add simple parser

src/main.rs

@@ -6,6 +6,44 @@ struct InputBuffer {
     buffer: Option<String>,
 }
 
+enum MetaCommandResult {
+    Success,
+    Unrecognized,
+}
+
+enum PrepareResult {
+    Success,
+    Unrecognized,
+}
+
+enum StatementType {
+    Insert,
+    Select,
+}
+
+struct Statement {
+    statement_type: StatementType,
+}
+
+impl Statement {
+    fn new(statement_type: StatementType) -> Self {
+        Self {
+            statement_type
+        }
+    }
+
+    pub(crate) fn execute(&self) {
+        match self.statement_type {
+            StatementType::Insert => {
+                println!("This is where you do an insert")
+            }
+            StatementType::Select => {
+                println!("This is where you do an select")
+            }
+        }
+    }
+}
+
 impl InputBuffer {
     pub fn new() -> Self {
         return Self {
@@ -38,7 +76,32 @@ impl InputBuffer {
     pub(crate) fn parse(&self) {
         match &self.buffer {
             Some(command) => {
-                match command.as_str().replace("\n", "").trim() {
+                if command.starts_with(".") {
+                    Self::handle_meta_statement(command);
+                } else {
+                    if let Ok(statement) = Self::prepare_statement(command) {
+                        statement.execute()
+                    } else {
+                        println!("could not recognize statement");
+                    }
+                }
+            }
+            None => {}
+        }
+    }
+
+    fn prepare_statement(command: &String) -> Result<Statement, String> {
+        if command.starts_with("insert") {
+            Ok(Statement::new(StatementType::Insert))
+        } else if command.starts_with("select") {
+            Ok(Statement::new(StatementType::Select))
+        } else {
+            Err(String::from("Unrecognized statement"))
+        }
+    }
+
+    fn handle_meta_statement(command: &String) {
+        match command.replace("\n", "").trim() {
             ".exit" => {
                 exit(0);
             }
@@ -47,9 +110,6 @@ impl InputBuffer {
             }
         }
     }
-            None => {}
-        }
-    }
 }