TableEngine and SqlHandler impl (#45)

* Impl TableEngine, bridge to storage

* Impl sql handler to process insert sql

* fix: minor changes and typo

* test: add datanode test

* test: add table-engine test

* fix: code style

* refactor: split out insert mod from sql and minor changes by CR

* refactor: replace with_context with context

src/sql/src/ast.rs

@@ -1 +1,2 @@
-
+pub use sqlparser::ast::Expr;
+pub use sqlparser::ast::Value;

src/sql/src/statements/insert.rs

@@ -1,12 +1,56 @@
-use sqlparser::ast::Statement;
+use sqlparser::ast::{SetExpr, Statement, Values};
 use sqlparser::parser::ParserError;
 
+use crate::ast::{Expr, Value};
+
 #[derive(Debug, Clone, PartialEq)]
 pub struct Insert {
     // Can only be sqlparser::ast::Statement::Insert variant
     pub inner: Statement,
 }
 
+impl Insert {
+    pub fn table_name(&self) -> String {
+        match &self.inner {
+            Statement::Insert { table_name, .. } => {
+                // FIXME(dennis): table_name may be in the form of "catalog.schema.table"
+                table_name.to_string()
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    pub fn columns(&self) -> Vec<&String> {
+        match &self.inner {
+            Statement::Insert { columns, .. } => columns.iter().map(|ident| &ident.value).collect(),
+            _ => unreachable!(),
+        }
+    }
+
+    pub fn values(&self) -> Vec<Vec<Value>> {
+        match &self.inner {
+            Statement::Insert { source, .. } => match &source.body {
+                SetExpr::Values(Values(values)) => values
+                    .iter()
+                    .map(|v| {
+                        v.iter()
+                            .map(|expr| match expr {
+                                Expr::Value(v) => v.clone(),
+                                Expr::Identifier(ident) => {
+                                    Value::SingleQuotedString(ident.value.clone())
+                                }
+                                _ => unreachable!(),
+                            })
+                            .collect::<Vec<Value>>()
+                    })
+                    .collect(),
+                _ => unreachable!(),
+            },
+            _ => unreachable!(),
+        }
+    }
+}
+
 impl TryFrom<Statement> for Insert {
     type Error = ParserError;