Session extension (#459)

Session extension bindings

src/types/from_sql.rs

@@ -22,6 +22,18 @@ pub enum FromSqlError {
     Other(Box<dyn Error + Send + Sync>),
 }
 
+impl PartialEq for FromSqlError {
+    fn eq(&self, other: &FromSqlError) -> bool {
+        match (self, other) {
+            (FromSqlError::InvalidType, FromSqlError::InvalidType) => true,
+            (FromSqlError::OutOfRange(n1), FromSqlError::OutOfRange(n2)) => n1 == n2,
+            #[cfg(feature = "i128_blob")]
+            (FromSqlError::InvalidI128Size(s1), FromSqlError::InvalidI128Size(s2)) => s1 == s2,
+            (_, _) => false,
+        }
+    }
+}
+
 impl fmt::Display for FromSqlError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {

src/types/value_ref.rs

@@ -104,3 +104,56 @@ impl<'a> From<&'a Value> for ValueRef<'a> {
         }
     }
 }
+
+#[cfg(any(feature = "functions", feature = "session", feature = "vtab"))]
+impl<'a> ValueRef<'a> {
+    pub(crate) unsafe fn from_value(value: *mut crate::ffi::sqlite3_value) -> ValueRef<'a> {
+        use crate::ffi;
+        use std::ffi::CStr;
+        use std::os::raw::c_char;
+        use std::slice::from_raw_parts;
+
+        match ffi::sqlite3_value_type(value) {
+            ffi::SQLITE_NULL => ValueRef::Null,
+            ffi::SQLITE_INTEGER => ValueRef::Integer(ffi::sqlite3_value_int64(value)),
+            ffi::SQLITE_FLOAT => ValueRef::Real(ffi::sqlite3_value_double(value)),
+            ffi::SQLITE_TEXT => {
+                let text = ffi::sqlite3_value_text(value);
+                assert!(
+                    !text.is_null(),
+                    "unexpected SQLITE_TEXT value type with NULL data"
+                );
+                let s = CStr::from_ptr(text as *const c_char);
+
+                // sqlite3_value_text returns UTF8 data, so our unwrap here should be fine.
+                let s = s
+                    .to_str()
+                    .expect("sqlite3_value_text returned invalid UTF-8");
+                ValueRef::Text(s)
+            }
+            ffi::SQLITE_BLOB => {
+                let (blob, len) = (
+                    ffi::sqlite3_value_blob(value),
+                    ffi::sqlite3_value_bytes(value),
+                );
+
+                assert!(
+                    len >= 0,
+                    "unexpected negative return from sqlite3_value_bytes"
+                );
+                if len > 0 {
+                    assert!(
+                        !blob.is_null(),
+                        "unexpected SQLITE_BLOB value type with NULL data"
+                    );
+                    ValueRef::Blob(from_raw_parts(blob as *const u8, len as usize))
+                } else {
+                    // The return value from sqlite3_value_blob() for a zero-length BLOB
+                    // is a NULL pointer.
+                    ValueRef::Blob(&[])
+                }
+            }
+            _ => unreachable!("sqlite3_value_type returned invalid value"),
+        }
+    }
+}