encoding: publicly expose identifier.{MIB,Interface}

encoding/ianaindex/ianaindex.go

@@ -104,6 +104,15 @@ func (x *Index) Name(e encoding.Encoding) (string, error) {
 	return x.names(v), nil
 }
 
+// FindMIB searches encoding by MIBenum identifier
+func (x *Index) FindMIB(mib identifier.MIB) (encoding.Encoding, error) {
+	v := findMIB(x.toMIB, mib)
+	if v == -1 {
+		return nil, errUnsupported
+	}
+	return x.enc[v], nil
+}
+
 // TODO: the coverage of this index is rather spotty. Allowing users to set
 // encodings would allow:
 // - users to increase coverage

encoding/ianaindex/ianaindex_test.go

@@ -105,6 +105,21 @@ func TestEncoding(t *testing.T) {
 		if got, err := tc.index.Name(enc); got != tc.canonical {
 			t.Errorf("%d: Name(Encoding(%q)) = %q; want %q (%v)", i, tc.name, got, tc.canonical, err)
 		}
+
+		id, ok := enc.(identifier.Interface)
+		if !ok {
+			t.Errorf("%d: encoding %q has no ID", i, tc.name)
+		}
+		mib, _ := id.ID()
+		if mib == 0 {
+			t.Errorf("%d: encoding %q returned 0 MIB enum", i, tc.name)
+		}
+		mibEnc, err := tc.index.FindMIB(mib)
+		if err != nil {
+			t.Errorf("%d: FindMIB error %q", i, err)
+		} else if mibEnc != enc {
+			t.Errorf("%d: FindMIB did not match encoding", i)
+		}
 	}
 }
 

encoding/identifier/identifier.go

@@ -0,0 +1,79 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package identifier defines the contract between implementations of Encoding
+// and Index by defining identifiers that uniquely identify standardized coded
+// character sets (CCS) and character encoding schemes (CES), which we will
+// together refer to as encodings, for which Encoding implementations provide
+// converters to and from UTF-8. This package is typically only of concern to
+// implementers of Indexes and Encodings.
+//
+// One part of the identifier is the MIB code, which is defined by IANA and
+// uniquely identifies a CCS or CES. Each code is associated with data that
+// references authorities, official documentation as well as aliases and MIME
+// names.
+//
+// Not all CESs are covered by the IANA registry. The "other" string that is
+// returned by ID can be used to identify other character sets or versions of
+// existing ones.
+//
+// It is recommended that each package that provides a set of Encodings provide
+// the All and Common variables to reference all supported encodings and
+// commonly used subset. This allows Index implementations to include all
+// available encodings without explicitly referencing or knowing about them.
+package identifier
+
+// Note: this package is internal, but could be made public if there is a need
+// for writing third-party Indexes and Encodings.
+
+// References:
+// - http://source.icu-project.org/repos/icu/icu/trunk/source/data/mappings/convrtrs.txt
+// - http://www.iana.org/assignments/character-sets/character-sets.xhtml
+// - http://www.iana.org/assignments/ianacharset-mib/ianacharset-mib
+// - http://www.ietf.org/rfc/rfc2978.txt
+// - https://www.unicode.org/reports/tr22/
+// - http://www.w3.org/TR/encoding/
+// - https://encoding.spec.whatwg.org/
+// - https://encoding.spec.whatwg.org/encodings.json
+// - https://tools.ietf.org/html/rfc6657#section-5
+
+// Interface can be implemented by Encodings to define the CCS or CES for which
+// it implements conversions.
+type Interface interface {
+	// ID returns an encoding identifier. Exactly one of the mib and other
+	// values should be non-zero.
+	//
+	// In the usual case it is only necessary to indicate the MIB code. The
+	// other string can be used to specify encodings for which there is no MIB,
+	// such as "x-mac-dingbat".
+	//
+	// The other string may only contain the characters a-z, A-Z, 0-9, - and _.
+	ID() (mib MIB, other string)
+
+	// NOTE: the restrictions on the encoding are to allow extending the syntax
+	// with additional information such as versions, vendors and other variants.
+}
+
+// A MIB identifies an encoding. It is derived from the IANA MIB codes and adds
+// some identifiers for some encodings that are not covered by the IANA
+// standard.
+//
+// See http://www.iana.org/assignments/ianacharset-mib.
+type MIB uint16
+
+// These additional MIB types are not defined in IANA. They are added because
+// they are common and defined within the text repo.
+const (
+	// Unofficial marks the start of encodings not registered by IANA.
+	Unofficial MIB = 10000 + iota
+
+	// Replacement is the WhatWG replacement encoding.
+	Replacement
+
+	// XUserDefined is the code for x-user-defined.
+	XUserDefined
+
+	// MacintoshCyrillic is the code for x-mac-cyrillic.
+	MacintoshCyrillic
+)

encoding/internal/identifier/identifier.go

@@ -4,78 +4,17 @@
 
 //go:generate go run gen.go
 
-// Package identifier defines the contract between implementations of Encoding
-// and Index by defining identifiers that uniquely identify standardized coded
-// character sets (CCS) and character encoding schemes (CES), which we will
-// together refer to as encodings, for which Encoding implementations provide
-// converters to and from UTF-8. This package is typically only of concern to
-// implementers of Indexes and Encodings.
-//
-// One part of the identifier is the MIB code, which is defined by IANA and
-// uniquely identifies a CCS or CES. Each code is associated with data that
-// references authorities, official documentation as well as aliases and MIME
-// names.
-//
-// Not all CESs are covered by the IANA registry. The "other" string that is
-// returned by ID can be used to identify other character sets or versions of
-// existing ones.
-//
-// It is recommended that each package that provides a set of Encodings provide
-// the All and Common variables to reference all supported encodings and
-// commonly used subset. This allows Index implementations to include all
-// available encodings without explicitly referencing or knowing about them.
 package identifier
 
-// Note: this package is internal, but could be made public if there is a need
-// for writing third-party Indexes and Encodings.
-
-// References:
-// - http://source.icu-project.org/repos/icu/icu/trunk/source/data/mappings/convrtrs.txt
-// - http://www.iana.org/assignments/character-sets/character-sets.xhtml
-// - http://www.iana.org/assignments/ianacharset-mib/ianacharset-mib
-// - http://www.ietf.org/rfc/rfc2978.txt
-// - https://www.unicode.org/reports/tr22/
-// - http://www.w3.org/TR/encoding/
-// - https://encoding.spec.whatwg.org/
-// - https://encoding.spec.whatwg.org/encodings.json
-// - https://tools.ietf.org/html/rfc6657#section-5
-
-// Interface can be implemented by Encodings to define the CCS or CES for which
-// it implements conversions.
-type Interface interface {
-	// ID returns an encoding identifier. Exactly one of the mib and other
-	// values should be non-zero.
-	//
-	// In the usual case it is only necessary to indicate the MIB code. The
-	// other string can be used to specify encodings for which there is no MIB,
-	// such as "x-mac-dingbat".
-	//
-	// The other string may only contain the characters a-z, A-Z, 0-9, - and _.
-	ID() (mib MIB, other string)
-
-	// NOTE: the restrictions on the encoding are to allow extending the syntax
-	// with additional information such as versions, vendors and other variants.
-}
-
-// A MIB identifies an encoding. It is derived from the IANA MIB codes and adds
-// some identifiers for some encodings that are not covered by the IANA
-// standard.
-//
-// See http://www.iana.org/assignments/ianacharset-mib.
-type MIB uint16
-
-// These additional MIB types are not defined in IANA. They are added because
-// they are common and defined within the text repo.
-const (
-	// Unofficial marks the start of encodings not registered by IANA.
-	Unofficial MIB = 10000 + iota
+import (
+	"golang.org/x/text/encoding/identifier"
+)
 
-	// Replacement is the WhatWG replacement encoding.
-	Replacement
+var Replacement = identifier.Replacement
 
-	// XUserDefined is the code for x-user-defined.
-	XUserDefined
+type Interface = identifier.Interface
+type MIB = identifier.MIB
 
-	// MacintoshCyrillic is the code for x-mac-cyrillic.
-	MacintoshCyrillic
-)
+var Unofficial = identifier.Unofficial
+var MacintoshCyrillic = identifier.MacintoshCyrillic
+var XUserDefined = identifier.XUserDefined