nushell/crates/nu-protocol/src/value/custom_value.rs

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2021-11-29 07:50:57 +01:00
use std::{cmp::Ordering, fmt};
use crate::{ast::Operator, Category, ShellError, Span, Value};
// Trait definition for a custom value
#[typetag::serde(tag = "type")]
pub trait CustomValue: fmt::Debug + Send + Sync {
fn clone_value(&self, span: Span) -> Value;
fn category(&self) -> Category;
// Define string representation of the custom value
fn value_string(&self) -> String;
// Converts the custom value to a base nushell value
// This is used to represent the custom value using the table representations
// That already exist in nushell
fn to_base_value(&self, span: Span) -> Result<Value, ShellError>;
// Json representation of custom value
fn to_json(&self) -> nu_json::Value {
nu_json::Value::Null
}
// Any representation used to downcast object to its original type
fn as_any(&self) -> &dyn std::any::Any;
// Follow cell path functions
fn follow_path_int(&self, count: usize, span: Span) -> Result<Value, ShellError>;
fn follow_path_string(&self, column_name: String, span: Span) -> Result<Value, ShellError>;
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// ordering with other value
fn partial_cmp(&self, _other: &Value) -> Option<Ordering> {
None
}
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// Definition of an operation between the object that implements the trait
// and another Value.
// The Operator enum is used to indicate the expected operation
fn operation(
&self,
_lhs_span: Span,
operator: Operator,
op: Span,
_right: &Value,
) -> Result<Value, ShellError> {
Err(ShellError::UnsupportedOperator(operator, op))
}
}