/* * Copyright © 2016 Keith Packard * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include "ao_scheme.h" static int lambda_size(void *addr) { (void) addr; return sizeof (struct ao_scheme_lambda); } static void lambda_mark(void *addr) { struct ao_scheme_lambda *lambda = addr; ao_scheme_poly_mark(lambda->code, 0); ao_scheme_poly_mark(lambda->frame, 0); } static void lambda_move(void *addr) { struct ao_scheme_lambda *lambda = addr; ao_scheme_poly_move(&lambda->code, 0); ao_scheme_poly_move(&lambda->frame, 0); } const struct ao_scheme_type ao_scheme_lambda_type = { .size = lambda_size, .mark = lambda_mark, .move = lambda_move, .name = "lambda", }; void ao_scheme_lambda_write(FILE *out, ao_poly poly, bool write) { struct ao_scheme_lambda *lambda = ao_scheme_poly_lambda(poly); struct ao_scheme_cons *cons = ao_scheme_poly_cons(lambda->code); putc('(', out); fputs(ao_scheme_args_name(lambda->args), out); while (cons) { putc(' ', out); ao_scheme_poly_write(out, cons->car, write); cons = ao_scheme_poly_cons(cons->cdr); } putc(')', out); } static ao_poly ao_scheme_lambda_alloc(struct ao_scheme_cons *code, int args) { struct ao_scheme_lambda *lambda; ao_poly formal; struct ao_scheme_cons *cons; formal = ao_scheme_arg(code, 0); while (formal != AO_SCHEME_NIL) { switch (ao_scheme_poly_type(formal)) { case AO_SCHEME_CONS: cons = ao_scheme_poly_cons(formal); if (ao_scheme_poly_type(cons->car) != AO_SCHEME_ATOM) return ao_scheme_error(AO_SCHEME_INVALID, "formal %p is not atom", cons->car); formal = cons->cdr; break; case AO_SCHEME_ATOM: formal = AO_SCHEME_NIL; break; default: return ao_scheme_error(AO_SCHEME_INVALID, "formal %p is not atom", formal); } } ao_scheme_cons_stash(code); lambda = ao_scheme_alloc(sizeof (struct ao_scheme_lambda)); code = ao_scheme_cons_fetch(); if (!lambda) return AO_SCHEME_NIL; lambda->type = AO_SCHEME_LAMBDA; lambda->args = args; lambda->code = ao_scheme_cons_poly(code); lambda->frame = ao_scheme_frame_mark(ao_scheme_frame_current); DBGI("build frame: "); DBG_POLY(lambda->frame); DBG("\n"); DBG_STACK(); return ao_scheme_lambda_poly(lambda); } ao_poly ao_scheme_do_lambda(struct ao_scheme_cons *cons) { return ao_scheme_lambda_alloc(cons, AO_SCHEME_FUNC_LAMBDA); } ao_poly ao_scheme_do_nlambda(struct ao_scheme_cons *cons) { return ao_scheme_lambda_alloc(cons, AO_SCHEME_FUNC_NLAMBDA); } ao_poly ao_scheme_do_macro(struct ao_scheme_cons *cons) { return ao_scheme_lambda_alloc(cons, AO_SCHEME_FUNC_MACRO); } ao_poly ao_scheme_lambda_eval(void) { struct ao_scheme_lambda *lambda = ao_scheme_poly_lambda(ao_scheme_v); struct ao_scheme_cons *cons = ao_scheme_poly_cons(ao_scheme_stack->values); struct ao_scheme_cons *code = ao_scheme_poly_cons(lambda->code); ao_poly formals; struct ao_scheme_frame *next_frame; int args_wanted; ao_poly varargs = AO_SCHEME_NIL; int args_provided; int f; struct ao_scheme_cons *vals; DBGI("lambda "); DBG_POLY(ao_scheme_lambda_poly(lambda)); DBG("\n"); args_wanted = 0; for (formals = ao_scheme_arg(code, 0); ao_scheme_is_pair(formals); formals = ao_scheme_poly_cons(formals)->cdr) ++args_wanted; if (formals != AO_SCHEME_NIL) { if (ao_scheme_poly_type(formals) != AO_SCHEME_ATOM) return ao_scheme_error(AO_SCHEME_INVALID, "bad lambda form"); varargs = formals; } /* Create a frame to hold the variables */ args_provided = ao_scheme_cons_length(cons) - 1; if (varargs == AO_SCHEME_NIL) { if (args_wanted != args_provided) return ao_scheme_error(AO_SCHEME_INVALID, "need %d args, got %d", args_wanted, args_provided); } else { if (args_provided < args_wanted) return ao_scheme_error(AO_SCHEME_INVALID, "need at least %d args, got %d", args_wanted, args_provided); } ao_scheme_poly_stash(varargs); next_frame = ao_scheme_frame_new(args_wanted + (varargs != AO_SCHEME_NIL)); varargs = ao_scheme_poly_fetch(); if (!next_frame) return AO_SCHEME_NIL; /* Re-fetch all of the values in case something moved */ lambda = ao_scheme_poly_lambda(ao_scheme_v); cons = ao_scheme_poly_cons(ao_scheme_stack->values); code = ao_scheme_poly_cons(lambda->code); formals = ao_scheme_arg(code, 0); vals = ao_scheme_poly_cons(cons->cdr); next_frame->prev = lambda->frame; ao_scheme_frame_current = next_frame; ao_scheme_stack->frame = ao_scheme_frame_poly(ao_scheme_frame_current); for (f = 0; f < args_wanted; f++) { struct ao_scheme_cons *arg = ao_scheme_poly_cons(formals); DBGI("bind "); DBG_POLY(arg->car); DBG(" = "); DBG_POLY(vals->car); DBG("\n"); ao_scheme_frame_bind(next_frame, f, arg->car, vals->car); formals = arg->cdr; vals = ao_scheme_poly_cons(vals->cdr); } if (varargs) { DBGI("bind "); DBG_POLY(varargs); DBG(" = "); DBG_POLY(ao_scheme_cons_poly(vals)); DBG("\n"); /* * Bind the rest of the arguments to the final parameter */ ao_scheme_frame_bind(next_frame, f, varargs, ao_scheme_cons_poly(vals)); } else { /* * Mark the cons cells from the actuals as freed for immediate re-use, unless * the actuals point into the source function (nlambdas and macros), or if the * stack containing them was copied as a part of a continuation */ if (lambda->args == AO_SCHEME_FUNC_LAMBDA && !ao_scheme_stack_marked(ao_scheme_stack)) { ao_scheme_stack->values = AO_SCHEME_NIL; ao_scheme_cons_free(cons); } } DBGI("eval frame: "); DBG_POLY(ao_scheme_frame_poly(next_frame)); DBG("\n"); DBG_STACK(); DBGI("eval code: "); DBG_POLY(code->cdr); DBG("\n"); return code->cdr; }