1 files changed, 184 insertions, 0 deletions
diff --git a/parse.c b/parse.c
new file mode 100644
index 0000000..b5101e1
--- /dev/null
+++ b/parse.c
@@ -0,0 +1,184 @@
+#include "parse.h"
+#include "tokens.h"
+#include "list.h"
+#include "atom.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+
+void print_list(struct list *list, int level)
+{
+    while (list)
+    {
+        struct atom *atom = LIST_GET_ATOM(list);
+
+        if (IS_TRUE(list))
+        {
+            printf("#t");
+        }
+        else if (IS_FALSE(list))
+        {
+            printf("#f");
+        }
+        else if (IS_NIL(list))
+        {
+            printf("nil");
+        }
+        else
+        {
+            switch (atom->type)
+            {
+                case ATOM_SYMBOL:
+                    printf("%.*s", atom->str.len, atom->str.str);
+                    break;
+
+                case ATOM_LIST:
+                    printf("(");
+                    print_list(atom->list, level+1);
+                    printf(")");
+                    break;
+
+                case ATOM_STR:
+                    printf("\"%.*s\"", atom->str.len, atom->str.str);
+                    break;
+
+                case ATOM_INT:
+                    printf("%ld", atom->l);
+            }
+        }
+
+        if (list->next)
+            printf(" ");
+
+        list = list->next;
+    }
+
+    if (level == 0)
+        printf("\n");
+}
+
+int parse_next(const char *src, int *pos, struct atom **result)
+{
+    struct token token;
+    int rc;
+
+    if ((rc = get_next_token(src, pos, &token)) > 0)
+    {
+        switch (token.type)
+        {
+            case TOKEN_INT:
+                *result = atom_new_int(strtol(token.s, NULL, 10));
+                break;
+
+            case TOKEN_STR:
+                *result = atom_new_str(token.s, token.len);
+                break;
+
+            case TOKEN_SYMBOL:
+                if (strncmp(token.s, "#t", 2) == 0)
+                    *result = &true_atom;
+                else if (strncmp(token.s, "#f", 2) == 0)
+                    *result = &false_atom;
+                else
+                    *result = atom_new_sym(token.s, token.len);
+                break;
+
+            case TOKEN_LPAREN:
+            {
+                struct list *l = parse(src, pos);
+                *result = atom_new_list(l);
+                break;
+            }
+
+            case TOKEN_RPAREN:
+                return -2;
+
+            case TOKEN_QUOTE:
+            {
+                struct atom *quoted = NULL;
+
+                parse_next(src, pos, &quoted);
+
+                struct list *qlist = list_append(NULL,
+                    atom_new_sym("quote", 5));
+
+                list_append(qlist, quoted);
+
+                *result = atom_new_list(qlist);
+
+                break;
+            }
+        }
+    }
+
+    return rc;
+}
+
+struct list *parse(const char *src, int *pos)
+{
+    int rc;
+    struct atom *atom;
+    struct list root, *last = &root;
+
+    list_init(last);
+
+    while ((rc = parse_next(src, pos, &atom)))
+    {
+        if (rc < 0)
+            break;
+
+        last = list_append(last, atom);
+    }
+
+    if (rc < 0 && rc != -2)
+        return NULL;
+
+    return root.next;
+}
+
+#ifdef BUILD_TEST
+
+#include "test_util.h"
+
+static const char *test_src_fact =
+    "(define fact\n"
+    "    ;; Factorial function\n"
+    "    (lambda (n)\n"
+    "        (if (eq n 0)\n"
+    "            1 ; Factorial of 0 is 1\n"
+    "            (* n (fact (- n 1))))))\n"
+    "(fact 5) ;; this should evaluate to 120\n";
+
+#define ASSERT_SYM(LIST, SYM) \
+    ASSERT_TRUE(IS_SYM(LIST)); \
+    ASSERT_STREQ(SYM, LIST_GET_ATOM(LIST)->str.str)
+
+TEST(test_parse)
+{
+    int pos = 0;
+    struct list *list;
+
+    list = parse(test_src_fact, &pos);
+
+    ASSERT_TRUE(list != NULL);
+
+    ASSERT_TRUE(IS_LIST(list));
+
+    list = LIST_GET_ATOM(list)->list;
+
+    ASSERT_TRUE(list != NULL);
+    ASSERT_SYM(list, "define");
+
+    list = list->next;
+
+    ASSERT_TRUE(list != NULL);
+    ASSERT_SYM(list, "fact");
+
+    list = list->next;
+
+    ASSERT_TRUE(list != NULL);
+}
+
+#endif