int8 vec from text (#17)

* parse int8 vec from json format text

* add small test cases for text based loading

sqlite-vec.c

@@ -557,6 +557,103 @@ static int int8_vec_from_value(sqlite3_value *value, i8 **vector,
     *cleanup = vector_cleanup_noop;
     return SQLITE_OK;
   }
+
+ if (value_type == SQLITE_TEXT) {
+    const char *source = (const char *)sqlite3_value_text(value);
+    int source_len = sqlite3_value_bytes(value);
+    int i = 0;
+
+    struct Array x;
+    int rc = array_init(&x, sizeof(i8), ceil(source_len / 2.0));
+    if (rc != SQLITE_OK) {
+      return rc;
+    }
+
+    // advance leading whitespace to first '['
+    while (i < source_len) {
+      if (jsonIsspace(source[i])) {
+        i++;
+        continue;
+      }
+      if (source[i] == '[') {
+        break;
+      }
+
+      *pzErr = sqlite3_mprintf(
+          "JSON array parsing error: Input does not start with '['");
+      array_cleanup(&x);
+      return SQLITE_ERROR;
+    }
+    if (source[i] != '[') {
+      *pzErr = sqlite3_mprintf(
+          "JSON array parsing error: Input does not start with '['");
+      array_cleanup(&x);
+      return SQLITE_ERROR;
+    }
+    int offset = i + 1;
+
+    while (offset < source_len) {
+      char *ptr = (char *)&source[offset];
+      char *endptr;
+
+      errno = 0;
+      long result = strtol(ptr, &endptr, 10);
+      if ((errno != 0 && result == 0) 
+          || (errno == ERANGE &&
+              (result == LONG_MAX || result == LONG_MIN)) 
+      ) {
+        sqlite3_free(x.z);
+        *pzErr = sqlite3_mprintf("JSON parsing error");
+        return SQLITE_ERROR;
+      }
+
+      if (endptr == ptr) {
+        if (*ptr != ']') {
+          sqlite3_free(x.z);
+          *pzErr = sqlite3_mprintf("JSON parsing error");
+          return SQLITE_ERROR;
+        }
+        goto done;
+      }
+
+      if (result < INT8_MIN || result > INT8_MAX) {
+        sqlite3_free(x.z);
+        *pzErr = sqlite3_mprintf("JSON parsing error: value out of range for int8");
+        return SQLITE_ERROR;
+      }
+
+      i8 res = (i8)result;
+      array_append(&x, (const void *)&res);
+
+      offset += (endptr - ptr);
+      while (offset < source_len) {
+        if (jsonIsspace(source[offset])) {
+          offset++;
+          continue;
+        }
+        if (source[offset] == ',') {
+          offset++;
+          continue;
+        }
+        if (source[offset] == ']')
+          goto done;
+        break;
+      }
+    }
+
+  done:
+
+    if (x.length > 0) {
+      *vector = (i8 *)x.z;
+      *dimensions = x.length;
+      *cleanup = (vector_cleanup)sqlite3_free;
+      return SQLITE_OK;
+    }
+    sqlite3_free(x.z);
+    *pzErr = sqlite3_mprintf("zero-length vectors are not supported.");
+    return SQLITE_ERROR;
+  }
+
   *pzErr = sqlite3_mprintf("Unknown type for int8 vector.");
   return SQLITE_ERROR;
 }

tests/test-loadable.py

@@ -211,6 +211,8 @@ def test_vec_int8():
     vec_int8 = lambda *args: db.execute("select vec_int8(?)", args).fetchone()[0]
     assert vec_int8(b"\x00") == _int8([0])
     assert vec_int8(b"\x00\x0f") == _int8([0, 15])
+    assert vec_int8("[0]") == _int8([0])
+    assert vec_int8("[1, 2, 3]") == _int8([1, 2, 3])
 
     if SUPPORTS_SUBTYPE:
         assert db.execute("select subtype(vec_int8(?))", [b"\x00"]).fetchone()[0] == 225