commit c0cfc8eb82516ca1588d418e1225cb29c62adf29
Author: Michael Pfaff <michael@pfaff.dev>
Date:   Thu May 19 12:27:06 2022 -0400

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..4fffb2f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+/target
+/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..68d5719
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "ql"
+version = "0.1.0"
+edition = "2021"
+
+[features]
+default = [ ]
+serde = [ "dep:serde" ]
+
+[dependencies]
+serde = { version = "1", optional = true, features = [ "derive" ] }
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..b70804f
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,33 @@
+/// A dynamic query structure.
+pub trait DynamicQuery {
+    type Definition;
+
+    fn filter_ref(&mut self, def: &Self::Definition);
+
+    fn filter(mut self, def: &Self::Definition) -> Self
+    where
+        Self: Sized,
+    {
+        self.filter_ref(def);
+        self
+    }
+}
+
+mod macros;
+
+#[cfg(test)]
+mod tests {
+    // just tests that the macro compiles
+    crate::query_def! {
+        Foo(FooDef) {
+            bar: 'dyn (Bar),
+            baz: (bool),
+            bars: 'vec (Bar),
+            bars_by_bazs: 'map (bool, Bar),
+        }
+
+        Bar(BarDef) {
+            baz: (bool),
+        }
+    }
+}
diff --git a/src/macros.rs b/src/macros.rs
new file mode 100644
index 0000000..6fb9f58
--- /dev/null
+++ b/src/macros.rs
@@ -0,0 +1,131 @@
+#[macro_export]
+macro_rules! query_def_type {
+    (@ ($type:ty)) => {
+        $type
+    };
+    (@ 'dyn ($type:ty)) => {
+        $type
+    };
+    (@ 'vec ($type:ty)) => {
+        Vec<$type>
+    };
+    (@ 'map ($key:ty, $value:ty)) => {
+        ::std::collections::HashMap<$key, $value>
+    };
+}
+
+#[macro_export]
+macro_rules! query_def_field {
+    (@dyn $type:ty) => {
+        Option<<$type as $crate::DynamicQuery>::Definition>
+    };
+    (@ ($type:ty)) => {
+        bool
+    };
+    (@ 'dyn ($type:ty)) => {
+        $crate::query_def_field!(@dyn $type)
+    };
+    (@ 'vec ($type:ty)) => {
+        $crate::query_def_field!(@dyn $type)
+    };
+    (@ 'map ($key:ty, $value:ty)) => {
+        $crate::query_def_field!(@dyn $value)
+    };
+}
+
+#[macro_export]
+macro_rules! query_def_filter {
+    // note about this: 'dyn is implied for 'vec and 'map because if the type is not 'dyn, then the
+    // special handling is not necessary in the first place.
+    (@ $query:expr, $value:ident, 'vec ($_type:path)) => {
+        match $query {
+            Some(query) => {
+                if let Some(ref mut value) = $value {
+                    for value in value.iter_mut() {
+                        value.filter_ref(&query);
+                    }
+                }
+            }
+            None => {
+                *$value = None;
+            }
+        }
+    };
+    (@ $query:expr, $value:ident, 'map ($_key:path, $_value:path)) => {
+        match $query {
+            Some(query) => {
+                if let Some(ref mut value) = $value {
+                    for (_, value) in value.iter_mut() {
+                        value.filter_ref(&query);
+                    }
+                }
+            }
+            None => {
+                *$value = None;
+            }
+        }
+    };
+    (@ $query:expr, $value:ident, 'dyn ($($_type:tt)+)) => {
+        if let Some(ref mut value) = $value {
+            if let Some(ref query) = $query {
+                value.filter_ref(&query);
+            }
+        }
+    };
+    (@ $query:expr, $value:ident, ($($_type:tt)+)) => {
+        if !*$query {
+            *$value = None;
+        }
+    };
+}
+
+/// Defines a dynamic query structure.
+#[macro_export]
+macro_rules! query_def {
+    (
+        $($vis:vis $data:ident($def:ident) {
+            $(
+                $(#[$field_meta:meta])
+                *
+                $field:ident: $($qualifier:lifetime)? ($($type:tt)+),
+            )+
+        })
+        *
+    ) => {
+        $(
+            #[derive(Debug, Clone)]
+            #[cfg_attr(feature = "serde", derive(::serde::Serialize, ::serde::Deserialize))]
+            $vis struct $data {
+                $(
+                    #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none"))]
+                    $(#[$field_meta])
+                    *
+                    pub $field: Option<$crate::query_def_type!(@ $($qualifier)? ($($type)+))>,
+                )+
+            }
+
+            #[derive(Debug, Clone)]
+            #[cfg_attr(feature = "serde", derive(::serde::Serialize, ::serde::Deserialize))]
+            $vis struct $def {
+                $(
+                    #[cfg_attr(feature = "serde", serde(default))]
+                    pub $field: $crate::query_def_field!(@ $($qualifier)? ($($type)+)),
+                )+
+            }
+
+            impl $crate::DynamicQuery for $data {
+                type Definition = $def;
+
+                fn filter_ref(&mut self, def: &Self::Definition) {
+                    $(
+                        let query = &def.$field;
+                        let value = &mut self.$field;
+                        $crate::query_def_filter!(@ query, value, $($qualifier)? ($($type)+));
+                    )
+                    +
+                }
+            }
+        )
+        *
+    };
+}