Initial commit

1 files changed, 96 insertions, 0 deletions

diff --git a/src/parser.c b/src/parser.c
new file mode 100644
index 0000000..99efe03
--- /dev/null
+++ b/src/parser.c
@@ -0,0 +1,96 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "types.h"
+#include "lexer.h"
+#include "parser.h"
+#include "runtime.h"
+
+static pit_lex_token peek(pit_parser *st) {
+    if (!st) return PIT_LEX_TOKEN_ERROR;
+    return st->next.token;
+}
+
+static pit_lex_token advance(pit_parser *st) {
+    if (!st) return PIT_LEX_TOKEN_ERROR;
+    st->cur = st->next;
+    st->next.token = pit_lex_next(st->lexer);
+    st->next.start = st->lexer->start;
+    st->next.end = st->lexer->end;
+    return st->cur.token;
+}
+
+static bool match(pit_parser *st, pit_lex_token t) {
+    if (peek(st) == t) {
+        advance(st);
+        return true;
+    } else return false;
+}
+
+static void get_token_string(pit_parser *st, char *buf, i64 len) {
+    i64 diff = st->cur.end - st->cur.start;
+    i64 tlen = diff >= len ? len - 1 : diff;
+    memcpy(buf, st->lexer->input + st->cur.start, tlen);
+    buf[tlen] = 0;
+}
+
+pit_parser *pit_parser_from_lexer(pit_lexer *lex) {
+    pit_parser *ret = malloc(sizeof(*ret));
+    ret->lexer = lex;
+    ret->cur.token = ret->next.token = PIT_LEX_TOKEN_ERROR;
+    ret->cur.start = ret->next.start = 0;
+    ret->cur.end = ret->next.end = 0;
+    advance(ret);
+    return ret;
+}
+
+// parse a single expression
+pit_value pit_parse(pit_runtime *rt, pit_parser *st) {
+    char buf[256] = {0};
+    pit_lex_token t = advance(st);
+    printf("token: %s\n", pit_lex_token_name(t));
+    switch (t) {
+    case PIT_LEX_TOKEN_ERROR:
+        pit_error(rt, "encountered an error token while parsing");
+        return PIT_NIL;
+    case PIT_LEX_TOKEN_EOF:
+        pit_error(rt, "end-of-file while parsing");
+        return PIT_NIL;
+    case PIT_LEX_TOKEN_LPAREN: {
+        i64 arg = 0; i64 args_cap = 32;
+        pit_value *args = calloc(args_cap, sizeof(pit_value));
+        while (!match(st, PIT_LEX_TOKEN_RPAREN)) {
+            args[arg++] = pit_parse(rt, st);
+            if (rt->error != PIT_NIL) return PIT_NIL; // if we hit an error, stop!
+            if (arg >= args_cap) args = realloc(args, (args_cap <<= 1) * sizeof(pit_value));
+        }
+        pit_value ret = PIT_NIL;
+        for (int i = 0; i < arg; ++i) {
+            ret = pit_cons(rt, args[arg - i - 1], ret);
+        }
+        return ret;
+    }
+    case PIT_LEX_TOKEN_QUOTE:
+        return pit_list(rt, 2, pit_intern_cstr(rt, "quote"), pit_parse(rt, st));
+    case PIT_LEX_TOKEN_INTEGER_LITERAL:
+        get_token_string(st, buf, sizeof(buf));
+        return pit_integer_new(rt, atoi(buf));
+    case PIT_LEX_TOKEN_STRING_LITERAL:
+        get_token_string(st, buf, sizeof(buf));
+        i64 len = strlen(buf);
+        i64 cur = 0;
+        for (i64 i = 1; i < len; ++i) {
+            if (buf[i] == '\\' && i + 1 < len) buf[cur++] = buf[++i];
+            else if (buf[i] != '"') buf[cur++] = buf[i];
+            else break;
+        }
+        return pit_bytes_new(rt, (u8 *) buf, cur);
+    case PIT_LEX_TOKEN_SYMBOL:
+        get_token_string(st, buf, sizeof(buf));
+        return pit_intern_cstr(rt, buf);
+    default:
+        pit_error(rt, "unexpected token: %s", pit_lex_token_name(t));
+        return PIT_NIL;
+    }
+}