diff --git a/nac3core/src/context/mod.rs b/nac3core/src/context/mod.rs
new file mode 100644
index 00000000..79f26bf5
--- /dev/null
+++ b/nac3core/src/context/mod.rs
@@ -0,0 +1,2 @@
+mod top_level_context;
+pub use top_level_context::TopLevelContext;
diff --git a/nac3core/src/context/top_level_context.rs b/nac3core/src/context/top_level_context.rs
new file mode 100644
index 00000000..004b271e
--- /dev/null
+++ b/nac3core/src/context/top_level_context.rs
@@ -0,0 +1,136 @@
+use crate::typedef::*;
+use std::collections::HashMap;
+use std::rc::Rc;
+
+/// Structure for storing top-level type definitions.
+/// Used for collecting type signature from source code.
+/// Can be converted to `InferenceContext` for type inference in functions.
+pub struct TopLevelContext<'a> {
+    /// List of primitive definitions.
+    pub(super) primitive_defs: Vec<TypeDef<'a>>,
+    /// List of class definitions.
+    pub(super) class_defs: Vec<ClassDef<'a>>,
+    /// List of parametric type definitions.
+    pub(super) parametric_defs: Vec<ParametricDef<'a>>,
+    /// List of type variable definitions.
+    pub(super) var_defs: Vec<VarDef<'a>>,
+    /// Function name to signature mapping.
+    pub(super) fn_table: HashMap<&'a str, FnDef>,
+    /// Type name to type mapping.
+    pub(super) sym_table: HashMap<&'a str, Type>,
+
+    primitives: Vec<Type>,
+    variables: Vec<Type>,
+}
+
+impl<'a> TopLevelContext<'a> {
+    pub fn new(primitive_defs: Vec<TypeDef<'a>>) -> TopLevelContext {
+        let mut sym_table = HashMap::new();
+        let mut primitives = Vec::new();
+        for (i, t) in primitive_defs.iter().enumerate() {
+            primitives.push(TypeEnum::PrimitiveType(PrimitiveId(i)).into());
+            sym_table.insert(t.name, TypeEnum::PrimitiveType(PrimitiveId(i)).into());
+        }
+        TopLevelContext {
+            primitive_defs,
+            class_defs: Vec::new(),
+            parametric_defs: Vec::new(),
+            var_defs: Vec::new(),
+            fn_table: HashMap::new(),
+            sym_table,
+            primitives,
+            variables: Vec::new(),
+        }
+    }
+
+    pub fn add_class(&mut self, def: ClassDef<'a>) -> ClassId {
+        self.sym_table.insert(
+            def.base.name,
+            TypeEnum::ClassType(ClassId(self.class_defs.len())).into(),
+        );
+        self.class_defs.push(def);
+        ClassId(self.class_defs.len() - 1)
+    }
+
+    pub fn add_parametric(&mut self, def: ParametricDef<'a>) -> ParamId {
+        let params = def
+            .params
+            .iter()
+            .map(|&v| Rc::new(TypeEnum::TypeVariable(v)))
+            .collect();
+        self.sym_table.insert(
+            def.base.name,
+            TypeEnum::ParametricType(ParamId(self.parametric_defs.len()), params).into(),
+        );
+        self.parametric_defs.push(def);
+        ParamId(self.parametric_defs.len() - 1)
+    }
+
+    pub fn add_variable(&mut self, def: VarDef<'a>) -> VariableId {
+        self.sym_table.insert(
+            def.name,
+            TypeEnum::TypeVariable(VariableId(self.var_defs.len())).into(),
+        );
+        self.add_variable_private(def)
+    }
+
+    pub fn add_variable_private(&mut self, def: VarDef<'a>) -> VariableId {
+        self.var_defs.push(def);
+        self.variables
+            .push(TypeEnum::TypeVariable(VariableId(self.var_defs.len() - 1)).into());
+        VariableId(self.var_defs.len() - 1)
+    }
+
+    pub fn add_fn(&mut self, name: &'a str, def: FnDef) {
+        self.fn_table.insert(name, def);
+    }
+
+    pub fn get_fn_def(&self, name: &str) -> Option<&FnDef> {
+        self.fn_table.get(name)
+    }
+
+    pub fn get_primitive_def_mut(&mut self, id: PrimitiveId) -> &mut TypeDef<'a> {
+        self.primitive_defs.get_mut(id.0).unwrap()
+    }
+
+    pub fn get_primitive_def(&self, id: PrimitiveId) -> &TypeDef {
+        self.primitive_defs.get(id.0).unwrap()
+    }
+
+    pub fn get_class_def_mut(&mut self, id: ClassId) -> &mut ClassDef<'a> {
+        self.class_defs.get_mut(id.0).unwrap()
+    }
+
+    pub fn get_class_def(&self, id: ClassId) -> &ClassDef {
+        self.class_defs.get(id.0).unwrap()
+    }
+
+    pub fn get_parametric_def_mut(&mut self, id: ParamId) -> &mut ParametricDef<'a> {
+        self.parametric_defs.get_mut(id.0).unwrap()
+    }
+
+    pub fn get_parametric_def(&self, id: ParamId) -> &ParametricDef {
+        self.parametric_defs.get(id.0).unwrap()
+    }
+
+    pub fn get_variable_def_mut(&mut self, id: VariableId) -> &mut VarDef<'a> {
+        self.var_defs.get_mut(id.0).unwrap()
+    }
+
+    pub fn get_variable_def(&self, id: VariableId) -> &VarDef {
+        self.var_defs.get(id.0).unwrap()
+    }
+
+    pub fn get_primitive(&self, id: PrimitiveId) -> Type {
+        self.primitives.get(id.0).unwrap().clone()
+    }
+
+    pub fn get_variable(&self, id: VariableId) -> Type {
+        self.variables.get(id.0).unwrap().clone()
+    }
+
+    pub fn get_type(&self, name: &str) -> Option<Type> {
+        // TODO: handle parametric types
+        self.sym_table.get(name).cloned()
+    }
+}
diff --git a/nac3core/src/lib.rs b/nac3core/src/lib.rs
index 53d5d36e..4c939d3e 100644
--- a/nac3core/src/lib.rs
+++ b/nac3core/src/lib.rs
@@ -6,6 +6,8 @@ extern crate inkwell;
 extern crate rustpython_parser;
 
 pub mod typedef;
+pub mod context;
+
 use std::error::Error;
 use std::fmt;
 use std::path::Path;