Add a new 'names.reserved' check (#22)

This checks allows you to extend the default list of reserved keywords
with additional names.

README.md

@@ -130,6 +130,20 @@ Some languages (e.g. JavaScript) don't support 64-bit integers.
 
 This check ensures that only primitive types are used for `map<>` keys.
 
+### `names.reserved`
+
+This checks allows you to extend the [default list of reserved keywords][] with
+additional disallowed names.
+
+```toml
+[checks.names]
+reserved = [
+	"template",
+]
+```
+
+[default list of reserved keywords]: https://github.com/thriftrw/thriftrw-go/blob/0cee03e01be6bbbd45303ca94663c951f0573fd0/idl/internal/lex.rl#L110-L218
+
 ### `namespace.patterns`
 
 This check ensures that a namespace's name matches a regular expression

ast.go

@@ -57,6 +57,16 @@ func Doc(node ast.Node) string {
 	return ""
 }
 
+// Name returns an ast.Node's Name string.
+func Name(node ast.Node) string {
+	if v := reflect.ValueOf(node); v.Kind() == reflect.Ptr {
+		if f := v.Elem().FieldByName("Name"); f.IsValid() {
+			return f.Interface().(string)
+		}
+	}
+	return ""
+}
+
 // Resolve resolves an ast.TypeReference to its target node.
 //
 // The target can either be in the current program's scope or it can refer to

checks/names.go

@@ -0,0 +1,34 @@
+// Copyright 2021 Pinterest
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package checks
+
+import (
+	"github.com/pinterest/thriftcheck"
+	"go.uber.org/thriftrw/ast"
+)
+
+// CheckNamesReserved checks if a node's name is in the list of reserved names.
+func CheckNamesReserved(names []string) *thriftcheck.Check {
+	reserved := make(map[string]bool)
+	for _, name := range names {
+		reserved[name] = true
+	}
+
+	return thriftcheck.NewCheck("names.reserved", func(c *thriftcheck.C, n ast.Node) {
+		if name := thriftcheck.Name(n); name != "" && reserved[name] {
+			c.Errorf(n, "%q is a reserved name", name)
+		}
+	})
+}

checks/names_test.go

@@ -0,0 +1,50 @@
+// Copyright 2021 Pinterest
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package checks_test
+
+import (
+	"testing"
+
+	"github.com/pinterest/thriftcheck/checks"
+	"go.uber.org/thriftrw/ast"
+)
+
+func TestCheckNamesReserved(t *testing.T) {
+	tests := []Test{
+		{
+			node: &ast.Struct{Name: "struct"},
+			want: []string{},
+		},
+		{
+			node: &ast.Struct{Name: "reserved"},
+			want: []string{
+				`t.thrift:0:1:error: "reserved" is a reserved name (names.reserved)`,
+			},
+		},
+		{
+			node: &ast.Field{Name: "field"},
+			want: []string{},
+		},
+		{
+			node: &ast.Field{Name: "reserved"},
+			want: []string{
+				`t.thrift:0:1:error: "reserved" is a reserved name (names.reserved)`,
+			},
+		},
+	}
+
+	check := checks.CheckNamesReserved([]string{"reserved"})
+	RunTests(t, check, tests)
+}

cmd/example.toml

@@ -6,7 +6,7 @@
 # Note that if  any -I options are specified on the command line, they will
 # be used instead of this configuration value.
 includes = [
-    'shared',
+    "shared",
 ]
 
 # Lists of checks to explicitly enable or disable. If a prefix is given (e.g.
@@ -26,6 +26,11 @@ error = 1000
 [[checks.include.restricted]]
 "*" = "(huge|massive).thrift"
 
+[checks.names]
+reserved = [
+    "template",
+]
+
 [checks.namespace]
 [[checks.namespace.patterns]]
 py = "^idl\\."

cmd/main.go

@@ -46,6 +46,10 @@ type Config struct {
 			Restricted map[string]string `fig:"restricted"`
 		}
 
+		Names struct {
+			Reserved []string `fig:"reserved"`
+		}
+
 		Namespace struct {
 			Patterns map[string]string `fig:"patterns"`
 		}
@@ -151,6 +155,7 @@ func main() {
 		checks.CheckIncludeRestricted(cfg.Checks.Include.Restricted),
 		checks.CheckInteger64bit(),
 		checks.CheckMapKeyType(),
+		checks.CheckNamesReserved(cfg.Checks.Names.Reserved),
 		checks.CheckNamespacePattern(cfg.Checks.Namespace.Patterns),
 		checks.CheckSetValueType(),
 	}