Add _operator module

Author: coolreader18

vm/src/stdlib/mod.rs

@@ -16,6 +16,7 @@ mod json;
 mod keyword;
 mod marshal;
 mod math;
+mod operator;
 mod platform;
 mod pystruct;
 mod random;
@@ -74,6 +75,7 @@ pub fn get_module_inits() -> HashMap<String, StdlibInitFunc> {
         "json".to_string() => Box::new(json::make_module),
         "marshal".to_string() => Box::new(marshal::make_module),
         "math".to_string() => Box::new(math::make_module),
+        "_operator".to_string() => Box::new(operator::make_module),
         "platform".to_string() => Box::new(platform::make_module),
         "regex_crate".to_string() => Box::new(re::make_module),
         "random".to_string() => Box::new(random::make_module),

vm/src/stdlib/operator.rs

@@ -0,0 +1,24 @@
+use crate::function::OptionalArg;
+use crate::obj::{objiter, objtype};
+use crate::pyobject::{PyObjectRef, PyResult, TypeProtocol};
+use crate::VirtualMachine;
+
+fn operator_length_hint(obj: PyObjectRef, default: OptionalArg, vm: &VirtualMachine) -> PyResult {
+    let default = default.unwrap_or_else(|| vm.new_int(0));
+    if !objtype::isinstance(&default, &vm.ctx.types.int_type) {
+        return Err(vm.new_type_error(format!(
+            "'{}' type cannot be interpreted as an integer",
+            default.class().name
+        )));
+    }
+    let hint = objiter::length_hint(vm, obj)?
+        .map(|i| vm.new_int(i))
+        .unwrap_or(default);
+    Ok(hint)
+}
+
+pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
+    py_module!(vm, "_operator", {
+        "length_hint" => vm.ctx.new_rustfunc(operator_length_hint),
+    })
+}