+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+
#include <gc.h>
#include <gmp.h>
+const char *BLANKS = " \t";
+const char *TEXT = " 23 [dup *] i hi there fr [[] ie]nd] [] 23 ";
+
+
enum JoyTypeType {
joySymbol,
joyTrue,
}
+char *
+trim_leading_blanks(char *str)
+{
+ size_t offset = strspn(str, BLANKS);
+ return (offset == strlen(str)) ? NULL : (str + offset);
+}
+
+
+/* Create a new list_node with a joySymbol head. */
+struct list_node*
+make_symbol_node(char *text, size_t size)
+{
+ struct list_node *node;
+ node = GC_malloc(sizeof(struct list_node));
+ node->head.kind = joySymbol;
+ node->head.value.symbol = (char *)GC_malloc(size + 1);
+ strncat(node->head.value.symbol, text, size);
+ printf("%s\n", node->head.value.symbol);
+ return node;
+}
+
+
+struct list_node*
+text_to_expression(char *text)
+{
+ char *rest;
+ ptrdiff_t diff;
+ struct list_node *current_list_node;
+ struct list_node *result;
+ struct list_node *head = NULL;
+
+ if (NULL == text) {
+ /* NULL string input. */
+ return (struct list_node*)NULL;
+ }
+ text = trim_leading_blanks(text);
+ if (NULL == text) {
+ /* All blanks. */
+ return (struct list_node*)NULL;
+ }
+
+ rest = strpbrk(text, " []");
+ /*
+ rest now points to a space or '[' or ']' after a term,
+ -or- it is NULL if the rest of the string is a single term
+ with no spaces nor brackets.
+ */
+
+ while (NULL != rest) {
+
+ /* How many chars have we got? */
+ diff = rest - text;
+ /*
+ diff can be zero when there is more than one space in
+ a sequence in the input string. This won't happen on
+ the first iteration but it can on later iterations.
+ */
+
+ if (diff) {
+ /* Allocate space and copy out the substring. */
+
+ current_list_node = make_symbol_node(text, diff);
+ if (head) {
+ head->tail = current_list_node;
+ } else {
+ /* There is no head now, so this must be the first
+ result, the head that we will eventually return. */
+ result = current_list_node;
+ }
+ head = current_list_node;
+ }
+
+ /* The next char is a space or '[' or ']'. */
+ if ('[' == rest[0] || ']' == rest[0]) {
+ printf("%c\n", rest[0]);
+ }
+
+ text = trim_leading_blanks(++rest);
+
+ /* calling strpbrk on NULL caused segfault! */
+ rest = (NULL != text) ? strpbrk(text, " []") : text;
+ }
+ if (text) {
+ current_list_node = make_symbol_node(text, strlen(text));
+ if (head) {
+ head->tail = current_list_node;
+ } else {
+ result = current_list_node;
+ }
+ }
+ return result;
+}
+
+
int
main(void)
{
gmp_printf("%Zd = %Zx\n", pi, pi);
el = push_integer_from_str("3141592653589793238462643383279502884", 0);
+ el = text_to_expression("char *te xt");
/*sexpr i = new_int();*/
/*mpz_add(i.i, pi, pi);*/