Careful debugging of the memory leak problem. At this stage,
stack frames for interpreted (but not primitive) functions appear not to be being reclaimed, and the oblist doesn't seem to be being fully reclaimed.
This commit is contained in:
parent
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14 changed files with 156 additions and 50 deletions
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@ -1,3 +1,5 @@
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# Implementing Post Scarcity Hardware
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The address space hinted at by using 64 bit cons-space and a 64 bit vector space containing objects each of whose length may be up to 1.4e20 bytes (2^64 of 64 bit words) is so large that a completely populated post-scarcity hardware machine can probably never be built. But that doesn't mean I'm wrong to specify such an address space: if we can make this architecture work for machines that can't (yet, anyway) be built, it will work for machines that can; and, changing the size of the pointers, which one might wish to do for storage economy, can be done with a few edits to consspaceobject.h.
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But, for the moment, let's discuss a potential 32 bit psh machine, and how it might be built.
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@ -1,5 +1,57 @@
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# State of Play
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## 20260220
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### State of the build
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The only unit tests that are failing now are the bignum tests, which I have
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consciously parked as a future problem, and the memory leak, similarly. The
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leak is a lot less bad than it was, but I'm worried that stack frames
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are not being freed.
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If you run
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```
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cat lisp/fact.lisp | target/psse -d 2>&1 |\
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grep 'Vector space object of type' | sort | uniq -c | sort -rn
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```
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you get a huge number (currently 394) of stack frames in the memory dump; they
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should all have been reclaimed. There's other stuff in the memory dump as well,
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```
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422 CONS ;; cons cells, obviously
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394 VECP ;; pointers to vector space objects -- specifically, the stack frames
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335 SYMB ;; symbols
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149 INTR ;; integers
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83 STRG ;; strings
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46 FUNC ;; primitive (i.e. written in C) functions
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25 KEYW ;; keywords
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10 SPFM ;; primitive special forms
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3 WRIT ;; write streams: `*out*`, `*log*`, `*sink*`
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1 TRUE ;; t
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1 READ ;; read stream: `*in*`
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1 NIL ;; nil
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1 LMDA ;; lambda function, specifically `fact`
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```
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Generally, for each character in a string, symbol or keyword there will be one
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cell (`STRG`, `SYMB`, or `KEYW`) cell, so the high number of STRG cells is not
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especially surprising. It looks as though none of the symbols bound in the
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oblist are being recovered on exit, which is undesirable but not catastrophic,
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since it's a fixed burden of memory which isn't expanding.
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But the fact that stack frames aren't being reclaimed is serious.
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### Update, 19:31
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Right, investigating this more deeply, I found that `make_empty_frame` was doing
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an `inc_ref` it should not have been, Having fixed that I'm down to 27 frames
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left in the dump. That's very close to the number which will be generated by
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running `(fact 25)`, so I expect it is now only stack frames for interpreted
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functions which are not being reclaimed. This give me something to work on!
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## 20260215
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Both of yesterday's regressions are fixed. Memory problem still in much the
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@ -14,8 +66,8 @@ It burned through 74 cons pages each of 1,024 cons cells, total 76,800 cells,
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and 19,153 stack frames. before it got there; and then threw the exception back
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up through each of those 19,153 stack frames. But the actual exception message
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was `Unrecognised tag value 0 ( )`, which is not enormously helpful.
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However, once I had recognised what the problem was, it was quickly fixed, with
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S
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However, once I had recognised what the problem was, it was quickly fSixed, with
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the added bonus that the new solution will automatically work for bignum
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fractions once bignums are working.
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@ -1,9 +1,9 @@
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(set! symbolp (lambda (x) (equal (type x) "SYMB")))
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(set! symbol? (lambda (x) (equal (type x) "SYMB")))
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(set! defun!
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(nlambda
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form
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(cond ((symbolp (car form))
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(cond ((symbol? (car form))
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(set (car form) (apply 'lambda (cdr form))))
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(t nil))))
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@ -17,7 +17,7 @@
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(set! defsp!
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(nlambda
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form
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(cond (symbolp (car form))
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(cond (symbol? (car form))
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(set! (car form) (apply nlambda (cdr form))))))
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(defsp! cube (x) ((* x x x)))
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@ -4,6 +4,6 @@
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(cond ((= n 1) 1)
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(t (* n (fact (- n 1)))))))
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; (fact 1000)
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(fact 25)
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@ -138,7 +138,7 @@ struct cons_pointer acquire_integer( int64_t value, struct cons_pointer more ) {
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if ( !small_int_cache_initialised ) {
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for ( int64_t i = 0; i < SMALL_INT_LIMIT; i++ ) {
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small_int_cache[i] = make_integer( i, NIL );
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pointer2cell( small_int_cache[i] ).count = UINT32_MAX; // lock it in so it can't be GC'd
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pointer2cell( small_int_cache[i] ).count = MAXREFERENCE; // lock it in so it can't be GC'd
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}
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small_int_cache_initialised = true;
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debug_print( L"small_int_cache initialised.\n", DEBUG_ALLOC );
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15
src/init.c
15
src/init.c
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@ -185,6 +185,7 @@ void print_options( FILE *stream ) {
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L"\t-d\tDump memory to standard out at end of run (copious!);\n" );
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fwprintf( stream, L"\t-h\tPrint this message and exit;\n" );
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fwprintf( stream, L"\t-p\tShow a prompt (default is no prompt);\n" );
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#ifdef DEBUG
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fwprintf( stream,
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L"\t-v LEVEL\n\t\tSet verbosity to the specified level (0...512)\n" );
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fwprintf( stream, L"\t\tWhere bits are interpreted as follows:\n" );
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@ -197,6 +198,7 @@ void print_options( FILE *stream ) {
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fwprintf( stream, L"\t\t64\tLAMBDA;\n" );
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fwprintf( stream, L"\t\t128\tREPL;\n" );
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fwprintf( stream, L"\t\t256\tSTACK.\n" );
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#endif
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}
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/**
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@ -384,14 +386,19 @@ int main( int argc, char *argv[] ) {
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repl( show_prompt );
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debug_dump_object( oblist, DEBUG_BOOTSTRAP );
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debug_print( L"Freeing oblist\n", DEBUG_BOOTSTRAP );
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while ( (pointer2cell(oblist)).count > 0) {
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fprintf( stderr, "Dangling refs on oblist: %d\n", (pointer2cell(oblist)).count );
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dec_ref( oblist );
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}
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free_init_symbols( );
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if ( dump_at_end ) {
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dump_pages( file_to_url_file( stdout ) );
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}
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debug_print( L"Freeing oblist\n", DEBUG_BOOTSTRAP );
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dec_ref( oblist );
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free_init_symbols( );
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summarise_allocation( );
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curl_global_cleanup( );
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return ( 0 );
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@ -116,6 +116,9 @@ void print_vso( URL_FILE *output, struct cons_pointer pointer ) {
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case HASHTV:
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print_map( output, pointer );
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break;
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case STACKFRAMETV:
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dump_stack_trace( output, pointer);
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break;
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// \todo: others.
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default:
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fwprintf( stderr, L"Unrecognised vector-space type '%d'\n",
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@ -126,9 +126,12 @@ void dump_pages( URL_FILE *output ) {
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url_fwprintf( output, L"\nDUMPING PAGE %d\n", i );
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for ( int j = 0; j < CONSPAGESIZE; j++ ) {
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dump_object( output, ( struct cons_pointer ) {
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i, j
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} );
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struct cons_pointer pointer = ( struct cons_pointer ) { i, j};
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if (!freep( pointer)) {
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dump_object( output, ( struct cons_pointer ) {
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i, j
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} );
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}
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}
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}
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}
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@ -64,6 +64,14 @@ struct cons_pointer inc_ref( struct cons_pointer pointer ) {
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if ( cell->count < MAXREFERENCE ) {
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cell->count++;
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#ifdef DEBUG
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debug_printf( DEBUG_ALLOC, L"\nIncremented cell of type %4.4s at page %d, offset %d to count %d", ((char *)cell->tag.bytes), pointer.page, pointer.offset, cell->count);
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if ( strncmp( cell->tag.bytes, VECTORPOINTTAG, TAGLENGTH) == 0) {
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debug_printf( DEBUG_ALLOC, L"; pointer to vector object of type %4.4s.\n", ((char *)(cell->payload.vectorp.tag.bytes)));
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} else {
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debug_println( DEBUG_ALLOC);
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}
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#endif
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}
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return pointer;
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@ -82,6 +90,14 @@ struct cons_pointer dec_ref( struct cons_pointer pointer ) {
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if ( cell->count > 0 && cell->count != UINT32_MAX ) {
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cell->count--;
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#ifdef DEBUG
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debug_printf( DEBUG_ALLOC, L"\nDecremented cell of type %4.4s at page %d, offset %d to count %d", ((char *)cell->tag.bytes), pointer.page, pointer.offset, cell->count);
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if ( strncmp( (char *)cell->tag.bytes, VECTORPOINTTAG, TAGLENGTH) == 0) {
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debug_printf( DEBUG_ALLOC, L"; pointer to vector object of type %4.4s.\n", ((char *)(cell->payload.vectorp.tag.bytes)));
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} else {
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debug_println( DEBUG_ALLOC);
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}
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#endif
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if ( cell->count == 0 ) {
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free_cell( pointer );
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@ -320,7 +336,7 @@ struct cons_pointer make_string_like_thing( wint_t c, struct cons_pointer tail,
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} else {
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// \todo should throw an exception!
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debug_printf( DEBUG_ALLOC,
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L"Warning: only NIL and %4.4s can be prepended to %4.4s\n",
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L"Warning: only %4.4s can be prepended to %4.4s\n",
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tag, tag );
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}
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@ -312,6 +312,11 @@
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*/
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#define exceptionp(conspoint) (check_tag(conspoint,EXCEPTIONTV))
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/**
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* true if `conspoint` points to an unassigned cell, else false
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*/
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#define freep(conspoint) (check_tag(conspoint,FREETV))
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/**
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* true if `conspoint` points to a function cell, else false
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*/
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@ -13,6 +13,8 @@
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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/*
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* wide characters
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*/
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#include "memory/conspage.h"
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#include "memory/consspaceobject.h"
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#include "debug.h"
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#include "io/io.h"
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#include "memory/hashmap.h"
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#include "memory/stack.h"
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#include "memory/vectorspace.h"
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@ -123,7 +126,8 @@ struct cons_pointer make_vso( uint32_t tag, uint64_t payload_size ) {
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void free_vso( struct cons_pointer pointer ) {
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struct cons_space_object cell = pointer2cell( pointer );
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debug_printf( DEBUG_ALLOC, L"About to free vector-space object at 0x%lx\n",
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debug_printf( DEBUG_ALLOC, L"About to free vector-space object of type %s at 0x%lx\n",
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(char *) cell.payload.vectorp.tag.bytes,
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cell.payload.vectorp.address );
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struct vector_space_object *vso = cell.payload.vectorp.address;
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@ -214,9 +214,9 @@ bool equal_number_number( struct cons_pointer a, struct cons_pointer b ) {
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case RATIOTV:
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switch ( cell_b->tag.value ) {
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case INTEGERTV:
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/* as all ratios are simplified by make_ratio, any
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/* as ratios are simplified by make_ratio, any
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* ratio that would simplify to an integer is an
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* integer, */
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* integer, TODO: no longer always true. */
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result = false;
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break;
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case REALTV:
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@ -278,6 +278,12 @@ bool equal( struct cons_pointer a, struct cons_pointer b ) {
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/* TODO: it is not OK to do this on the stack since list-like
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* structures can be of indefinite extent. It *must* be done by
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* iteration (and even that is problematic) */
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#ifdef DEBUG
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debug_print( L"Comparing '", DEBUG_ARITH);
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debug_print_object( a, DEBUG_ARITH);
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debug_print( L"' to '", DEBUG_ARITH);
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debug_print_object( b, DEBUG_ARITH);
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#endif
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result =
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cell_a->payload.string.hash == cell_b->payload.string.hash
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&& cell_a->payload.string.character ==
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@ -18,6 +18,7 @@
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*/
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#include <stdbool.h>
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#include <string.h>
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/*
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* wide characters
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*/
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@ -309,7 +310,7 @@ internedp( struct cons_pointer key, struct cons_pointer store ) {
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debug_print( L"`", DEBUG_BIND );
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debug_print_object( key, DEBUG_BIND );
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debug_print( L"` is a ", DEBUG_BIND );
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debug_print_object( c_type( key ), DEBUG_BIND );
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debug_printf( DEBUG_BIND, L"%4.4s", (char *)pointer2cell(key).tag.bytes);
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debug_print( L", not a KEYW or SYMB", DEBUG_BIND );
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}
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@ -361,7 +362,7 @@ struct cons_pointer c_assoc( struct cons_pointer key,
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result = hashmap_get( store, key );
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} else if ( !nilp( store ) ) {
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debug_print( L"c_assoc; store is of unknown type `", DEBUG_BIND );
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debug_print_object( c_type( store ), DEBUG_BIND );
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debug_printf( DEBUG_BIND, L"%4.4s", (char *)pointer2cell(key).tag.bytes);
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debug_print( L"`\n", DEBUG_BIND );
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result =
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throw_exception( c_append
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@ -398,8 +399,8 @@ struct cons_pointer hashmap_put( struct cons_pointer mapp,
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// hashmap to a bigger number of buckets, and return that.
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map->payload.hashmap.buckets[bucket_no] =
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inc_ref( make_cons( make_cons( key, val ),
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map->payload.hashmap.buckets[bucket_no] ) );
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make_cons( make_cons( key, val ),
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map->payload.hashmap.buckets[bucket_no] );
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}
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return mapp;
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@ -413,6 +414,7 @@ struct cons_pointer set( struct cons_pointer key, struct cons_pointer value,
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struct cons_pointer store ) {
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struct cons_pointer result = NIL;
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#ifdef DEBUG
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debug_print( L"set: binding `", DEBUG_BIND );
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debug_print_object( key, DEBUG_BIND );
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debug_print( L"` to `", DEBUG_BIND );
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@ -421,8 +423,15 @@ struct cons_pointer set( struct cons_pointer key, struct cons_pointer value,
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debug_dump_object( store, DEBUG_BIND );
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debug_println( DEBUG_BIND );
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debug_printf( DEBUG_BIND, L"set: store is %s\n`",
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lisp_string_to_c_string( c_type( store ) ) );
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debug_printf( DEBUG_BIND, L"set: store is %4.4s",
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pointer2cell(store).tag.bytes );
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if (strncmp(pointer2cell(store).tag.bytes, VECTORPOINTTAG, TAGLENGTH) == 0) {
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debug_printf( DEBUG_BIND, L" -> %4.4s\n",
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pointer2cell(store).payload.vectorp.tag.bytes );
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} else {
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debug_println( DEBUG_BIND);
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}
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#endif
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if ( nilp( value ) ) {
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result = store;
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} else if ( nilp( store ) || consp( store ) ) {
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@ -440,8 +449,7 @@ struct cons_pointer set( struct cons_pointer key, struct cons_pointer value,
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}
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/**
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* @brief Binds this key to this value in the global oblist.
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* @brief Binds this `key` to this `value` in the global oblist, and returns the `key`.
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*/
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struct cons_pointer
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deep_bind( struct cons_pointer key, struct cons_pointer value ) {
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@ -92,7 +92,7 @@ struct cons_pointer eval_form( struct stack_frame *parent,
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{
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struct cons_pointer next_pointer =
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make_empty_frame( parent_pointer );
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inc_ref( next_pointer );
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// inc_ref( next_pointer );
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struct stack_frame *next = get_stack_frame( next_pointer );
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set_reg( next, 0, form );
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@ -362,7 +362,7 @@ c_apply( struct stack_frame *frame, struct cons_pointer frame_pointer,
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struct cons_pointer exep = NIL;
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struct cons_pointer next_pointer =
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make_stack_frame( frame_pointer, args, env );
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inc_ref( next_pointer );
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// inc_ref( next_pointer );
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if ( exceptionp( next_pointer ) ) {
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result = next_pointer;
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} else {
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@ -391,7 +391,7 @@ c_apply( struct stack_frame *frame, struct cons_pointer frame_pointer,
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struct cons_pointer exep = NIL;
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struct cons_pointer next_pointer =
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make_stack_frame( frame_pointer, args, env );
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inc_ref( next_pointer );
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// inc_ref( next_pointer );
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if ( exceptionp( next_pointer ) ) {
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result = next_pointer;
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} else {
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@ -424,7 +424,7 @@ c_apply( struct stack_frame *frame, struct cons_pointer frame_pointer,
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{
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struct cons_pointer next_pointer =
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make_special_frame( frame_pointer, args, env );
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inc_ref( next_pointer );
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// inc_ref( next_pointer );
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if ( exceptionp( next_pointer ) ) {
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result = next_pointer;
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} else {
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@ -1269,7 +1269,6 @@ struct cons_pointer lisp_repl( struct stack_frame *frame,
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struct cons_pointer input = get_default_stream( true, env );
|
||||
struct cons_pointer output = get_default_stream( false, env );
|
||||
// struct cons_pointer prompt_name = c_string_to_lisp_symbol( L"*prompt*" );
|
||||
struct cons_pointer old_oblist = oblist;
|
||||
struct cons_pointer new_env = env;
|
||||
|
||||
|
|
@ -1342,6 +1341,7 @@ struct cons_pointer lisp_repl( struct stack_frame *frame,
|
|||
if ( exceptionp( expr )
|
||||
&& url_feof( pointer2cell( input ).payload.stream.stream ) ) {
|
||||
/* suppress printing end of stream exception */
|
||||
dec_ref( expr);
|
||||
break;
|
||||
}
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue