99 lines
2.5 KiB
C
99 lines
2.5 KiB
C
#include "syntax.h"
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#include "eval.h"
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#include "object.h"
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#include <assert.h>
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/*******************************************
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* Special syntax to use in the executable *
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*******************************************/
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struct Object *syntax_repl(
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struct Object *args,
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struct Object *const environment
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) {
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return eval(args, environment);
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}
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struct Object *syntax_script(
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struct Object *args,
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struct Object *const environment
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) {
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return eval(args, environment);
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}
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/*******************
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* Syntax keywords *
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*******************/
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struct Object *syntax_begin(
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struct Object *args,
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struct Object *const environment
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) {
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assert(OBJECT_IS_LIST_HEAD(args));
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struct Object *result = NULL;
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while (!OBJECT_IS_NULL(args)) {
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assert(Object_is_pair(args));
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result = eval(args->pair.car, environment);
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args = args->pair.cdr;
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}
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return result;
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}
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struct Object *syntax_define(
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struct Object *const args,
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struct Object *const environment
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) {
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assert(Object_is_pair(args));
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struct Object *const name = args->pair.car;
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assert(Object_is_symbol(name));
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assert(Object_is_pair(args->pair.cdr));
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struct Object *const value_expr = args->pair.cdr->pair.car;
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assert(OBJECT_IS_NULL(args->pair.cdr->pair.cdr));
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assert(Object_is_pair(environment));
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assert(OBJECT_IS_NULL(environment->pair.cdr));
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assert(OBJECT_IS_LIST_HEAD(environment->pair.car));
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environment->pair.car = Object_new_pair(
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Object_new_pair(name, eval(value_expr, environment)),
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environment->pair.car
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);
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return NULL;
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}
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struct Object *syntax_if(
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struct Object *const args,
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struct Object *const environment
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) {
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assert(Object_is_pair(args));
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struct Object *const cond = args->pair.car;
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struct Object *const then_else_list = args->pair.cdr;
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assert(then_else_list);
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assert(Object_is_pair(then_else_list));
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struct Object *const then_branch = then_else_list->pair.car;
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struct Object *const else_list = then_else_list->pair.cdr;
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assert(else_list);
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assert(Object_is_pair(else_list));
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struct Object *const else_branch = else_list->pair.car;
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assert(OBJECT_IS_NULL(else_list->pair.cdr));
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if (Object_is_false(cond)) {
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return eval(else_branch, environment);
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} else {
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return eval(then_branch, environment);
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}
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}
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struct Object *syntax_quote(
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struct Object *const args,
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struct Object *const environment
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) {
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(void)environment; // unused
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assert(Object_is_pair(args));
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assert(OBJECT_IS_NULL(args->pair.cdr));
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return args->pair.car;
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}
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