705 lines
22 KiB
C
705 lines
22 KiB
C
/*
|
|
* lispops.c
|
|
*
|
|
* List processing operations.
|
|
*
|
|
* The general idea here is that a list processing operation is a
|
|
* function which takes two arguments, both cons_pointers:
|
|
*
|
|
* 1. args, the argument list to this function;
|
|
* 2. env, the environment in which this function should be evaluated;
|
|
*
|
|
* and returns a cons_pointer, the result.
|
|
*
|
|
* They must all have the same signature so that I can call them as
|
|
* function pointers.
|
|
*
|
|
* (c) 2017 Simon Brooke <simon@journeyman.cc>
|
|
* Licensed under GPL version 2.0, or, at your option, any later version.
|
|
*/
|
|
|
|
#include <ctype.h>
|
|
#include <stdbool.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
|
|
#include "consspaceobject.h"
|
|
#include "conspage.h"
|
|
#include "equal.h"
|
|
#include "integer.h"
|
|
#include "intern.h"
|
|
#include "lispops.h"
|
|
#include "print.h"
|
|
#include "read.h"
|
|
#include "stack.h"
|
|
|
|
/*
|
|
* also to create in this section:
|
|
* struct cons_pointer lisp_let( struct cons_pointer args, struct cons_pointer env,
|
|
struct stack_frame* frame);
|
|
* struct cons_pointer lisp_mapcar( struct cons_pointer args, struct cons_pointer env,
|
|
struct stack_frame* frame);
|
|
*
|
|
* and others I haven't thought of yet.
|
|
*/
|
|
|
|
/**
|
|
* Implementation of car in C. If arg is not a cons, does not error but returns nil.
|
|
*/
|
|
struct cons_pointer c_car( struct cons_pointer arg ) {
|
|
struct cons_pointer result = NIL;
|
|
|
|
if ( consp( arg ) ) {
|
|
result = pointer2cell( arg ).payload.cons.car;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* Implementation of cdr in C. If arg is not a cons, does not error but returns nil.
|
|
*/
|
|
struct cons_pointer c_cdr( struct cons_pointer arg ) {
|
|
struct cons_pointer result = NIL;
|
|
|
|
if ( consp( arg ) ) {
|
|
result = pointer2cell( arg ).payload.cons.cdr;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
/**
|
|
* Useful building block; evaluate this single form in the context of this
|
|
* parent stack frame and this environment.
|
|
* @param parent the parent stack frame.
|
|
* @param form the form to be evaluated.
|
|
* @param env the evaluation environment.
|
|
* @return the result of evaluating the form.
|
|
*/
|
|
struct cons_pointer eval_form( struct stack_frame *parent,
|
|
struct cons_pointer form,
|
|
struct cons_pointer env ) {
|
|
fputws( L"eval_form: ", stderr );
|
|
print( stderr, form );
|
|
fputws( L"\n", stderr );
|
|
|
|
struct cons_pointer result = NIL;
|
|
struct stack_frame *next = make_empty_frame( parent, env );
|
|
next->arg[0] = form;
|
|
inc_ref( next->arg[0] );
|
|
result = lisp_eval( next, env );
|
|
|
|
if (!exceptionp( result)) {
|
|
/* if we're returning an exception, we should NOT free the
|
|
* stack frame. Corollary is, when we free an exception, we
|
|
* should free all the frames it's holding on to. */
|
|
free_stack_frame( next );
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* eval all the forms in this `list` in the context of this stack `frame`
|
|
* and this `env`, and return a list of their values. If the arg passed as
|
|
* `list` is not in fact a list, return nil.
|
|
*/
|
|
struct cons_pointer eval_forms( struct stack_frame *frame,
|
|
struct cons_pointer list,
|
|
struct cons_pointer env ) {
|
|
return consp( list ) ?
|
|
make_cons( eval_form( frame, c_car( list ), env ), eval_forms( frame, c_cdr( list), env)) :
|
|
NIL;
|
|
}
|
|
|
|
|
|
/**
|
|
* used to construct the body for `lambda` and `nlambda` expressions.
|
|
*/
|
|
struct cons_pointer compose_body( struct stack_frame *frame ) {
|
|
struct cons_pointer body =
|
|
!nilp( frame->arg[args_in_frame - 1] ) ? frame->more : NIL;
|
|
|
|
for ( int i = args_in_frame - 1; i >= 0; i-- ) {
|
|
if ( !nilp( frame->arg[i] ) ) {
|
|
body = make_cons( frame->arg[i], body );
|
|
}
|
|
}
|
|
|
|
return body;
|
|
}
|
|
|
|
/**
|
|
* Construct an interpretable function.
|
|
*
|
|
* @param frame the stack frame in which the expression is to be interpreted;
|
|
* @param env the environment in which it is to be intepreted.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_lambda( struct stack_frame *frame, struct cons_pointer env ) {
|
|
return make_lambda( frame->arg[0], compose_body( frame ) );
|
|
}
|
|
|
|
/**
|
|
* Construct an interpretable special form.
|
|
*
|
|
* @param frame the stack frame in which the expression is to be interpreted;
|
|
* @param env the environment in which it is to be intepreted.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_nlambda( struct stack_frame *frame, struct cons_pointer env ) {
|
|
return make_nlambda( frame->arg[0], compose_body( frame ) );
|
|
}
|
|
|
|
void log_binding( struct cons_pointer name, struct cons_pointer val ) {
|
|
print( stderr, c_string_to_lisp_string( "\n\tBinding " ) );
|
|
print( stderr, name );
|
|
print( stderr, c_string_to_lisp_string( " to " ) );
|
|
print( stderr, val );
|
|
fputws( L"\"\n", stderr );
|
|
}
|
|
|
|
/**
|
|
* Evaluate a lambda or nlambda expression.
|
|
*/
|
|
struct cons_pointer
|
|
eval_lambda( struct cons_space_object cell, struct stack_frame *frame,
|
|
struct cons_pointer env ) {
|
|
struct cons_pointer result = NIL;
|
|
fwprintf( stderr, L"eval_lambda called" );
|
|
|
|
struct cons_pointer new_env = env;
|
|
struct cons_pointer names = cell.payload.lambda.args;
|
|
struct cons_pointer body = cell.payload.lambda.body;
|
|
|
|
if ( consp( names ) ) {
|
|
/* if `names` is a list, bind successive items from that list
|
|
* to values of arguments */
|
|
for ( int i = 0; i < args_in_frame && consp( names ); i++ ) {
|
|
struct cons_pointer name = c_car( names );
|
|
struct cons_pointer val = frame->arg[i];
|
|
|
|
new_env = bind( name, val, new_env );
|
|
log_binding( name, val );
|
|
|
|
names = c_cdr( names );
|
|
}
|
|
} else if ( symbolp( names ) ) {
|
|
/* if `names` is a symbol, rather than a list of symbols,
|
|
* then bind a list of the values of args to that symbol. */
|
|
struct cons_pointer vals = frame->more;
|
|
|
|
for ( int i = args_in_frame - 1; i >= 0; i-- ) {
|
|
struct cons_pointer val = eval_form( frame, frame->arg[i], env );
|
|
|
|
if ( nilp( val ) && nilp( vals ) ) { /* nothing */
|
|
} else {
|
|
vals = make_cons( val, vals );
|
|
}
|
|
}
|
|
|
|
new_env = bind( names, vals, new_env );
|
|
}
|
|
|
|
while ( !nilp( body ) ) {
|
|
struct cons_pointer sexpr = c_car( body );
|
|
body = c_cdr( body );
|
|
fputws( L"In lambda: ", stderr );
|
|
result = eval_form( frame, sexpr, new_env );
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
/**
|
|
* Internal guts of apply.
|
|
* @param frame the stack frame, expected to have only one argument, a list
|
|
* comprising something that evaluates to a function and its arguments.
|
|
* @param env The evaluation environment.
|
|
* @return the result of evaluating the function with its arguments.
|
|
*/
|
|
struct cons_pointer
|
|
c_apply( struct stack_frame *frame, struct cons_pointer env ) {
|
|
struct cons_pointer result = NIL;
|
|
|
|
struct stack_frame *fn_frame = make_empty_frame( frame, env );
|
|
fn_frame->arg[0] = c_car( frame->arg[0] );
|
|
inc_ref( fn_frame->arg[0] );
|
|
struct cons_pointer fn_pointer = lisp_eval( fn_frame, env );
|
|
|
|
if (!exceptionp( result)) {
|
|
/* if we're returning an exception, we should NOT free the
|
|
* stack frame. Corollary is, when we free an exception, we
|
|
* should free all the frames it's holding on to. */
|
|
free_stack_frame( fn_frame );
|
|
}
|
|
|
|
struct cons_space_object fn_cell = pointer2cell( fn_pointer );
|
|
struct cons_pointer args = c_cdr( frame->arg[0] );
|
|
|
|
switch ( fn_cell.tag.value ) {
|
|
case EXCEPTIONTV:
|
|
/* just pass exceptions straight back */
|
|
result = fn_pointer;
|
|
break;
|
|
case FUNCTIONTV:
|
|
{
|
|
struct stack_frame *next =
|
|
make_stack_frame( frame, args, env );
|
|
result = ( *fn_cell.payload.special.executable ) ( next, env );
|
|
if (!exceptionp( result)) {
|
|
/* if we're returning an exception, we should NOT free the
|
|
* stack frame. Corollary is, when we free an exception, we
|
|
* should free all the frames it's holding on to. */
|
|
free_stack_frame( next );
|
|
}
|
|
}
|
|
break;
|
|
case LAMBDATV:
|
|
{
|
|
struct stack_frame *next =
|
|
make_stack_frame( frame, args, env );
|
|
fputws( L"Stack frame for lambda\n", stderr );
|
|
dump_frame( stderr, next );
|
|
result = eval_lambda( fn_cell, next, env );
|
|
if (!exceptionp( result)) {
|
|
/* if we're returning an exception, we should NOT free the
|
|
* stack frame. Corollary is, when we free an exception, we
|
|
* should free all the frames it's holding on to. */
|
|
free_stack_frame( next );
|
|
}
|
|
}
|
|
break;
|
|
case NLAMBDATV:
|
|
{
|
|
struct stack_frame *next =
|
|
make_special_frame( frame, args, env );
|
|
result = ( *fn_cell.payload.special.executable ) ( next, env );
|
|
if (!exceptionp( result)) {
|
|
/* if we're returning an exception, we should NOT free the
|
|
* stack frame. Corollary is, when we free an exception, we
|
|
* should free all the frames it's holding on to. */
|
|
free_stack_frame( next );
|
|
}
|
|
}
|
|
break;
|
|
case SPECIALTV:
|
|
{
|
|
struct stack_frame *next =
|
|
make_special_frame( frame, args, env );
|
|
result = ( *fn_cell.payload.special.executable ) ( next, env );
|
|
if (!exceptionp( result)) {
|
|
/* if we're returning an exception, we should NOT free the
|
|
* stack frame. Corollary is, when we free an exception, we
|
|
* should free all the frames it's holding on to. */
|
|
free_stack_frame( next );
|
|
}
|
|
}
|
|
break;
|
|
default:
|
|
{
|
|
char *buffer = malloc( 1024 );
|
|
memset( buffer, '\0', 1024 );
|
|
sprintf( buffer,
|
|
"Unexpected cell with tag %d (%c%c%c%c) in function position",
|
|
fn_cell.tag.value, fn_cell.tag.bytes[0],
|
|
fn_cell.tag.bytes[1], fn_cell.tag.bytes[2],
|
|
fn_cell.tag.bytes[3] );
|
|
struct cons_pointer message =
|
|
c_string_to_lisp_string( buffer );
|
|
free( buffer );
|
|
result = lisp_throw( message, frame );
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
/**
|
|
* Get the Lisp type of the single argument.
|
|
* @param pointer a pointer to the object whose type is requested.
|
|
* @return As a Lisp string, the tag of the object which is at that pointer.
|
|
*/
|
|
struct cons_pointer c_type( struct cons_pointer pointer ) {
|
|
char *buffer = malloc( TAGLENGTH + 1 );
|
|
memset( buffer, 0, TAGLENGTH + 1 );
|
|
struct cons_space_object cell = pointer2cell( pointer );
|
|
strncpy( buffer, cell.tag.bytes, TAGLENGTH );
|
|
|
|
struct cons_pointer result = c_string_to_lisp_string( buffer );
|
|
free( buffer );
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
/**
|
|
* (eval s_expr)
|
|
*
|
|
* function.
|
|
* If s_expr is a number, NIL, or T, returns s_expr.
|
|
* If s_expr is an unprotected string, returns the value that s_expr is bound
|
|
* to in the evaluation environment (env).
|
|
* If s_expr is a list, expects the car to be something that evaluates to a
|
|
* function or special form.
|
|
* If a function, evaluates all the other top level elements in s_expr and
|
|
* passes them in a stack frame as arguments to the function.
|
|
* If a special form, passes the cdr of s_expr to the special form as argument.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_eval( struct stack_frame *frame, struct cons_pointer env ) {
|
|
struct cons_pointer result = frame->arg[0];
|
|
struct cons_space_object cell = pointer2cell( frame->arg[0] );
|
|
|
|
fputws( L"Eval: ", stderr );
|
|
dump_frame( stderr, frame );
|
|
|
|
switch ( cell.tag.value ) {
|
|
case CONSTV:
|
|
{
|
|
result = c_apply( frame, env );
|
|
}
|
|
break;
|
|
|
|
case SYMBOLTV:
|
|
{
|
|
struct cons_pointer canonical =
|
|
internedp( frame->arg[0], env );
|
|
if ( nilp( canonical ) ) {
|
|
struct cons_pointer message =
|
|
c_string_to_lisp_string
|
|
( "Attempt to take value of unbound symbol." );
|
|
result = lisp_throw( message, frame );
|
|
} else {
|
|
result = c_assoc( canonical, env );
|
|
inc_ref( result );
|
|
}
|
|
}
|
|
break;
|
|
/*
|
|
* the Clojure practice of having a map serve in the function place of
|
|
* an s-expression is a good one and I should adopt it; also if the
|
|
* object is a consp it could be interpretable source code but in the
|
|
* long run I don't want an interpreter, and if I can get away without
|
|
* so much the better.
|
|
*/
|
|
}
|
|
|
|
fputws( L"Eval returning ", stderr );
|
|
print( stderr, result );
|
|
fputws( L"\n", stderr );
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
/**
|
|
* (apply fn args)
|
|
*
|
|
* function. Apply the function which is the result of evaluating the
|
|
* first argoment to the list of arguments which is the result of evaluating
|
|
* the second argument
|
|
*/
|
|
struct cons_pointer
|
|
lisp_apply( struct stack_frame *frame, struct cons_pointer env ) {
|
|
fputws( L"Apply: ", stderr );
|
|
dump_frame( stderr, frame );
|
|
|
|
frame->arg[0] = make_cons( frame->arg[0], frame->arg[1] );
|
|
inc_ref( frame->arg[0] );
|
|
frame->arg[1] = NIL;
|
|
|
|
struct cons_pointer result = c_apply( frame, env );
|
|
|
|
fputws( L"Apply returning ", stderr );
|
|
print( stderr, result );
|
|
fputws( L"\n", stderr );
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
/**
|
|
* (quote a)
|
|
*
|
|
* Special form
|
|
* Returns its argument (strictly first argument - only one is expected but
|
|
* this isn't at this stage checked) unevaluated.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_quote( struct stack_frame *frame, struct cons_pointer env ) {
|
|
return frame->arg[0];
|
|
}
|
|
|
|
/**
|
|
* (set! symbol value)
|
|
* (set! symbol value namespace)
|
|
*
|
|
* Special form.
|
|
* `namespace` defaults to the oblist.
|
|
* Binds `symbol` to `value` in the namespace, altering the namespace in so doing.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_set_shriek( struct stack_frame *frame, struct cons_pointer env ) {
|
|
struct cons_pointer result = NIL;
|
|
struct cons_pointer namespace =
|
|
nilp( frame->arg[2] ) ? oblist : frame->arg[2];
|
|
|
|
if ( symbolp( frame->arg[0] ) ) {
|
|
deep_bind( frame->arg[0], eval_form( frame, frame->arg[1], env ) );
|
|
result = frame->arg[1];
|
|
} else {
|
|
result =
|
|
make_exception( c_string_to_lisp_string
|
|
( "The first argument to `set!` is not a symbol" ),
|
|
frame );
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* (cons a b)
|
|
*
|
|
* Function.
|
|
* Returns a cell constructed from a and b. If a is of type string but its
|
|
* cdr is nill, and b is of type string, then returns a new string cell;
|
|
* otherwise returns a new cons cell.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_cons( struct stack_frame *frame, struct cons_pointer env ) {
|
|
struct cons_pointer car = frame->arg[0];
|
|
struct cons_pointer cdr = frame->arg[1];
|
|
struct cons_pointer result;
|
|
|
|
if ( nilp( car ) && nilp( cdr ) ) {
|
|
return NIL;
|
|
} else if ( stringp( car ) && stringp( cdr ) &&
|
|
nilp( pointer2cell( car ).payload.string.cdr ) ) {
|
|
result =
|
|
make_string( pointer2cell( car ).payload.string.character, cdr );
|
|
} else {
|
|
result = make_cons( car, cdr );
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* (car s_expr)
|
|
* Returns the first item (head) of a sequence. Valid for cons cells,
|
|
* strings, and TODO read streams and other things which can be considered as sequences.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_car( struct stack_frame *frame, struct cons_pointer env ) {
|
|
struct cons_pointer result = NIL;
|
|
|
|
if ( consp( frame->arg[0] ) ) {
|
|
struct cons_space_object cell = pointer2cell( frame->arg[0] );
|
|
result = cell.payload.cons.car;
|
|
} else if ( stringp( frame->arg[0] ) ) {
|
|
struct cons_space_object cell = pointer2cell( frame->arg[0] );
|
|
result = make_string( cell.payload.string.character, NIL );
|
|
} else {
|
|
struct cons_pointer message =
|
|
c_string_to_lisp_string( "Attempt to take CAR of non sequence" );
|
|
result = lisp_throw( message, frame );
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* (cdr s_expr)
|
|
* Returns the remainder of a sequence when the head is removed. Valid for cons cells,
|
|
* strings, and TODO read streams and other things which can be considered as sequences.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_cdr( struct stack_frame *frame, struct cons_pointer env ) {
|
|
struct cons_pointer result = NIL;
|
|
|
|
if ( consp( frame->arg[0] ) ) {
|
|
struct cons_space_object cell = pointer2cell( frame->arg[0] );
|
|
result = cell.payload.cons.cdr;
|
|
} else if ( stringp( frame->arg[0] ) ) {
|
|
struct cons_space_object cell = pointer2cell( frame->arg[0] );
|
|
result = cell.payload.string.cdr;
|
|
} else {
|
|
struct cons_pointer message =
|
|
c_string_to_lisp_string( "Attempt to take CDR of non sequence" );
|
|
result = lisp_throw( message, frame );
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* (assoc key store)
|
|
* Returns the value associated with key in store, or NIL if not found.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_assoc( struct stack_frame *frame, struct cons_pointer env ) {
|
|
return c_assoc( frame->arg[0], frame->arg[1] );
|
|
}
|
|
|
|
/**
|
|
* (eq a b)
|
|
* Returns T if a and b are pointers to the same object, else NIL
|
|
*/
|
|
struct cons_pointer lisp_eq( struct stack_frame *frame,
|
|
struct cons_pointer env ) {
|
|
return eq( frame->arg[0], frame->arg[1] ) ? TRUE : NIL;
|
|
}
|
|
|
|
/**
|
|
* (eq a b)
|
|
* Returns T if a and b are pointers to structurally identical objects, else NIL
|
|
*/
|
|
struct cons_pointer
|
|
lisp_equal( struct stack_frame *frame, struct cons_pointer env ) {
|
|
return equal( frame->arg[0], frame->arg[1] ) ? TRUE : NIL;
|
|
}
|
|
|
|
/**
|
|
* (read)
|
|
* (read read-stream)
|
|
* Read one complete lisp form and return it. If read-stream is specified and
|
|
* is a read stream, then read from that stream, else stdin.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_read( struct stack_frame *frame, struct cons_pointer env ) {
|
|
FILE *input = stdin;
|
|
|
|
if ( readp( frame->arg[0] ) ) {
|
|
input = pointer2cell( frame->arg[0] ).payload.stream.stream;
|
|
}
|
|
|
|
return read( frame, input );
|
|
}
|
|
|
|
|
|
/**
|
|
* (print expr)
|
|
* (print expr write-stream)
|
|
* Print one complete lisp form and return NIL. If write-stream is specified and
|
|
* is a write stream, then print to that stream, else stdout.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_print( struct stack_frame *frame, struct cons_pointer env ) {
|
|
FILE *output = stdout;
|
|
|
|
if ( writep( frame->arg[1] ) ) {
|
|
output = pointer2cell( frame->arg[1] ).payload.stream.stream;
|
|
}
|
|
|
|
print( output, frame->arg[0] );
|
|
|
|
return NIL;
|
|
}
|
|
|
|
|
|
/**
|
|
* Function: Get the Lisp type of the single argument.
|
|
* @param frame My stack frame.
|
|
* @param env My environment (ignored).
|
|
* @return As a Lisp string, the tag of the object which is the argument.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_type( struct stack_frame *frame, struct cons_pointer env ) {
|
|
return c_type( frame->arg[0] );
|
|
}
|
|
|
|
|
|
/**
|
|
* Function; evaluate the forms which are listed in my single argument
|
|
* sequentially and return the value of the last. This function is called 'do'
|
|
* in some dialects of Lisp.
|
|
*
|
|
* @param frame My stack frame.
|
|
* @param env My environment (ignored).
|
|
* @return the value of the last form on the sequence which is my single
|
|
* argument.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_progn( struct stack_frame *frame, struct cons_pointer env ) {
|
|
struct cons_pointer remaining = frame->arg[0];
|
|
struct cons_pointer result = NIL;
|
|
|
|
while ( consp( remaining ) ) {
|
|
struct cons_space_object cell = pointer2cell( remaining );
|
|
result = eval_form( frame, cell.payload.cons.car, env );
|
|
|
|
remaining = cell.payload.cons.cdr;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* Special form: conditional. Each arg is expected to be a list; if the first
|
|
* item in such a list evaluates to non-NIL, the remaining items in that list
|
|
* are evaluated in turn and the value of the last returned. If no arg (clause)
|
|
* has a first element which evaluates to non NIL, then NIL is returned.
|
|
* @param frame My stack frame.
|
|
* @param env My environment (ignored).
|
|
* @return the value of the last form of the first successful clause.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_cond( struct stack_frame *frame, struct cons_pointer env ) {
|
|
struct cons_pointer result = NIL;
|
|
bool done = false;
|
|
|
|
for ( int i = 0; i < args_in_frame && !done; i++ ) {
|
|
struct cons_pointer clause_pointer = frame->arg[i];
|
|
fputws( L"Cond clause: ", stderr );
|
|
print( stderr, clause_pointer );
|
|
|
|
if ( consp( clause_pointer ) ) {
|
|
struct cons_space_object cell = pointer2cell( clause_pointer );
|
|
|
|
if ( !nilp( eval_form( frame, cell.payload.cons.car, env ) ) ) {
|
|
struct stack_frame *next = make_empty_frame( frame, env );
|
|
next->arg[0] = cell.payload.cons.cdr;
|
|
inc_ref( next->arg[0] );
|
|
result = lisp_progn( next, env );
|
|
done = true;
|
|
}
|
|
} else if ( nilp( clause_pointer ) ) {
|
|
done = true;
|
|
} else {
|
|
result = lisp_throw( c_string_to_lisp_string
|
|
( "Arguments to `cond` must be lists" ),
|
|
frame );
|
|
}
|
|
}
|
|
/* TODO: if there are more than 8 clauses we need to continue into the
|
|
* remainder */
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* TODO: make this do something sensible somehow.
|
|
*/
|
|
struct cons_pointer
|
|
lisp_throw( struct cons_pointer message, struct stack_frame *frame ) {
|
|
fwprintf( stderr, L"\nERROR: " );
|
|
print( stderr, message );
|
|
struct cons_pointer result = NIL;
|
|
|
|
struct cons_space_object cell = pointer2cell( message );
|
|
|
|
if ( cell.tag.value == EXCEPTIONTV ) {
|
|
result = message;
|
|
} else {
|
|
result = make_exception( message, frame );
|
|
}
|
|
|
|
return result;
|
|
}
|