Add format builtin and String formatting stuff.

This includes everything needed to call str.format with integers
as positional and keyword parameters.

Author: johndaniels

tests/snippets/builtin_format.py

@@ -0,0 +1,8 @@
+assert format(5, "b") == "101"
+
+try:
+	format(2, 3)
+except TypeError:
+    pass
+else:
+    assert False, "TypeError not raised when format is called with a number"

tests/snippets/strings.py

@@ -40,3 +40,9 @@
 
 c = 'hallo'
 assert c.capitalize() == 'Hallo'
+
+# String Formatting
+assert "{} {}".format(1,2) == "1 2"
+assert "{0} {1}".format(2,3) == "2 3"
+assert "--{:s>4}--".format(1) == "--sss1--"
+assert "{keyword} {0}".format(1, keyword=2) == "2 1"

vm/src/builtins.rs

@@ -317,7 +317,15 @@ fn builtin_filter(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     Ok(vm.ctx.new_list(new_items))
 }
 
-// builtin_format
+fn builtin_format(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(
+        vm,
+        args,
+        required = [(obj, None), (format_spec, Some(vm.ctx.str_type()))]
+    );
+
+    vm.call_method(obj, "__format__", vec![format_spec.clone()])
+}
 
 fn builtin_getattr(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(
@@ -756,6 +764,7 @@ pub fn make_module(ctx: &PyContext) -> PyObjectRef {
     ctx.set_attr(&py_mod, "float", ctx.float_type());
     ctx.set_attr(&py_mod, "frozenset", ctx.frozenset_type());
     ctx.set_attr(&py_mod, "filter", ctx.new_rustfunc(builtin_filter));
+    ctx.set_attr(&py_mod, "format", ctx.new_rustfunc(builtin_format));
     ctx.set_attr(&py_mod, "getattr", ctx.new_rustfunc(builtin_getattr));
     ctx.set_attr(&py_mod, "hasattr", ctx.new_rustfunc(builtin_hasattr));
     ctx.set_attr(&py_mod, "hash", ctx.new_rustfunc(builtin_hash));

vm/src/exceptions.rs

@@ -86,6 +86,8 @@ pub struct ExceptionZoo {
     pub syntax_error: PyObjectRef,
     pub assertion_error: PyObjectRef,
     pub attribute_error: PyObjectRef,
+    pub index_error: PyObjectRef,
+    pub key_error: PyObjectRef,
     pub name_error: PyObjectRef,
     pub runtime_error: PyObjectRef,
     pub not_implemented_error: PyObjectRef,
@@ -129,6 +131,18 @@ impl ExceptionZoo {
             &exception_type.clone(),
             &dict_type,
         );
+        let index_error = create_type(
+            &String::from("IndexError"),
+            &type_type,
+            &exception_type.clone(),
+            &dict_type,
+        );
+        let key_error = create_type(
+            &String::from("KeyError"),
+            &type_type,
+            &exception_type.clone(),
+            &dict_type,
+        );
         let name_error = create_type(
             &String::from("NameError"),
             &type_type,
@@ -184,6 +198,8 @@ impl ExceptionZoo {
             syntax_error: syntax_error,
             assertion_error: assertion_error,
             attribute_error: attribute_error,
+            index_error: index_error,
+            key_error: key_error,
             name_error: name_error,
             runtime_error: runtime_error,
             not_implemented_error: not_implemented_error,