reader: add position restoration for read_vec and read_list

Same as read_str really, using a label to push control flow.
lisp: lisp_print: implement support for strings
2026-03-05 20:27:13 +00:00 · 2026-03-05 20:27:00 +00:00 · 2026-03-05 20:26:40 +00:00 · 2026-03-05 20:25:03 +00:00 · 2026-03-05 20:13:52 +00:00 · 2026-03-05 20:13:18 +00:00
6 changed files with 79 additions and 17 deletions
--- a/2
+++ b/2
@@ -5,7 +5,7 @@ OUT=$(DIST)/alisp.out
 TEST=$(DIST)/test.out

 LDFLAGS=
-GFLAGS=-Wall -Wextra -Wpedantic -Werror -std=c23 -I./include/
+GFLAGS=-Wall -Wextra -Wswitch-enum -Wpedantic -Werror -std=c23 -I./include/
 DFLAGS=-ggdb -fsanitize=address -fsanitize=undefined
 RFLAGS=-O3

--- a/include/alisp/reader.h
+++ b/include/alisp/reader.h
@@ -17,6 +17,7 @@ typedef enum
  READ_ERR_EOF,
  READ_ERR_EXPECTED_CLOSED_BRACE,
  READ_ERR_EXPECTED_CLOSED_SQUARE_BRACKET,
+  READ_ERR_EXPECTED_CLOSING_SPEECHMARKS,
  READ_ERR_UNEXPECTED_CLOSED_BRACE,
  READ_ERR_UNEXPECTED_CLOSED_SQUARE_BRACKET,
  READ_ERR_UNKNOWN_CHAR,
--- a/include/alisp/sys.h
+++ b/include/alisp/sys.h
@@ -30,6 +30,7 @@ u64 sys_cost(sys_t *);
 lisp_t *make_int(i64);
 lisp_t *intern(sys_t *, sv_t);
 lisp_t *cons(sys_t *, lisp_t *, lisp_t *);
+lisp_t *make_list(sys_t *, lisp_t **, u64);
 lisp_t *make_vec(sys_t *, u64);
 lisp_t *make_str(sys_t *, u64);

--- a/src/lisp.c
+++ b/src/lisp.c
@@ -174,7 +174,7 @@ void lisp_print(FILE *fp, lisp_t *lisp)
    {
      lisp_t *item = VEC_GET(vec, i, lisp_t *);
      lisp_print(fp, item);
-      if (i < VEC_SIZE(vec, lisp_t *))
+      if (i < VEC_SIZE(vec, lisp_t *) - 1)
      {
        fprintf(fp, " ");
      }
@@ -188,8 +188,23 @@ void lisp_print(FILE *fp, lisp_t *lisp)
    break;
  }
  case TAG_STR:
-    TODO("Implement lisp_print for strings");
+  {
+#if VERBOSE_LOGS == 2
+    fprintf(fp, "STR[");
+#else
+    fprintf(fp, "\"");
+#endif
+
+    sv_t sv = string_sv(as_str(lisp));
+    fprintf(fp, PR_SV, SV_FMT(sv));
+
+#if VERBOSE_LOGS == 2
+    fprintf(fp, "]");
+#else
+    fprintf(fp, "\"");
+#endif
    break;
+  }
  default:
    FAIL("Unreachable");
    break;
--- a/src/reader.c
+++ b/src/reader.c
@@ -20,11 +20,12 @@ const char *read_err_to_cstr(read_err_t err)
    return "EOF";
  case READ_ERR_UNKNOWN_CHAR:
    return "UNKNOWN_CHAR";
-    break;
  case READ_ERR_EXPECTED_CLOSED_BRACE:
    return "EXPECTED_CLOSED_BRACE";
  case READ_ERR_EXPECTED_CLOSED_SQUARE_BRACKET:
    return "EXPECTED_CLOSED_SQUARE_BRACKET";
+  case READ_ERR_EXPECTED_CLOSING_SPEECHMARKS:
+    return "EXPECTED_CLOSING_SPEECHMARKS";
  case READ_ERR_UNEXPECTED_CLOSED_BRACE:
    return "UNEXPECTED_CLOSED_BRACE";
  case READ_ERR_UNEXPECTED_CLOSED_SQUARE_BRACKET:
@@ -37,7 +38,7 @@ const char *read_err_to_cstr(read_err_t err)
 // Accepted characters for symbols.
 static const char *SYMBOL_CHARS =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!$%&*+,-./"
-    ":<=>?@\\^_`{|}~0123456789";
+    ":<=>?@\\^_{|}~0123456789";

 // Little predicate using SYMBOL_CHARS
 bool is_sym(char c)
@@ -76,9 +77,9 @@ read_err_t read_int(sys_t *sys, stream_t *stream, lisp_t **ret)
    return read_sym(sys, stream, ret);
  }

-  if (digits_sv.size > 19)
+  if (digits_sv.size >= 18)
  {
-    TODO("alisp doesn't support big integers (bigger than 63 bits) yet");
+    TODO("alisp doesn't support big integers (bigger than 56 bits) yet");
  }

  i64 n = 0;
@@ -92,7 +93,7 @@ read_err_t read_int(sys_t *sys, stream_t *stream, lisp_t **ret)
    // => i > (INT_MAX - digit) / 10
    if (n > (INT_MAX - digit) / 10)
    {
-      TODO("alisp doesn't support big integers (bigger than 63 bits) yet");
+      TODO("alisp doesn't support big integers (bigger than 56 bits) yet");
    }

    n *= 10;
@@ -111,9 +112,7 @@ read_err_t read_negative(sys_t *sys, stream_t *stream, lisp_t **ret)
    read_err_t err = read_int(sys, stream, ret);
    if (err)
      return err;
-    i64 n = as_smi(*ret);
-    n *= -1;
-    *ret = make_int(n);
+    *ret = make_int(as_smi(*ret) * -1);
    return READ_ERR_OK;
  }
  else if (is_sym(c) || isspace(c))
@@ -122,11 +121,14 @@ read_err_t read_negative(sys_t *sys, stream_t *stream, lisp_t **ret)
    return read_sym(sys, stream, ret);
  }
  else
+  {
    return READ_ERR_UNKNOWN_CHAR;
+  }
 }

 read_err_t read_list(sys_t *sys, stream_t *stream, lisp_t **ret)
 {
+  u64 old_pos = stream->position;
  // skip past the open parentheses '('
  (void)stream_next(stream);

@@ -138,7 +140,7 @@ read_err_t read_list(sys_t *sys, stream_t *stream, lisp_t **ret)
    read_err_t err = read(sys, stream, &item);
    if (err == READ_ERR_EOF)
    {
-      return READ_ERR_EXPECTED_CLOSED_BRACE;
+      goto no_close_brace;
    }
    else if (err)
    {
@@ -157,16 +159,23 @@ read_err_t read_list(sys_t *sys, stream_t *stream, lisp_t **ret)
  }

  if (stream_peek(stream) != ')')
-    return READ_ERR_EXPECTED_CLOSED_BRACE;
+  {
+    goto no_close_brace;
+  }

  stream_next(stream);
  *ret = top;
  return READ_ERR_OK;
+no_close_brace:
+  stream->position = old_pos;
+  return READ_ERR_EXPECTED_CLOSED_BRACE;
 }

 read_err_t read_vec(sys_t *sys, stream_t *stream, lisp_t **ret)
 {
+  u64 old_pos = stream->position;
  (void)stream_next(stream);
+
  lisp_t *container = make_vec(sys, 0);
  while (!stream_eoc(stream) && stream_peek(stream) != ']')
  {
@@ -174,7 +183,7 @@ read_err_t read_vec(sys_t *sys, stream_t *stream, lisp_t **ret)
    read_err_t err = read(sys, stream, &item);
    if (err == READ_ERR_EOF)
    {
-      return READ_ERR_EXPECTED_CLOSED_BRACE;
+      goto no_close_square_bracket;
    }
    else if (err)
    {
@@ -187,10 +196,33 @@ read_err_t read_vec(sys_t *sys, stream_t *stream, lisp_t **ret)
  }

  if (stream_peek(stream) != ']')
-    return READ_ERR_EXPECTED_CLOSED_SQUARE_BRACKET;
+    goto no_close_square_bracket;
+
  stream_next(stream);
  *ret = container;
  return READ_ERR_OK;
+no_close_square_bracket:
+  stream->position = old_pos;
+  return READ_ERR_EXPECTED_CLOSED_SQUARE_BRACKET;
+}
+
+read_err_t read_str(sys_t *sys, stream_t *stream, lisp_t **ret)
+{
+  u64 old_pos = stream->position;
+
+  (void)stream_next(stream);
+  sv_t contents = stream_till(stream, "\"");
+  if (stream_eoc(stream) || stream_peek(stream) != '\"')
+  {
+    stream->position = old_pos;
+    return READ_ERR_EXPECTED_CLOSING_SPEECHMARKS;
+  }
+
+  stream_next(stream);
+  lisp_t *lisp = make_str(sys, contents.size);
+  vec_append(&as_str(lisp)->data, contents.data, contents.size);
+  *ret = lisp;
+  return READ_ERR_OK;
 }

 read_err_t read_quote(sys_t *sys, stream_t *stream, lisp_t **ret)
@@ -200,8 +232,8 @@ read_err_t read_quote(sys_t *sys, stream_t *stream, lisp_t **ret)
  read_err_t err = read(sys, stream, &to_quote);
  if (err)
    return err;
-  *ret = cons(sys, to_quote, NIL);
-  *ret = cons(sys, intern(sys, SV_AUTO("quote")), *ret);
+  lisp_t *items[] = {intern(sys, SV_AUTO("quote")), to_quote};
+  *ret            = make_list(sys, items, ARRSIZE(items));
  return READ_ERR_OK;
 }

@@ -243,6 +275,8 @@ read_err_t read(sys_t *sys, stream_t *stream, lisp_t **ret)
    return read_vec(sys, stream, ret);
  else if (c == ']')
    return READ_ERR_UNEXPECTED_CLOSED_SQUARE_BRACKET;
+  else if (c == '\"')
+    return read_str(sys, stream, ret);

  return READ_ERR_UNKNOWN_CHAR;
 }
--- a/src/sys.c
+++ b/src/sys.c
@@ -59,6 +59,17 @@ lisp_t *cons(sys_t *sys, lisp_t *car, lisp_t *cdr)
  return cons;
 }

+lisp_t *make_list(sys_t *sys, lisp_t **lisps, u64 size)
+{
+  lisp_t *root = NIL;
+  for (u64 i = size; i > 0; --i)
+  {
+    lisp_t *node = lisps[i - 1];
+    root         = cons(sys, node, root);
+  }
+  return root;
+}
+
 lisp_t *make_vec(sys_t *sys, u64 capacity)
 {
  lisp_t *vec = sys_alloc(sys, TAG_VEC);
Author	SHA1	Message	Date
Aryadev Chavali	775d9f51bf	reader: add position restoration for read_vec and read_list Same as read_str really, using a label to push control flow.	2026-03-05 20:27:13 +00:00
Aryadev Chavali	c65ec319f5	lisp: lisp_print: implement support for strings	2026-03-05 20:27:00 +00:00
Aryadev Chavali	fd9cc93c45	lisp: lisp_print: fix issue with extra space when printing vectors	2026-03-05 20:26:40 +00:00
Aryadev Chavali	e594b6ce70	reader: read_str restores stream position for no closing speechmarks Say you have the following Lisp code: `"hello world` (no closing speechmark). This read_str implementation will now place stream->position at the first speechmark rather than at the EOF (what happened previously) which is a bit nicer.	2026-03-05 20:25:03 +00:00
Aryadev Chavali	fee6614670	reader: implement reader for strings	2026-03-05 20:13:52 +00:00
Aryadev Chavali	1998954b56	reader: slight adjustments based on change INT -> SMI	2026-03-05 20:13:18 +00:00
Aryadev Chavali	e629b9919e	Makefile: added -Wswitch-enum to warning flags	2026-03-05 19:59:59 +00:00
Aryadev Chavali	37d1764c6e	reader: use make_list in read_quote	2026-03-05 19:59:46 +00:00
Aryadev Chavali	cb8d1b1139	sys: make_list constructor Takes a fixed array of lisp_t pointers, and makes a cons list out of them.	2026-03-05 19:59:23 +00:00