Added a table field.

src/data/mod.rs

@@ -1,11 +1,40 @@
-pub mod id;
-pub mod record;
+mod id;
+mod record;
 
-struct Table;
+use crate::data::record::Record;
+use std::collections::HashMap;
+
+struct FieldDef;
+
+impl FieldDef {
+    fn new() -> Self {
+        Self {}
+    }
+}
+
+struct Table {
+    fields: HashMap<String, FieldDef>,
+}
 
 impl Table {
     fn new() -> Self {
-        Self {}
+        Self {
+            fields: HashMap::new(),
+        }
+    }
+
+    fn len(&self) -> usize {
+        self.fields.len()
+    }
+
+    fn add_field(&mut self, name: &str, field_type: &str) -> Result<(), String> {
+        match self.fields.get(name) {
+            Some(_) => Err("duplicate field name".to_string()),
+            None => {
+                self.fields.insert(name.to_string(), FieldDef::new());
+                Ok(())
+            },
+        }
     }
 }
 
@@ -16,5 +45,23 @@ mod table {
     #[test]
     fn new_table() {
         let tbl = Table::new();
+        assert_eq!(tbl.len(), 0);
+    }
+
+    #[test]
+    fn add_field() {
+        let mut tbl = Table::new();
+        tbl.add_field("one", "id");
+        assert_eq!(tbl.len(), 1);
+    }
+
+    #[test]
+    fn error_on_duplicate_name() {
+        let mut tbl = Table::new();
+        tbl.add_field("one", "id");
+        match tbl.add_field("one", "id") {
+            Ok(_) => unreachable!(" Should not duplicates."),
+            Err(_) => {},
+        }
     }
 }