Add end_plugin and sum

src/plugins/sum.rs

@@ -0,0 +1,99 @@
+use indexmap::IndexMap;
+use nu::{
+    serve_plugin, CallInfo, CommandConfig, Plugin, Primitive, ReturnSuccess, ReturnValue,
+    ShellError, Spanned, Value,
+};
+
+struct Sum {
+    total: Option<Spanned<Value>>,
+}
+impl Sum {
+    fn new() -> Sum {
+        Sum { total: None }
+    }
+
+    fn sum(&mut self, value: Spanned<Value>) -> Result<(), ShellError> {
+        match value.item {
+            Value::Primitive(Primitive::Int(i)) => {
+                match self.total {
+                    Some(Spanned {
+                        item: Value::Primitive(Primitive::Int(j)),
+                        span,
+                    }) => {
+                        //TODO: handle overflow
+                        self.total = Some(Spanned {
+                            item: Value::int(i + j),
+                            span,
+                        });
+                        Ok(())
+                    }
+                    None => {
+                        self.total = Some(value);
+                        Ok(())
+                    }
+                    _ => Err(ShellError::string(format!(
+                        "Could not sum non-integer or unrelated types"
+                    ))),
+                }
+            }
+            Value::Primitive(Primitive::Bytes(b)) => {
+                match self.total {
+                    Some(Spanned {
+                        item: Value::Primitive(Primitive::Bytes(j)),
+                        span,
+                    }) => {
+                        //TODO: handle overflow
+                        self.total = Some(Spanned {
+                            item: Value::bytes(b + j),
+                            span,
+                        });
+                        Ok(())
+                    }
+                    None => {
+                        self.total = Some(value);
+                        Ok(())
+                    }
+                    _ => Err(ShellError::string(format!(
+                        "Could not sum non-integer or unrelated types"
+                    ))),
+                }
+            }
+            x => Err(ShellError::string(format!(
+                "Unrecognized type in stream: {:?}",
+                x
+            ))),
+        }
+    }
+}
+
+impl Plugin for Sum {
+    fn config(&mut self) -> Result<CommandConfig, ShellError> {
+        Ok(CommandConfig {
+            name: "sum".to_string(),
+            positional: vec![],
+            is_filter: true,
+            is_sink: false,
+            named: IndexMap::new(),
+            rest_positional: true,
+        })
+    }
+    fn begin_filter(&mut self, _: CallInfo) -> Result<(), ShellError> {
+        Ok(())
+    }
+
+    fn filter(&mut self, input: Spanned<Value>) -> Result<Vec<ReturnValue>, ShellError> {
+        self.sum(input)?;
+        Ok(vec![])
+    }
+
+    fn end_filter(&mut self) -> Result<Vec<ReturnValue>, ShellError> {
+        match self.total {
+            None => Ok(vec![]),
+            Some(ref v) => Ok(vec![ReturnSuccess::value(v.clone())]),
+        }
+    }
+}
+
+fn main() {
+    serve_plugin(&mut Sum::new());
+}