
7 changed files with 145 additions and 8 deletions
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97
src/io/read.c
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@ -60,6 +60,77 @@ struct cons_pointer c_quote( struct cons_pointer arg ) {
make_cons( arg, NIL ) );
}
/**
* Read a path macro from the stream. A path macro is expected to be
* 1. optionally a leading character such as '/' or '$', followed by
* 2. one or more keywords with leading colons (':') but no intervening spaces; or
* 3. one or more symbols separated by slashes; or
* 4. keywords (with leading colons) interspersed with symbols (prefixed by slashes).
*/
struct cons_pointer read_path( URL_FILE * input, wint_t initial,
struct cons_pointer q ) {
bool done = false;
struct cons_pointer prefix = NIL;
switch ( initial ) {
case '/':
prefix = c_string_to_lisp_symbol( L"oblist" );
break;
case '$':
case L'§':
prefix = c_string_to_lisp_symbol( L"session" );
break;
}
while ( !done ) {
wint_t c = url_fgetwc( input );
if ( iswblank( c ) || iswcntrl( c ) ) {
done = true;
} else if ( url_feof( input ) ) {
done = true;
} else {
switch ( c ) {
case ':':
q = make_cons( read_symbol_or_key
( input, KEYTV, url_fgetwc( input ) ), q );
break;
case '/':
q = make_cons( make_cons
( c_string_to_lisp_symbol( L"quote" ),
make_cons( read_symbol_or_key
( input, SYMBOLTV,
url_fgetwc( input ) ),
NIL ) ), q );
break;
default:
if ( iswalpha( c ) ) {
q = make_cons( read_symbol_or_key
( input, SYMBOLTV, c ), q );
} else {
// TODO: it's really an error. Exception?
url_ungetwc( c, input );
done = true;
}
}
}
}
// right, we now have the path we want (reversed) in q.
struct cons_pointer r = NIL;
for ( struct cons_pointer p = q; !nilp( p ); p = c_cdr( p ) ) {
r = make_cons( c_car( p ), r );
}
dec_ref( q );
if ( !nilp( prefix ) ) {
r = make_cons( prefix, r );
}
return make_cons( c_string_to_lisp_symbol( L"->" ), r );
}
/**
* Read the next object on this input stream and return a cons_pointer to it,
* treating this initial character as the first character of the object
@ -149,6 +220,27 @@ struct cons_pointer read_continuation( struct stack_frame *frame,
result =
read_symbol_or_key( input, KEYTV, url_fgetwc( input ) );
break;
case '/':
{
/* slash followed by whitespace is legit provided it's not
* preceded by anything - it's the division operator. Otherwise,
* it's terminal, probably part of a path, and needs pushed back.
*/
wint_t cn = url_fgetwc( input );
if ( nilp( result )
&& ( iswblank( cn ) || iswcntrl( cn ) ) ) {
url_ungetwc( cn, input );
result = make_symbol_or_key( c, NIL, SYMBOLTV );
} else {
url_ungetwc( cn, input );
result = read_path( input, c, NIL );
}
}
break;
case '$':
case L'§':
result = read_path( input, c, NIL );
break;
default:
if ( iswdigit( c ) ) {
result =
@ -398,9 +490,10 @@ struct cons_pointer read_symbol_or_key( URL_FILE * input, uint32_t tag,
/* unwise to allow embedded quotation marks in symbols */
case ')':
case ':':
case '/':
/*
* symbols and keywords may not include right-parenthesis
* or colons.
* symbols and keywords may not include right-parenthesis,
* slashes or colons.
*/
result = NIL;
/*