Still got some failures, but a basic stream implementation

Need to fix what's going on with the example in main.c using stdin.

5 files changed, 373 insertions, 3 deletions

diff --git a/alisp.h b/alisp.h
index e9694d9..dba0485 100644
--- a/alisp.h
+++ b/alisp.h
@@ -17,14 +17,18 @@
 
 #include <assert.h>
 #include <stdalign.h>
+#include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
+#include <stdio.h>
 
 /// The bare fucking minimum
 #define MAX(A, B)      ((A) > (B) ? (A) : (B))
 #define MIN(A, B)      ((A) < (B) ? (A) : (B))
 #define ARRSIZE(A)     (sizeof(A) / sizeof((A)[0]))
 #define NTH_BYTE(X, N) (((X) >> (8 * N)) & ((1 << 8) - 1))
+#define FAIL(MSG)      assert(false && "FAIL: " #MSG)
+#define TODO(MSG)      assert(false && "TODO: " #MSG)
 
 typedef uint8_t u8;
 typedef uint16_t u16;
@@ -91,6 +95,61 @@ void sym_table_init(sym_table_t *);
 char *sym_table_find(sym_table_t *, sv_t);
 void sym_table_cleanup(sym_table_t *);
 
+/// Streams
+typedef enum
+{
+  STREAM_TYPE_STRING,
+  STREAM_TYPE_FILE,
+} stream_type_t;
+
+typedef enum
+{
+  STREAM_ERR_INVALID_PTR      = -4,
+  STREAM_ERR_FILE_NONEXISTENT = -3,
+  STREAM_ERR_FILE_READ        = -2,
+  STREAM_ERR_PIPE_NONEXISTENT = -1,
+  STREAM_ERR_OK               = 0,
+} stream_err_t;
+
+typedef struct
+{
+  vec_t cache;
+  FILE *file;
+} stream_pipe_t;
+
+typedef struct
+{
+  stream_type_t type;
+  char *name;
+  u64 position;
+  union
+  {
+    sv_t string;
+    stream_pipe_t pipe;
+  };
+} stream_t;
+
+#define STREAM_DEFAULT_CHUNK 64
+
+stream_err_t stream_init_string(stream_t *, char *, sv_t);
+stream_err_t stream_init_file(stream_t *, char *, FILE *);
+void stream_stop(stream_t *);
+
+// end of stream
+bool stream_eos(stream_t *);
+// end of cache
+bool stream_eoc(stream_t *);
+u64 stream_size(stream_t *);
+
+bool stream_chunk(stream_t *);
+char stream_next(stream_t *);
+char stream_peek(stream_t *);
+bool stream_seek(stream_t *, i64);
+bool stream_seek_forward(stream_t *, u64);
+bool stream_seek_backward(stream_t *, u64);
+sv_t stream_substr(stream_t *, u64);
+sv_t stream_substr_abs(stream_t *, u64, u64);
+
 /// Basic defintions for a Lisp
 #define NIL 0
 
diff --git a/build.sh b/build.sh
index 544f623..6e42066 100644
--- a/build.sh
+++ b/build.sh
@@ -4,7 +4,7 @@ set -xe
 
 CFLAGS="-Wall -Wextra -std=c11 -ggdb -fsanitize=address -fsanitize=undefined"
 LINK=""
-LIB="sv.c vec.c symtable.c tag.c constructor.c sys.c"
+LIB="sv.c vec.c symtable.c tag.c constructor.c stream.c sys.c"
 OUT="alisp.out"
 
 build() {
diff --git a/main.c b/main.c
index f7f290f..98f2878 100644
--- a/main.c
+++ b/main.c
@@ -20,6 +20,21 @@
 
 int main(void)
 {
-  puts("Watch this space\n");
+  stream_t stream = {0};
+  // const char data[] = "Hello, world!";
+  // const sv_t sv     = SV(data, ARRSIZE(data) - 1);
+  // stream_init_string(&stream, NULL, sv);
+
+  // stream_init_file(&stream, "test.txt");
+
+  stream_init_file(&stream, "stdin", stdin);
+  printf("[debug]: setup stream pipe\n");
+  do
+  {
+    printf("%s[%lu]: `%c`\n", stream.name, stream.position,
+           stream_next(&stream));
+  } while (!stream_eoc(&stream));
+  printf("%lu/%lu\n", stream.position, stream_size(&stream));
+  stream_stop(&stream);
   return 0;
 }
diff --git a/stream.c b/stream.c
new file mode 100644
index 0000000..a7fb72e
--- /dev/null
+++ b/stream.c
@@ -0,0 +1,296 @@
+/* Copyright (C) 2025 Aryadev Chavali
+
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the Unlicense for details.
+
+ * You may distribute and modify this code under the terms of the Unlicense,
+ * which you should have received a copy of along with this program.  If not,
+ * please go to <https://unlicense.org/>.
+
+ * Created: 2025-08-26
+ * Description: Stream implementation
+ */
+
+#include <string.h>
+
+#include "./alisp.h"
+
+stream_err_t stream_init_string(stream_t *stream, char *name, sv_t contents)
+{
+  if (!stream)
+    return STREAM_ERR_INVALID_PTR;
+  name = name ? name : "<stream>";
+  memset(stream, 0, sizeof(*stream));
+
+  stream->type   = STREAM_TYPE_STRING;
+  stream->name   = name;
+  stream->string = contents;
+
+  return STREAM_ERR_OK;
+}
+
+stream_err_t stream_init_file(stream_t *stream, char *name, FILE *pipe)
+{
+  if (!stream || !pipe)
+    return STREAM_ERR_INVALID_PTR;
+  name = name ? name : "<stream>";
+  memset(stream, 0, sizeof(*stream));
+
+  stream->type      = STREAM_TYPE_FILE;
+  stream->name      = name;
+  stream->pipe.file = pipe;
+
+  vec_init(&stream->pipe.cache, STREAM_DEFAULT_CHUNK);
+
+  return STREAM_ERR_OK;
+}
+
+void stream_stop(stream_t *stream)
+{
+  if (!stream)
+    return;
+  switch (stream->type)
+  {
+  case STREAM_TYPE_STRING:
+    // Nothing to do, all dealt with outside of stream
+    break;
+  case STREAM_TYPE_FILE:
+    // Must cleanup vector
+    vec_free(&stream->pipe.cache);
+    break;
+  }
+  memset(stream, 0, sizeof(*stream));
+}
+
+u64 stream_size(stream_t *stream)
+{
+  assert(stream);
+  switch (stream->type)
+  {
+  case STREAM_TYPE_STRING:
+    return stream->string.size;
+  case STREAM_TYPE_FILE:
+    return stream->pipe.cache.size;
+  default:
+    FAIL("Unreachable");
+    return 0;
+  }
+}
+
+bool stream_eos(stream_t *stream)
+{
+  assert(stream);
+  switch (stream->type)
+  {
+  case STREAM_TYPE_STRING:
+    return stream->position >= stream->string.size;
+  case STREAM_TYPE_FILE:
+    return feof(stream->pipe.file);
+  default:
+    FAIL("Unreachable");
+    return 0;
+  }
+}
+
+bool stream_eoc(stream_t *stream)
+{
+  assert(stream);
+  switch (stream->type)
+  {
+  case STREAM_TYPE_STRING:
+    return stream->position >= stream->string.size;
+  case STREAM_TYPE_FILE:
+    return stream->position >= stream->pipe.cache.size;
+  default:
+    FAIL("Unreachable");
+    return 0;
+  }
+}
+
+bool stream_chunk(stream_t *stream)
+{
+  assert(stream);
+  switch (stream->type)
+  {
+  case STREAM_TYPE_STRING:
+    // vacuously true
+    return true;
+  case STREAM_TYPE_FILE:
+  {
+    if (feof(stream->pipe.file))
+      return false;
+    vec_ensure_free(&stream->pipe.cache, STREAM_DEFAULT_CHUNK);
+    int read = fread(vec_data(&stream->pipe.cache), 1, STREAM_DEFAULT_CHUNK,
+                     stream->pipe.file);
+    stream->pipe.cache.size += read;
+    return true;
+  }
+  default:
+    FAIL("Unreachable");
+    return 0;
+  }
+}
+
+char stream_next(stream_t *stream)
+{
+  char c = stream_peek(stream);
+  if (c != '\0')
+    ++stream->position;
+  return c;
+}
+
+char stream_peek(stream_t *stream)
+{
+  if (stream_eos(stream))
+    return '\0';
+
+  switch (stream->type)
+  {
+  case STREAM_TYPE_STRING:
+    return stream->string.data[stream->position];
+  case STREAM_TYPE_FILE:
+  {
+    // Cached already?  We are done.
+    if (stream->position < stream->pipe.cache.size)
+      return ((char *)vec_data(&stream->pipe.cache))[stream->position];
+
+    // Try to read chunks in till we've reached it or we're at the end of the
+    // file.
+    for (bool read_chunk = stream_chunk(stream);
+         read_chunk && stream->position >= stream->pipe.cache.size;
+         read_chunk = stream_chunk(stream))
+      continue;
+
+    // Same principle as the stream_eos(stream) check.
+    if (stream->position >= stream->pipe.cache.size)
+      return '\0';
+    return ((char *)vec_data(&stream->pipe.cache))[stream->position];
+  }
+  default:
+    FAIL("Unreachable");
+    return 0;
+  }
+}
+
+bool stream_seek(stream_t *stream, i64 offset)
+{
+  if (offset < 0)
+    return stream_seek_backward(stream, offset * -1);
+  else if (offset > 0)
+    return stream_seek_forward(stream, offset);
+  else
+    // vacuously successful
+    return true;
+}
+
+bool stream_seek_forward(stream_t *stream, u64 offset)
+{
+  if (stream_eos(stream))
+    return false;
+  switch (stream->type)
+  {
+  case STREAM_TYPE_STRING:
+  {
+    if (stream->position + offset < stream->string.size)
+    {
+      stream->position += offset;
+      return true;
+    }
+    return false;
+  }
+  case STREAM_TYPE_FILE:
+  {
+    // Similar principle as stream_peek really...
+
+    // Cached already?  We are done.
+    if (stream->position + offset < stream->pipe.cache.size)
+    {
+      stream->position += offset;
+      return true;
+    }
+
+    // Try to read chunks in till we've reached it or we're at the end of the
+    // file.
+    for (bool read_chunk = stream_chunk(stream);
+         read_chunk && stream->position + offset >= stream->pipe.cache.size;
+         read_chunk = stream_chunk(stream))
+      continue;
+
+    // Same principle as the stream_eos(stream) check.
+    if (stream->position + offset >= stream->pipe.cache.size)
+      return false;
+    stream->position += offset;
+    return true;
+  }
+  default:
+    FAIL("Unreachable");
+    return 0;
+  }
+}
+
+bool stream_seek_backward(stream_t *stream, u64 offset)
+{
+  assert(stream);
+  if (stream->position < offset)
+    return false;
+  stream->position -= offset;
+  return true;
+}
+
+sv_t stream_substr(stream_t *stream, u64 size)
+{
+  if (stream_eos(stream))
+    return SV(NULL, 0);
+  u64 current_position = stream->position;
+  bool successful      = stream_seek_forward(stream, size);
+  // In case we did happen to move forward
+  stream->position = current_position;
+  if (!successful)
+    return SV(NULL, 0);
+
+  char *ptr = NULL;
+  switch (stream->type)
+  {
+  case STREAM_TYPE_STRING:
+    ptr = stream->string.data;
+    break;
+  case STREAM_TYPE_FILE:
+    ptr = vec_data(&stream->pipe.cache);
+    break;
+  default:
+    FAIL("Unreachable");
+    return SV(NULL, 0);
+  }
+
+  return SV(ptr + stream->position, size);
+}
+
+sv_t stream_substr_abs(stream_t *stream, u64 index, u64 size)
+{
+
+  switch (stream->type)
+  {
+  case STREAM_TYPE_STRING:
+    if (index + size < stream_size(stream))
+      return SV(stream->string.data + index, size);
+    return SV(NULL, 0);
+  case STREAM_TYPE_FILE:
+  {
+    if (index + size < stream_size(stream))
+      return SV(vec_data(&stream->pipe.cache) + index, size);
+    // stream_size(stream) <= index + size => try reading chunks
+    for (bool read_chunk = stream_chunk(stream);
+         read_chunk && index + size >= stream->pipe.cache.size;
+         read_chunk = stream_chunk(stream))
+      continue;
+
+    if (index + size >= stream_size(stream))
+      return SV(NULL, 0);
+    return SV(vec_data(&stream->pipe.cache) + index, size);
+  }
+  default:
+    assert("Unreachable");
+    return SV(NULL, 0);
+  }
+}
diff --git a/symtable.c b/symtable.c
index 15c6cd0..39139eb 100644
--- a/symtable.c
+++ b/symtable.c
@@ -38,7 +38,7 @@ char *sym_table_find(sym_table_t *table, sv_t sv)
   if (table->entries.capacity == 0)
     sym_table_init(table);
 
-  // WIP: Deal with resizing this when table->count > table->size / 2
+  // TODO: Deal with resizing this when table->count > table->size / 2
   u64 index = djb2(sv) & (table->capacity - 1);
 
   for (sv_t comp = VEC_GET(&table->entries, sv_t)[index]; comp.data; index += 1,