test_stream: implement stream_test_seek

If a forward/backward offset is too big, we'll clamp to the edges of
the file rather than failing completely.  We return the number of
bytes moved so callers can still validate, but the stream API can now
deal with these situations a bit more effectively.

alisp.org

@@ -52,20 +52,20 @@ other state do we need to encode?
 *** TODO Write the general parser
 ** WIP Unit tests :tests:
 *** TODO Test streams
-**** TODO Test file init
+**** DONE Test file init
 [[file:test/test_stream.c::void stream_test_file(void)]]
-***** TODO Test successful init from real files
+***** DONE Test successful init from real files
 Ensure stream_size is 0 i.e. we don't read anything on creation.
 Also ensure stream_eoc is false.
-***** TODO Test failed init from fake files
-**** TODO Test peeking and next
+***** DONE Test failed init from fake files
+**** DONE Test peeking and next
 [[file:test/test_stream.c::void stream_test_peek_next(void)]]
 - Peeking with bad streams ('\0' return)
 - Peeking with good streams (no effect on position)
 - Next with bad streams ('\0' return, no effect on position)
 - Next with good streams (effects position)
 - Peeking after next (should just work)
-**** TODO Test seeking
+**** DONE Test seeking
 [[file:test/test_stream.c::void stream_test_seek(void)]]
 - Seeking forward/backward on a bad stream (should stop at 0)
 - Seeking forward/backward too far (should clamp)

include/alisp/stream.h

@@ -40,7 +40,7 @@ typedef struct
 typedef struct
 {
   stream_type_t type;
-  char *name;
+  const char *name;
   u64 position;
   union
   {
@@ -51,9 +51,9 @@ typedef struct
 
 #define STREAM_DEFAULT_CHUNK 64
 
-stream_err_t stream_init_string(stream_t *, char *, sv_t);
-stream_err_t stream_init_pipe(stream_t *, char *, FILE *);
-stream_err_t stream_init_file(stream_t *, char *, FILE *);
+stream_err_t stream_init_string(stream_t *, const char *, sv_t);
+stream_err_t stream_init_pipe(stream_t *, const char *, FILE *);
+stream_err_t stream_init_file(stream_t *, const char *, FILE *);
 void stream_stop(stream_t *);
 
 // End of Content (i.e. we've consumed all cached content/file)
@@ -66,9 +66,9 @@ char stream_next(stream_t *);
 // Peek current character, do not push position
 char stream_peek(stream_t *);
 // Move forward or backward in the stream, return success of operation
-bool stream_seek(stream_t *, i64);
-bool stream_seek_forward(stream_t *, u64);
-bool stream_seek_backward(stream_t *, u64);
+u64 stream_seek(stream_t *, i64);
+u64 stream_seek_forward(stream_t *, u64);
+u64 stream_seek_backward(stream_t *, u64);
 
 // Return a relative substring of a given size
 sv_t stream_substr(stream_t *, u64);

src/main.c

@@ -24,6 +24,9 @@ void usage(FILE *fp)
 int main(int argc, char *argv[])
 {
   int ret         = 0;
+  FILE *pipe      = NULL;
+  stream_t stream = {0};
+
   if (argc == 1)
   {
     usage(stderr);
@@ -35,8 +38,6 @@ int main(int argc, char *argv[])
     TODO("alisp doesn't support multiple files currently.");
   }
 
-  FILE *fp        = NULL;
-  stream_t stream = {0};
   if (strncmp(argv[1], "--", 2) == 0)
   {
     stream_err_t err = stream_init_pipe(&stream, "stdin", stdin);
@@ -55,8 +56,8 @@ int main(int argc, char *argv[])
   }
   else
   {
-    fp               = fopen(argv[1], "rb");
-    stream_err_t err = stream_init_file(&stream, argv[1], fp);
+    pipe             = fopen(argv[1], "rb");
+    stream_err_t err = stream_init_file(&stream, argv[1], pipe);
     if (err)
     {
       fprintf(stderr, "ERROR: %s from `%s`\n", stream_err_to_cstr(err),
@@ -68,8 +69,8 @@ int main(int argc, char *argv[])
 
   LOG("[INFO]: Initialised stream for `%s`\n", stream.name);
 end:
-  if (fp)
-    fclose(fp);
+  if (pipe)
+    fclose(pipe);
   stream_stop(&stream);
   return ret;
 }

src/stream.c

@@ -35,7 +35,8 @@ const char *stream_err_to_cstr(stream_err_t err)
   }
 }
 
-stream_err_t stream_init_string(stream_t *stream, char *name, sv_t contents)
+stream_err_t stream_init_string(stream_t *stream, const char *name,
+                                sv_t contents)
 {
   if (!stream)
     return STREAM_ERR_INVALID_PTR;
@@ -49,7 +50,7 @@ stream_err_t stream_init_string(stream_t *stream, char *name, sv_t contents)
   return STREAM_ERR_OK;
 }
 
-stream_err_t stream_init_pipe(stream_t *stream, char *name, FILE *pipe)
+stream_err_t stream_init_pipe(stream_t *stream, const char *name, FILE *pipe)
 {
   if (!stream)
     return STREAM_ERR_INVALID_PTR;
@@ -68,7 +69,7 @@ stream_err_t stream_init_pipe(stream_t *stream, char *name, FILE *pipe)
   return STREAM_ERR_OK;
 }
 
-stream_err_t stream_init_file(stream_t *stream, char *name, FILE *pipe)
+stream_err_t stream_init_file(stream_t *stream, const char *name, FILE *pipe)
 {
   if (!stream)
     return STREAM_ERR_INVALID_PTR;
@@ -82,8 +83,6 @@ stream_err_t stream_init_file(stream_t *stream, char *name, FILE *pipe)
   stream->name      = name;
   stream->pipe.file = pipe;
 
-  vec_init(&stream->pipe.cache, STREAM_DEFAULT_CHUNK);
-
   return STREAM_ERR_OK;
 }
 
@@ -236,7 +235,7 @@ char stream_peek(stream_t *stream)
   }
 }
 
-bool stream_seek(stream_t *stream, i64 offset)
+u64 stream_seek(stream_t *stream, i64 offset)
 {
   if (offset < 0)
     return stream_seek_backward(stream, offset * -1);
@@ -247,20 +246,20 @@ bool stream_seek(stream_t *stream, i64 offset)
     return true;
 }
 
-bool stream_seek_forward(stream_t *stream, u64 offset)
+u64 stream_seek_forward(stream_t *stream, u64 offset)
 {
   if (stream_eoc(stream))
-    return false;
+    return 0;
 
   switch (stream->type)
   {
   case STREAM_TYPE_STRING:
   {
     if (stream->position + offset >= stream->string.size)
-      return false;
+      return 0;
 
     stream->position += offset;
-    return true;
+    return offset;
   }
   case STREAM_TYPE_PIPE:
   case STREAM_TYPE_FILE:
@@ -271,7 +270,7 @@ bool stream_seek_forward(stream_t *stream, u64 offset)
     if (stream->position + offset < stream->pipe.cache.size)
     {
       stream->position += offset;
-      return true;
+      return offset;
     }
 
     // Try to read chunks in till we've reached it or we're at the end of the
@@ -283,9 +282,11 @@ bool stream_seek_forward(stream_t *stream, u64 offset)
 
     // Same principle as the stream_eoc(stream) check.
     if (stream->position + offset > stream->pipe.cache.size)
-      return false;
+    {
+      offset = stream->pipe.cache.size - stream->position;
+    }
     stream->position += offset;
-    return true;
+    return offset;
   }
   default:
     FAIL("Unreachable");
@@ -293,13 +294,16 @@ bool stream_seek_forward(stream_t *stream, u64 offset)
   }
 }
 
-bool stream_seek_backward(stream_t *stream, u64 offset)
+u64 stream_seek_backward(stream_t *stream, u64 offset)
 {
   assert(stream);
   if (stream->position < offset)
-    return false;
+  {
+    offset = stream->position;
+  }
+
   stream->position -= offset;
-  return true;
+  return offset;
 }
 
 sv_t stream_substr(stream_t *stream, u64 size)

test/main.c

@@ -6,7 +6,9 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
+#include <time.h>
 
 #include "./data.h"
 #include "./test.h"
@@ -18,18 +20,19 @@
 #include "./test_vec.c"
 
 test_suite_t SUITES[] = {
-    VEC_SUITE, SV_SUITE, SYMTABLE_SUITE, STREAM_SUITE, LISP_API_SUITE,
+    SV_SUITE, VEC_SUITE, SYMTABLE_SUITE, STREAM_SUITE, LISP_API_SUITE,
 };
 
 int main(void)
 {
+  // Seed the pseudorandom gen for subsequent tests.
+  srand(time(NULL));
   for (u64 i = 0; i < ARRSIZE(SUITES); ++i)
   {
     test_suite_t suite = SUITES[i];
     printf("Suite [%s]\n", suite.name);
     for (u64 j = 0; j < suite.size; ++j)
     {
-      printf("\t[%s]: Running...\n", suite.tests[j].name);
       suite.tests[j].fn();
     }
   }

test/test.h

@@ -14,8 +14,16 @@
 #define TEST_VERBOSE 0
 #endif
 
-#define TEST_PASSED() printf("\t[%s]: Passed\n", __func__)
+#define TEST_END() printf("\t[%s]: Passed\n", __func__)
+#define TEST_INFO(...)   \
+  do                     \
+  {                      \
+    printf("\tINFO: ");  \
+    printf(__VA_ARGS__); \
+  } while (0);
+
 #if TEST_VERBOSE
+#define TEST_START() printf("\t[%s]: Running...\n", __func__)
 #define TEST(COND, ...)                  \
   do                                     \
   {                                      \
@@ -36,6 +44,7 @@
     }                                    \
   } while (0)
 #else
+#define TEST_START()
 #define TEST(COND, ...) \
   do                    \
   {                     \

test/test_lisp_api.c

@@ -12,6 +12,7 @@
 
 void smi_test(void)
 {
+  TEST_START();
   // Standard old testing, checking both sides of the number line and our set
   // bounds.
   i64 ints[] = {
@@ -27,11 +28,12 @@ void smi_test(void)
     TEST(in == out, "%ld == %ld", in, out);
   }
 
-  TEST_PASSED();
+  TEST_END();
 }
 
 void smi_oob_test(void)
 {
+  TEST_START();
   // These are integers that are completely out of the bounds of our standard
   // tagging system due to their size.  We need to use big integers for this.
   i64 ints[] = {
@@ -50,11 +52,12 @@ void smi_oob_test(void)
     TEST(in != out, "%ld != %ld", in, out);
   }
 
-  TEST_PASSED();
+  TEST_END();
 }
 
 void sym_fresh_test(void)
 {
+  TEST_START();
   sys_t system = {0};
   sys_init(&system);
 
@@ -71,11 +74,12 @@ void sym_fresh_test(void)
   }
 
   sys_free(&system);
-  TEST_PASSED();
+  TEST_END();
 }
 
 void sym_unique_test(void)
 {
+  TEST_START();
   sys_t system = {0};
   sys_init(&system);
 
@@ -102,11 +106,12 @@ void sym_unique_test(void)
   }
 
   sys_free(&system);
-  TEST_PASSED();
+  TEST_END();
 }
 
 void cons_test(void)
 {
+  TEST_START();
   sys_t system = {0};
   sys_init(&system);
 
@@ -138,11 +143,12 @@ void cons_test(void)
   }
 
   sys_free(&system);
-  TEST_PASSED();
+  TEST_END();
 }
 
 void sys_test(void)
 {
+  TEST_START();
   sys_t sys = {0};
   sys_init(&sys);
   u64 old_memory_size = sys.memory.size;
@@ -158,14 +164,14 @@ void sys_test(void)
        "Interning doesn't affect system memory size");
   TEST(sys.symtable.count > 0, "Interning affects symbol table");
 
-  // Creating cons' do affect memory size
+  // Creating conses do affect memory size
   (void)cons(&sys, make_int(1), make_int(2));
-  TEST(sys.memory.size > 0, "Creating cons' affects memory size");
+  TEST(sys.memory.size > 0, "Creating conses affects memory size");
   old_memory_size = sys.memory.size;
 
   (void)cons(&sys, intern(&sys, SV("test", 4)), NIL);
   TEST(sys.memory.size > old_memory_size,
-       "Creating cons' back to back affects memory size");
+       "Creating conses back to back affects memory size");
   old_memory_size = sys.memory.size;
 
   // Creating vectors does affect memory size
@@ -183,7 +189,7 @@ void sys_test(void)
   TEST(sys.memory.size == 0, "sys_free cleans up memory (shallow check)");
   TEST(sys.symtable.count == 0, "sys_free cleans up symtable (shallow check)");
 
-  TEST_PASSED();
+  TEST_END();
 }
 
 MAKE_TEST_SUITE(LISP_API_SUITE, "LISP API Tests",

test/test_stream.c

@@ -6,14 +6,63 @@
  */
 
 #include <malloc.h>
+#include <stdio.h>
 
 #include "./data.h"
 #include "./test.h"
 
 #include <alisp/stream.h>
+#include <string.h>
+
+char valid_filename[50];
+FILE *valid_fp   = NULL;
+FILE *invalid_fp = NULL;
+
+void stream_test_prologue(void)
+{
+  const char filename_prefix[]                = "build/stream_test_";
+  valid_filename[ARRSIZE(valid_filename) - 1] = '\0';
+  memcpy(valid_filename, filename_prefix, ARRSIZE(filename_prefix) - 1);
+  for (u64 i = ARRSIZE(filename_prefix) - 1; i < ARRSIZE(valid_filename) - 1;
+       ++i)
+  {
+    u8 num = (rand() % 36);
+    if (num < 26)
+    {
+      valid_filename[i] = num + 'a';
+    }
+    else
+    {
+      valid_filename[i] = num + '0';
+    }
+  }
+
+  TEST_INFO("Creating file named `%.*s`\n", (int)ARRSIZE(valid_filename),
+            valid_filename);
+  valid_fp = fopen(valid_filename, "wb");
+  // This should do a few things for us
+  // 1) Create a file, or clear the contents of it if it exists already.
+  // 2) Write some content to it.
+  assert(valid_fp);
+  fwrite(words_text, ARRSIZE(words_text) - 1, 1, valid_fp);
+  fclose(valid_fp);
+  valid_fp = fopen(valid_filename, "rb");
+  assert(valid_fp);
+
+  invalid_fp = NULL;
+}
+
+void stream_test_epilogue(void)
+{
+  TEST_INFO("Freeing resources and deleting file `%s`\n", valid_filename);
+  assert(valid_fp);
+  fclose(valid_fp);
+  remove(valid_filename);
+}
 
 void stream_test_string(void)
 {
+  TEST_START();
   sv_t test_strings[] = {
       SV("hello, world!", 13),
       SV("another string", 14),
@@ -49,47 +98,214 @@ void stream_test_string(void)
   TEST(stream_eoc(&stream), "NULL stream is always at end of content");
   stream_stop(&stream);
 
-  TEST_PASSED();
+  TEST_END();
 }
 
 void stream_test_file(void)
 {
-  TODO("Not implemented");
+  TEST_START();
+
+  // Test that initialising works correctly
+  {
+    stream_t stream = {0};
+    {
+      stream_err_t err = stream_init_file(&stream, valid_filename, valid_fp);
+      TEST(err == STREAM_ERR_OK, "Expected initialisating to be okay: %s",
+           stream_err_to_cstr(err));
+    }
+    TEST(stream_size(&stream) == 0, "Stream doesn't read on init: size = %lu",
+         stream_size(&stream));
+    TEST(!stream_eoc(&stream), "Stream should not be at the EoC from init.");
+  }
+
+  // try to initialise the stream again but against a nonexistent file - we're
+  // expecting an error.
+  {
+    stream_t stream = {0};
+    {
+      stream_err_t err = stream_init_file(&stream, NULL, invalid_fp);
+      TEST(err != STREAM_ERR_OK, "Expected initialisating to not be okay: %s",
+           stream_err_to_cstr(err));
+    }
+  }
+
+  TEST_END();
 }
 
 void stream_test_peek_next(void)
 {
-  TODO("Not implemented");
+  TEST_START();
+
+  // Valid streams
+  {
+    stream_t stream = {0};
+    stream_init_file(&stream, valid_filename, valid_fp);
+
+    u64 old_position = stream.position;
+    char c1          = stream_peek(&stream);
+    TEST(c1 != '\0', "Peek should provide a normal character (%c)", c1);
+    TEST(stream.position == old_position,
+         "Peek should not shift the position (%lu -> %lu)", old_position,
+         stream.position);
+
+    char c2 = stream_next(&stream);
+    TEST(c2 != '\0', "Next should provide a normal character (%c)", c2);
+    TEST(stream.position > old_position,
+         "Next should shift the position (%lu -> %lu)", old_position,
+         stream.position);
+    TEST(c2 != c1,
+         "Next should yield a different character (%c) to the previous peek "
+         "(%c)",
+         c2, c1);
+
+    char c3 = stream_peek(&stream);
+    TEST(c3 == c2,
+         "Peeking should yield the same character (%c) as the previous next "
+         "(%c)",
+         c3, c2);
+
+    stream_stop(&stream);
+  }
+
+  // Invalid streams
+  {
+    stream_t stream = {0};
+    stream_init_file(&stream, NULL, invalid_fp);
+    char c = stream_peek(&stream);
+    TEST(c == '\0', "Invalid streams should have an invalid peek (%c)", c);
+
+    u64 old_position = stream.position;
+    c                = stream_next(&stream);
+    TEST(c == '\0', "Invalid streams should have an invalid next (%c)", c);
+    TEST(old_position == stream.position,
+         "Next on an invalid stream should not affect position (%lu -> %lu)",
+         old_position, stream.position);
+
+    stream_stop(&stream);
+  }
+  TEST_END();
 }
 
 void stream_test_seek(void)
 {
-  TODO("Not implemented");
+  TEST_START();
+  // Seeking on invalid streams
+  {
+    stream_t stream = {0};
+    stream_init_file(&stream, NULL, invalid_fp);
+
+    u64 old_position = stream.position;
+    TEST(!stream_seek_forward(&stream, 1),
+         "Shouldn't be possible to seek forward on an invalid stream.");
+    TEST(old_position == stream.position,
+         "Position shouldn't be affected when seeking forward on an invalid "
+         "stream"
+         "(%lu -> %lu)",
+         old_position, stream.position);
+
+    TEST(!stream_seek_backward(&stream, 1),
+         "Shouldn't be possible to seek backward on an invalid stream.");
+    TEST(old_position == stream.position,
+         "Position shouldn't be affected when seeking backward on an invalid "
+         "stream (%lu -> %lu)",
+         old_position, stream.position);
+
+    stream_stop(&stream);
+  }
+
+  // Valid streams
+  {
+    stream_t stream = {0};
+    stream_init_file(&stream, valid_filename, valid_fp);
+
+    u64 old_position = stream.position;
+    TEST(stream_seek_forward(&stream, 1),
+         "Okay to seek forward on a valid stream.");
+    TEST(old_position < stream.position,
+         "Position should be greater than before when seeking forward on a "
+         "valid stream (%lu -> %lu)",
+         old_position, stream.position);
+
+    TEST(stream_seek_backward(&stream, 1),
+         "Okay to seek backward on a valid stream.");
+    TEST(old_position == stream.position,
+         "stream_seek_forward and stream_seek_backward are inverse operations");
+
+    u64 forward_offset = stream_seek_forward(&stream, ARRSIZE(words_text) * 2);
+    TEST(forward_offset < ARRSIZE(words_text) * 2,
+         "Forward seeking by offsets greater than file size clamps (%lu "
+         "clamps to %lu)",
+         ARRSIZE(words_text) * 2, forward_offset);
+
+    u64 file_size       = stream_size(&stream);
+    u64 backward_offset = stream_seek_backward(&stream, file_size + 1);
+    TEST(backward_offset == file_size,
+         "Backward seeking by offsets greater than file size clamps (%lu "
+         "clamps to %lu)",
+         file_size + 1, backward_offset);
+
+    TEST(stream.position == 0,
+         "Clamped forward and clamped backward seeking "
+         "leads to start of stream (position=%lu)",
+         stream.position);
+
+    i64 r_forward_offset  = (rand() % (file_size - 1)) + 1;
+    i64 r_backward_offset = (rand() % (file_size - 1)) + 1;
+    while (r_backward_offset >= r_forward_offset)
+      r_backward_offset = (rand() % (file_size - 1)) + 1;
+
+    TEST(stream_seek(&stream, r_forward_offset) == (u64)r_forward_offset,
+         "Seeking by a random positive offset (%lu) is valid",
+         r_forward_offset);
+
+    TEST(stream_seek(&stream, -r_backward_offset) == (u64)r_backward_offset,
+         "Seeking backward by a random negative offset (%lu) is valid",
+         r_backward_offset);
+
+    TEST(
+        (i64)stream.position == r_forward_offset - r_backward_offset,
+        "Stream position (%lu) is exactly shifted by seeking offsets described "
+        "above.",
+        stream.position);
+
+    stream_stop(&stream);
+  }
+
+  TEST_END();
 }
 
 void stream_test_substr(void)
 {
+  TEST_START();
   TODO("Not implemented");
 }
 
 void stream_test_till(void)
 {
+  TEST_START();
   TODO("Not implemented");
 }
 
 void stream_test_while(void)
 {
+  TEST_START();
   TODO("Not implemented");
 }
 
 void stream_test_line_col(void)
 {
+  TEST_START();
   TODO("Not implemented");
 }
 
 MAKE_TEST_SUITE(STREAM_SUITE, "Stream Tests",
 
-                MAKE_TEST_FN(stream_test_string), );
+                MAKE_TEST_FN(stream_test_prologue),
+                MAKE_TEST_FN(stream_test_string),
+                MAKE_TEST_FN(stream_test_file),
+                MAKE_TEST_FN(stream_test_peek_next),
+                MAKE_TEST_FN(stream_test_seek),
+                MAKE_TEST_FN(stream_test_epilogue), );
 
 /* Copyright (C) 2026 Aryadev Chavali
 

test/test_sv.c

@@ -13,6 +13,7 @@
 
 void sv_copy_test(void)
 {
+  TEST_START();
   static_assert(ARRSIZE(unique_words) > 3, "Expected at least 3 unique words");
   for (u64 i = 0; i < 3; ++i)
   {

test/test_symtable.c

@@ -10,6 +10,7 @@
 
 void symtable_test(void)
 {
+  TEST_START();
   sym_table_t table = {0};
   sym_table_init(&table);
   for (u64 i = 0; i < ARRSIZE(words); ++i)
@@ -19,7 +20,7 @@ void symtable_test(void)
        ARRSIZE(unique_words));
 
   sym_table_free(&table);
-  TEST_PASSED();
+  TEST_END();
 }
 
 MAKE_TEST_SUITE(SYMTABLE_SUITE, "Symbol Table Tests",

test/test_vec.c

@@ -10,6 +10,7 @@
 
 void vec_test_concat(void)
 {
+  TEST_START();
   sys_t system = {0};
   sys_init(&system);
 
@@ -33,11 +34,12 @@ void vec_test_concat(void)
        strlen(words_text));
 
   sys_free(&system);
-  TEST_PASSED();
+  TEST_END();
 }
 
 void vec_test_substr(void)
 {
+  TEST_START();
   sys_t system = {0};
   sys_init(&system);
   // Generating substrings
@@ -66,7 +68,7 @@ void vec_test_substr(void)
   }
 
   sys_free(&system);
-  TEST_PASSED();
+  TEST_END();
 }
 
 MAKE_TEST_SUITE(VEC_SUITE, "Vector Tests",